NORDA S!eport"3 Tlie Taxonomy and Distribution of La,ntemfislies {Family Viyctophidae) of the Eastern Pacific Ocean ^— ^ m ^' >u NORDA Report-3 The Taxonomy and Distribution of Lanternfishes (Family Myctophidae) of the Eastern Pacific Ocean Robert L. Wisner University of Californiu, San Die^o Scripps Institution of Oceanography NAVY OCEAN RESEARCH AND DEVELOPMENT ACTIVITY Bay St. Louis, Mississippi For sale by the Superintendent of Documenla, US Government Printing OfTice. Washington, DC. 20402 - Price $6.30 Stock No 008-042-00067-5 PREFACE This study of the lanternfishes (family Myctophidae) of the eastern Pacific Ocean is in- tended to meet the need for one pubhcation in which the available information on their taxonomy, distribution, variation, and natural history (the latter information is meager ) can be found. It also provides keys to their identification. The study is admittedly a preliminary effort. It is also necessarily incomplete in regard to some genera, notably Diaphus and Gymnoscopelus. Further collection in the far southern and central Pacific and comparison with worldwide collections are needed before a definitive work on these two genera is accomplished. Similarly, the short-pectoral-fin species group of the genus Lampanyctus needs much more study in all oceans. It is hoped that flaws in the keys and data of this work will be remedied by subsequent workers, and that the present effort will be perfected and expanded to include the entire Pacific Ocean, and perhaps all oceans. This book was originally designated to be a technical report of the U.S. Naval Oceano- graphic Office. Intensive work was begun in 1968, and a date in 1970 was set for publication . This markedly later date of appearance is due to delays on my part and to the Oceanographic Office's problems in preparing and scheduling the work for publication. Robert L. Wisner Specialist, Marine Biology (Retired) Scripps Institution of Oceanography May 1, 1974 111 ACKNOWLEDGMENTS This publication was made possible largely by the generous support of the U.S. Naval Oceanographic Office (Contract N62306-67-C-0318), through the Scripps Institution of Oceanography (Carl L. Hubbs, Principal Investigator) during the most intensive part of the investigations (1968). I am most grateful for that support. In particular, I wish to thank Bernard J. Zahuranec and G. Brooke Farquhar, of the Division of Acoustical Oceanography of that Office, for instigating both the study and the initial funding. Particular thanks are also due to the National Science Foundation for support through grants to Carl L. Hubbs during the early and final stages of the work. The following also deserve special thanks. John C. Marr and Richard Shomura, formerly of the National Marine Fisheries Biological Laboratory, Honolulu, gave permission to examine a large series of collections from the central Pacific area. Thomas A. Clarke, Univer- sity of Hawaii, provided specimens and unpublished data on vertical distributions of some species from Hawaiian waters; he and his co-workers offered valuable criticism of some keys to identification. C. Karrer, Zoologisches Museum, Berlin, provided type material of Diaphus fulgens. G. E. Maul, Museo Municipal do Funchal, Madeira, and Jorgen Nielsen, Univer- sitetets Zoologiske Museum, Copenhagen, have kindly lent specimens from the Atlantic Ocean for comparative studies. Dr. Nielsen made available a large unstudied collection of lanternfishes made by several Danish expeditions, principally the Galathea. Dr. P. A. Hulley, South African Museum, Cape Town, kindly permitted me to retain for study a large collection of lanternfishes taken in waters surrounding the tip of South Africa. The latter specimens and those of the Danish expeditions have been of great value as comparative material. I also wish to thank Drs. E. H. Ahlstrom and G. H. Moser, and their coworkers at the National Marine Fisheries Service, Southwest Fisheries Center, La Jolla, California, for specimens, many discussions, and much testing of the various keys to identification. Michael Barnett has also tested many of the keys during preparation of his doctoral dissertation; his criticisms and suggestions are greatly appreciated. Bernard J. Zahuranec contributed generously of his time and effort in guiding the manu- script through the technical details of Government publication. I am grateful to Betty N. Shor for her very considerable efforts in typing the original manuscript. Charmion B. McMillan typed and gave valuable help In proofreading the final manuscript. Carl L. Hubbs kindly gave advice on nomenclature. Lastly, I am most grateful to the late Rolf L. Bolin, who, upon his retirement from active ichthyological work, very kindly presented to me his valuable files of notes and illustrations of type specimens, and of microfilms of old and difficult-to-obtain literature, compiled during his studies of type material of myctophid fishes in the various museums of the world. I have presented these to Dr. Basil G. Nafpaktitis, University of Southern California, Los Angeles. CONTENTS Preface iii Acknowledgments v Introduction 1 Methods 4 LIST OF GENERA AND SPECIES 6 KEY TO GENERA OF FAMILY MYCTOPHIDAE 10 DISCUSSION OF GENERA AND SPECIES 13 Protomyctophum Fraser-Brunner, 1949 13 Electrona Goode and Bean, 1896 27 Metelectrona Wisner, 1963 31 Hygophum Taning (In: Bolin, 1939) 32 Benthosema Goode and Bean, 1896 40 Diogenichthys Bolin, 1939 46 Symbolophorus Bolin and Wisner (In: Bolin, 1959) 48 Myctophum Rafinesque, 1810 53 Loweina Fowler, 1925 70 Tarletonbeania Eigenmann and Eigenmann, 1890 81 Gonichthys Gistel, 1850 83 Centrobranchus Fowler, 1904 87 The Diaphid Fishes 91 Lobianchia Gatti, 1903 93 Diaphus Eigenmann and Eigenmann, 1890 97 Notolychnus Fraser-Brunner, 1949 144 Taaningichthys Bolin, 1959 145 Lampadena Goode and Bean, 1896 149 Dorsadena Coleman and Nafpaktitis, 1972 156 Lampanyctodes Fraser-Brunner, 1949 157 Stenobrachius Eigenmann and Eigenmann, 1890 159 Parvilux Hubbs and Wisner, 1964 162 Triphoturus Fraser-Brunner, 1949 164 Lampanyctus Bonaparte, 1840 167 Bolinichthys Paxton, 1972 198 Ceratoscopelus Giinther, 1864 205 Gymnoscopelus Giinther, 1873 209 Lampichthys Fraser-Brunner, 1949 214 Notoscopelus Giinther, 1864 215 Hintonia Fraser-Brunner, 1949 217 Scopelopsis Brauer, 1906 221 References 224 vu INTRODUCTION This account of the taxonomy and distribution of the lanternfishes (family Myctophidae) is intended to include species that are known, or may reasonably be expected, to occur in the eastern Pacific Ocean, the Polar regions, and eastward of 16(]f longitude. This westward limit was imposed because of the paucity of collections from west of the Hawaiian Islands and also to avoid the high probability of encountering the poorly understood myctophid fauna of the Indo-Pacific region. Indeed, some species of that fauna were found in both the central and eastern Pacific sectors. Even in this restricted area, a total of 31 genera (all those currently recognized in the family) and nearly 150 species are recognized as occurring. Some questionable species in the genera Diaphus and Symbolophorus may later be described as new. Such action is withheld at this time because knowledge of these fishes in the eastern and central Pacific area is incom- plete. Also, several of the questionable species appear to be related to forms from the South Atlantic and Indian Oceans. Further comparative studies will be necessary before firm conclu- sions are warranted. Prior to this work, few keys to myctophid fishes of the eastern Pacific have encompassed wide ranges of genera or species, and most have been constructed for use in rather restricted areas. This is the first attempt at a key for the entii e area and for so many genera and species. A task of this magnitude could not be accomplished without substantial reliance on existing literature. I have drawn heavily from Andriashe v's ( 1962 ) work on Antarctic myctophids for information on poorly known southern forms of the genera Gymnoscopelus and Protomyc- tophum, and on Becker's ( 1963) study of the latter genus, because of a lack of available study material. Also, as the genus Lampadena is poorly represented in the eastern Pacific, and in available study material, I have used keys, illustrations, and data from Nafpaktitis and Pax- ton (1968). I have used illustrations of other authors when I felt that redrawing would yield no significant improvement or when inadequate material left me no choice. I have restricted my investigation to adults and subadults, because during the earlier part of the study information on larval stages of myctophid fishes of the eastern Pacific was scant. For such information I refer the reader to the recent works of Moser and Ahlstrom ( 1970, 1972, and 1974). These authors are now completing a study on larval forms of lampanyctid species. At present, the myctophid fauna from far southern waters of the eastern Pacific are poorly understood, and until very recently the central Pacific area was inadequately collected. Much of the early literature is inadequate or incorrect, particularly that regarding far southern fauna of the Electronini and the genus Gymnoscopelus . Most problems with these genera stem from a lack of specimens. In the near future, some of these difficulties may be resolved by study of collections gathered by cruises of the USNS Eltanin in far southern waters and now under investigation. Although almost all species treated here are known to occur in the eastern Pacific Ocean, a few from other oceans are included, either because of questionable identification or because they are essential to a discussion of species that do occur in the western Pacific. This is particularly true of the genus Loweina; understanding the total problem requires extended discussion of early systematics and the designation and detailed description of lectotypes for two species known mainly from the Atlantic and Indian Oceans, L. rara and L. interrupta. A similar situation involves the species Myctophum selenoides from the Atlantic Ocean; type material of the Atlantic form is not discussed in detail. Unfortunately, there is little information on the exact depths inhabited by most midwater fishes in the eastern Pacific Ocean; the vast majority of captures have been made with nets that fished open at all times, many fishing from the surface to 1000 m or more. (This range certainly contains most myctophid fishes.) Thus, the depths of capture given in this work are often necessarily imprecise. Also, many of the depths listed for earlier collections, particularly for the Isaacs-Kidd Midwater Trawl (IKMT), were derived from calculations based on wire angles measured at the surface (Clarke, 1963). The resulting depths range from near-surface to 4000 m or more, with the net fishing open at all times. Such records are uninformative of depths actually inhabited by a species, even if the maximum depths calculated are correct. Occasional captures with the opening-closing, paired zooplankton net (Bongo-net, McGowan and Brown, 1966) have given more precise information. However, this net has a much smaller mouth opening and requires a much slower towing speed than the IKMT, and captures consist mostly of the smaller specimens. In this report it is to be assumed, unless otherwise stated, that captures were made with nets that fished open at all times. Depths of capture are thus simply given as "To .... m" or "O ... . m". If known, it is stated whether captures were in daylight or darkness. Data refer only to adults or young adults. Some information on the approximate levels inhabited by lanternfishes in the eastern Pacific Ocean is offered by Paxton ( 1967 ) and Pearcy ( 1964). Paxton sampled to about 900 m in the San Pedro Basin, southern California, and Pearcy mostly to 200 m, with a few trawls to 1000 m. Unfortunately, both studies were made with nonclosing nets, and both areas have a rather sparse myctophid fauna. The only major sampling effort with opening-closing trawls was made in the Atlantic Ocean near Bermuda, during the Ocean Acre Project. Gibbs, Goodyear, Keene, and Brown ( 1971 ) provide capture data for 52 species of lanternfishes collected with discrete-depth sampl- ing gear. The distribution charts are based mainly on material in the Marine Vertebrate Collection of the Scripps Institution of Oceanography. This is particularly true for species that are poorly known or easily confused with related forms. Distributional data from recent revisions have been accepted and credited to the authors. Discussions of zoogeography are offered only in individual species accounts rather than in one formally designated section. Detailed discussions on this aspect of myctophid fishes of the Pacific Ocean have been presented by various Russian ichthyologists, principally Andriashev (1962), Parin (1968), and Becker ( 1964b). The extensions of range of several species of the genus Diaphus, known previously only from the western Pacific and the Indo-Pacific areas, are reported for the first time; most of these new occurrences appear to be confined to tropical and subtropical regions of the central Pacific. In some instances too few collections were available to permit firm zoogeographical statements, or too few specimens to permit adequate assessment of specific relationships. Perhaps the most interesting finding was the absence of certain species from a wide area of the extreme eastern Pacific between Baja California and central Chile. Some species were absent throughout this broad area but others from only the northern sector. These absences were evident only for species that are numerous around the periphery of the area but were not taken there despite considerable collecting effort. Thus far involved are the species Diogenichthys atlanticus, Myctophum nitidulum, the four species of Centrobranchus, BoUnkhthys photothorax and B. longipes. The reasons for these absences are not clear, and a solution or detailed discussion of the problem is beyond the scope of this publication. However, I am inclined to believe that the absences are related to the layer of oxygen-deficient water (containing 1.0 milliliter or less of oxygen per liter of water, ml/1) underlying a large part of the east-central Pacific Ocean, from about central Baja California to central Chile and extending in a narrowing wedge into the central tropical region. Austin ( 1960) delineated this oxygen minimum in the central area, to 170° W, and Wyrtki (1967) presented a detailed analysis for the eastern area. Wyrtki placed the upper limit of the layer at depths ranging from 50 to 500 m and showed the thickness of the layer to vary from 200 to 1200 m. This most interesting problem of interrupted distributions in apparent association with the oxygen minimum should be investigated by the use of depth-selective gear in conjunction with synoptic hydrological observations. Concurrent with that investigation, perhaps some- thing could be learned of the ecology and physiology of those species that must certainly spend much of their lives in this oxygen-minimum layer. I have arranged the list of genera and species in alphabetical order mainly for ease in finding the account of a particular species. However, in the text I have followed a phylogenetic arrangement so that illustrations and accounts of related forms could be more juxtaposed than would be possible in a strictly alphabetical order. In general, the phylogeny follows the system proposed by Bolin (1939) and further developed by Fraser-Brunner (1949) — a system based on an ancestor having one or more ventral series of photophores, some of which moved dorsally to form patterns of the modern myctophid while others were presumably lost. I have done so because this study is more concerned with aiding the student in ready identification of species than with following the most recent thought on the phylogeny of lanternfishes. I wish to stress, however, that this action is in no way to be regarded as an intent to ignore or disparage the works of Paxton ( 1972) and of Moser and Ahlstrom (1970, 1972, and 1974), in which the arrangement employed by Fraser-Brunner (1949) was significantly altered. I agree generally with Paxton's division of the family into the subfamilies Myctophinae (tribes Myc- tophini and Gonichthini) and the subfamily Lampanyctinae (tribes Diaphini, Notolychnini, Lampanyctini, and Gymnoscopelini). Nor have I any quarrel with Moser and Ahlstrom (1974), who, although in essential agreement with Paxton's suprageneric categories, formulated a somewhat different arrangement based on the sequence of appearance of certain photophores in developing larvae. Also, I readily accept the proposal by Moser and Ahlstrom (1972) to consider the species Scopelopsis multipunctatus Brauer ( 1906), a species with minute photophores on each scale pocket of head and body, as representing the ancestral form. These authors stated (p. 562): "Whatever were the adaptive forces that marshalled the light organs of myctophids into specific patterns, we believe that the ancestral myctophids had unspecialized photophores distributed over the head and body (one at the margin of each scale pocket) and that the specific patterns were derived by enhancement of some photophores and the concomitant deletion of others." These authors stated further (p. 563): "Such a mechanism for the evolution of photophore pattern seems much less cumbersome than the theory of upward migration of photophores from the ventral series." Most certainly, as the knowledge of these fishes advances, the traditional phylogeny followed here must give way to a more coherent one encompassing larval development, general morphology, physiology, and ecology, as well as taxonomy. METHODS Except as noted, methods of measuring and counting followed those suggested by Hubbs and Lagler (1947). All measurements were made with dial calipers and recorded to the nearest tenth of a millimeter. All lengths refer to standard length unless otherwise stated. The count of dorsal and anal fin rays did not include the anteriormost, often difficult to perceive, small ray; the last ray of these fins was bifurcate to the base and was counted as one. The tiny, often nearly invisible lower rays of the pectoral fins were counted while immersed in water. Only the principal gill rakers were counted (on the upper and lower limbs of the outer arch only), except for the genus Gonichthys, in which the rakers became progressively shorter on the lower limb without the usual sudden decrease in size (to "nubs") anteriorly. Both sides were counted for pectoral rays and for anal ( AO) photophores. Also, if only a few specimens were available, both sides were counted for gill rakers. In the tabular data on numbers of gill rakers, the central raker (at the juncture of the upper and lower limbs) was included in the count for lower rakers. The depth of head was measured vertically through the end of the upper jaw, rather than vertically from the occiput. The distance the upper jaw extended beyond the orbit was derived by subtracting from the length of the upper jaw the distance from the tip of the upper jaw to the posteriormost margin of the orbit. The remainder was calculated as percent of upper jaw extending behind the orbit. This method yields a more precise value than the commonly used visual determination of a vertical from the rear margin of the orbit to the upper jaw, or a perpendicular from upper jaw to there. All measures of distance from tip of snout (upper jaw) to fins were made to origins of the fins, except for the adipose fin; in this case the end of the base of the fin, rather than the origin, was used as it afforded a more precise point than the often difficult to perceive (and often arbitrarily selected) origin of the gently rising "ramp" of this base. Thus, the values for "preadipose length" given in the various tables may be slightly greater than those given by other authors. Unless otherwise stated, all values for body proportions, given in the various tables, are expressed as thousandths of standard length. The location and terminology of the photophores and other luminous organs of head and body used in the identification of myctophid fishes are shown in Figs. 1, 78, and 84. In general. Vn So Bu Op PLO Supracaudal Gland AOp \ Pre Infracaudal Gland AOa Fig. 1— Diagram of a myctophid fish showing the location and terminology of commonly occurring photophores. No one species will bear all the photophores shown. only the symbol, e.g., SAO, is used, rather than a name, to denote a group of photophores or a single one, or other organs, but for convenience to the reader the following list of symbols and their commonly accepted names is offered (some alternate names are suggested): Names of Luminous Organs Symbol Commonly used names Ant Antorbital Dn Dorsonasal Vn Ventronasal So Suborbital Suo Supraorbital Br Branchiostegal Bu Buccal Ce Cervical Op Opercular PLO Suprapectoral organ PVO Subpectoral organ PO Thoracic VLO Supraventral VO Ventral organs SAO Supralateral AO Anal organs (when in unbroken series) AOa Anal organs, anterior AOp Anal organs, posterior Suggested alternate names Pectorolateral organ Pectoroventral organ Ventrolateral organ Supraanal organs LIST OF GENERA AND SPECIES An alphabetically arranged list of the genera and species of myctophid fishes recognized as occurring, or possibly occuring, in the eastern Pacific Ocean between the polar regions and 16CP longitude; others, not known to occur in this area, are included for purposes of information and comparison, and for convenience to the student. ){ Benthosema Goode and Bean, 1896 40 fibulatum (Gilbert and Cramer, 1897) 42 glaciale (Reinhardt, 1837) 40 panamense (Taning, 1932) 43 suborbitale (Gilbert, 1913) 41 Bolinichthys Paxton, 1972 198 longipes (Brauer, 1906) 204 photothorax (Parr, 1928) 202 supralateralis (Parr, 1928) 200 Centrobranch us Fowler, 1904 87 andreae (Liitken, 1892) 87 brevirostris Becker, 1964 • 89 choerocephalus Fowler, 1904 91 nigroocellatus (Giinter, 1873) 90 Ceratoscopelus Giinther, 1864 205 townsendi (Eigenmann and Eigenmann, 1889) 206 warmingii (Liitken, 1892) 206 X Diaphus Eigenmann and Eigenmann, 1890 97 adenomus Gilbert, 1905 118 anderseni Taning, 1932 143 brachycephalus Taning, 1928 121 chrysorhynchus Gilbert and Cramer, 1897 118 coeruleus (Klunzinger, 1871) 117 diadematus Taning, 1932 107 ? dumerilii (Bleeker, 1856) 102 elucens (Brauer, 1904) 121 fragilis Taning, 1928 116 ? fulgens (Brauer, 1904) (A Species Complex) 125 garmani Gilbert, 1906 109 gigas Gilbert, 1913 120 jenseni Taning, 1932 112 ? longleyi Fowler, 1934 139 lucidus (Goode and Bean, 1896) 115 luetkeni (Brauer, 1904) 107 malayanus Weber, 1913 113 metopoclampus (Cocco, 1829) 124 mollis Taning, 1928 129 ostenfeldi Taning, 1932 123 pacificus Parr, 1931 114 problematic us Parr, 1928 109 regani Taning, 1932 112 6 richardsoni Taning, 1932 143 rolfbolini Wisner, 1971 122 schmidti Taning, 1932 Ill signatus Gilbert, 1908 115 similis Wisner, 1974 105 splendidus (Brauer, 1904) Ill termophilus Taning, 1928 103 theta Eigenmann and Eigenmann, 1890 (A Species Complex) 140 trachops Wisner, 1974 106 Dwgenichthys Bolin, 1939 46 atlanticus (Taning, 1928) 48 laternatus (Garman, 1899) 46 Dorsadena Coleman and Nafpaktitis, 1972 156 yaquinae Coleman and Nafpaktitis, 1972 157 Electrona Goode and Bean, 1896 27 antarctica (Giinther, 1878) 28 carlsbergi (Taning, 1932) 27 paucirastra Bolin (In: Becker, 1963) 29 risso (Cocco, 1829) 30 subaspera (Giinther, 1864) 28 Gonichthys Gistel, 1850 83 barnesi Whitley, 1943 84 cocco (Cocco, 1829) 85 tenuiculus (Garman, 1899) 84 venetus Becker, 1964 85 Gymnoscopelus Giinther, 1873 209 bolini Andriashev, 1962 210 braueri (Lonnberg, 1905) 211 nicholsi (Gilbert, 1911) 210 opisthopterus Fraser-Brunner, 1949 212 Subgenus Nasolychnus Smith, 1933 209 fraseri Fraser-Brunner, 1931 213 piabilis (Whitley, 1931) 213 Hierops Subgenus — See Protomyctophum 18 Hintonia Fraser-Brunner, 1949 217 candens Fraser-Brunner, 1949 217 Hygophum Taning (In: Bolin, 1939) 32 atratum (Garman, 1899) 35 bruuni Wisner, 1971 37 hygomi (Liitken, 1892) 33 proximum Becker, 1965 34 reinhardtii (Liitken, 1892) 36 Lampadena Goode and Bean, 1896 149 anomala Parr, 1928 156 chavesi Collett, 1905 155 dea Fraser-Brunner, 1949 154 luminosa (Garman, 1899) 151 notialis Nafpaktitis and Paxton, 1968 154 speculigera Goode and Bean, 1896 153 urophaos Paxton, 1963 152 Lampanyctodes Fraser-Brunner, 1949 157 hectoris (Giinther, 1876) 158 Lampanyctus Bonaparte, 1840 167 7 acanthurus Wisner, 1974 185 ? achirus Andriashev, 1962 (A Species Complex) 176 australis Taning, 1932 193 fernae Wisner, 1971 172 hubbsi Wisner, 1963 189 idostigma Parr, 1931 174 intricarius Taning, 1928 195 iselinoides Bussing, 1965 194 jordani Gilbert, 1913 190 lepidolychnus Becker, 1967 196 macdonaldi (Goode and Bean, 1896) 198 macropterus (Brauer, 1904) 186 niger (Giinther, 1887) (A Species Complex) 175 nobilis Taning, 1928 186 omostigma Gilbert, 1908 189 parvicauda Parr, 1931 188 pusillus (Johnson, 1890) 194 regalis (Gilbert, 1891) 173 ritteri Gilbert, 1915 170 simulator Wisner, 1971 191 steinbecki Bolin, 1939 181 ? tenuiformis-festivus (A Species Complex) 181 Lampichthys Fraser-Brunner, 1949 214 procerus (Brauer, 1904) 214 Lobianchia Gatti, 1903 93 dofleini (Zugmayer, 1911) 96 gemellarii (Cocco, 1838) 95 urolampa (Gilbert and Cramer, 1897) 94 Loweina Fowler, 1925 70 interrupta (Taning, 1928) 79 laurae Wisner, 1971 71 rara (Liitken, 1892) 78 terminate Becker, 1964 70 Metelectrona Wisner, 1963 31 ahlstromi Wisner, 1963 32 ventralis (Becker, 1963) 31 Myctophum Rafinesque, 1810 53 ? asperum (Richardson, 1844) 61 aurolaternatum Garman, 1899 54 brachygnathum (Bleeker, 1856) 65 nitidulum Garman, 1899 62 obtusirostrum Taning, 1928 65 phengodes (Lutken, 1892) 56 lychnobium Bolin, 1946 58 selenoides Wisner, 1971 66 spinosum (Steindachner, 1867) 59 Nasolychnus Smith, 1933 (A subgenus: See Gymnoscopelus) 209 Notolychnus Fraser-Brunner, 1949 144 valdiviae (Brauer, 1904) 144 Notoscopelus Giinther, 1864 215 resplendens (Richardson, 1844) 215 Parvilux Hubbs and Wisner, 1964 162 boschmai Hubbs and Wisner, 1964 163 8 ingens Hubbs and Wisner, 1964 162 Protomyctophum Fraser-Brunner, 1949 13 Subgenus Protomyctophum Fraser-Brunner, 1949 13 anderssoni (Lonnberg, 1905) 14 andriashevi Becker, 1963 17 bolini (Fraser-Brunner, 1949) 17 normani (Taning, 1932) 16 tenisoni (Norman, 1930) 15 Subgenus Hierops Fraser-Brunner, 1949 18 beckeri Wisner, 1971 22 chilense Wisner, 1971 23 crockeri (Bolin, 1939) 19 parallelum (Lonnberg, 1905) 26 subparallelum (Taning, 1932) 25 thompsoni (Chapman, 1944) 25 Scopelopsis Brauer, 1906 221 multipunctatus Brauer, 1906 222 Stenobrachius Eigenmann and Eigenmann, 1890 159 leucopsarus Eigenmann and Eigenmann, 1890 159 nannochir (Gilbert, 1890) 161 V Symbolophorus Bolin and Wisner (In: Bolin, 1959) 48 ? boops (Richardson, 1844) (A Species Complex) 51 californiensis (Eigenmann and Eigenmann, 1889) 52 evermanni (Gilbert, 1905) (A Species Complex) 50 Taaningichthys Bolin, 1959 145 bathyphilus (Taning, 1928) 145 minimus (Taning, 1928) 147 paurolychnus Davy, 1970 147 X. Tarletonbeania Eigenmann and Eigenmann, 1890 81 crenularis (Jordan and Gilbert, 1880) 82 taylori Mead, 1953 82 Triphoturus Fraser-Brunner, 1949 164 mexicanus (Gilbert, 1890) (A Species Complex) 164 nigrescens (Brauer, 1904) 165 oculeus (Garman, 1899) 164 KEY TO GENERA OF FAMILY MYCTOPHIDAE la. Primary photophores small, usually indistinguishable from minute secondary ones pres- ent under each scale of head and body. Bases of dorsal and anal fins very long, about equal in length, their combined lengths contained about 1.75 times in SL Scopelopsis lb. Primary photophores larger than and readily distinguishable from any minute secondary ones 2 2a. No more than 2 Pre. PO^ not elevated 3 2b. More than 2 Pre. PO4 elevated or not 15 3a. Base of adipose fin far behind vertical from end of anal base. VLO, SAO3, and Pol far above lateral line near dorsal profile. Upper Pre well above lateral line and about over the lower one. Prominent transparent dome covering pineal organ on top of head Notolychnus 3b. Base of adipose fin over or slightly before or behind vertical from end of anal base. No primary photophore above lateral line by more than about its diameter. Prc^ always behind vertical from Pre, 4 4a. PLC far below origin of pectoral fin, about on level of base of lowest ray 5 4b. PLC ranging from about level of pectoral origin to on or slightly above lateral line 7 5a. Lateral line pores not visible. PLO and PVO, juxtaposed, nearly on same level and well below level of PVO^. AG series in continuous, nearly straight line Protomyctophum 5b. Lateral line pores readily visible but the line incomplete in some genera 6 6a. AG series undivided but often undulating near end of anal base, no distinct Pol. VO2 not, or but slightly, elevated; VG series curved. PLO above PVO,, about level with PVO-, the three forming a right-angled triangle Electrona 6b. AG series divided into AGa and AGp. One or more distinct Pol. VOo notably elevated, the series not curved, VG;, and VO^ about level with VG, Metelectrona 7a. Mouth subterminal, a fleshy snout protruding notably. PLO slightly below or above pectoral origin. Lateral line absent or partly to entirely complete 8 7b. Mouth terminal 11 8a. Lateral line absent. Gill rakers reduced to tiny nubs tipped with spinules Centrobranchus 8b. Lateral line present but incomplete in some genera 9 9a. Least depth of caudal peduncle slightly greater than orbital diameter. Two to 4 VG (rarely 5); 5 PO (rarely 4 to 8); 2 or 3 SAO. Palatine teeth fanglike. Lateral line incom- plete, only a few anteriormost scales perforated Loweina 9b. Least depth of caudal peduncle less than orbital diameter. Palatine teeth not fanglike 10 10a. One Pre; 6 (5-9) PO; 6 VO. Lateral line poorly developed, only a few anterior scales perforated Tarletonbeania 10b. Two Pre; 5 PO; 4 VG. Lateral line complete or nearly so, extending to at least near a vertical from adipose fin base Gonichthys 11a. Prc2 at or near lateral line, far above level of Pre, 12 lib. Pre2 clo.se Pre,, well below lateral line 13 r2a. Two Pol. PVO, well below level of PVO^. VG series level. Both Dn and Vn present. Suo present, often indistinct. SAO series angulate Hygophum 12b. One Pol. PVO, and PVO,. about on same level. VG- markedly elevated. Dn present, Vn and Suo absent. SAO series angulate Benthosema 10 13a. One Pol. PVO, and PVO^ about on same level. VOj markedly elevated. Dn present, Vn absent. SAO series in straight line, or SAO;, offset slightly behind a line through SA0,-2- A few posterior teeth ofjaws broad-based with hooked tips Diogenichthys 13b. PVO, well below level of PVOj. VO series level. One Pol. Dn and Vn present. No broad- based hooked teeth on jaws 14 14a. SAO series markedly angulate Symbolophorus 14b. SAO series straight or slightly angulate Myctophum 15a. Caudal luminous glands undivided, large, silvery, usually deeply set into vertical sur- faces of caudal peduncle. PO4 notelevated 16 15b. Caudal luminous glands, if present, divided into platelets or scales that often appear to be coalesced, not deeply set into vertical surface of caudal peduncle. PO4 elevated or not 18 16a. Lateral line very indistinct or absent. Prominent crescent of whitish tissue on posterior half of iris. Photophores weakly developed, easily lost, apparently absent on one species Taaningichthys 16b. Lateral line prominent. No crescent of whitish tissue on posterior half of iris. Photo- phores strongly to moderately developed 17 17a. Large, elongate luminous gland in front of adipose fin. Four or five Pre, one or two Pre far above lateral line and under dorsal procurrent caudal rays. Numerous minute secondary photophores on head, body, and proximal part of caudal fin Dorsadena 17b. No luminous gland in front of adipose fin. No Pre above lateral line. No secondary photophores on body Lampadena 18a. PO4 elevated 19 18b. PO4 not elevated 27 19a. First 3 VO in ascending straight line, subsequent VO on level of VOi 20 19b. First 3 VO not in ascending straight line. VO2 and VO3 may be abruptly elevated, or the VO series curved 21 20a. Vn, Ant, and So absent. Dn present but often inconspicuous. Large supracaudal luminous gland in males, much smaller infracaudal gland in females. No luminous scale on PLO Lobianchia 20b. Dn and Vn always present; So and Ant present in some species. No caudal luminous glands. More or less prominent luminous scale at PLO in nearly all species Diaphus 21a. Small luminous scales at bases of rays of dorsal and anal fins, 5 VO 22 21b. No small luminous scales at bases of rays of dorsal and anal fins; 4 or 5 VO, the second and third elevated in some genera 24 22a. Five Pre closely spaced in continuous, nearly straight line. All upper photophores well below lateral line; 5 VO, the series curved. VO2, VO3, and VO4 above level of VO, and V0= Lampanyctodes 22b. Three or four Pre, the series angulate. Upper photophores immediately above or below lateral line; 5 VO, only VO2 elevated, the rest on same level 23 23a. Three Pre. Crescent of whitish tissue on posterior half of iris. Upper photophores touch- ing slightly below or above lateral line. SAO series only slightly angulate Bolinichthys 23b. Four Pre. No crescent of whitish tissue on posterior half of iris. Upper photophores touching but not above lateral line. SAO series notably angulate Lepidophanes 24a. SAO series in straight or very slightly angulate line; 3 to 4 Pre 25 24b. SAO series markedly angulate 26 25a. One Pol. All upper photophores several diameters below lateral line; 3 or 4 Pre, evenly spaced incurve Stenobrachius 25b. Two Pol. All upper photophores touching or very near lateral line; 4 Pre, the series angulate, upper Pre widely separated from the rest Parvilux 11 26a. Five VO, the second always, the third occasionally, elevated and displaced forward; 3 Pre evenly spaced and usually separate from AOp. Upper photophores touching lateral line either above or below it Triphoturus 26b. Four VO, the second, but never the third, sometimes elevated and occasionally displaced forward. Upper photophores sometimes touching, but never above lateral line Lampanyctus 27a. First AOa, and occasionally last, highly elevated 28 27b. First AOa never last occasionally, elevated 29 28a. Bases of dorsal fin notably longer than base of anal fin. Primary photophores large, indistinct. Scales of luminous tissue in rows along bases of rays of dorsal and anal fins, and elsewhere on body. No caudal luminous glands. SAO series forming straight, steeply oblique line; 2 Pol in nearly horizontal line; 3 to 6 Pre Hintonia 28b. Base of dorsal fin variably slightly longer or shorter than base of anal fin. Primary photophores small but distinct. Scattered small scales of luminous tissue on body, often arranged in short rows. No caudal luminous glands. SAO in straight, nearly vertical line. One Pol; 4 to 9 Pre Gymnoscopelus 29a. VO2 and VO3 elevat«d, the series curved. PV2 below origin of pectoral fin and on line through PO, and PVO,; 2 Pol in steeply oblique line. Luminous scales on dorsal midline before and behind, but not at base of, dorsal fin. Similar scales on ventral midline between origins of pelvic and anal fins, along base of anal fin, at bases of ventral procur- rent caudal rays, between PO, and PVO-, and near PLO. Infracaudal gland long, with 6-8 scales Ceratoscopelus 29b. VO series level. PVO2 above origin of pectoral fin and about directly over PVO,; 2 or 3 Pol, at least 2 Pol in horizontal line 30 30a. Base of dorsal fin much longer than base of anal fin. No photophores on cheek. No minute secondary photophores on body; 2 or 3 Pol in a horizontal line; 3 Pre, the upper widely distant from the first two. A few small scales of luminous tissue randomly scattered over body, often in short rows above lateral line near head and below dorsal base and at bases of procurrent caudal rays. Supraeaudal luminous gland large, infracaudal gland very small Notoscopelus 30b. Base of dorsal fin slightly shorter than base of anal fin. Three to five photophores on cheek. Minute secondary photophore under each scale of body; 3 Pol, 2 near and parallel with lateral line, a third directly below the anteriormost of the upper two; 4 Pre. Small scales of luminous tissue scattered over body. Caudal luminous glands small and incon- spicuous Lampichthys 12 DISCUSSION OF GENERA AND SPECIES Protomyctophum Fraser-Brunner, 1949 PLC before and nearly touching PVO,, the two on about the same level and usually below level of PVOj, the latter lying at bases of lower pectoral rays. Lateral line pores not visible. AG series undivided, no Pol. SAO series in a straight or slightly angulate line. Interorbital width as great or greater than width of expanded distal portion of upper jaw. A subgenus, Hierops Fraser-Brunner- (1949), is separable, in part, in that the interorbital width is seldom more than half (usually less) the expanded portion of upper jaw. In the eastern Pacific Ocean most species of Protomyctophum occur in Antarctic waters and northward along the coast of Chile to about 30° S. Only three species (all of the subgenus Hierops) occur north of the equator; one of these, P. (H.J beckeri, is a tropical species which may occur on either side of the equator. Since the circumglobal waters of the Antarctic are still poorly collected, it is not possible to give exact ranges for the species of this genus; it is assumed that all may be circumglobal in distribution. When known, an eastern Pacific range is given. As a result of participation in several trans-Pacific cruises of the USNS Eltanin in antarc- tic and subantarctic waters, personnel of the University of Southern California obtained large collections of fishes of the tribe Electronini Wisner (1963b). These collections, now being studied, should further the understanding of these fishes. The following species accounts and figures for Protomyctophum are taken largely from Andriashev (1962) and Becker (1963a), whose studies were the result of several cruises of Soviet vessels into far southern waters. Key to species o{ Protomyctophum la. Interorbital width as great or greater (rarely slightly less) than greatest width of distal portion of upper jaw, the upper orbital margins converging anteriorly (subgenus Pro- tomyctophum ) 2 lb. Least interorbital width seldom more than half (usually less) than greatest width of distal portion of upper jaw, the upper orbital margins parallel (subgenus Hierops) 6 2a. Two SAO (rarely 3), the series very low on body and lying between verticals from VO4 and AOi. The 2 Pre separated by about half a photophore diameter P. (P.) anderssoni 2b. Three SAO (rarely 4); SAO, about over VO;i 3 3a. SAO series distinctly angulate; SAO.j interspace greater than that of SAO^-ii 4 3b. SAO series in a straight line, evenly spaced 5 4a. SAO, slightly behind a vertical from VO). AO 17-19; 4 AO behind end of anal base P. (P.) tenisoni 4b. SAO, over VO:,. AO 15-17; 3 AO behind end of anal base P. (P.) normani 5a. SAO series in a flatly oblique line. AO 17-19 4 AO behind end of anal base. Gill rakers 5-1- 1-H5-16, total 21-22. The Pre separated by 1.0 to 1.5 photophore diameters P. (P.) bolini 5b. SAO in a steeply oblique line. AO 16-17; 3 AG behind end of anal base. Gill rakers 4-1- H- 14, total 19. Pre very close together P. (P.) andriashevi 13 Interorbital width contained 2 to 3 times in width of distal portion of upper jaw 7 Interorbital width very narrow, contained 5 to 7 times in width of distal portion of upper jaw 10 SAO series angulate. SAOij interspace greater than that of SA02.,t; SAO.) usually well above a line through SAO,..; SAO, over VO;,. AO 16 (15-17); 3 or 4 AO behind end of anal base P. (H.) thompsoni SAO series usually in an evenly spaced straight line; SAO, over or slightly before VO^. AO usually 12-14 (rarely more); 2 or 3 AO behind end of anal base 8 Gill rakers 4 -H1-H2 (11-13), total 17(16-18) P.iH.) beckeri Gill rakers 4-5 -I- 1-f- 15-17, total 20-23 9 Head and prepectoral lengths about 30-33% of SL. AO 13-14 (12-16); 2 or 3 AO behind end of anal base P. (H.) cracker Head length 37-38% of SL; prepectoral length 34-39% of 81. AO 13 (12-14); 2 (rarely 1 or 3) AO behind end of anal base P. (H.) chilense Pre interspace equal to 1.0 to 1.5 photophore diameters. AO 14 (13-15), usually 3 AO behind end of anal base P. (H.) subparallelum 10b. Pre interspace equal to 3 to 4 photophore diameters, about equal to AO-Prc interspace. AO 17-19; 6 to 7 AO behind end of anal base P. (H.) parallelum 6a. 6b. 7a. 7b. 8a. 8b. 9a. 9b. 10a. Protomyctophum (Protomyctophum) anderssoni (Lonnberg, 1905) Fig. 2 — Protomyctophum (P.) anderssoni . female. 68.0 mm. From Andriashev ( 1962, p. 227, fig. 6). Description D. 11-12; A. 18-19; P. 14-15; AO. 12-13; gill rakers 6-8 + 1 + 19-22, total 26-30; vertebrae 38(37-39). Two SAO (rarely 3) low on body, horizontal, over space between VO and AO series. Pre a little less than a photophore diameter apart. VLO low, a little above and behind pelvic origin. Four AO behind end of anal base. Greatest depth of body about 20% of SL. Supracaudal luminous glands of males with 5 to 7 rounded, deeply set scales (Fig. 3). Infracaudal glands of females with to 3 to 5 weakly outlined spots. In either sex these glands do not form until 30 mm or larger. 14 Size: Females to 68 mm, males to 58 mm. Least depth of capture: To 100 m. Distribution: Circumglobal between about 40° S and 65° S. Fig. 3 — Supracaudal luminous glands of males of certain species of the genera Protomyctophum and Electrona. (1) Protomyctophum (Protomyctophum) anderssoni, (2) P. (P.I temsoni, (3) P. (P.) bolini, (4) P. (Hierops) crockeri, (5) P. (H.) thompsom, (6) P. (H.) subparallelum , (7) P. (H.) parallelum, (8) Electrona antarctica, (9 E. subaspera. From Andriashev (1962, p. 217, fig. 1). Protomyctophum (Protomyctophum) tenisoni (Norman, 1930). Fig. 4 — Protomyctophum (P.) tenisoni, male, 39.0 mm. From Andriashev (1962, p. 229, fig. 8). 15 Description D. 12-13; A. 22-23; P. 14-15; AO 17-19; gill rakers 6+1 + 17, total 24; vertebrae 40 (39). Three SAO (seldom 4) in nearly straight, very slightly oblique line; SAOij interspace a little greater than that of SAO-:). Pre juxtaposed. Photophores light, silvery. Greatest depth of body not more than 25*% of SL, usually less. Males with 6 to 7 supracaudal luminous glands, rather trapezoidal in shape (Fig. 3); females with 4 to 5 weakly outlined spots infracaudally. Size: To about 70 mm (Norman, 1930). Least depth of capture: To 77 m (Norman, 1930). Distribution: Possibly circumglobal in Antarctic waters below 41° S; has been taken most often in the South Atlantic but also near Australia. Protomyctophum (Protomyctophum) normani (Taning, 1932) Fig. 5 — Protomyctophum (P.) normani, sex unknown, 34.0 mm. From Andriashev (1962, p. 231, fig. 10). Description D. 13; A. 22-23; P. 14-15; AO 15-17; gill rakers 6 (5-7) + 1 + 16-19, total 24-25 (22-27); . vertebrae 37-38. SAO in a distinct, broadly obtuse angle; SAO,.j interspace a little greater than that of SAO2.3. Pre nearly touching each other. Usually 3 AO behind end of anal base. Eye large, over two-fifths of head length. Greatest depth of body 25-30'?^ of SL. Both supracaudal and infracaudal luminous glands may be present in each sex (definitely in females) from 25 mm and larger. Caudal glands of males are similar to those of P. (H.) crockeri; those of females are 2 to 4 small, overlapping, muddy-gray scales. Size: To about 60 mm. Least depth of capture: Andriashev ( 1962) listed 3 specimens taken with 4700 m of wire out. Distribution: Probably circumglobal in sub-antarctic waters; known from near the Cape of Good Hope, from east of New Zealand, and from the southeastern Atlantic Ocean. Discussion This species is poorly known, and few specimens have been available for study. Becker ( 1963a) reported that 8 specimens from the southwestern Atlantic differed from 3 specimens from near New Zealand in having a blunter snout and fewer gill rakers (20-25 vs 25-26). 16 Protomyctophum (Protomyctophum) bolini (Fraser-Brunner, 1949) Fig. 6— Protomyctophum (P.) bolim. male, 52.5 mm. From Andriashev (1962, p. 233, fig. 11). Description D. 12-13; A. 24-25; P. 14-15; AO 17-19; gill rakers 5+1 + 15-16, total 21-22; vertebrae 39-40. Three SAO (seldom 4), closely spaced in a very oblique, nearly horizontal, line. SAO, over V0.3., interspace, usually nearer VO.,. Pre 1.0 to 1.5 photophore diameters apart. Usually 4 AO behind end of anal base. All photophores dull and dark in appearance. Supracaudal glands of males ( Fig. 3 ) a single (or coalesced double ) small luminous patch just before first procurrent caudal ray; a constriction near the middle suggests two parts. The gland is rather prominently outlined with black pigment. Infracaudal glands of females usu- ally with three small, weakly outlined spots. Size: To about 55.0 mm. Least depth of capture: To about 200 m. Distribution: Apparently circumglobal between about 40° and 60° S. Protomyctophum (Protomyctophum) andriashevi Bekcer, 1963 *^^/ Fig. 1 —Protomyctophum (P.) andriashevi. sex unknown, 29.7 mm. From Becker 1 1963a, p. 19, fig. 2). 17 Description D. 12-13; A. 22-23; P. 16; AO 16-17; gill rakers 4 -h 1 -t- 14, total 19; vertebrae 38-39. SAO evenly spaced in a usually straight, oblique line that passes through VOo. SAO, nearer VO;j than to VOj. Pre very close together, the last often slightly elevated. Snout obtuse, not steeply rounded. Supracaudal glands of males described by Becker, from only two of six specimens, as a muddy-gray narrow band extending the length of the caudal peduncle. The caudal glands of females are unknown. Size: To about 35 mm. Least depth of capture: Recorded by Becker ( 1963a) as from 312 to 624 m. Distribution: The species is known only from the southern Atlantic Ocean, at about 42° S, 39° W. Subgenus Hierops Fraser-Brunner, 1949 The subgenus Hierops is very similar to but differs from the subgenus Protomyctophum in that the interorbital space is generally less than half as great as the widest part of the expanded distal portion of the upper jaw, rather than equal to it or greater; the frontal bones over the orbit are nearly parallel, or are slightly closer together posteriorly than anteriorly, rather than considerably wider posteriorly and converging anteriorly, as in the subgenus Protomyctophum . In correlation with this narrowing of the frontal bones the eyes are canted inward toward the dorsal midline. Also, the dorsal portion of the iris is noticeably narrower than the ventral portion, and the lens is often directed more dorsally than laterally — a condi- tion that has been referred to as "telescopic." Fraser-Brunner (1949) divided the genus Electrona Goods and Bean (1896) into four subgenera, Protomyctophum, Hierops, Electrona, and Elampa. Bolin (1959) raised the first three to full generic status but did not discuss the subgenus Elampa; Wisner (1963b) referred the latter to the genus Electrona. Since its introduction the subgenus Hierops has been alter- nately accepted and rejected, both as a genus and subgenus. Andriashev (1962) considered but two genera as valid, Protomyctophum and Electrona, and reduced Hierops to a subgenus of the first, stating that he had found at least one specimen of the subgenus with an interorbital width nearly as great as the width of the expanded distal portion of the upper jaw — a basic character separating Protomyctophum and Hierops. Becker (1963a and b), although appearing to agree with the subgenus status oi Hierops, used only Protomyctophum as a generic term in dealing with primitive electronins from the North and South Pacific Oceans. More recent authors have been divided on the use of the subgeneric name Hierops. Nafpaktitis and Nafpaktitis (1969) retained it, but Moser and Ahlstrom (1970) at first did not and subsequently did (1974). In an effort to determine the limits of variation of two basic characters that distinguish the subgenus Hierops (the very narrow interorbital space and asymmetrical iris), 351 speci- mens of P. (H.) crockeri (15 to 47 mm) and 207 specimens of P. (H.) thompsoni (16 to 51 mm) were examined. The interorbital space ranged from 21*7^ to S&'/f of greatest width of upper jaw in P. (H.) thompsoni. In P. (H.) crockeri the interorbital space was half or less the greatest width of upper jaw in 89% of the specimens, and half or less in 76% of P. (H.) thompsoni. Of those specimens of P. (H.) crockeri with values below the 50% level 57% were in the 31%-45% bracket, whereas of those of P. (H.) thompsoni 50% were in this bracket. In regard to the characters of asymmetrical iris and "telescopic eyes," of 270 specimens of P. (H.) crockeri with the eyes intact, 97.4% had asymmetrical irises but only 27.4% had the lens directed upward. Of 196 specimens of P. (H.) thompsoni with intact eyes, 79.6% had asymmetrical irises and only 23.5% had lenses directed upward ("telescopic eyes"). It may be that the dorsal displacement of the lens is an artifact of crowding in the net during capture, or of preservation: but the predominant asymmetry of the iris does not appear 18 to be an artifact and thus, along with the concomitant narrowed interorbit bones, offers justification for retaining Hierops as a subgenus of Protomyctophum . Protomyctophum (Hierops) crockeri (Bolin, 1939) Fig. 8 — Protomyctophum (H.) crockeri. male, 34.5 mm. (Photophores retouched). Description D. 11-13; A. 21-22 (19-24); P. 15-16 (13-17); AO 13-14 (12-16); gill rakers 4-5 (6) -F- 1 -H 15 ( 13-17 ), total 20-22 ( 18-24) (see Table 1 ); vertebrae 36-37. Three (rarely 4) SAO, usually equally spaced and in a straight, or nearly so, flatly oblique line; SAO, usually over or just before VO4, rarely over midpoint of VO.^.j interspace. Interorbi- tal width usually half or less than width of expanded end of upper jaw. Supracaudal luminous glands of males ( Fig. 3 ) begin to appear on specimens of about 25 mm and are single, prominent glands that protrude well above the dorsal profile of the caudal peduncle, just before the procurrent caudal rays, and extend somewhat down along the lateral surface of the peduncle. Infracaudal glands of females with 3 (rarely 2 or 4) small, oblong, juxtaposed spots embedded in the caudal peduncle. Size: To about 46 mm. Least depth of capture: Commonly taken at night above 100 m but apparently not at the surface; find no record of capture by surface nets. Distribution: Across the North Pacific, primarily within the sub-arctic and California Current systems, to about 25° N (rarely beyond) (Fig. 9). At the seaward edge of these currents the species apparently occurs in the transition zone of the North-Central Water. The capture localities include those from Aron (1960), Becker (1963b), and Berry and Perkins (1966) and from many trawls by Scripps vessels. Only a relatively small part of these collections was immediately available for study. 19 Fig. 9 — Capture localities of Protomycotphum (Hierops) crockeri (small solid circles), P. (H.) thonipsoni (X), P. (H.) chilense (large solid circles). P. (H.) becken (solid triangles). Discussion Becker ( 1963b) stated that, based primarily on meristic characters, within the total popu- lation of P. (H.) crockeri three areal groups were evident. He defined them broadly as: Western (coastof Honshu to 165° E), Eastern (coast of Oregon to 155° W), and Southeastern (coast of California). Becker concluded that despite an almost complete overlap in counts the numbers of pectoral and dorsal rays and gill rakers increased from west to east but that the number of AO photophores increased from east to west. Unfortunately, Becker had few specimens from the we.stern and southeastern areas (no more than 13 counts and as few as 7) and from 34 to 52 counts from the eastern area. No specimens were available to the present study from the western area, but a large number were available from the areas corresponding to the eastern and southeastern areas, as defined by Becker. Specimens from these areas were separated into the following four subareas (Table 1): 40° to 50° N, west of 130° W; coasts of Washington and Oregon; southern California 20 (San Diego Trough); Guadalupe Island, Mexico, and southward. Numbers of pectoral and anal rays, AO photophores, and gill rakers from these four areas are given in Table 1. Dorsal rays numbered 12 (11-13) and were virtually identical for all four areas. Table 1. Numbers of Pectoral and Anal Fin Rays, AO Photophores, and Gill Rakers FOR Protomyctophum (Hierops) crockeri from Four Areas of the North- eastern Pacific Ocean Area 40''-50° N, west ofl30°W. Near coasts of Wash- ington and Oregon Southern California (San Diego Trough) Guadalupe Island and southward 13 14 15 Pectoral rays 16 17 Mean 12 87 80 11 191 15.47 5 35 33 3 76 15.45 16 48 36 3 103 15.25 5 27 57 1 90 15.60 40°-50'' N, west of 130° W. Near coasts of Wash- ington and Oregon Southern California (San Diego Trough) Guadalupe Island and southward 19 20 21 Anal rays 22 23 24 Mean - — 5 19 23 1 48 22.42 1 4 16 23 3 1 48 21.54 4 6 30 26 2 — 68 21.24 _ 11 12 13 4 _ 40 21.25 40°-50° N, west ofl30°W. Near coasts of Wash- ington and Oregon Southern California (San Diego Trough) Guadalupe Island and southward 12 13 AO photophores 14 15 16 Mean 2 91 296 37 1 427 13.87 1 35 66 6 — 108 13.71 6 112 103 6 2 229 13.50 5 61 36 2 104 13.34 40°-50° N, west of 130° W. 111 54 Near coasts of Wash- ington and Oregon 63 37 Southern California (San Diego Trough) 39 94 Guadalupe Island and southward — 91 Upper gill rakers N Mean 165 4.33 100 4.37 133 4.71 99 5.08 40° -50° N, west of 130° W. Near coasts of Wash- ington and Oregon 14 15 Lower gill rakers 16 17 18 33 110 20 17 63 21 20 N 165 100 Mean 15.90 16.03 Table 1 (Continued) Southern California (San Diego Trough) — 10 71 46 6 133 16.36 Guadalupe Island and southward — 2 11 57 29 99 17.11 rotal gill rakers 18 19 20 21 22 23 24 N Mean 40°-50° N, west ofl30°W. 2 26 80 47 10 — — 165 20.22 Near coasts of Wash- ington and Oregon — 15 40 35 10 — — 100 20.40 Southern California iSan Diego Trough) — 8 30 46 43 6 — 133 21.07 Guadalupe Island and southward — — 2 11 50 34 2 99 22.23 The data in Table 1 support Becker's conclusions in part. The numbers of anal rays and AO photophores increase slightly from south to north, but the reverse is true for pectoral rays and gill rakers. The greatest variation among the four areas of the eastern Pacific is in the numbers of gill rakers. There is an average difference of 2 total rakers between the northern and southern extremes of the total range, with both the upper and lower counts contributing to the difference. Protomyctophum (Hierops) beckeri Wisner, 1971 Fig. 10— Protomyctophum (H.I beckeri, female, 36.4 mm. Description D. 11-12; A. 21-23; P. 14-15: AO 14 (13-15); gill rakers 4 + 1 -I- 13 (12-14), total 18 (17-19); vertebrae 37 (4 specimens). P. (H.J beckeri is superficially very similar to P. (H.l crockeri and P. (H.) chilense in having similar arrangements of photophores and precaudal luminous glands. It differs princi- pally in having fewer total gill rakers (16-18) than the other two species (20-23) (Table 2). The relationships of these three species are discussed following the account of P. (H.) chilense. Size: To about 37 mm. Least depth of capture: To 326 m at night, near Hawaii. Becker ( 1963b) reported the capture of one specimen at the surface at night in the central tropical Pacific. Distribution: Known only from the five localities indicated by solid triangles in Fig. 9. 22 Table 2. Numbers of Fin Rays, Anal Photophores (AO), and Gill Rakers for Pro- tomyctophum (hierops) chilense, p. (h.) crockeri, and p. (h.) beckerl* P. (H.) chilense P. (H. ) Crocker i P. (H.) beckeri Dorsal rays Anal rays Species 11 12 13 20 21 22 23 P. (H.) chilense P.(H.)crockeri P. (H.) beckeri 1 2 1 13 19 3 2 5 2 8 12 2 7 11 1 1 1 1 Pectoral rays AO photophores 14 15 16 17 12 13 14 15 16 P. (H.) chilense P. (H.) crockeri P. (H.) beckeri 4 1 12 42 7 16 24 4 2 7 4 29 42 2 2 32 7 2 1 2 Gill rakers Upper Lower 4 5 12 13 14 15 16 17 18 P. (H.) chilense — 38 — — — — 23 15 — P. (H.) crockeri 18 50 — — — — 35 28 5 P. (H.) beckeri 10 — 1 8 1 — — — — Total rakers 16 17 18 19 20 21 22 23 15 23 23 15 25 1 *Data for P. (H.) crockeri are taken only from specimens from the type locality, off San Diego, California. Protomyctophum (Hierops) chilense Wisner, 1971 .JKi- sat^mt^-v^: i- Fig. 11 — Protomyctophum (H.) chilense, male, 38.0 mm. Description D. 12 (11-13); A. 21-22 (23); P. 16 (15-17); AO 13 (12-14); gill rakers 5 + 1 + 16-17(18), total 21-22 (23); vertebrae 36 (35). This species is closely related and superficially very similar to P. (H.) crockeri and P. (H.) beckeri, particularly in numbers and arrangements of photophores and precaudal glands. The relationships of these three species are discussed below. 23 Size: To 38 mm. Least depth of capture: To 350 m at night. Distribution: Known only from ofTChile near Valparaiso northward to about Iquique and westward to about 79° W. Apparently does not occur northward of about 21° S for it was not recorded from north of that latitude by Bussing ( 1965); not taken on Cruise 12 of the R/V Anton Bruun off Peru in 1965, nor during the Scripps expedition Piquero in 1969, on the R/V Thomas Washington. Most captures lie well within the confines of the Peru-Chile Current. Discussion The preceding three species Protomyctophum (Hierops) chilense, P. (H.) beckeri, and P. (H. ) crockeri are closely related and superficially very similar. They are separable by only a few of the characters listed in Tables 2 (counts) and 3 (body proportions). In each table, data for P. (H.) crockeri are only from specimens from the type locality, Cortes Bank, about 100 mi (160 km) west of San Diego, California. This restriction was imposed because of the existence of subpopulations throughout the range of the species, as demonstrated above. Table 3. Body Proportions for Protomyctophum (Hierops) chilense, P. (H.) beckeri, AND P.(H.) crockeri P. iH.) chilense N = 15 (21-38 mm) P. (H.) beckeri P.(H.)c N (25-4 rockeri** Measurement Holotype Paratypes Becker (1963b)* = 12 1 mm) Ave Range 27.0 mm 36.5 mm 36.4 mm 34.0 mm 34.3 mm Ave Range Head length 376 367-385 344 331 324 344 356 315 303-330 Head depth 302 289-325 288 280 280 294 — 299 289-310 Upper jaw length 244 234-261 234 219 223 230 — 217 206-237 Orbit length 148 137-160 133 126 126 — — 135 122-144 Interorbital width 31 25-42 48 41 41 44 — 23 17-26 Prepectoral length 352 336-366 330 324 310 324 348 315 297-331 Prepelvic length 452 442-468 450 460 462 459 483 444 418-465 Predorsal length 532 517-547 511 520 495 533 526 511 501-520 Preanal length 588 562-620 589 590 590 586 643 587 561-615 Preadipose length 810 802-823 834 833 830 827 813 812 793-827 Dorsal origin to pelvic origin 320 306-340 319 324 324 318 354 307 291-318 Dorsal origin to anal origin 308 296-325 312 320 316 318 321 294 279-304 Anal base length 290 272-305 293 271 278 280 — 283 256-309 Dorsal base length 155 141-177 167 154 159 165 — 150 137-162 Caudal peduncle length 161 151-171 152 159 170 153 187 170 159-187 Caudal peduncle depth 98 89-105 96 110 102 106 105 96 85-112 Pectoral-fin length 232 217-245 222 214 220 209 — 197 186-221 Pelvic-fin length 176 157-191 — 165 126 109 — 159 130-173 *0ne specimen only. "'Data for P. (H.) crockeri are taken from specimens from near type locality, off San Diego, California. The similarity of these three species is attested by the complete overlap in numbers of fin rays and AO photophores and in most body proportions. Only the numbers of lower and total gill rakers (Table 2) serve to separate P. iH.) beckeri from the other two species. Of the body proportions (Table 3) the head and prepectoral lengths are most useful in distinguishing the three species. The head of P. (H.) chilense averages 4% longer than that of P. (H.) beckeri and 6.1'7f longer than that of P. (H.) crockeri, with no overlap in values. The prepectoral length of P. (H.) chilense averages 2.2% greater than that of P. (H.) beckeri and 3.7% greater than that 24 of p. (H.) crockeri, again with no overlap in values. However, due to the paucity of specimens, it cannot now be said that the limits of variability of P. (H.) beckeri have been approximated. Protomyctophum (Hierops) thompsoni (Chapman, 1944) Fig. 12— Protomyctophum (H.) thompsoni. male, 47.5 mm. (Photophores retouched). Description D. 12 (11-13); A. 23 (21-25); P. 15 (14-17); AO 16 (15-17); gill rakers 4 (3) -I- 1 -H 13 (12-15), total 18 (16-20); vertebrae 38 (37-39). SAO in a distinct but very wide angle; SAOg slightly elevated above a line through SAO, -2. SAOj usually before a vertical from VO.i, rarely at or behind this vertical. SAOj always nearer SA0:j than to SAO,, usually twice nearer. Interorbital width usually half or less the width of expanded distal portion of upper jaw. Precaudal luminous glands very similar to those of P. (H.) crockeri; supracaudal glands of males average somewhat smaller (Fig. 3). Becker (1963b) stated that these glands begin to develop in specimens of about 25 mm, but are sometimes lacking at 33-36 mm. Size: To about 52 mm. Least depth of capture: 0 to 500 m at night. Distribution: This species occurs across the North Pacific Ocean, usually north of 40° N (Fig. 9). It also occurs in the Bering Sea near the central Aleutian Islands, but is probably carried there by currents through the many interisland passes. It has not been taken elsewhere in the Bering Sea. No population structure is evident. Protomyetophum (Hierops) subparallelum (Taning, 1932) Fig. 13 — Protomyctophum I H.I suhparallchnn . female, 29.0 mm. From Andriashev (1962, p. 2.35, fig. 14). 25 Description D. 11-12; A. 20-21; AO 13-14 (rarely 15); gill rakers 3-4 + 1 + 13-14, total 17-19; vertebrae 36-37. PrCi.2 interspace notably less than that of last AO-Prci; usually 3 AO behind end of anal base. Body depth greater than 25*^ of SL. PVO2, VLO, SAOi.^ usually in a straight, nearly horizontal line, SAOn only slightly above this line. SAO, nearer VO:) than to VOj. SAO, -2 interspace only slightly greater than that of SAO^.:!. Supracaudal glands of males single, prominent, heavily bordered with dark pigment (Fig. 3); infracaudal glands of females elongate, oval, lightly outlined in black. Size: To about 40 mm. Least depth of capture: To 100 m at night. Distribution: Apparently circumglobal between about 45° and 50° S. In the eastern Pacific the species occurs off Chile, where it maybe abundant. Craddock and Mead (1970) reported the capture of 376 specimens at 37 stations between about 30° and 35° S, 72° and 92° W. Protomyctophum (Hierops) parallelum (Lonnberg, 1905) \ Fig. 14 — Caudal region of Protomyctophum (H.) parallelum. male. 34.0 mm. (1 ) dorsal view, (2) lat- eral view. From Andriashev ( 1962, p. 238. fig. 16). Description D. 1 1-12; A. 24-25; P. 14-15; AO 17-19; gill rakers 3-4 + 1 + 12-13, total 16-18; vertebrae 40-41. Pre,.; interspace about equal to that between last AO and Pre,; usually 6 AO behind end of anal base. Body depth slightly less than 25% of SL. PVO,, VLO, SAO,., in a usually straight, nearly horizontal line, SAO,, slightly above that line. SAO, usually nearer VO2 than to VO3. SAO 1.2 interspace much greater than that of SA02-,i. Supracaudal glands of males single, small, heavily bordered with black (Fig. 3); in- fracaudal glands of females small, consisting of 2 or 3 rounded spots, lightly bordered with black. Size: To about 35 mm. Least depth of capture: At surface at night (Andriashev, 1962); the specimen off Chile was taken in a nighttime haul to 1,000 m. Distribution: Poorly understood, but probably circumglobal between about 50° and 55° S. Like P. (H.I subparallelum, it occurs off Chile but possibly in smaller numbers; Craddock and Mead (1970) reported the capture of one specimen at 33° 31' S, 77° 29' W. 26 Electrona Goode and Bean, 1896 Lateral line well developed. PLO and PVOi.j form a nearly right-angled triangle, SAO series slightly to markedly angulate. Last few photophores behind end of anal base often below level of preceding ones. The following key to species and illustrations of Electrona are taken largely from An- driashev, 1962. Key to species of Electrona la. Body short, deep, its depth about 3 in its length. SAO series about equally spaced, straight or very slightly angulate. AO 12 (10-13) E. risso lb. Body relatively elongate, its depth much more than 3 in the length. SAOi.j interspace distinctly greater than that of SAO0.3 2 2a. So (posteriorly displaced Vn) present about under midorbit. SAO.t nearer SAO^ than to lateral line. Gill rakers 9-10 + 1 + 21-23, total 31-34. About 3 AO behind end of anal base E. carlsbergi 2b. So present 3 3a. SAO series only moderately angulate. Exposed margins of all scales smooth. PO5 not elevated. Four or 5 behind end of anal base. Gill rakers 4-5 -1- 1 -I- 12-14, total 17-20 E. antarctica 3b. SAO series strongly angulate. Exposed margins of scales more or less crenulate. PO5 slightly but distinctly elevated. One or 2 AO photophores over end of anal base, slightly but distinctly raised 4 4a. Exposed margins of all scales notably crenulate. Upper jaw barely reaching to a vertical from rear margin of orbit. Total gill rakers 29 (27-31) E. subaspera 4b. Exposed margins of scales of lateral line only are notched at center, with weak crenula- tions above and below. Upper jaw reaching to well behind a vertical from rear margin of orbit. Total gill rakers 20-23 E . paucirastra Electrona carlsbergi (Taning, 1932) Fig. 15 — Electrona carlsbergi. female, 72.5 mm. From Andriashev (1962, p. 244, fig. 20). Description D. 13-14; A. 19 (18-20); P. 11-13 (long, narrow, reaching to vent); AO 13-15; gill rakers 9-10 -t- 1 + 21-23, total 31-34; vertebrae 35-37. Small suborbital organ (So) present below about midorbit (a greatly displaced Vn). SAO3 nearer SAO2 than to lateral line; 2 Pre half a diameter or less apart. More than 30 small 27 "fangs" on palatines. Three or 4 (rarely 5) AO behind anal base, the last few below level of preceding ones. Both sexes bear single, small, scale-like supracaudal and infracaudal luminous glands. Size: To about 100 mm. Least depth of capture: Andriashev (1962) reported captures with wire lengths of 1000 to 4700 m. Distribution: Between 40° and 68° S in the South Pacific. Electrona antarctica (Giinther, 1878) Fig. 16— Electrona antarctica, male, 66.5 mm. From Andriashev (1962, p. 241, fig. 18). Description D. 14 (13-15); A. 20-21 (22); P. 12-13; AO 17-18 (16-19); gill rakers 4-5 -(- 1 -h 12-14, total 18 (17-20); vertebrae 40 (39-41). No So. SAO3 nearer lateral line than to SAO,. Pre usually separated by 1.0 to 1.5 diameters. Palatines bear 7 to 9 rather large, curved "fangs". Four (3-5) AO behind end of anal base. Supracaudal glands of males with 6-7 (8) rounded spots ringed with dark pigment (Fig. 3); infracaudal glands of females with 1 to 3 weakly developed grayish spots, weakly outlined with dark pigment in adults; both glands are evident at about 40 mm. Size: Males to 82 mm, females to 110 mm (Andriashev, 1962). Least depth of capture: To 100 m. Distribution: Circumglobal, usually south of the Antarctic Convergence; smaller speci- mens often range somewhat farther north. Reported to be the most common myctophid in Antarctic Waters. Electrona subaspera (Giinther, 1864) Fig. \7— Electrona subaspera. male, 92.0 mm. From Andriashev (1962, p. 246, fig. 21). 28 Description D. 14(13-15);A. 21(20-22);P. 15-17; AO 16 (.15-17); gill rakers 8-9 + 1 + 19-20, total 29 (28-30); vertebrae 38 (37-39). Scale margins crenulate. Upper jaw short, barely extending beyond hind margin of orbit. SAO series sharply angulate, the angle only slightly greater than 90°. SAO.i nearer lateral line than to SAO2. Four (3-5) AO behind anal base. PO.^ slightly but distinctly elevated to level of base of outer pelvic ray. Caudal luminous glands small, triangular, overlapping (Fig. 3), 2-3 supracaudally and 1-2 infracaudally. Andriashev (1962) reported that males had no infracaudal glands and that most females also had one supracaudal gland. In both sexes the glands are evident at about 60-65 mm. Size: To about 110 mm. Least depth of capture: At surface at night. Distribution: Probably circumglobal above the Antarctic Convergence; apparently com- mon in the southeastern Pacific Ocean. Electrona paucirastra Bolin (In: Becker, 1963) Fig. 18 — Electrona paucirastra, male. 59.5 mm. Fig. 19 — Electrona paucirastra, sex unknown, 44.3 mm. 29 Description D. 14 (15); A. 20 (19-21); P. 15 (14-16); AO 15 (14-16); gill rakers 6 (5-6) + 1 + 15(14-16), total 22 (21-23); vertebrae 37-38. PO-, elevated to above level of pelvic base. VO series level. AO series in a very slightly curved and ascending line to about over end of anal base, where the last 4 or 5 photophores drop noticeably. Two Pre about a photophore diameter apart. Exposed margin of lateral line scales notched at center with weak crenulations above and below. Supracaudal and infracaudal glands of one or two small, somewhat triangular luminous scales; none of the 12 specimens (58-69 mm) examined bore glands on both surfaces of the caudal peduncle. Size: To 69 mm. Distribution and depth ofcapture: Presently known from 39° 30' S, 71° 15' E, where 85 specimens were dipnetted at night, and 3 were taken between 0 and 1000 m (Becker, 1963a); 12 specimens dipnetted at 41° 01' S, 75° 00' E (R/V Anton Bruiin. Sta. 308A). Electrona risso (Cocco, 1829) Fig. 20— Electrona risso. male, 64.5 mm. From Andriashev (1962. p. 248, fig. 23\ Description D. 13-15; A. 19 (18-20); P. 13-16; AO 12 (10-13); gill rakers 8-9-^1 + 17-20, total 26-30; vertebrae 33-34. Body short and deep, its depth slightly greater than a third of SL; head short, about 3 in SL, and as deep as long. Upper jaw short, barely or not at all extending beyond hind margin of orbit. Caudal peduncle short and deep, with depth nearly equal to length. SAO series in a very broad, moderately steep angle, often in a nearly straight line. AO series slightly uundulating near end of anal base; usually 3 AO behind end of anal base. Precaudal luminous glands unusual in electronin fishes; only the females bear these glands as tiny white spots on both surfaces of the caudal peduncle; males bear no glands (Brauer, 1906; Andriashev, 1962). Size: To about 90 mm. Least depth ofcapture: At surface at night in southeastern Pacific; to 170 m at night in northeastern Pacific (time not given). Distribution: Northern Pacific Ocean, Mediterranean Sea, northwestern Atlantic Ocean, Gulf of Guinea, South Africa, tropical Indian Ocean, and near New Zealand. Kubota and rio Uyeno (1972) reported nine specimens collected at Miho Beach in Suruga Bay in April and May, 1971 (the first records from the northwestern Pacific). Discussion Possibly two subspecies, or species, may be involved in this wide distribution. Whitley (1933) named E. rissoi salubris from near New Zealand. Bolin (personal communication) expressed the opinion that the northeastern Pacific form represents a new species. Two few specimens were available to me to provide data on variation. Unfortunately, E. risso is not taken in numbers and usually suffers considerable damage during capture; thus, the species is still poorly understood. Metelectrona Wisner, 1963 PLO and PVO photophores as in genus Electrona. PO-, and VO,, elevated by two or more diameters above adjacent ones. One or more AO photophores distinctly elevated as Pol, the elevation varying from slight to marked; the first or second Pol is randomly higher than the other. Prcj elevated its diameter or more above level of Prci. Metelectrona ventralis (Becker, 1963) ^ ^ Fig. 21— Metelectrona ventralis. 26.2 mm. From Becker (1963a, p. 26, fig. 5l. Description D. 13 (12-14); A. 19-20; P. 15-16; AOa 8 (9-10) + 4 (3-5), total 13-14 (12-15); gill rakers 5-6 + 1 + 16 (15-17), total 22-23; vertebrae 37 (36-38). VLO about midway between lateral line and pelvic origin. The elevated VO-j is about its diameternearer V0| than to VO.,. SAO series in abroad angle of about 135°-145°. SAO, over VO3.4 interspace or a little nearer VO4; SAO- well behind anal origin, and SAO,; about over AOa-j; a line through SAO^.;) passes well behind VO4. Origin of anal base under beginning of last third of dorsal base. AOai.^ interspace about a photophore diameter greater than between the others. Elevation of Pol variable; 1 or 2 may be elevated and either higher than the other (Bussing, 1965). Palatine fangs large, 3 to 5 in number and preceded by 5 or 6 small teeth. A small, roughly square luminous gland on both surfaces of caudal peduncle near the anterior procurrent caudal rays (Fig. 22). Sexual differences, or development of these glands with age offish, are not known. Size: To about 70 mm. Least depth of capture: To 860 m. 31 Distribution: Probably circumglobal in southern temperature waters. It is known from near New Zealand, Valparaiso, Chile, and off South Africa. Discussion The genus Metelectrona has been relegated to the synonymy of Electrona by some authors, principally Becker (1967) and Paxton (1972). However I retain the genus principally because of the statement of Moser and Ahlstrom (1974, p. 395) that the larva of Metelectrona resembled larvae of the genus Hygophum in some features but had characters found in neither Hygophum nor Electrona, and stated that, ". . . the uniqueness of the larva strongly suggests the resurrection of Metelectrona as a valid genus." Becker, 1963a, based the species M. ventralis on two small specimens (26.2 and 25.3 mm) that bore no luminous caudal glands. Wisner, 1963b, based M. alhstromi on a single adult that bore a small, roughly square luminous gland on each surface of the caudal peduncle near the first procurrent caudal ray. Counts and measurements of the two forms are very similar. Dr. P. Alexander Hulley, South Africa Museum, Cape Town, has recently informed me that he had examined a large number of adults from the South Atlantic Ocean and found the caudal glands to be similar to those described and figured for M. ahlstromi and was satisfied that there was but one species. Publication of the name ventralis predates that of the name ahlstromi by about 38 days (February 21 vs March 30, 1963). Fig. 22 — Metelectrona ahlstromi. sex unknown, 66.3 mm. Hygophum Tuning (In: Bolin, 1939) SAO markedly angulate. Two Pol; 2 Pre, widely separated, the upper usually near lateral line. VO level: PO usually level, PO.-, slightly elevated in one species. Upper jaw broadly expanded posteriorly, reaching little if at all past a vertical from posterior margin or orbit. Key to species of Hygophum la. AOa series distinctly curved 2 lb. AOa series straight 3 2a. PO.-, slightly but distinctly elevated. A line through Pol passes through or before next to last AOa. VLO well below lateral line. AOa series moderately curved H. bruuni 2b. PO.-, not elevated. A line through Pol passes through or before first AOa. VLO very near lateral line. AOa slightly curved H. hygomi 3a. A line through SAO,. 2 passes well below PVO,. Origin of pectoral fin below level of center of eye. Greatest depth of body about 25*^^ of SL. Upper jaw barely extends past hind margin of orbit H.proximum 3b. A line through SAOi.^^ passes through or above PVOi. Origin of pectoral fin on or above level of center of eye. Greatest depth of body about 20'/f ofSL 4 32 4a. Anal rays 19-20; total gill rakers 21 (19-22). Upper Pol under base of adipose fin; 2 or 3 AOp over anal base. Upper jaw extends well past hind margin of orbit H. atratum 4b. Anal rays 23 (21-25); total gill rakers 18 (17-20). Upper Pol well before base of adipose fin; 4 (3-5) AOp over anal base. Upper jaw extends only slightly past hind margin of orbit H. reinhardtii Hygophum hygomi (Liitken, 1892) Fig. 2Z— Hygophum hygomi, male, 34.3 mm. From Becker ( 1965, p. 71, fig. 3). Fig. 24 — Hygophum hygomi, female, 47.6 mm. (Photophores retouched). Description D. 14 (13-15); A. 21 (20-22); P. 15-16; AO 6-7 + 6-7, total 13 (12-14); gill rakers 5-6 -f- 1 -H 15 (14-16), total 22 (21-23); vertebrae 36-37. VLO, SAO;i, and upper Pol at or very near lateral line. Pol series in a flatly oblique line that passes through or before first AOa; SAOi over or before VO^; 2 or 3 AOp over anal base. Supracaudal glands of males small, undivided (2 mm long, 1 mm wide on a 49.5-mm male). The glands bifurcate posteriorly, with short projections along bases of first two procur- rent caudal rays; bifurcation capped with darkly pigmented tissue. Infracaudal glands of females small, about half those of males of same size, more weakly developed and not bifurcate or pigment-capped posteriorly. Glands evident in each sex at about 35 mm. Size: Females to about 60 mm, males to 50 mm. Least depth of capture: At surface at night. Distribution: H. hygomi is apparently circumglobal in southern waters and is also known from the North Atlantic Ocean and Mediterranean Sea. In the southeastern Pacific it has been taken off Chile between about 18°-34° S, 75°-95° W (Fig. 25). 33 Fig. 25 — Capture localities for spt^cies of Hygophum in the eastern Pacific Ocean. Hygophum proximum Becker, 1965 Fig. 26 — Hygophum proximum, male, 42.2 mm. 34 Fig. 27 — Hygophum proximum , holotype, male, 37.8 mm. From Becker (1965, p. 82, fig. 7). Description D. 13 (12-14); A. 19-20 (18-21); P. 14 (13-15); AO 5-6 (4-7) + 6-7 (5-8), total 11-12 (10-14); gill rakers 4-5 +1 + 13 (11-14), total 18-19 (16-20); vertebrae 36 (35-37). Pectoral origin below level of center of pupil. SAO, usually nearer VO3 than to VO2, but occasionally about midway between. Three or 4 AOp over anal base. Upper jaw short, barely reaching past hind margin of orbit. Body rather deep, about 4 in SL. Supracaudal glands of males large, undivided, filling three-fourths or more of the supra- caudal space (Figs. 26, 27). H. proximum has a larger supracaudal gland than any other species of the genus. Females bear a small, elongate infracaudal gland, consisting of 2 or 3 fused elements. The glands of both sexes are evident at about 25 mm. Size: To about 50 mm. Least depth of capture: At surface at night. Distribution: This species is widespread in the warmer waters of the Pacific and Indian Oceans (Fig. 25). It has not been reported from the Atlantic Ocean. Hygophum atratum (Carman, 1899) Fig. 28 — Hygophum atratum, female, 55.0 mm. 35 Fig. 29 — Hygophum atratum, male, 41.6 mm. From Becker (1965, p. 88. fig. 8). Description D. 12 (11-14); A. 19-20(18-21); P. 13-14 (12-15); AO 6 (5-7) + 5-6 (4-7), total 11 (10-13); gill rakers 4-5 (6) -I- 1 + 14-15 ( 13-16), total 20-21 (19-22); vertebrae 36 (37-35). Body moderately slender, its greatest depth about 5 in SL. Origin of pectoral base high, about level with center of pupil. Two or 3 AOp over anal base. SAO, usually over midpoint of VOj.) interspace but sometimes over V0:(. Upper jaw extends well behind hind margin of orbit. Upper Pol under adipose base. Supracaudal glands of males undivided, short, extending over only about one-third of the supracaudal space (Fig. 29); infracaudal glands of females with 2 to 4 small, rounded scales lying between last AOp and first Pre (Fig. 28). Size: To about 60 mm. Least depth of capture: At surface at night. Distribution: Hygophum atratum is confined to the eastern Pacific Ocean, primarily be- tween 15° and 30° N and into the Gulf of California (Fig. 25). The westward range beyond 120° W is uncertain; the few captures may represent strays. Hygophum reinhardtii (Lutken, 1892) Fig. 30 — Hygophum reinhardtii, female, 44..') mm. Description D. 14(13-15); A. 23 (21-25); P. 14 (13-15); AO 7 (5-8) -h 7 (6-9), total 14 (11-16); gill rakers 4 (5) -h 1 -I- 13 (12-14), total 18 (17-20); vertebrae 39 (38-40). 36 Fig. 31 — Hygophum reinhardtii . male, 47.2 mm. From Becker (1965, p. 91. fig. 9). Body generally more slender than in H. atratum, body depth about 4.0 to 4.5 times in SL. Four (3-5) AOp over anal base. Upper Pol noticeably before a vertical from adipose base. A narrow, pale, whitish crescent present on posterior margin of iris. Supracaudal luminous glands of males undivided (Fig. 31), filling about half the supra- caudal space; infracaudal glands of females of 3 or 4 coalesced or seldom separated spots (Fig. 30). The glands of males begin to appear before 25 mm, but those of females are not apparent until about 30 mm. Size: To about 55 mm. Least depth of capture: At surface at night. Distribution: H. reinhardtii occupies the warmer waters of the eastern Pacific Ocean between about 30° N and 30° S, except for a hiatus of about 20° of latitude north of the eastern equatorial region (Fig. 25). In view of the collecting effort in that region and the finding of other species of the genus, it seems likely that this species is indeed absent or very uncommon there. The lack of collections in the south-central Pacific precludes discussion of its occurrence there, but Becker (1965 ) reported it from the southwestern sector (northeast of New Zealand andTasman Sea). H. reinhardtii is not known from the Indian Ocean. Becker (1965) ques- tioned its reported occurrence in the South Atlantic. Discussion The apparent geographical separation of the two groups of//, reinhardtii in the eastern Pacific Ocean is supported by the occurrence of one more ray in the anal fin of the southern group than in that of the northern; the respective averages and ranges of counts are: 22.63 (21-25) vs 21.37 (20-23). All other meristic and morphometric characters for each group are very similar. Hygophum bruuni Wisner, 1971 Description D. 11 (10-12); A. 21 (20-22); P. 15 (14-16); AO 5 (4-6) + 7 (6-8), total 12 (11-13); gill rakers 5 (4-6) -^ 1 -f- 15(14-16), total 20 (19-21); vertebrae 36 (35). PLO about midway between lateral line and origin of pectoral fin; VLO slightly above midway between lateral line and pelvic origin and about over the latter. SAO series in a wide angle varying from 130° to 160°. AOa series evenly and moderately curved, with A0a2 seldom higher than AOa.,. Greatest body depth about 25% of SL. Supracaudal luminous glands of males undivided, small but prominent, standing well above profile of caudal peduncle; infracaudal glands of females undivided, smaller than those 37 Fig. 32 — Hygophum bruuni . holotype, male, 39.0 mm. From Wisner (1971, p. 41, fig. 2). of males and not extending above the peduncular profile. These glands are visible on speci- mens of about 23 mm and appear to be fully formed at about 30 mm; a female (33.5 mm) bore both glands, each weakly but about equally developed. Size: To 53 mm. Least depth of capture: At surface at night. Distribution: Known only from off Chile between about 30°-33° S, 72°-92° W. (Fig. 25). The species is apparently abundant and gregarious. Bussing (1965) reported the capture (as H. hanseni) of 236 specimens in three collections, and Craddock and Mead (1970) reported (as H. hanseni ) a total of 9280 specimens from 45 collections, in surface and deeper hauls. Three of these hauls took 2000, 2500, and 3000 specimens, respectively. Discussion Hygophum bruuni is closely related to H. hanseni (Taning, 1932) and has previously been so identified. Each has the AOa series notably curved, but in H. bruuni the series is less sharply curved and A0a2 is less elevated than in H. hanseni. Meristic characters (Table 4) are very similar for the two species, except that the numbers of gill rakers average nearly three more total rakers in H. bruuni. Most body proportions are also very similar (Table 5). H. bruuni has a greater depth of body than does H. hanseni, with no overlap in values, and a somewhat greater depth of head, prepelvic, and preanal lengths, and distance from dorsal to anal origins, with but slight overlap. Also, in H. bruuni the upper jaw usually extends farther beyond the rear margin of orbit than in H. hanseni, the respective values being 15.85% (10.1-22.4) for 30 specimens of H. bruuni and 10.1% (7.0-11.1) for 8 specimens of //. hanseni from off South Africa. Differences were also observed in positions of some photophores; in 90% of a total of 50 specimens of H. bruuni, PLO was on a posteriorly oblique line with PVOj and PO2; in the remaining 10% , PLO was distinctly, although slightly, behind this line, a condition found in 68.5% of the 8 South African specimens. In H. bruuni VLO was always about midway, or but slightly higher, between lateral line and pelvic base, rather than the higher position common to H. hanseni — three-fourths of this distance nearer the lateral line; this higher position of VLO was shown by Taning (1932, p. 132, fig. 4) and both described and figured by Becker (1965, p. 96, fig. 1 1 ) and figured by Nafpaktitis and Nafpaktitis ( 1969, p. 20, fig. 18). 38 Table 4. Numbers of Fin Rays, AO Photophores, and Gill Rakers for Hygophum bruuii and h. hanseni* H. bruuni H. hanseni Species Dorsal rays Iprincipal)** Anal rays (total) Pectoral rays (both sides) 10 11 12 19 20 21 22 14 15 16 17 H. bruuni H. hanseni 8 16 3 1 10 3 5 2 11 18 3 1 2 5 5 28 6 9 - 2 AO photophores AOa AOp Total AO 4 5 6 6 7 8 11 12 13 14 4 121 - 28 30 30 35 2 116 30 4 24 12 2 128 6 16 39 5 Gill rakers Upper rakers Lower rakers 4 5 6 13 14 15 16 H. bruuni H. hanseni 3 68 30 — 23 51 15 Total rakers 17 18 19 20 21 H. bruuni H. hanseni 23 — 9 7 — 47 16 *Data for AO photophores of//, hanseni include those given by Becker (1965, p. 95, table 15) for specimens from the southwestern Atlantic Ocean. **Two small anterior dorsal rays are not included in the count. Table 5. Body Proportions for Hygophum bruuni and H. hanseni Hygoph um bruuni Hygoph um hanseni S.E. Pacific South Africa A* B** Ct Measurement N = 16 N=8 SI^ SI^ SI^ SI^23-48 mm SL— 27-41 mm 28.5 mm 39.9 mm 35.0 mm Ave. Range Ave. Range Head length 322 298-334 293 271-308 312 251 282 Head depth 245 222-257 215 204-225 224 — 204 Upper jaw length 210 192-223 195 182-208 211 — 187 Orbit length 127 115-141 121 111-137 116 112 Interorbital width 85 69-98 83 80-86 95 — 80 Snout length ^60 47-68 55 46-62 56 — 80 Prepectoral length 345 327-362 315 302-336 337 281 311 Prepelvic length 445 421-462 416 395-425 428 416 416 Predorsal length 492 477-510 472 460-486 495 454 453 Preanal length 609 591-632 580 565-597 603 577 563 Preadipose length 820 801-841 788 772-801 840 780 801 Dorsal origin to pelvic origins 236 222-249 208 192-232 221 — 221 Dorsal origin to anal origins 272 258-296 244 231-261 260 — 244 Dorsal base length 157 146-172 160 151-175 177 151 158 Anal base length 260 248-285 258 229-276 280 281 272 Caudal peduncle length 151 141-164 165 159-175 144 196 175 Caudal peduncle depth 78 69-85 71 62-81 77 83 71 Pectoral fin length 281 243-311 262 247-279 291 — 230 *From about 210 mi northwesterly from Tristan de Cunha. **Data from Becker il965, p. 96), based on one female; the capture locality was not given, but Becker reported one specimen from ca. 42° S. 159° E. and 15 specimens from the southwestern Atlantic Ocean. tFrom the southern Indian Ocean, 41° 01' S, 75° 00' E. Benthosema Goode and Bean, 1896 Vn absent; Dn present. PVO series nearly horizontal. Five PO, none elevated; 5 VO, the second elevated and displaced forward. One Pol; 2 Pre, the upper one at lateral line and distant from the lower. Key to species o( Benthosema la. SAO series in a flatly oblique, straight or slightly angulate, line. VO2 slightly but dis- tinctly elevated and displaced forward by no more than its diameter B. glaciale lb. SAO series notably angulate. VO- highly elevated and displaced forward to nearly over VO, 2 2a. Suborbital organ (So) present about under high margin of pupil. SAOi about on level of SAOo. PLO nearer pectoral base than to lateral line. VLO about four of its diameters below lateral line, about on a line from PLO to SAO^ B. suborbitale 2b. So absent 3 3a. SAO, below level of SAO,, far below a line through PLO, VLO and SAO,. PLO about two, VLO two or three, diameters below lateral line. OP2 only slightly above level of lower margin of orbit B.fibulatum 3b. SAO, above level of SAO2, the two on an ascending line with VLO and PLO. OP, high, about on level of pupil B.panamense Benthosema glaciale (Reinhardt, 1837) Fig. 33 — Benthosema glaciale, sex unknown, 40.0 mm. From the Norweigan Sea. Description D. 13 (12-15); A. 18 (17-19); P. 11 (10-12); AO 6 (5-7) + 7 (5-8), total 13 (11-14); gill rakers 4 (4-5)+ 1 + 11(10-12), total 17 (15-18); vertebrae 36 (35-37). VLO about midway between lateral line and pelvic base, about on level of PVO and SAO, .2. VO2 but little elevated, about over middle of VO,..) interspace. PLO nearer pectoral base than to lateral line. SAO series in a flatly oblique, nearly horizontal and nearly straight angle; SAOj slightly below a line from SAO,.:t. The supracaudal gland is small, translucent (in preservative), elongate, and heavily bor- dered with dark pigment, beginning just before first procurrent caudal ray. The infracaudal gland is smaller, of two coalesced parts, and also heavily bordered with dark pigment. Of the 40 material examined (14 specimens), the smallest male with glands was 59 mm, the smallest female 36 mm. Size: To about 70 mm. Least depth of capture: Has been taken at night with 100 m of wire out. Distribution: Primarily from the North Atlantic and Arctic Oceans, and Mediterranean Sea. Included as a remotely possible item in the Pacific fauna on the basis of one specimen reported from the Arctic Ocean off Point Barrow, Alaska (Walters, 1955). Has not been re- ported from there since, and not at all from the Pacific Ocean. Benthosema suborbitale Gilbert, 1913 Fig. 34 — Benthosema suborbitale, male, 30.3 mm. Description D. 13 (12-14); A. 17 (16-19); P. 14 (13-15); AO 6 (5-7) -I- 5 (4-6), total 11 (10-12); gill rakers 3 (3-4) -h 1 -F 10 (9-10), total 13-15; vertebrae 34 (33-35). VLO high, near lateral line; VO^ much elevated and displaced forward to nearly over VOi, nearly on a line with PVO and SAO,.j. PLO nearer pectoral base than to lateral line. So present below orbital margin about under posterior margin of pupil. Supracaudal luminous gland single, large, extending from first procurrent caudal ray to over half the distance to base of adipose fin. Infracaudal gland of 2 or 3 luminous scales either lightly ringed with pigment or somewhat coalesced with slight indentations laterally. Size: To about 30 mm. Least depth of capture: Has been taken at night with 100 m of wire out. Distribution: A warm water, apparently circumglobal, species. In the eastern Pacific it has been taken mostly in southern latitudes and from near Hawaii (Fig. 35). Two records, one from about 28° N, 126° W, and one outside the Gulf of Tehuantepec, Mexico, may be question- able; the specimens cannot now be found, and their capture localities lie far away from the others. The only evidence of differentiation within this wide distribution is that specimens from the Pacific tend to have a more prominent, usually larger, suborbital photophore than those from the Atlantic Ocean. 41 Fig. 35— Capture localities for Benthosema panamense (solid circles) and for B. suburbitale (Xs) in the eastern Pacific Ocean. Benthosema fibulatum (Gilbert and Cramer, 1897) Fig. 36 — Benthosema fibulatum, male. 62.6 mm. 42 Fig. 37— Supracaudal gland of the male B. fibulatum shown in fig. 36. Description D. 13 (12-14); A. 19 (18-20); P. 16 (14-17); AO 6 (5-7) -^ 4 (3-5), total 10 (9-11); gill rakers 7 (6-7) -H 1 -h 15 ( 14-16), total 23 (21-24); vertebrae 32 (31-33). VLO and PLO near lateral line. VO2 notably elevated, lying over midpoint of VO1.3 interspace. Suboperculum produced into a short, bluntly pointed flap at level of pectoral origin. Supracaudal glands of males (Fig. 37) are largest of the genus, and consist of 3 to 5 well-formed, translucent, luminous scales plus a posterior small, whitish patch at base of first procurrent caudal ray. The entire gland fills the supracaudal space. Apparently the translu- cent scales are easily lost, as many males of adequate size ( sexed by dissection) bear no glands save the small white posterior patch. Females bear two small patches of luminous tissue, lying just before the first ventral procurrent ray, and often a tiny one ventrally a little before lower Pre. Size: To about 90 mm. Least depth of capture: To 122 m in early evening near Hawaii. Distribution: Not well known. Taken in Hawaiian waters, north of New Guinea, off Japan, and from the Indian Ocean off South Africa. Presumably a warm water species. Benthosema panamense (Taning, 1932) Fig. 38 — Benthosema panamense. male, 40.6 mm. 43 Fig. 39 — Supracaudal luminous glands of B. panamense, female, 41.5 mm. Description D. 13(12-13); A. 21 (20-22); P. 14 (13-15); AO 4 (3-4) + 6 (5-7), total 10 (9-11); gill rakers 9 (8-10) + 1 + 18 (16-20), total 28 (26-31); vertebrae 32 (31-33). SAO, above level of SAO^. OP2 about on level of pupil. FLO nearer lateral line than to pectoral origin. FLO, VLO, and SAO1.2 from a straight line. Opercular margin laterally pro- duced into a long, pointed flap. The relationship of sex and caudal luminous glands in this species is uncommon in myc- tophid fishes. Dissection of 80 specimens with and 80 without supracaudal glands showed that only females bore these glands; males bore no glands, and no specimen bore an infracaudal gland. The supracaudal glands of females are usually two (rarely one or three) small, ovoid, weakly developed spots, lightly bordered with dark pigment (Fig. 39); these spots (easily lost) are evident on females of about 34 mm. Size: To about 55 mm. Least depth of capture: At surface at night. This species is the "Red-bait" reported by Alverson (1961 ) as forming dense "balls" at the surface in daylight, and being fed upon by yellowfin and skipjack tuna. Distribution: B. panamense appears to be a relatively near-shore form confined to the eastern Pacific Ocean, principally between about 25° and 10° N, and to the Gulf of California to about 28° N (Fig. 35); the two localities shown outside the main body of collections may represent strays. Discussion In regard to caudal luminous glands, Bolin, (1939, fig. 13) stated: "One or two small, poorly developed, widely separated infracaudal luminous patches at vertical of AOp-Prc in- terspace on a few individuals, presumably females; 1 specimen with a very small indistinct supracaudal luminous patch at the same vertical is a male. In most specimens, even the largest ones, no caudal luminous patches are developed." At odds with my findings, Bolin's specimens were from Japan and Philippine waters and may represent Benthosema pterotum (Alcock, 1890), or a related form. Many authors of studies on eastern Pacific myctophids have used the name pterotum for this species. Although quite closely related, it appears that Benthosema panamense from the eastern Pacific Ocean is distinct from its Indian Ocean relative, B. pterotum. As noted by Tuning (1932), the FLO and VLO are consistently somewhat higher and the eyes smaller in B. panamense. Taning also reported the snout of the former to be more pointed, but this may be of limited taxonomic importance as it is not a consistent characteristic. Body proportions (Table 6) for 12 specimens each of S. panamense from the eastern Pacific Ocean near the Gulf of California, and of B. pterotum from the northern Indian Ocean near the Gulf of Oman, indicate that only the lengths of orbit and pectoral fins differ appreciably, each being smaller in the eastern Pacific with little or no overlap. 44 Table 6. Body Proportions for 12 Specimens each of Benthosema panamense (from THE Eastern Pacific Ocean) and B. pterotum (from the Northern Indian Ocean) B. panamense Measurement SL— 34. 1-49.6 mm Ave. Range B. pterotum SL— 32.1-41.5 mm Ave. Range Head length Head depth Orbit length Upper jaw length Prepectoral length Prepelvic length Predorsal length Preanal length Preadipose length Dorsal origin to pelvic origin Dorsal origin to anal origin Caudal peduncle length Caudal peduncle depth Dorsal base length Anal base length Pectoral fin length 367 354-385 374 356-393 222 214-234 230 221-242 99 93-105 117 110-124 204 195-211 208 203-217 349 337-358 352 337-360 436 422-454 447 430-462 489 465-510 491 480-505 600 584-623 618 599-632 825 805-843 826 806-841 227 215-236 242 234-252 259 249-272 263 255-270 159 149-170 153 145-166 92 85-99 86 81-89 174 161-188 161 150-171 272 258-287 272 265-283 319 302-340 358 338-372 Taning ( 1932) indicated that B. panamense had about two more anal fin rays than did B. pterotum (citing Norman (1929, p. 513) as authority); but it is possible that Norman had confused B. fibulatum with B. pterotum ; the number of anal rays are 19 (18-20) in the B. fibulatum before me. It is also possible that B. pterotum from throughout the Indian Ocean is highly variable in this regard, for the counts given in Table 7 do not support the difference stated by Taning. The numbers of dorsal rays, AO photophores ( AOa, AOp, and total), and vertebrae of S. panamense and B. pterotum overlap almost completely; the respective counts are as follows (those for B. panamense given first); dorsal rays 13(12-14), 13 (12); AOa 6 (5-7) + 4 (3) for both species, total 10 (9-11), 10 (9); vertebrae 32 (31) for both species. Thus, the two species are very much alike in counts and proportions. It may be that a study of abundant material of B. pterotum from throughout its presumed range (the Indo- Table 7. Numbers of Anal and Pectoral Fin Rays and Total Gill Rakers for Bentho- sema PANAMENSE -FROM THE EASTERN PACIFIC OCEAN AND FOR B. PTEROTUM FROM THE Northern Indian Ocean Species Anal rays 19 20 21 22 N B. panamense B. pterotum 3 22 14 35 3 4 1 61 21 Pectoral rays 12 13 14 15 B. panamense B. pterotum 8 15 22 9 Total gill rakers 25 B. panamense B. pterotum 26 4 19 27 22 9 28 57 5 29 31 2 30 13 31 32 31 128 42 45 Pacific area and much of the Indian Ocean) will show the above slight differences in mor- phometry and counts to be clinal and require the return of S. panamense to subspecific status or to synonymy with B. pterotum. Diogenichthys Bolin, 1939 SAO series in a steeply oblique line, usually with SAO.^ well behind a line through SAO,.; VOj elevated but not displaced forward. One Pol, at lateral line; 2 Pre, on same level. Dn present; Vn absent. Key to species of Diogenichthys la. lb. Upper jaw reaches well behind a vertical from hind margin of orbit. VLO no higher, usually noticeably less, than midway between lateral line and ventral profile of body. Pre interspace much less than thatof AOp-Prc D. laternatus Upper jaw scarcely reaches a vertical from hind margin of orbit. VLO no lower, usually noticeably higher, than midway between lateral line and ventral profile of body. Pre interspace as wide as thatof AOp-Prc D. atlanticus Diogenichthys laternatus (Carman, 1899) Fig. iO— Diogenichthys laternatus. From Bolin (1939, p. 120, fig. 15i. (A) adult female, (B) head of adult male, (C) caudal peduncle of adult male. Description D. 11 (10-12); A. 16 (15-17); P. 11(10-12); AO 6 (5-7) + 2-3, total 8-9 (7); gill rakers 3 (4) -H 1 -I- 9-10, total 13-14; vertebrae 30 (29-31). Upper jaw reaches well beyond a vertical from hind margin of orbit. VLO usually nearer pelvic base than to lateral line. SAO, over or slightly behind VO4. SAO., usually well behind a line through SAO 1.2. Dn of males much larger than Dn of females. Supracaudal glands of adult males (Fig. 40C ) large, undivided, occupying over half the dorsal surface of caudal peduncle. Infracaudal glands of females (Fig. 40A) small, usually of two coalesced spots, beginning about under Pre, and extending halfway or slightly less to last AOp. Size: To about 25 mm. Least depth of capture: 0-100 m at night, 600-650 m in daylight. 46 Distribution: D. laternatus is found in warmer waters from off San Diego, California, to about 33° S, off Chile (Fig. 41). Occurrence in the coastal waters of Chile, which are normally quite cold, may be due to a tongue of submerged warm water present along the coast at a depth of about 300 m to as far as 40° S (Wooster and Gilmartin, 1961). Fig. 41 — Capture localities for Diogenichthys laternatus in the eastern Pacific Ocean. Discussion Diogenichthys panurgus Bolin (1946), a small species (to 23 mm) more related to D. laternatus than D. atlanticus, occurs in the Indian Ocean. A very similar form (possibly a new species) is known from the Indo-Pacific region and the far western Pacific but has not been reported from the central or eastern Pacific Ocean. 47 Diogenichthys atlanticus (Taning, 1928) Fig. 42 — Diogenichthys atlanticus, male. From Bolin (1939. p. 22, fig. 16) (as D, scofieldi n. sp.i. Description D. 11 (10-12); A. 16 (14-17); P. 11 (10-12); AO 6 (5-7) + 3 (2-4), total 9 (8-10): gill rakers 2 -I- 1 + 11 (10-12), total 14 (13-15); vertebrae 33 (31-34). Upper jaw barely reaches to a vertical from hind margin of orbit. VLO usually nearer lateral line than to ventral profile of body. SAOi over or slightly before VO^; SAO series in a straight line on 30 of 41 sides, SAO;, behind a line through SAO,. j on 11 of 41 sides. Dn of males larger than in females, but contrast in size is much less than that between the sexes in D. laternatus. Supracaudal luminous glands of males small, undivided, covering less than half the dorsal surface of caudal peduncle; infracaudal glands of females very similar to those of D. laternatus. Size: To about 25 mm. Least depth of capture: To 100 m at night, 600-650 m in daylight. Distribution: D. atlanticus, unlike its congener D. laternatus, has a disjunct distribution in the eastern Pacific Ocean (Fig. 43). Although at the extremes of their ranges the two species are found together, D. atlanticus is absent from the vast eastern area wherein D. laternatus occurs commonly (Fig. 41). This hiatus in distribution coincides roughly with the area of low oxygen (1.0 ml/1 and less) that dominates the subsurface waters of the eastern tropical Pacific, as delineated by Wyrtki (1967) for the area east of 140° W and by Austin (1960) for the central area. Off Chile, D. atlanticus was not taken quite as close to shore as D. laternatus, except off Valparaiso; in this area Craddock and Mead ( 1970) reported the capture of 87 specimens from 18 stations between about 33°-34° S, 73° -90° W. Discussion The disjunct distribution of Z). atlanticus suggests the possibility of a racial or population structure, but superficial examination of specimens from each of the three areas of occurrence (Fig. 43) indicated no obvious differentiation. A more detailed comparative study should be made. Symbolophorus Bolin and Wisner (In: Bolin, 1959) SAO markedly angulate. One Pol; 2 Pre, about a photophore diameter apart, the last slightly elevated. Five PO, only the last slightly elevated. Four VO, none elevated. The genus Symbolophorus is difficult taxonomically. Although species groups are readily separable, species within a group often show a remarkable degree of similarity in counts, body 48 Fig. 43 — Capture localities for Diogenichthys atlanticus in the eastern Pacific Ocean. proportions, and photophore patterns. Mature males within a species group may be separated on the basis of appearance and structure of the supracaudal luminous glands, but the in- fracaudal glands of females are very similar throughout the genus. Immature specimens are almost impossible to determine specifically, especially where geographic ranges overlap. The genus is worldwide in distribution. Although most species are essentially tropical, one (possibly two) is found to about 45° N in the northwestern Pacific, and one to at least 55° S in the southeastern Pacific (probably a new species). In the entire eastern Pacific Ocean only three species have previously been recorded, S. californiensis, S. evermanni, and S. boops, but there may be five or six undescribed forms. The following key will serve to segregate at least the species groups to be found in the eastern Pacific. Key to species groups of Symbolophorus in eastern Pacific 49 la. Pol slightly before a vertical from end of base of adipose fin. Usually 1, seldom 2 (occasion- ally none) AOp over anal base. AOa series level S. evermanni species group lb. Pol well before a vertical from end of base of adipose fin; 3 to 5 AOp over anal base 2 2a. Palatine teeth in a narrow band, villiform, none enlarged. AOa series level S. californiensis species group 2b. Palatine teeth much enlarged, in a single row. AOa series distinctly curved S. boops (?) "southern" species group Symbolophorus evermanni species group Fig. 44 — Symbolophorus n. sp. i?i (short gland form), male, 65.0 mm. The pattern of photophores is characteristic of the evermanni species group. Description D. 15 (13-16); A. 20 (18-22); P. 15-16 (13-18); AO 8 (6-9) + 5 (4-7), total 13 (11-15); gill rakers 6 (5-7) +1 + 14-15 (13-16), total 21-22 (19-23); vertebrae 37 (36-39). At least three forms from the eastern Pacific may be involved in the evermanni species group. As the counts for all forms overlap completely, only one set is given above. SAO, about over VOj. SAO,.j interspace greater than that of SAOj.r Palatine teeth in a narrow band, villiform, none enlarged. Adult males of three presently recognized forms have notably different types of supracaudal luminous glands (Fig. 45). Size: To about 80 mm for all three forms. Least depth of capture: At surface at night, all three forms. Discussion and Distribution The name evermanni has been applied to specimens taken in tropical waters of the Pacific and Indian Oceans. It is apparent, however, that several species occupy this wide area, with perhaps slight or only moderate overlap in ranges. As presently understood, S. evermanni (sensu stricto), the form in which the concavities of the luminous scales of the supracaudal gland face forward (Fig. 45A), may be more or less restricted to the central and western tropical Pacific, with perhaps some penetration into the Indo-Pacific region. A few specimens with this type of supracaudal gland have been found in the extreme eastern Pacific from Panama to Ecuador; possibly these are migrants with the easterly flowing Equatorial Counter Current. The "reverse-concavity" form, with the concavities of the luminous scales of the supra- caudal gland facing posteriorly (Fig. 45 C), is very common in the eastern Pacific between 20° N and 20° S along the American continents. An occasional specimen is found near Hawaii, perhaps migrants with the westerly flowing North Equatorial Current. The "short-gland" form (Fig. 45B ) is known only from southeast of Hawaii near the equator. 50 |p»>v4 Fig. 45 — Supracaudal luminous glands of males of three forms of the Symbolophorus evermanni species group. A. Symbolophurus evermanni (sensu stricto) (Gilbert, 1905), 69.0 mm. B. Symbolophorus n. sp. ? (short-gland form), 62.0 mm. Although basically like those of S. evermanni, the structureof the individual luminous scales differs notably. C. Symbolophorus n. sp. ? (re versed-concavity form), 67.3 mm. Note the reversed position of the concave borders of the luminous scales, as compared to those of S. evermanni. Symbolophorus boops (?), "Southern" species group This category contains a group of poorly understood species found only in southern waters. Within the southeastern Pacific there are at least three forms whose relationships are by no means clear (Table 8). The principal differences known thus far are the structure and ar- rangement of the caudal luminous glands. On this character the three forms may be separated as follows (otherwise, in external appearance they are very similar to S. californiensis): 1. Both supracaudal and infracaudal luminous glands present just before the first procur- rent caudal rays. Each gland composed of two small, closely spaced, but distinctly separate scales, beginning to form on specimens of about 40 mm. This form is known from off southern Peru and northern Chile. It is tentatively regarded as a new species. 2. Only a supracaudal gland present; this gland is large, with seven large plates nearly filling the space between adipose base and caudal fin. Only a few specimens are known, one from 44° S, 112° W, and two from Drake Passage near Cape Horn. These are also tentatively regarded as undescribed. 3. Andriashev (1962) reported on specimens taken from off Chile, to as far south as 55° S, and identified them as Symbolophorus boops (Richardson, 1844). The supracaudal glands are described and figured (Andriashev, 1962, p. 253, fig. 25) as small, separate, and located just before the procurrent caudal rays; these glands are similar to those described above from off Peru-Chile. 51 Table 8. Selected Meristic Characters for Three Forms of Symbolophorus from the Southeastern Pacific Ocean Character n. sp. (Peru-Chile) n. sp. (Large gland) S. boops (Andriashev, 1962) Dorsal rays Anal rays Pectoral rays AO photophores Gill rakers Supracaudal glands Infracaudal glands 13-14 12 13-14 21-22 22 21-24 13-15 14 12-14 8(7-9)-!- 8(7-10) 8-F9 7-9 + 6-10 5(4)-t- 1 -M -1- 11-13 6-1-1-1-15 5-6 -(- l-t- 13-15 2 7 2 2 0(?) 4-5 Andriashev indicated that those specimens (bearing both supracaudal and infracaudal glands) were males but prefaced the statement with "(?)." He stated (without a question mark ) that the females bore only an infracaudal gland of 4 or 5 small juxtaposed scales lying about midway between the end of the anal base and the first procurrent caudal rays. Symbolophorus californiensis (Eigenmann and Eigenmann, 1889) Fig. 46~Symbolophorus californiensis. From Bolin (1939, p. 106, fig. 9). (A.) Adult female, (B.) Caudal peduncle of adult male. Description D. 14 ( 13-15); A. 20 (19-21 ); P. 17 ( 15-19); AO 7 (6-8) + 9 (8-10), total 16 ( 14-17); gill rakers 6 (7) -^ 1 -^ 15 ( 14-16), total 22 (21-23); vertebrae 39 (38-40). SAO interspaces about equal; SAO, midway between VO^..,. Pol well before vertical from end of base of adipose fin; 4 (3-5) AOp over anal base. Supracaudal glands of males with 6 (5-7) small, round or oval, nonoverlapping luminous scales; infracaudal glands of females with 4 (3-5) small, rounded, nonoverlapping spots. These luminous organs begin to appear on males of 55 to 60 mm and on females of 65 to 70 mm. Size: To about 100 mm. Least depth of capture: At surface at night. Distribution: S. californiensis is apparently confined to the California Current from about 27° N to British Columbia and perhaps westward in the Subarctic Current to at least 155° W. 52 Some authors have placed the species off Japan, but, as discussed below, an undescribed form may occupy those waters. Discussion A probably new, closely related species occurs in the northwestern Pacific from Japan to at least 170° E. It differs from S. californiensis in having generally higher counts, with little or no overlap, and a shorter head and upper jaw. Due to inadequate collections from the north- central Pacific, it is not now possible to establish either a distinct break in distribution of the two forms or a cline in the respective characters. Myctophum Rafinesque, 1810 SAO series in a straight or slightly curved oblique line. SAOi well below level of SAO2 and always behind a vertical from VO3; 1 Pol; 2 Pre. Key to species of Myctophum la. Pol behind a vertical from origin of base of adipose fin 2 lb. Pol on or before a vertical from origin of base of adipose fin 4 2a. Body short, deep, the greatest depth about 3 in SL. Least depth of caudal peduncle 2 or less in the length. Body scales markedly ctenoid. SAO in a straight or slightly curved line. SAOi behind a vertical fromcenter of VO4 M. selenoides 2b. Greatest body depth 4 or more in SL. Least depth of caudal peduncle much more than 2 in the length. Body scales with smooth or weakly crenulated margins 3 3a. Posterodorsal margin of operculum markedly angulate, often recurved or hooked, very slightly or not at all striate or dentate. All body scales with smooth margins. SAO in a straight line that passes behind VO.t M. nitidulum 3b. Posterodorsal margin of operculum rounded; scales on anterolateral part of body weakly crenulate, all others with smooth margins. SAO curved. A line through SAO1.2 passes through or before VO3 M. obtusirostrum 4a. Upper Pre near lateral line, widely distant from lower Pre. Dorsolateral portion of opercle moderately enlarged, the margin notably striate and dentate. SAO series in a straight line that passes over VO3. Pol far before origin of base of adipose fin M. phengodes 4b. Upper Pre far below lateral line, near lower Pre 5 5a. Body scales with smooth margins. Body slender, its greatest depth about 5.5 in SL. Posterodorsal margin of operculum notably striate and dentate, particularly in large specimens , M. aurolaternatum 5b. Body scales markedly ctenoid 6 6a. Scales over AO photophores with 1 to 3 elongate, sharp spines that project posteriorly 7 6b. Scales over AO photophores without elongate spines 8 7a. SAO series straight, or aberrantly and very slightly angulate, a line through the series passing through or very near VO3. Greatest depth of body 4.0 or less in SL. Least depth of caudal peduncle about 3.2 (3.1-3.4) in the length M. lychnobium 7b. SAO series always slightly angulate. A line through SAO,.j passes before VO3, often through VO2. Greatest body depth 4.0 to 4.5 in SL. Least depth of caudal peduncle about 2.9 (2.8-3.0) in the length M.spinosum 8a. Total gill rakers 14-17. A line through SAO, .2 passes variously between VO, and VO2, or before VO, M.asperum 8b. Total gill rakers 27-29. A line through SAO1.2 passes variously through or between VO3 and VO2 M. brachygnathum 53 Myctophum aurolaternatum Garman, 1899 Fig. 47 — Myctophum aurolaternatum, male. From Bolin (1939, p. 108, fig. 10). Description Counts for M. aurolaternatum (Table 9) vary significantly between areas of its total range, particularly between three sectors of the eastern Pacific Ocean. SAO series in a straight line: SAO, over or slightly behind 'V0^. Pol well before base of adipose fin. Prc2 only slightly elevated. Exposed margins of all scales smooth. Posterodorsal margin of operculum rounded, increasingly striate and serrate with size, beginning at about 30 mm. Usually 2 AOp over anal base. Supracaudal luminous glands of males with 6 to 9 triangular, overlapping scales that begin to form at about 50 mm; infracaudal glands of females with 3 to 7 rounded, usually contiguous luminous scales, evident at 55 to 60 mm. Size: To about 105 mm. Least depth of capture: At surface at night. Distribution: Widely distributed: commonly taken from about 25° N to 17° S in the ex- treme eastern Pacific Ocean (Fig. 48) but much less common in the central and far western Pacific, or these areas are inadequately collected. Also common in the Indo-Pacific region and Indian Ocean. The scarcity of captures in the far western Pacific may not be due entirely to a lack of collecting effort. V. E. Becker (personal communication) has stated that the expeditions of the Vitiaz did not find M. aurolaternatum between 180° and 150° E. Becker also stated that 206 specimens (from 73 stations) were taken in the Indian Ocean from Zanzibar and the Gulf of Aden to the Andaman Islands and Bali. Discussion The distribution of M. aurolaternatum in the eastern Pacific Ocean (Fig. 48) is similar to that reported by Wisner ( 1963a) for Lampanyctus omostigma and L. parvicauda ; those dis- tributions appeared to coincide with the pronounced oxygen-minimum layer which underlies much of the eastern tropical Pacific (Austin, 1960, Wyrtki, 1967). The latter two species were mostly taken at depth, but virtually all specimens of M. aurolaternatum were taken with dip net and surface light; possibly this species spends the daylight hours in or at least near the upper limits of the oxygen-minimum layer. In the eastern sector, east of about 145° W, a pronounced racial or population structure is evident in specimens from between about 25° N and 17° S. Highly significant differences occur in nearly all meristic characters between three contiguous groups of specimens (24°29' N to 11°30' N, 11°29' Nto00°30' N, and 00°30' Stol7°17' S). These differences form a definite clinical trend in all characters, the counts averaging lower in the north and grading rather evenly into higher counts in the south. Differences in meristic characters are relatively slight in specimens from the remaining areas (the mid-Pacific and westward through the Indian 54 Table 9. Numbers of Total Gill Rakers, Total AO Photophores, Vertebrae, and Fin Rays for M. aurolaternatum from the Eastern and Mid-Pacific Ocean, and FROM THE INDO-PACIFIC AREA AND THE INDIAN OCEAN. DATA FOR THE EASTERN Pacific Are Arranged in Three Latitudinal Groups. Total gill rakers 14 15 16 17 18 19 20 N Mean Eastern Pacific 24° 29' -11° 30' N 2 70 52 20 — — — 144 15.62 11° 29' -00° 30' N — 8 77 138 86 1 — 310 16.98 00°30'-17°17' S — — 2 36 37 1 — 76 17.49 Mid-Pacific — 1 2 11 32 5 — 51 17.75 Indo-Pacific — — 59 64 114 5 1 243 17.28 Indian Ocean — — 12 11 22 1 — 46 17.26 Total AO photopho res 13 14 15 16 17 18 19 N Mean Eastern Pacific 24°29'-ir30'N — — 41 75 25 3 — 144 15.93 11°29'-00°30'N — 1 25 111 135 36 — 308 16.58 00°30'-17°17' S — — — 9 37 28 2 76 17.30 Mid-Pacific — — 7 18 25 2 1 53 16.47 Indo-Pacific 1 4 18 116 105 12 1 257 16.40 Indian Ocean — 2 3 19 26 — — 50 16.38 Vertebrae 42 43 44 45 46 N Mean Eastern Pacific 24°29'-ll°30'N 14 37 10 — — 61 42.93 ll°29'-00°30' N 2 49 79 30 — 160 43.86 00°30'-17°17' S 1 1 19 16 1 38 44.39 Mid-Pacific 1 3 4 1 — 9 43.56 Indo-Pacific 3 26 64 13 — 106 43.82 Indian Ocean — 11 11 — — 22 43.50 Principal dorsal rays 9 10 11 12 N Mean Eastern Pacific 24°29'-ll°30'N 1 16 34 4 55 10.75 11°29'-00°30'N — 19 67 20 106 11.01 00°30'-17°17' S — 1 20 16 37 11.41 Mid-Pacific — — 10 1 11 11.09 Indo-Pacific — 10 67 31 108 11.19 Indian Ocean — 1 16 8 25 11.28 ' Total anal rays 21 22 23 24 25 26 27 N Mean Eastern Pacific 24°29'-ir30' N 1 6 18 25 4 — — 54 23.46 ir29'-00°30'N — 4 14 52 29 3 — 102 24.13 00°30'-iri7' S — — 4 19 14 2 1 40 24.43 Mid-Pacific — 1 2 6 2 — — 11 23.82 Indo-Pacific 1 2 17 64 23 2 — 109 24.03 Indian Ocean — 1 7 11 2 — — 21 23.67 Pectoral rays 12 13 14 15 16 N Mean Eastern Pacific 24°29'-ir30'N 2 64 33 — — 99 13.13 11°29'-00°30'N 4 44 130 23 — 201 13.86 00°30'-17°17' S — 4 31 35 2 72 14.49 Mid-Pacific — 5 14 1 — 20 13.80 Indo-Pacific — 3 23 99 32 157 14.02 Indian Ocean — 2 31 10 — 43 14.19 55 Fig. 48 — Capture localities for Myctophum aurolaternatitm in the eastern Pacific Ocean. Ocean). Counts for total gill rakers, AO photophores, fin rays, and vertebrae are given in Table 9. No significant sexual dimorphism was demonstrated in meristic characters or body propor- tions in specimens from any of the geographical areas. The most significant differences in counts occur in the extreme eastern Pacific sector of the range. Originally the data were arranged by each degree of latitude, north to south; the latitudinal groupings of data in Table 9 were derived from that arrangement and appear to represent natural breaks in the frequenty distributions of the various counts. These breaks also appear to coincide rather well with the boundaries of the major equatorial currents, as delineated by Wyrtki (1965). Myctophum phengodes (Liitken, 1892) Description D. 12-13; A. 21 (20-22); P. 15-16; AO 7 (6-8) + 8 (7-9), total 15 ( 14-16); gill rakers 7-8 + 1 + 17-18, total 26 (25-27); vertebrae 37 (36-38). Upper Pre much elevated. Eye large, 1.5 in upper jaw. Usually 4 AOp over anal base. Upper margin of operculum markedly angulate and serrate in young and adults. SAO series straight; SAO, a little before a vertical from VO,. AOa, often depressed below level of AOa^. 56 Fig. 49 — Myctophum phengodes, male, 54.5 mm. Fig. 50 — Supracaudal gland of the male M. phengodes shown in fig. 49. Six to 8 luminous scales in the supracaudal gland are evident at about 30 mm (Fig. 50); 3 or 4 luminous scales in the infracaudal gland. The limited material at my disposal does not permit an estimate of size at early development. Size: To about 60 mm. Least depth of capture: At surface at night. Craddock and Mead ( 1970) reported the capture of 614 specimens from the southeastern Pacific Ocean, off Chile, between about 30° and 34° S, 77° and 92° W; of this number, 320 were taken with surface nets at night, the rest by subsurface trawl. Distribution: Apparently circumglobal only in southern oceans from about 25° to 50° S. Fowler (1901, p. 260) identified as Myctophum phengodes a specimen from 60° N, between Greenland and North America (the Labrador Sea). I have examined this specimen (ANSP 7987, 79.5 mm SL) and found it to be Myctophum punctatum Rafinesque, 1810, a very common species of the North Atlantic Ocean. Discussion Only 11 specimens were available to me for study: 4 from the southeastern Pacific Ocean, 6 from the Indian Ocean, and 1 from the southeastern Atlantic Ocean. Among these few specimens an interesting difference was observed in position of the Pol photophore relative to the base of the adipose fin. In the four specimens from the southeastern Pacific, Pol was under only the first or second lateral line pore before end of adipose base; in the six specimens from the Indian Ocean, Pol was under the third or fourth pore; and in the single specimen from the southeastern Atlantic, Pol was under the third pore. Both sides of each specimen were examined. Counts on these few specimens indicated no significant differences among the three areas. 57 Myctophum lychnobium Bolin, 1946 Fig. 51 — Myctophum lychnobium. female, 98.0 mm. Fig. 52 — Myctophum lychnobium. From Sarenas (1954, p. 411, fig. 9) (sex not stated.) Description D. 13 (12-14); A. 19 (17-20); P. 15-16 (14-17); AO 7 (6-8) + 7 (6-8), total 14 (12-16); gill rakers 6-7 (8) -K 1 -I- 14-15 (13-17), total 22 (20-24); vertebrae 38 (37-39). Exposed margins of scales strongly ctenoid. One to three serrations on the scales over the AO series, and often over ventral midline, are markedly elongated into spines which project posteriorly. Upper opercular margin serrate. One, rarely 2, AOpover anal base. SAO series usually straight and in a steep angle (about 60°). SAO, over VO4. AOa, over fourth to sixth anal ray base; A0ai.2 interspace greater than those of remaining ones of series. Forebody deep, 4 in SL. Body color very dark brown or black in preservative. Males of about 60 mm begin to develop 6 to 8 luminous scales in the supracaudal gland and females of about 50 mm begin to develop from 1 to 4 scales in the infracaudal gland. Size: To about 116 mm. Least depth of capture: At surface at night. Distribution: Known from tropical waters from eastern Pacific (Fig. 53) to Mozambique Channel, Indian Ocean. Discussion See M. spinosum. 58 7 / ^ r\ '^ T \ * \ 1 1 / V^ ^ ^ ^ :§ 'Uio° < I • \ 'V, 1 \ \ \ ^ • 1 * 1 \ • — •-^ • • • • • \ 1 1 • • •• • 4 • ; • \ ^ 17 3° 1 16 p 0° ' 1= 0° n 0° 130° ■• — 120° 110° 100° 90° 80° • • • • *: ■ i • 1 • • 1 1 1 J / ~n T^ -/lOo 1 / i d ^ d. L^ 1 ± J. J Fig. 53 — Capture localities for Myctophum lychnobium in the eastern Pacific Ocean. Myctophum spinosum (Steindachner, 1867) i^f&»: Fig. 54 — Myctophum spinosum, male, 84.8 mm. 59 Fig. 55 — Myctophum spinosum, female, From Sarenas (1954, p. 406, fig. 8). Description D. 13 (12-14); A. 19 (18-20); P. 14 (12-15); AO 7 (6-8) + 7 (5-8), total 14 (12-15); gill rakers 7 (6-8) + 1 + 16 (14-18), total 23 (21-25); vertebrae 39 (37-40). Exposed margins of scales strongly ctenoid. As in M. lychnobium, 1 to 3 elongated spines project posteriorly from hind margins of scales overlying the AO series of photophores, and often on those over the ventral midline. SAO series slightly but distinctly angulate; SAOi over VO.j.j interspace, usually nearer to VO.^. AOi over second to fourth anal ray base; A0a,.2 interspace not greater than those of rest of series. Forebody only moderately deep, about 5 in SL. Body color light to warm brown in preservative. From about 55 mm on, males bear 6 (5-7) luminous scales in the supracaudal gland, each with a black rim, and females bear 1 to 4 smaller scales in the infracaudal gland. Specimens from the South China Sea, Philippine, Sulu, and Celebes Seas show a high incidence of both supracaudal and infracaudal glands on one individual; of the 35 specimens used in this study, 14 (40% ) bore both glands. In these cases the supracaudal luminous scales numbered from 1 to 3. Size: To about 90 mm. Least depth of capture: At surface at night. Distribution: Tropical waters of Pacific, Indo-Pacific, Indian, and possibly Atlantic Oceans ( Wisner, 1970a). Not found in the extreme eastern Pacific but has been reported from the Hawaiian region. Discussion Myctophum lychnobium is usually separable from M. spinosum by the more straight and steeply angled SAO series and the position of SAO, more nearly over VO4. However, in the Hawaiian area some specimens presumed to be M. lychnobium have a more angulate SAO series and the first SOA about over a midpoint between VO;, and 4, conditions approaching those characters presumed to be characteristic of M. spinosum. At present it is not known whether these are local variations or, possibly, the result of hybridization. Studies of adequate material from throughout the total range may show the existence of but one highly variable species. Some authors have placed M. lychnobium in synonymy with M. spinosum but Moser and Ahlstrom ( 1974) show the larvae of these two species to be distinctively different. 60 Myctophum asperum (?) (Richardson, 1844) Fig. 56 — Myctophum asperum (?), male 54.7 mm. From the central tropical Pacific Ocean. (Photophores retouched). Description D. 10-11; A. 17 (16); P. 14 (13-15); AO 6 (7-8) + 6 (4-7), total 13 (11-14); gill rakers 4 + 1 -l- 10 (9-12 ), total 15 (14-17); vertebrae 36 (35-38). (Counts given only for specimens from the eastern tropical Pacific Ocean.) No elongate sharp spines on the strongly ctenoid exposed scale margins. SAO forming a moderate but distinct angle; SAO, over VO^..^ interspace. Males bear 4 to 6 luminous scales in the supracaudal gland which fill most of the space between end of adipose base and base of first procurrent caudal ray. Females bear 1 or 2 small ovate scales in the infracaudal gland. Size: To about 70 mm. Least depth of capture: At surface at night. Distribution: Fishes corresponding to the diagnosis of M. asperum are known from the northwestern, eastern, central, and southwestern Pacific Ocean, and from the tropical Atlantic and Indian Oceans ( Wisner, 1970a). Discussion Myctophum asperum forms a complex of at least two forms in the Pacific Ocean. The holotype has no recorded locality, merely, "habitat — ?"; however, as the collecting vessels (HMS EREBUS and TERROR ) collected primarily in southern seas, it may be assumed that the type locality lies there, but collections could have been made along the entire track (Richardson, 1844). Of the material used in this study, specimens from the east-central tropi- cal Pacific (Fig. 56) appear to differ specifically from those of the tropical Atlantic and from the northwestern Pacific near Japan (Wisner, 1970a) in having fewer anal and pectoral rays, vertebrae, and AOp photophores. Also the two Pacific forms differ in at least 10 characters, with little or no overlap in percent of SL. Superficially, all forms key out to M. asperum, but at this time it is not possible to state which of the Pacific forms, if either, constitutes the true Myctophum asperum . More study on specimens from all oceans is needed. 61 Myctophum nitidulum Garman, 1899 Fig. 57 — Myctophum nitidulum. female, 68.5 mm. Description D. 13 (12-14); A. 19 (18-20); P. 14 (13-15); AO 8 (6-10) -h 5 (4-7), total 13 -14(10-17); gill rakers 6 (5-8) + 1 + 15 (12-18), total 20-22 (18-27— see discussion of variation); vertebrae 38 (37-39). SAO series in an essentially straight, steeply oblique line; SAO, over or slightly behind VO4. Pol nearly under or slightly before end of adipose base. Exposed margins of scales smooth; posterodorsal margin of operculum distinctly angulate, often more or less recurved; this angu- lation is discernible in specimens as small as 20 mm. Supracaudal glands of males with 5 to 8 (3-6 in eastern tropical Pacific area) rather triangular, overlapping luminous scales; infracaudal glands of females with 2 to 6 small, round to oblong spots; in each sex the luminous scales are evident at about 35 mm. Size: To about 75 mm. Least depth of capture: At surface at night. Distribution: Myctophum nitidulum is widespread throughout the warmer waters of the Pacific Ocean, and perhaps in the Atlantic and Indian Oceans. The localities shown in Fig. 58 represent only those specimens examined by me, for reasons discussed below. The southern parts of the Pacific are too poorly collected to warrant firm statements of occurrence of the species. Whitley (1968) did not include the species in his checklist of fishes from the New Zealand area. Craddock and Mead ( 1970) reported two adults taken off Chile, at 30°59' S, 92°28' W. A hiatus in the distribution of M. nitidulum occurs in the eastern Pacific Ocean westward of the coasts of Mexico and Central America, from about 25°-05° N and about 120°-125° W (Fig. 58). This broad area has been repeatedly collected with surface and subsurface nets without taking the species. The area corresponds roughly with the region of very low oxygen concen- trations (0.25 to 0.50 ml/1) as delineated by Wyrtki ( 1967), Discussion For at least the past 50 years the name Myctophum affine has been applied by most authors to the species herein referred to as M. nitidulum. The following brief account is intended as an aid in clarifying the current status of that name. 62 Fig. 58 — Capture localities for Myctophum mtidulum in the Pacific Ocean. Scopelus affinis ( = M. affine) was described by Liitken (1892), based on 38 collections from the Atlantic and Indian Oceans. Carman (1899) described Myctophum nitiduliim from the northeastern Pacific, type locality 27°50' N, 145°45' W. Gilbert (1905) described M. mar- garitatum, based on material from the Hawaiian area and from about 28°13' N, 145°44' W (the latter position is very near the type locality of M. mtidulum ). Gilbert (1908) synonymized both these Pacific forms with M. affine. Gibbs (1957), reporting on material from the northwestern Atlantic Ocean and the Gulf of Mexico, segregated two forms, each referrable to M. affine of Liitken. Gibbs characterized one form as having ctenoid scales and a rounded dorsal portion of the opercular margin, and the other form as having cycloid scales and a distinctly angulate posterodorsal margin of the operculum. On the advice of Bolin, Gibbs applied the name M. affine to the form having ctenoid scales and rounded opercular margin, and chose M. nitidulum as the earliest available name for the cycloid-scaled form with the angulate posterodorsal margin of the operculum. Bolin (1959) reported that Liitken's original study material of M. affine, composed mostly of juveniles, contained at least two species, one being M. asperum (Richardson), the other the ctenoid-scaled, round-operculumed form reported by Gibbs (1957) as M. affine; Bolin desig- nated a lectotype with the type locality in the Atlantic Ocean at 08° 44' N, 21° W for this latter form. With some hesitation, Bolin accepted Gibbs' designation of the cycloid-scaled, angulate- operculumed form as M. nitidulum. 63 Based on the criteria provided by Gibbs and Bolin, I have found only M. nitidulum among hundreds of specimens from throughout the Pacific Ocean and from much of the Indian Ocean. Becker (1967b), however, reported one occurrence of M. affine from the southwestern Pacific, at Lord Howe Island, and at the same time indicated the occurrence of M. nitidulum in the tropical Pacific. As the south-central and southwestern Pacific Ocean is still rather in- adequately collected or reported on, it is not certain that the true M. affine (as restricted by both Gibbs and Bolin) does not occur here, or perhaps elsewhere in the Pacific. For this reason the localities for M. nitidulum shown in Fig. 58 represent only specimens examined by me. Variation: The numbers of total gill rakers (Table 10) indicate the existence of several populations (or one highly variable population) of M. nitidulum in the Pacific Ocean, and particularly the eastern equatorial area. Specimens from this area, bounded roughly by about 05° S to 10° N, 70° to 150° W, have significantly higher numbers of total gill rakers than those from other areas of the Pacific and from the Indian and Atlantic Oceans. Also, in the eastern equatorial region many specimens bear both supracaudal and infracaudal luminous glands, the scales in the supracaudal glands of all males from the area being fewer (3-5) than in other areas (5-9). Corollary to the higher numbers of gill rakers is an increase in numbers of AO photophores and vertebrae, but to a lesser degree of significance. Table 10. Numbers of Total Gill Rakers for Myctophum nitidulum from Selected Areas of the Pacific Ocean and from the Indian and Atlantic Oceans Area 17 18 19 20 21 22 23 24 25 26 27 N Mean Pacific Ocean 07°-28° S, Coast to 1 14° W 1 IS'-SS" N, Coast to 1 22° W - 10° -40° N, 135°-170° W Japan area — Equatorial area 05°-08° N 75°-85°W _ _ _ 1 24 24 11 8 1 — — 69 22.06 86°-99°W _ _ _ 1 4 16 52 72 29 2 2 178 23.66 100°-129°W _ _ _ _ 1 8 22 58 49 30 2 170 24.44 130°-150°W ___ 2 20 8 — — — — — 30 21.20 South-Central Pacific 27°-28° S, 157°-159°W 3 5 3 ________ n 18.00 Indian Ocean — — 1 7 42 20 — — — — — 70 21.16 Atlantic Ocean — 18 31 12 8 — — — — — — 69 19.14 21 31 4 20 24 22 146 5 78 5 2 — — 100 19.56 — 259 21.24 1 7 12 31 10 3 1 — - — 65 20.85 ? 36 154 27 1 — 220 19.95 64 Myctophum obtusirostrum Taning, 1928 Fig. 59 — Myctophum obtusirostrum , male, 61.5 mm. Description D. 13(12); A. 18(17-19); P. 18 (17-19); AO 7 (6-8) + 4-5 (6), total 12 (11-13); gill rakers 7 (6-8)4- 1 + 16-17(15-18), total 25 (24-27); vertebrae 35. Distance between hind margin of orbit and upper opercular margin greater than orbital diameter. Upper opercular margin straight and serrate in specimens of about 30 mm and larger. Scales weakly crenulate along forepart of body below lateral line. PLO nearer pectoral origin than to lateral line. Males with 5 (4-6) luminous scales in the supracaudal gland, with pigmented margins, covering one-half to three-fourths of the upper surface of the peduncle; females with 2 (1-3) luminous scales in the infracaudal gland, smaller and less sharply outlined with pigment. Size: To about 80 mm. Least depth of capture: At surface at night. Distribution: In central tropical Pacific waters, but eastward only to about 130° W; also found in the western Pacific and Indo-Pacific region and in the Indian and Atlantic Oceans. Discussion Recent action regarding the synonymy of this species is discussed under M. brachyg- nathuni. Myctophum brachygnathum (Bleeker, 1856) Fig. 60 — Myctophum brachygnathum . female, From Sarenas, (1954, p. 403, fig. 7) (as M. pristilepsis). 65 Description D. 13 (12); A. 18 (19); P. 17 (16-18); AO 7 (6-8) + 4 (3-5), total 11(10-12); gill rakers 8 + 1 -I- 18 (17-19), total 26-28; vertebrae 35. Distance from hind margin of orbit to upper opercular margin equal to or less than orbital diameter; upper opercular margin neither striate nor serrate. Exposed margins of scales dis- tinctly ctenoid. PLO about midway between pectoral origin and lateral line. Males have 2 (1-3) small supracaudal luminous glands, with rather heavily pigmented margins, lying about over AOp-Prc interspace. Females have 1 (2) smaller infracaudal glands with lightly pigmented margins, lying below the AOp-Prc interspace. The size at which these fishes first develop luminous caudal glands is not known. Size: To about 65 mm. Least depth of capture: At surface at night. Distribution: Apparently similar to that of M. obtusirostrum. Discussion The three species, Myctophum obtusirostrum, M. brachygnathum and M. pristilepis (Gil- bert and Cramer, 1897) have usually been confused, particularly the latter two. Fraser- Brunner (1949) placed M. pristilepis in the synonymy of M. brachygnathum , but Sarenas (1954) regarded the two as distinct. Sarenas stated that in M. brachygnathum the distance from hind margin of orbit to posterodorsal margin of operculum was greater than the length of orbit, whereas these two characters were of nearly equal length in M. pristilepis; he also stated that the scales of the latter were much more ctenoid than those of M. brachygnathum. In view of the synonymy of these two species (see below), it seems possible that Sarenas worked with misidentified material. Nafpaktitis (1973), after examining Bleeker's and Taning's type material and the holotype of M. pristilepis, concluded that in M. obtusirostrum the distance from hind margin of orbit to posterodorsal margin of operculum is greater than the length of orbit, but that these two characters were of nearly equal length in M. brachygnathum. Nafpaktitis agreed with Fraser-Brunner (1949) in placing M. pristilepis in the synonymy of M. brachygnathum. I have examined several adult specimens of M. "pristilepis" from the central Pacific and have found all body scales to be markedly ctenoid, whereas only a few weakly crenulate scales occur anterolaterally near the pectoral fins in M. obtusirostrum. Myctophum selenoides Wisner, 1971 Fig. 61 — Myctophum selenoides. holotype. male, 58.0 mm From Wisner 11971. p. 43, fig. 8.) 66 Description D. 13; A. 18 (17-19); P. 17 (16-18); AO 6-7 + 3 (4), total 9 (10); gill rakers 7 (6) -I- 1 -^ 15 (14-17), total 22 (20-24); vertebrae 35. Frequency distributions of the above meristics, except vertebrae, are given in Table 11. Body and head deep, each about 31% of SL; head as deep as long. Caudal peduncle short, 6 in SL, and deep, 1.5 in its length. Exposed margins of body scales strongly ctenoid but without the elongated spines, on scales over the AO series, found in Myctophum spinosum and M. lychnobium . Three SAO in a straight or slightly angulate, steeply oblique line, at an angle of about 20° ( 17°-23°) from the vertical. Only supracaudal glands occur in each sex; those of males strongly developed with 6 or 7 somewhat overlapping luminous scales that fill the supracaudal space (Fig. 61 ). The sup- racaudal glands of females have only 3 or 4 weakly developed, usually contiguous scales that fill about half the supracaudal space. No infracaudal luminous scales were found on any specimen. Size: To about 60 mm. Least depth of capture: To 20 m at night; this species is not yet reported as taken from the surface. Table 11. Numbers of Fin Rays, AO Photophores, and Gill Rakers for Myctophum selenoides from the central pacific ocean and for m. selenops from the Atlantic and Pacific Oceans Dorsal rays Anal rays Pectoral rays Species and area 12 13 17 18 19 16 17 18 M. selenoides Near Hawaii — 6 2 3 1 3 7 2 Near Equator — 2 — 2 — 1 1 — M. selenops Atlantic Ocean 1 7- 1 5 1 4 11 1 Indian Ocean — 1 — 1 — — 2 — AO photophores AOa AOp Total AO 6 7 8 2 3 4 9 10 M. selenoides Near Hawaii 3 9 — — 11 1 2 10 Near Equator — 4 — — 4 — — 4 M. selenops ., Atlantic Ocean — 13 3 3 13 — — 16 Indian Ocean — 2 — — 2 — — 2 Gill rakers Upper - Lower - Total 6 7 14 15 16 17 20 21 22 23 24 M. selenoides Near Hawaii 6 8 5 9 — — 4 3 7 — — Near Equator — 4 — — 2 2 — — — 2 2 M. selenops Atlantic Ocean 2 14 — 1 11 4 — 1 1 10 4 Indian Ocean — 2 — — 2 — — — — 2 — 67 Distribution: Known only from a few specimens from near Hawaii and southward to near the equator (Fig. 62). Becker (1967b) recorded as M. selenops two specimens from the western Pacific (Fig. 62B) that may represent M. selenoides, but no descriptions or counts were given. Fig. 62 — Capture localities for Myctophum selenoides (open squares), and for M. selenops (open cirlces). "B" refers to localities given for "M. selenops" by Becker (1967b). Discussion Myctophum selenoides is closely related to M. selenops Taning (1928), from the Atlantic Ocean (Fig. 63). It differs primarily in that the SAO series is at an angle of 20° (17°-23°) to the vertical axis of the body, rather than about 30° (28°-31°) as in M. selenops. Meristic data (Table 11) and body proportions (Table 12) are given for both species. Meristic characters appear to be essentially the same, but because of the few specimens involved it is probable that the limits of variation are not yet observed. The rather wide range in numbers of lower and total gill rakers (Table 1 1 ) among the two specimens from the equatorial region and the six from near Hawaii indicates a potential bimodality; however, in all other respects these two specimens are much more like those from Hawaii than like M. selenops. Of the body proportions given in Table 12, only the orbit length differs notably between the two species, averaging 12% of SL vs 15% for M. selenops. The orbit averages 58% of upper jaw in M. selenoides vs 67% in M. selenops. Fig. 63 — Myctophum selenops, holotype, male, 51.6 mm. An unpublished drawing by Rolf L. Bolin. 68 Table 12. Body Proportions for Myctophum selenoides from the Pacific Ocean and for m. selenops from the atlantic and indian oceans M. selenoides M. selenops Central Pacific Ocean Indian Atlantic ; Ocean mt Ocean Measuremj Holotype Para types N = 7 N=l N = = 7 SI^58.0 mm SL— 25.3-60.8 mm SL — 55.5 mm SI^57. 8-67.5 mm Ave. Range Ave. Range Head length 317 307 298-320 317 318 312-329 Head depth 288 268 260-281 283 272 259-280 Upper jaw length 214 207 198-211 213 216 209-224 Orbit length 122 120 117-123 147 148 143-154 Prepectoral length 319 311 300-326 324 332 322-341 Prepelvic length 445 447 435-452 461 449 434-461 Predorsal length 497 480 479-488 472 485 468-487 Preanal length 597 606 592-626 613 614 602-627 Preadipose length 812 812 799-826 802 825 815-835 Dorsal origin to pelvic origin 323 315 306-324 315 304 282-314 Dorsal origin to ana 1 origin 334 331 313-340 337 332 320-340 Dorsal base length 153 167 154-178 157 157 152-168 Anal base length 276 272 263-281 279 275 264-288 Caudal peduncle ler igth 166 166 150-187 184 163 153-178 Caudal peduncle depth 114 100 95-106 99 97 83-111 Pectoral fin length 310 307 296-325 — 299 289-315 Pelvic fin length 150 148 137-156 — 147 134-161 The study material of M. selenops includes the specimen reported on by Maul (1952, p. 52, fig. 15); two discrepancies may be noted between this and Maul's report. The specimen (No. 3108, Museu Municipal do Funchal), taken from the stomach of an Alepisaurus ferox Lowe captured near Madeira, although in fair condition, has lost all scales and the last few lateral line pores on the left side. Maul recorded counts of 33 lateral line scales and 5 supracaudal luminous scales; because of damage to the caudal base and midbody, an accurate count cannot be made of either character on the left side. However, 37 lateral line pores are evident on the nearly intact right side. Also, as there is a fragment of whitish tissue in the area normally occupied by this scale, plus an indentation in the fiesh having the characteristic shape of such a scale, the total number of supracaudal scales may be considered as 6 rather than 5. Also, for this specimen Maul stated "SAO 3, upper well separated from lateral line; Pol 1, well removed from lateral line." However, both the upper SAO and Pol nearly touch the lower border of the lateral line pore structure, a condition very like that shown for M. selenops (Fig. 63). A discrepancy also exists between the two sets of data in regard to head length. Maul recorded the head as "5 1/3 in total length without caudal" for his specimen (No. 3108). This proportion must be regarded as in error, for the head is relatively undamaged on either side and its length is contained about 3.2 times in standard length (total length without caudal); this proportion is in agreement with those I have found for other specimens of M. selenops. All other proportions and counts are in agreement with those recorded by Maul. The Dn organ of M. selenops has not previously been reported. Taning (1928) mentioned no preorbital organs (species not figured). Fraser-Brunner (1949), in the first illustration of the species, may have attempted to illustrate the Vn and Dn, but the resulting print shows only faint indications, albeit in the proper locations; no mention of the organs was made. Maul (1952), offering the second published figure of M. selenops (of the specimen discussed above. No. 3108) figured neither the Dn nor Vn, although both are present, but stated "preorbital 1." 69 However, the seven undamaged specimens before me all have a well-developed, but often obscure, Dn. Loweina Fowler, 1925 Distance from snout to origin of dorsal base greater than that from dorsal origin to end of vertebral column. Deeply buried, often indistinct, Suo present behind posterior end of supraor- bital bone, at about the level of Dn. PLO slightly below pectoral origin; 5 PO (rarely more); 2 to 4 VO; no PO or VO elevated. Two or 3 SAO in an oblique straight line that passes through or near VO4; 1 Pol; 2 Pre closely spaced in a horizontal line. Lateral line incomplete, the external pores (perforated scales) seldom extending much beyond a vertical from pelvic origin. Supra- caudal luminous gland of males single, large, filling half or more of the supracaudal space. Females bear no caudal luminous glands. Key to species of Loweina la. Three SAO 2 lb. Two SAO, widely separate. PVO, behind a vertical from posterior margin of PO2 3 2a. Four VO. PVO, behind a vertical from POj L. terminata 2b. Two VO (abnormally 3 but never 4), 1 near pelvic base, 1 near anus. PVO, before a vertical from PO2 L. interrupta 3a. Head length 297f (27-31) of SL; head depth 65% (61-69) of head length. Hind margin of operculum extends well past origin of pectoral fin L. laurae 3b. Head length about 25% of SL; head depth about 73% of head length. Hind margin of operculum barely reaches to PLO, well short of pectoral origin L. rara Loweina terminata Becker, 1964 Fig. 64 — Loweina terminata. holotype, male, 28.0 mm. From Becker (1964a. p. 19, fig. 2). Description D. 12 (11-13); A. 16 (15-17); P. 11 (9-12); AO 6 (5-8) + 5(4-7), total 11 (10-13); gill rakers 2 -1-1 + 6 (5-7), total 8-10; 38 (39-42) (sic) scales over lateral line— only the anteriormost 2 or 3 are perforated, (data from Becker, 1964a); vertebrae? Three SAO in a steeply oblique, generally straight line and in series with VO4. SAO2-3 interspace about twice that of SAO,. j. AOa,.> interspace but little greater than those of remain- ing AOa. Only 2 or 3 perforated lateral line scales. A single, large undivided supracaudal gland, without a dark margin, extends from first procurrent caudal ray to end of base of adipose fin (Fig. 64). 70 Size: To about 30 mm. Least depth of capture: At surface at night. Distribution: Becker (1964a) stated: (translation by Edith Roden) "Although our material is scanty, its fortunate geographical distribution permits us to conclude that, within its entire range, L. terminata does not occur to the south of the North Tropical Convergence and that in its western part it does not touch the Kuroshio Convergence, nor in its central and eastern part the waters of the North Pacific Drift and the California Current. Thus, the range of L. ter- minata lies completely within the borders of the western and eastern North Pacific Central Water masses, at the northern boundary of the distribution of the tropical species of myctophids (Parin, 1961)." Loweina laurae Wisner, 1971* Fig. 65 — Loweina laurae, holotype, male, .36.8 mm. Description D. 11-12 (10-13); A. 15 (13-17); P. 10-11 (9-13); AO 6 (4-7) + 5 (4-6), total 11 (8-13); gill rakers 2 (always) + 6 (4-7), total 9 (7-10); vertebrae 38 (37-39 ). Correlated counts of dorsal and anal fin rays and AO photophores are given in Table 13. Two SAO, the lower over anus and about its diameter behind VO^; the upper, one or two of its diameters below lateral midline. Four VO, the series curved, the VOi.j interspace slightly greater than the others. Dorsal origin slightly behind midbody and about over midpoint be- tween origins of pelvic and anal fins; anal origin under last third of dorsal base. Caudal peduncle short, about 5 in SL, and moderately deep, its depths about equal to orbit length. Lateral line incompletely developed, an average of 12 (2-19) perforated scales, at anterior end only (Table 14). Supracaudal luminous gland large, undivided, filling about 70% (50%-85% ) of supra- caudal space. Females bear no caudal luminous glands. Size: 36.8 mm, the largest of 93 specimens. Least depth of capture: At surface at night. *As stated in Copeia (1972: (1): 206— Erratum), fig. 4, p. 46, in Copeia, 1971 (1) is incorrectly stated to represent the holotype of Loweina laurae. Instead, it represents a specimen that was originally a syntype of Scope lus (Rhinoscopelus) rarus Liitken, 1892, and subsequently a syntype of Myctophum interruptum Taning, 1928. This specimen has been selected and labeled as the lectotype of Loweina interrupta (Taning) and is so designated below. 71 Table 13. Correlated Counts of Dorsal and Anal Rays, and AO Photophores for loweina laurae Anal rays 10 13 14 15 16 17 Total — — 1 — 1 Dorsal rays 11 12 1 6 6 25 24 9 17 1 41 48 13 — — 1 1 — 2 Total 1 12 51 27 1 92 4 AOp 4 5 6 Total 1 1 12 AOa 5 6 30 12 48 6 12 73 38 123 7 2 5 6 13 Total 21 108 57 186 Table 14. Numbers of Perforated Scales in the Lateral Line of Loweina laurae FROM Four Areas of the Eastern Pacific Ocean Area Number Guadalupe 28°-21"N ii°-orN ir-29°S of pores Island 2 3 4 5 6 7 8 — — — 4 1 3 1 1 — — 2 1 — 3 9 4 — 1 — 10 6 10 6 — 11 8 4 8 — 12 9 5 10 — 13 5 11 14 — 14 2 9 17 — 15 — 6 4 — 16 — — 2 — 17 — 2 — — N 37 47 65 10 Average 10.00 12.70 12.51 3.40 Distribution: L. laurae is known from the eastern Pacific Ocean between about 30° N and 30° Sand westerly to 150° W (Fig. 66). Becker (1964a) reported asL. rara nine specimens from the west-central Pacific and southern tropical Indian Ocean; these specimens are herein provi- sionally assigned to L. laurae. The possible population structure in the eastern Pacific is discussed below. Discussion The presently known distribution o^ Loweina laurae in the eastern Pacific Ocean strongly suggests the existence of three discrete populations (Fig. 66). However, this apparent discrete- ness may be an artifact of sampling as most specimens were taken up with dip net and surface 72 66. Capture localities for Loiveina laurae. light, and the species is small and not readily visible under even slightly unfavorable condi- tions. Also, it is possible that no, or only minimal, netting effort was made in the regions lacking collections. Meristic data for L. laurae from the eastern Pacific Ocean are arranged in four geographi- cal units (Table 15). The northernmost group is divided into two units, one from Guadalupe Island, Mexico, the other from collections made elsewhere north of about 21° N (Fig. 66); this division was made as the specimens from Guadalupe Island (31 in 7 collections) were all taken in upwelled water close to shore while the vessels were at anchor, a circumstance suggesting endemism. A fifth group comprises data from Becker (1964a) for specimens designated as L. rara, from the west-central Pacific and southern tropical Indian Oceans. 73 Table 15. Numbers of Dorsal, Anal, and Pectoral Fin Rays; AO Photophores; and Total Gill Rakers for Loweina laurae from Four Areas of the Eastern Pacific Ocean, Compared with Data on L. rara of Becker (1964a) from the Western Pacific, the Indopacific Area, and Indian Ocean Area Guadalupe Island 27°-21°N 06°-0r N ir-29°S Becker (1964a) 10 11 Dorsal rays 12 13 17 12 1 10 11 — 13 20 5 6 1 2 _ N Mean 31 11.42 21 11.52 34 11.65 5 — 8 — Guadalupe Island 27°-21°N 06°-01°N ir-29° S Becker (1964a) 13 14 Anal rays 15 16 17 5 19 6 6 14 1 1 18 15 - — 4 1 5 3 N Mean 31 14.97 21 14.76 34 15.41 5 — 9 — Pectoral rays (both sides) 10 11 12 Guadalupe Island 3 23 29 7 2r-2rN 5 16 20 1 06°-0r N 8 32 23 2 17°-29''S — 1 6 — Becker (1964a) 6 8 4 — Mean 62 10.65 42 10.40 65 10.23 7 — 18 9.89 Guadalupe Island 27°-21° N 06°-01° N 17°-29°S Becker (1964a) 20 16 8 2 9 AOa photophores 37 23 52 8 9 Mean 62 5.61 42 5.69 68 6.00 10 5.80 18 5.50 Guadalupe Island 2r-2r N 06° -or N 17°-29°S Becker (1964a) AOp photophores 6 10 3 1 2 31 20 46 8 13 25 12 19 1 3 N Mean 62 5.31 42 5.05 68 5.24 10 5.00 18 5.06 Guadalupe Island 27°-2rN off'-orN 17°-29°S Becker (1964a) Total AO photophores 10 11 12 13 1 23 17 20 4 11 19 8 - 9 40 13 _ 3 6 1 _ 9 8 1 N Mean 62 10.87 42 10.74 68 11.24 10 10.80 18 10.56 Total gill rakers Guadalupe Island — — 39 23 27°-2rN — — 25 17 06° -or N — 3 22 43 17°-29°S 4 2 — — Becker (1964a) 6 2 — — N Mean 62 8.37 42 8.40 68 8.59 10 6.60 8 — 74 No endemisim is indicated between specimens from Guadalupe Island and the adjacent group, 27°-21° N. In general, specimens from the central group (06°-01° N) have slightly higher counts than do those from Guadalupe Island and from 27°-21° N (Table 15). This tendency toward higher counts in southern specimens is supported in counts for the southernmost group (17°-29° S) only in numbers of dorsal and anal fin rays; the counts are near the upper limits found for the more northern groups. The numbers of total gill rakers in the southernmost group shown an interesting reduction of two rakers below the combined count for the northern groups. No significant differences in body proportions were demonstrated between specimens from the four areas. These data are combined for all areas (Table 16) and are compared with similar data for Loiveina rara, L. interrupta, and L. terminata. The five specimens (four collections) comprising the southernmost group of L. laurae (17°-29° S, Fig. 66) show a very significant reduction in numbers of pores in the lateral line (Table 14). The more northern groups average 12 (7-17) pores, 149 sides counted, but the five southernmost specimens ( 10 sides) average about 3 (2-6) pores; in other respects, excepting the reduced numbers of gill rakers, these specimens are indistinguishable from those farther north. These very low counts appear valid, as there is no indication of damage to the anterior portions of the lateral line sufficient to have eradicated the pore structures. Becker (1964a, p. 19) reported 2 (2-4) developed pores in the lateral line of L. terminata (see above); this species is primarily distinguished from L. laurae by having 3 SAO rather than 2. Table 16. Body Proportions for the Four Species of the Genus Loweina Measurement L. laurae Eastern Pacific Becker (1964a) N= 15 (24.4-26.1 mm) N = 9 (20.6-32.5 mm) Ave. Range Ave. Range L. rara L. inter- L. terminata Lecto- type (39.2 mm) rupta Paralecto- Lecto- type type (36.2 mm) (37.2 mm) Becker (1964a)* Holo- Para- type types N= 10 (28.0 (23.7-29.5 mm) mm) Head length 290 273-307** 292 265-319 255 257 259 286 249-289 Head depth 181 168-197** — — 186 188 185 — — Snout length 50 47-57 — — 38 44 45 — — Orbit length 80 71-88 ** — — 66 69 79 — — Interorbital width 78 71-83 — — 71 69 79 — — Upper jaw length 171 159-189** — — 163 163 1.59 — — Dorsal origin to anal origin 219 203-253 — — 222 229 217 — — Dorsal origin to pelvic origin 241 217-264 — — 255 260 238 — — Prepectoral length 280 265-299** 287 259-301 260 257 259 268 253-293 Prepelvic length 424 406-437 431 410-442 421 428 418 411 398-464 Predorsal length 536 510-562 539 512-571 548 552 532 542 524-577 Preanal length 604 590-618 606 593-623 621 625 611 619 579-621 Preadipose length 827 803-845 811 753-837 829 842 799 819 770-828 Greatest body depth 213 201-226 217 199-256 219 243 212 196 186-227 Caudal peduncle length 222 192-229** 215 208-221 182 184 222 196 172-200 Caudal peduncle depth 79 58-88 77 65-89 64 69 63 79 59-80 Dorsal base length 147 125-171 142 134-151 149 153 135 140 132-155 Anal base length 209 182-224 203 186-218 193 209 191 207 200-235 Pectoral fin length 139 122-156 137 126-144 126 127 108 146 132-157 Pelvic fin length 127 115-142 — — 115 119 106 — — Supracaudal gland length 126 105-137 _ _ _ _ 106 — — *Becker indicated that all specimens were males. **From 31 to 33 specimens of L. laurae were measured for characters marked by a double asterisk. 75 In the five southernmost specimens before me there is no indication of the present or past occurrence of a third SAO; therefore, these specimens are assigned to L. laurae. Aberrations in photophore patterns: The spacing of the first few photophores of the AOa series of L. laurae is inconsistent. In the most common pattern, the first two AOa are notably farther apart than the rest (Fig. 65). Of the 186 sides (93 specimens) examined, this wider space was lacking on both sides of 30 specimens, on the left side only of 8 specimens, and on the right only of 7 specimens. Aberrations in the PO series occurred in three instances and in four in the VO series. One specimen had an extra PO on the left side, equally spaced between PO2 and PO.-s; in another specimen PO^ was missing on the left side; in still another specimen 8 equally spaced PO were present on the right side. Of the four aberrant VO series, 5 evenly spaced VO occurred on the right side of one specimen, another had but 3 VO on the right side (VO, missing), and another had 5 evenly spaced VO on both sides. Also, a specimen from the Indian Ocean had but 3 VO on both sides (VO2 missing). Becker (1964a) reported that a specimen of L. "rara" from the southern Indian Ocean had but one SAO on each side (the position corresponding to that of a normally placed SAO , ) and also had an extra PO (a total of 6) on the left side close behind PO4. All specimens of L. laurae before me had two SAO. Additional remarks: A discussion and redescription of L. rara (Liitken, 1892) and L. interrupta (Tdning, 1928), and designation of lectotypes for each: Loweina laurae is very closely related to L. rara and to a lesser extent to L. interrupta. Although L. rara has only twice been reported from the Pacific Ocean (Beebe and Vander Pyl, 1944, and Becker, 1964a, — specimens now referred to L. laurae ), and L. interrupta not at all, these two species are included in this report to clarify certain points of taxonomy (in the event they should be found). The two species, L. rara and L. interrupta, have often been confused by authors, perhaps because of a rather confusing action by Liitken in his original description of L. rara and because of a paucity of specimens by which his action could since have been evaluated. A translation of the original description by Liitken (1892, p. 246, fig. 4) is presented in an attempt to clarify the basic confusion. The following translation from the Danish was very kindly provided by Rolf L. Bolin: Scopelus (Rhinoscopelus) rarus n. sp. is represented by only a few specimens of 38-40 mm length (without caudal ). The light snout protrudes very distinctly out over the mouth, but the edge of the opercle is as good as perpendicular. Body shape fairly short and plump; total length 40 mm, height 9 mm, head length dVz mm, gape 6 mm, diameter of eye 2 mm. The anal fin is shorter than the previous species i.e. Scopelus andreae (ca. 15 rays). The scales are ribbed — 3 or 4 ribs at the base. Lateral line scales high and narrow, ca. 39. There is as usual a light spot on the gill cover, 3 close in front of the pectoral base (the most posterior one directly under or behind the pectoral) and 5 in front of the ventrals; the distance between the fifth and fourth pair of these is almost twice as large as that between the more anterior pairs; the distance between the second and third pairs is also normally larger than between the others. In regard to the ventral light spots it is to be noted, that the two of the first pair always are pulled close together, while the distance between those of the second pair is distinctly larger, whereupon it decreases regularly between the following pairs. Of the supraanals there are normally only 2 (not so commonly 3), of which the lower one lies straight above the anus, the upper one a little farther back.' The count of the anal light spots is 12-13 = 6-7 -I- 6-7, in addition to which are the two closely approximated caudals. One of 'Two of the four specimens show the anomaly, that they lack the second and third pair of ventrals and have on one side 3 supraanals, in that there occurs 1 below and in front of that one, which above is designated as the lower one; in these is the space between the second and third pair of thoracics not either larger than between the others. (The silhouette sketch is made from one of these specimens) Some of these are probably only individual anomalies, but that both lack the two pair of ventral light spots, can possibly signify a sexual difference? It is, therefore, a form which needs to be illuminated further on the basis of more material. 76 the specimens has behind the adipose fin a coalescent, oblong, shining spot, of which Capt. Andrea writes: "the white spot on the tail was golden." Localities: 39° N Lat. (?); 20° N. Lat., 50° -48° W. Long.; 34°50' S. Lat., 4°30' W. Long.; 37°40' S. Lat., 12° E. Long. No doubt because of the paucity of the original material (four specimens), even those authors who were aware that Liitken had figured a specimen considered by him to be only an anomal- ous form of L. rara, briefly diagnosed in the footnote, were uncertain as to the limitations of the obvious variability. Taning ( 1928), in a brief diagnostic key, gave the name Myctophum interruptum to the form described by Liitken in the footnote and illustrated in fig. 4. Since, however, the two species have often been confused, perhaps again due to a paucity of study material and the lack of detailed descriptions of the original type material. The paucity of study material of the genus Loweina is illustrated by the few numbers of authors who have recorded the number of specimens studied (Table 17). It is of interest that despite the many expeditions conducted by various nations, including the recent extensive coverage of the world oceans by the various Soviet vessels, a total of only 54 specimens referable to the genus Loweina have been recorded by all authors from all oceans. It is then of great interest that a total of 93 specimens representing the new species L. laurae have been taken in the eastern Pacific Ocean. Because of the basic similarity ofL. rara andL. laurae and the lack of information on L. interrupta, and because of confusion in the early literature, it is now important that a type specimen be formally designated for both L. rara and L. interrupta and that detailed descrip- tions of each be provided. Table 17. Previously Reported Numbers and Areas of Capture of Specimens of Genus Loweina Author. Date, and Species Area of Capture L. rara L. interrupta L. termmata L. laurae Liitken, 1892 N. Atlantic 2 — — — Brauer. 1906 N. Atlantic 4 9 — — Pappenheim, 1914 S.Atlantic — 1 _ _ Tuning. 1928 N. Atlantic — 2 — — Norman, 1930 S. Atlantic " — 2 — — Beebe, 1937 Bermuda 10* — — Beebe and Vander Pyl, 1944.S. E.Pacific — _ _ 1 Maul. 1946 Madeira — 1 — — Nybelin, 1948 N. Atlantic — 1 — — Becker, 1964a W. Pacific and Indian Oceans — — 11 9 (?) Nafpaktitis and Nafpaktitis, 1969, Indian Ocean — 1 — — Totals 16 17 11 10 *Donn E. Rosen (personal communication) reported that these specimens are no longer at the American Museum of Natural History, and, as there is no record of their disposal, they are presumed to be lost. 77 Loweina rara (Liitken, 1892) Designation and Description of Lectotype As stated above, Liitken's type material of Scopelus rarus consisted of four specimens. Due to the kindness of Dr. Jorgen Nielsen, Universitetets Zoologiske Museum, Copenhagen, I was privileged to examine these specimens. Two of them were labeled as Myctophum rarum, and two as Myctophum interruptum. Accompanying each of the four specimens (each in a separate vial) was aslipof paper bearing the single word "Type" printed in large bold letters. Thus, both specimens of both species have been regarded as types by some investigator, but without formal publication of the action. Therefore, I hereby designate as lectotype of Loweina rara (Fig. 67), Number 223, a female (no caudal glands), 39.2 mm in standard length, deposited in the Universitetets Zoologiske Museum, Copenhagen, Denmark. The label bears the following data: "Scopelus rarum (sic) Ltk, 20° N.B. 48°-50° V.L., 10-9-1871, Iversen." I also designate as paralectotype of Loweina rara Number 224, of the same museum, a female (no caudal glands), 36.2 mm in standard length. The label bears only the following data: "Scopelus rarum (sic) Ltk. 33° N, 1863, Warming. Fig. 67 — Loweina rara. lectotype, female, 39.2 mm. (Photophores retouched). In the following counts, those for the lectotype are given first and are followed by those for the paralectotype, in parentheses if different. D. 11 (12); A. 16; pectoral 11-11; pelvic 8-8; AO 7 -I- (6 + 6); gill rakers 2-1-1 + 6. The incomplete lateral line has 6 or 7 weakly expressed pores that extend to about over the end of the pectoral fin. Body proportions for the lectotype and paralectotype of L. rara, and lectotype of L. inter- rupta, are given in Table 15 and are compared with those of L. laurae and L. terminata. Dentition: Teeth of upper jaw in a single row of straight, alternately long and short, conical teeth that extend along entire outer margin to the slightly rounded expansion at end of upper jaw. The longer teeth are from two to three times longer than shorter ones, which in turn are rather typically cardiform. On the dentary, to its occlusion by the upper jaw, is a narrow band of cardiform teeth 2 or 3 teeth in width. An inner band of about 15 longer, backward curving, fanglike teeth extends from the symphysis to about under midorbit; posteriorly, these enlarged teeth become somewhat smaller, straight, and more closely set; those near the end of the gape tend to have a forward slant. The palatine teeth occur in a row of about 10 widely spaced fangs, curved strongly back- ward, which extends continuously from the vomer heads (which bear a single fang each) to about under the hind orbital margin. No small teeth are evident on either vomer heads or palatines. The paralectotype has the palatines slightly damaged anteriorly, and some fangs 78 may be missing. Posteriorly, several smaller replacement (?) teeth are developing mesially to some of the principal fangs. In each of these two specimens the longest fangs are about half the width of the end of the premaxillary. The vomer heads bear a single fang similar to and continuous with those of the palatines. Teet of mesopterygoids comprise a narrow patch of small, backward-curving, fanglike teeth, beginning about under anterior margin of pupil and extending posteriorly to a little beyond hind margin of orbit. At the ends the patch is 2 to 3 teeth in width and increases to about 6 teeth near the middle. Photophores: The following description of photophores pertains to the lectotype; any dif- ferences between it and the paralectotype are stated; Dn and Vn exposed, prominent; Dn before and slightly below level of upper orbital margin; Vn a little behind a vertical from Dn and slightly above level of lower orbital margin. A small Suo at posterodorsal margin of orbit, nearly on same level as Dn. OP^ no larger than other body photophores; OP, a half smaller than OPj, partially hidden by preoperculum, in line with and just behind end of jaw; 0P| a little less than its diameter before a vertical from anterior margin of OPj. PLO half the size of other body photophores, its diameter before, and its upper margin level with, pectoral origin. PVO, about three of its diameters below PLO and slightly before a vertical from center of PO^; PVOj below and touching bases of lower pectoral rays. A line through anterior margins of PLO and PVO i passes through or behind center of PO j; a line through PVOj and PVO , passes through PO,; a line through PLO and PVOj passes through P04. Five PO, unequally spaced; the first pair close to ventral septum, the succeeding pairs very gradually diverging, the last just before origin of outer pelvic rays; POi.- interspace nearly a photophore diameter less than thatof P0:;.3but about half a diameter greater than thatof PO^.j and slightly less than half of the interspace between POj..-,. The PO spacing of the paralectotype differs in that the PO1.2 interspace is a full diameter less than that of PO.i.4, and the PO2.3 interspace is equal to that of P04,5. VLO above and nearer to pelvic origin by about one-third the distance from there to lateral septum and about on level of midpoint between PLO and OP^. Four VO, the first pair in contact at ventral septum and close to inner pelvic rays; the second pair is elevated about two of its diameters above the septum, the third and fourth pairs converging toward the anus, the fourth its diameter from the septum and before the anus; VO1.2 interspace a photophore diameter greater than those between the remaining pairs. Two SAO in steeply oblique line; line through their anterior margins touches the posterior margin of VO4. SAO, two of its diameters above and one behind VO^; SAOj at lower edge of lateral line scale and over base of first or second anal ray. In the paralectotype, SAOj is but half a diameter behind and about 1.5 diameters above VO4; SAO2 is farther forward, a little before base of first anal ray. SAO 1.2 and VO4 form a straight line. AO 7+6, each side (6 + 6, each side, in paralectotype), the series straight. The first 2 AO are separated by a space equal to that between the AOa-AOp series. Pol its diameter behind a vertical from last AOa, a little higher than midway between there and lateral septum, and at the second lateral scale before end of adipose base. Two Pre, separated by nearly a photophore diameter. The interspaces between AOai.2, AOa-AOp, and AOp-Prc are equal. No luminous caudal organs present. Loweina interrupts (Taning, 1928) Designation and Description of Lectotype Although Loweina interrupta has been reported primarily from the Atlantic Ocean, and but once from the southern Indian Ocean, it may eventually be found in the Pacific Ocean. Regardless of its possible occurrence there, it appears fitting to deal with the species at this time. 79 Fig. 68 — Loweina interrupta, lectotype, male, 37.6 mm. Much of the confusion of the species L. rara and L. interrupta appears to stem from Brauer's action in applying the name "rarus" to the specimen figured by Liitken (1892, fig. 4, p. 246) and briefly described in a footnote as an anomalous form (see above). According to more modern concepts of systematic procedure Brauer may have acted correctly, but to follow his action at this date would only serve to compound the existing confusion. I therefore retain the name "interruptum," applied by Taning (1928) to the species so figured by Liitken and de- scribed in the footnote; the name "rara" is then retained for the species described (but not figured) by Liitken in the body of the text. Since no definite type specimen hsa been designated for, and as only a brief key furnished the original description of, L. interrupta , I hereby designate as lectotype o^ Loweina interrupta (Fig. 68) specimen Number 18, a male (supracaudal gland present), 37.6 mm in standard length, deposited in the Universitetets Zoologiske Museum, Copenhagen, Denmark. The specimen is in good condition except for some slight damage to the mouth; the lower jaw is split apart at the symphysis. The label bears the following data: "Myctophum interruptum Taning iScopelus rarum (sic) Ltk.). 37°40' S.B. 12 0 L, 1864. Andrea." Also, I designate as paralec- totype of Loweina interrupta specimen Number 225 of the same museum; the label bears this information: "Myctophum interruptum Taning (Scopelus rarum (sic) Ltk.) 34°50' S.B. 4°30' V.L., 1864. Andrea." The paralectotype is in poor condition. The forepart of the head is missing and only the gill arches, remnants of opercular bones, and a portion of the cranium are left. The rest of the body is relatively intact, except for slight damage to the caudal peduncle, but is quite soft and flaccid; however, most photophores are legible, and a few scales and a large supracaudal gland are retained. The length of the paralectotype, in its present condition, is about 33 mm, exclud- ing the caudal fin; accurate standard length measurement is not possible. Body proportions for the lectotype only are given in Table 16. In the following counts, those for the lectotype are given first and are followed by those for the paralectotype in parentheses, if different. D. 12 (damaged), A. 15 (damaged), pectoral 10-9 (10-10), pelvic 8 + 8; AO 6 + 8 (7 -H 8) gill rakers 34-1 + 10(4+1-^9, 3-H1 + 10). There are about 8 very weakly developed lateral line pores that extend to about over the end of the pectoral fin. Dentition: The dentition of L. interrupta is essentially like that of L. laurae and L. rara, but the teeth appear to be much smaller, particularly the fangs on the palatines and vomer heads. Also, the patch of teeth on the mesopterygoids is narrower than in the other two species. Photophores: The photophores of the head of L. interrupta are very similar to those of L. laurae and L. rara. PVO, its diameter before a vertical from PLO and three diameters below it. PVO2 below and touching bases of lower pectoral rays. A line through PLO and PVOi passes well forward of PO^; a line through PLO and PVO.. passes a little before PO4. Five PO, unevenly spaced and in a straight row which diverges but little from the ventral septum. POi is close to the septum, and PO-, is but its diameter farther away and just before base of outer pelvic ray. P0,.2 interspace a photophore diameter greater than those of PO2-:! and PO.i-j; the interspace between PO2.4 is equal to that between PO4..-, and is two diameters greater than that ofPO,... 80 VLO low, directly above pelvic origin about one-third the distance from there to the lateral septum. Two VO; the first pair nearly touch the ventral septum just behind the inner pelvic rays; the second pair about two diameters before the anus and one distant from the ventral septum. Three SAO in a wide angle; SAO, about two diameters above and two behind VOj; SAO2 about two diameters above and two behind SAO,, and about over the anus; SAO^ high, on lower edge of the lateral line scale which lies over base of first anal ray; it is distant from SAOj by twice the SAOi.j interspace. A line through the posterior margins of SAO, .2 touches the anterior margin of VO^; a line through the anterior margins of SAO., and ■, touches the posterior margin of VO4. On the right side of the paralectotype there are but two SAO, arranged much as in L. rara ; it would appear that SAO, is missing, but there is no evidence of damage. AO 6+8, each side (7 + 8 in paralectotype): A0a,.2 interspace about a photophore diameter greater than those of rest of series; this interspace is about half that between the AOa- AOp series. It is noteworthy that the present count of 8 AOp differs from that of 7 as shown by Liitken (1892, fig. 4) and as listed by Taning (1928) when describing the species. The eighth photophore is not readily visible but is definitely present on each side. There is no enlarged space between the AOp and Pre series. Damage to the ventral margin of the posterior part of the peduncle in the paralectotype renders an accurate count of the AOp uncertain, but remaining pits and bits of luminous tissue indicate that 8 photophores were once present. One Pol, a diameter behind a vertical from posterior margin of last AOa and a little over halfway between there and lateral septum, and on the second scale row before a vertical from end of adipose base. Two Pre, low on caudal profile, are separated by about one and one-half diame- ters and are continuous with AOp; the first is well before, the second over, the first procurrent caudal ray; the second is elevated about one diameter above level of the first. A large, massive supracaudal gland, beginning at first procurrent caudal ray, occupies three-fourths the distance from there to end of base of adipose fin. This gland extends above the dorsal profile and slightly down along the lateral surface of the peduncle; its width is about one-fourth its length. The paralectotype has a gland of almost identical proportions. As in Loweina laiirae, L. rara, and L. terminata, the numbers of photophores of L. inter- rupta may be variable within the i-espective patterns. Maul (1946, p. 26, fig. 9) reported a male (28.5 mm) of L. interrupta, caught alive at night in Funchal Harbor, that had 3 VO, "One close behind ventral base and two close together just before vent, leaving thus a long interval between them and the front one." This specimen also had 5 PO and 4 AOa on the left side, and 6 PO and AOa on the right side. Tarletonbeania Eigenmann and Eigenmann, 1890 One Pre; 1 Pol. Lateral line undeveloped externally, only the first 2 or 3 scales perforated. Suo present. PO 6-7; VO 5-7; 3 SAO, the series slightly angulate. Caudal luminous glands on males only. Key to species of Tarletonbeania la. Supracaudal luminous gland of males long, slender, usually filling the supracaudal space; infracaudal gland of males, if present, is short, very weakly developed, and hidden under body scales T. crenularis lb. Males with short, bulky luminous glands on both surfaces of caudal peduncle T. taylori 81 TarletonbeanJa crenularis (Jordan and Gilbert, 1880) Fig. 69 — Tarletonbeania crenularis. From Bolin (1939, p. 101, female, (B. ) Caudal peduncle of adult male. fig. 5). (A.) Adult D. 12 (11-14); A. 18 (17-20); P. 13 (11-15); AO 10 (9-11) + 4 (3-5), total 15 (13-16); gill rakers 5 (4-6) + 1 + 10 (9-11), total 16 (15-18); vertebrae 40-41. Dorsal origin slightly before midpoint of body and about over a point midway between pelvic and anal origins. One undivided, long, thin supracaudal luminous gland and occasion- ally a very weakly developed, inconspicuous infracaudal gland, in males only. Females bear no caudal luminous glands. Size: To about 70 mm. Least depth of capture: At surface at night. Distribution: Pacific coast of North America from about 50° to 30° N. The seaward range within these latitudes is not well delineated but probably lies within the California Current. Records of occurrences from above 45° N are unreliable unless based on males (see T. taylori). Tarletonbeania taylori Mead, 1953 Fig. 70 — Caudal peduncle of adult male of Tarletonbeania taylori, showing the short, bulky supracaudal and infracaudal glands. 82 Description D. 13 (12-14); A. 18 (17-20); P. 13 (11-15); AO 11 (10-13) + 5 (3-6), total 16 (14-18); gill rakers 5 (4-6) -I- 1 -h 10 (9-11), total 16 (14-18); vertebrae 41 (40-42). Basically, T. taylori is very similar in appearance to T. crenularis. It differs principally in the short, bulky supracaudal and infracaudal luminous glands of males that stand well above the peduncular profiles; this is in contrast to the thin, elongate band of T. crenularis, in which neither of the caudal glands are raised above the peduncular profiles. Females bear no caudal luminous glands. Size: To about 70 mm. Least depth of capture: At surface at night. Distribution: Across the North Pacific from norther Honshu, Japan, to about 45° N along the North American coast. Discussion The existence of the infracaudal luminous gland of T. cren ularis has been discussed by Wisner (1959) and Becker (1963c). Wisner stated that the males of T. crenularis bore only a pale, elongate area in the region usually occupied by the infracaudal gland of T. taylori. Becker interpreted this pale area as an infracaudal gland and reduced T. taylori to a sub- species of T. crenularis, despite the very notable differences in the appearance and size of both the supracaudal and infracaudal glands of each species. Subsequent examination has shown that a thin, fragile layer of apparently luminous tissue, coinciding with the pale infracaudal area, is present on some but not all males of T. crenularis; the overlying scales must be removed before this tissue is visible. In no way does this fragile tissue resemble in appearance the bulky infracaudal gland of males of T. taylori (Fig. 70). Also, in none of hundreds of specimens of T. taylori examined did the short and bulky supracaudal gland resemble the long and thin one of T. crenularis. Although the females of the two species bear no caudal luminous glands, and they and the immature forms cannot now be separated as to species by reason of very similar counts and body proportions, the marked difference in the caudal glands of males appears to justify retention of T. crenularis and T. taylori as separate species until more detailed studies of these glands are made. Gonicthys Gistel, 1850 Supraorbital (Suo) photophore absent. Lateral line complete, or nearly so. PLO at level of origin of pectoral fin. SAO broadly angulate. Caudal peduncle long, slender, its least depth less than orbital length. Two Pre on same level, very low on caudal peduncle. Luminous scales in caudal glands separate or slightly overlapping. The four presently recognized species of Gonichthys in the eastern Pacific Ocean are superficially very similar, and only the species G. tenuiculus is figured. Key to species of Gonichthys la. Lateral line complete, all scales perforated 2 lb. Lateral line incomplete, at least a few of the posteriormost scales not perforated 3 2a. Anal rays 18(17-20); pectoral rays 12-13; 3 to 5 AOp over anal base G. tenuiculus 2b. Anal rays 22 (20-24); pectoral rays 16(13-18); 5 to 7 AOp over anal base G. barnesi 3a. Only the last 3 or 4 scales of lateral line unperforated; 5 to 6 (rarely 7) AOp over anal base G. venetus 3b. Last perforated scale of lateral line under or before adipose-fin base; 4 to 6 AOp over anal base G. cocco 83 Gonichthys tenuiculus (Garman, 1899) Fig. 71 — Gonichthys tenuiculus, male, 52.5 mm. Description D.IK 10-12); A. 18 (17-20); P. 12-13; AO 6 (5-7) + 11 (9-13), total 17 (15-19); gill rakers (all rudiments included) 5 (4-6) -H 1 + 9 (7-11), total 14 (12-17); vertebrae 39-40 (38-41 ). Only G. tenuiculus is illustrated, since all other species of the genus are superficially very similar. Body elongate, slender, deepest anteriorly, tapering evenly from origin of dorsal fin to long, slender caudal peduncle. Pectoral fin reaches to over VO^. SAO, over VO^;.., interspace, slightly nearer to VOj. SAO^ about over VOj; SAO;, about over, or a little before, first AOa. SAO:i and Pol about two diameters below lateral line. VLO its diameter behind a vertical from origin of pelvic base and above it by a third, often slightly less, of the distance to lateral line, and usually slightly below, occasionally on, a line from PVO:> to SAO,. Usually 3 or 4 AOp over anal base north of, and 4 or 5 south of, the equator. Size: To about 50 mm. Least depth of capture: At surface at night. Distribution: Found principally in tropical waters but also near the Americas to about 32° N and 22° S (Fig. 72). The lack of collections in the southeastern area, west of the Peru Current, precludes conjecture as to its occurrence there. I did not take the species in 1969 while working on a northeasterly course from Easter Island to about 90° W. Discussion Although G. tenuiculus has a wide north-south distribution, I have found no appreciably significant differences in meristic characters between specimens from the extremes of the range. Gonichthys barnesi Whitley, 1043) Description D. 12 (11-13); A. 22 (21-23, rarely 20 or 24); P. 16 (14-17, rarely 13 or 18); AO 7 (5-8) + 12 (10-14), total 19 (16-21 ); gill rakers (including all rudiments) 5 (4-6) -h 1 -H 8-9 (7-11), total 15 (12-18); vertebrae 40-41. Gonichthys barnesi is basically similar to G. tenuiculus, differing primarily in having a shorter pectoral fin, reaching to about over VO^ rather than to over VO4, and Pol somewhat farther forward. Also, body proportions listed by Becker (1964a) indicate the anal base of G. barnesi to be somewhat longer than that of G. tenuiculus: (in percent of standard length) 28.1 (27.1-29.5) vs 24.3 (23.0-26.1 ). Five to 6, occasionally 7, AOp over anal base. 84 Size: To about 50 mm. Least depth of capture: At surface at night. Distribution: Probably circumglobal between 30° and 40° S. The localities of the few specimens examined in this study are shown in Fig. 72. Craddock and Mead (1970) reported (as questionable) 172 specimens (21-49 mm) from the southeastern Pacific Ocean between about 3 1° and 34° S, west of 77° W. I have seen one specimen (25 mm SL) from 25° S, 155° W. Gonichthys venetus Becker, 1964 Description D. 11 (10-12); A. 20 (19-21); P. 14 (13-16); AO 5-6 (4-7) + 12 (10-14), total 18 (16-19); gill rakers (including rudiments) 4 (3-5) +1 + 8 (6-9), total 13 (11-14); vertebrae 40-41. Lateral line incomplete, the last 3 or 4 scales not perforated (see discussion below). Greatest body depth at vertical of pectoral origin, rather than at dorsal origin. Size: To about 40 mm. Least depth of capture: At surface at night. Distribution: Known from northerly of New Zealand and from about 20°-30° S, 80°-110° W (Fig. 72). A possible subspecies (see below) occurs in equatorial waters south and southeasterly of Hawaii (designated by solid squares in Fig. 72). Gonichthys cocco (Cocco, 1829) Description D. 11-12; A. 20 (19-21); P. 13 (11-14); AO 6 (5-7) + 12-13 (11-14), total 18 (17-19); gill rakers (including all rudiments) 4-5 (6) + 1 + 7 (6), total 12 (11-13); vertebrae 40-41. Lateral line incomplete, the last perforated scale lying under, or slightly before or behind, base of adipose fin. Five to 6 AOp over anal base. Size: To 36 mm. Least depth of capture: At surface at night. Distribution and discussion: The placing of G. cocco, known primarily from the North Atlantic Ocean, in the southeastern Pacific Ocean is based principally on the finding of 36 specimens from five localities (Fig. 72) that have the first externally visible lateral line pore (and perforated scale) before a vertical from origin of adipose fin, a diagnostic character cited by Bolin (1959) and Becker (1964a). In general, the counts for the southeastern Pacific speci- mens agree well with those giv€n by Bolin for the North Atlantic specimens, except that the numbers of rays in the anal fin average 2 less in the southeastern Pacific, and are similar to the count for G. venetus (see above). 85 1 \ A n T r \^ X^'-" 1 1 \w \ • J_— A—— J^ m \ \. \ \ • ». T'^ v \ .t • \ -tn • • • ••1 • \ 4myT r< ■• • 1^ • • • • . 1 »' 0 16 0° ■ a '^ 0° *• • 130° 120° . 11 y° • • • *00°» • J I 80'' • • • • > • 1, 1 1 •1 H •1 ; 4i4 P' 1 44 m - L^ ' frrt^ ^ 1 1 / / i h ^ L // V v; / ^ / J Fig. 72 — Capture localities in the eastern Pacific Ocean for Gonichthys tenuicutus (small solid circles), G. venetus (large open circles), G. venetus s. sp. (open squares), G. cocco (open triangles), and G. barnesi (solid triangles). Bolin (1959) stated that a form with an incomplete lateral line ranged westward from the coast of South America in a narrow band centered on 25° S; he further stated that it was uncertain whether these fishes represented an isolated population of Gonichthys cocco (Cocco, 1829) or an undescribed species. As suggested by Becker (1964a), it is probable that this form is referrable to G. venetus. However, Becker stated that G. venetus is closely related to G. cocco and it may eventually be reduced to a subspecies. The principal character separating the two is that in G. cocco the last perforated scale of the lateral line lies under or in advance of the tip of the adipose fin (Bolin, 1959, key). Becker (1964a) gave a somewhat more anterior position for this scale, "beside a vertical from the origin of the adipose base," and stated that in G. venetus only the last 3 to 6 lateral line scales were unperforated. Most of Becker's study material (124 specimens) of G. venetus was from the west-central Pacific Ocean, northerly of New Zealand, and formed the basis for diagnosis of the species; all these specimens apparently have the last 3 to 6 lateral line scales unperforated. Becker discussed as a possible subspecies seven specimens from near the equator between about 140° and 155° W (Fig. 72, solid squares) that differed from the rest of the material principally in having all the lateral line scales perforated. Becker also stated that these specimens had a 86 somewhat greater preanal and predorsal length, a slightly shorter caudal peduncle, and longer pectoral fins. This form was not found among the few specimens examined by me. Based primarily on the above criterion, specimens answering well to both G. venetus and G. cocco were found in the southeastern Pacific (Fig. 72). However, in these specimens provi- sionally identified as G. cocco, the position of the last perforated scale generally was more in agreement with the criterion given by Bolin than that given by Becker, in that this scale was from 4 lateral line scales before to 2 behind a vertical from the tip of the adipose fin. Centrobranchus Fowler, 1904 Gill rakers poorly developed, reduced to a few small protuberances topped by slender spinules. Lateral line undeveloped, no perforated scales. One Pol; 2 Pre, close together on same level and widely separate from AOp. The four currently recognized species of Centrobranchus have been delineated by Becker ( 1964a); the following key to species and data have been taken largely from that study. Key to species of Centrobranchus la. SAO, usually slightly behind VO4 C. andreae lb. SAO, over or before VO;, (rarely slightly behind) 2 2a. Nasal rosette oval; snout length considerably greater than least depth of caudal peduncle. Four or 5 AOp over anal base C. choerocephalus 2b. Nasal rosette round; snout short, about equal to least depth of caudal peduncle 3 3a. Snout short, equal to or less than least depth of caudal peduncle. Depth of body slightly less than 4 times in standard length. Three or 4 AOp over anal base C. brevirostris 3b. Snout length equal to or slightly greater than least depth of caudal peduncle. Depth of body slightly greater than four times in standard length. Three (rarely 2 or 2) AOp over anal base C. nigroocellatus Centrobranchus andreae (Liitken, 1892) Fig. 73 — Centrobranchus andreae, male, 62.4 mm. Description D. 11(10-12); A. 18-19(17-20); P. 12-13 (11-14); AO 6-7 (rarely 5-8) -t- 10-11 (rarely 7-12), total 17 (15-19); vertebrae 38 (37-39). 87 SAO in a straight, or nearly so, steeply oblique line that passes through or near VO,. Nasal rosette always round. Three to 4 AOp over anal base. Five to 8 supracaudal and 4 to 7 infracaudal glands are evident on specimens of 22-25 mm. Numbers of AO photophores for the four species of Centrobranch us are given in Table 18. Size: To about 65 mm. Least depth of capture: At surface at night. Distribution: C. andreae may have a divided distribution, north and south of the equator, except in the east-central Pacific (Fig. 74). As yet not enough collections have been made to establish definite patterns of distribution. ^IVBE^"^ S flZiMuTn EOua.-a,e)E.l poCjE Fig. 74 — Capture localities for species of the genus Centrobranchus in the Pacific Ocean and a portion of the Indo-Pacific region, including species listed by Becker. 1964a (as noted). 88 Table 18. Numbers of AO Photophores for Species of the Genus Centrobranchus Species AOa Mean C. andreae* — 7 177 230 C. brevirostris* 30 309 81 — C. nigroocellalus (Atlantic Ocean) 23 104 19 — (Indian Ocean)* 11 131 51 9 C. choerocephalus (E.Pacific Ocean) 4 53 29 2 17 431 6.60 420 5.12 146 4.97 202 5.29 5.33 C. andreae* C. brevirostris* C. nigroocellatus (Atlantic Ocean I (Indian Ocean)* C. choerocephalus (E. Pacific Ocean) AOp 10 11 12 1 45 272 105 23 243 150 4 70 64 9 3 111 79 9 41 35 Mean 431 10.16 420 9.32 146 8.54 202 9.47 10.36 Total AO photophores 12 13 14 15 16 17 C. andreae* — — — 13 123 252 C. brevirostris* — 7 229 175 9 — C. nigroocellatus (Atlantic Ocean) 5 69 65 6 1 — (Indian Ocean)* — 6 72 92 30 2 C. choerocephalus (E.Pacific Ocean) — — 6 28 43 9 42 19 Mean 431 16.76 420 14.44 146 13.51 202 14.75 15.69 *Data taken from Becker, 1964a. Centrobranchus brevirostris Becker, 1964 Fig. 75 — Centrobranchus brevirostris. From Becker (1964a, p. 53, fig. 21). Description D. IK 10-12); A. 17 (16-19); P. 15 (14-16); AO 5 (4-6) + 9 (8-11), total 14-15 (13-16); vertebrae 36-37. SAO usually in a straight, or nearly so, moderately oblique line which passes through or near VO^. Snout short, usually less than least depth of caudal peduncle. Body depth equal at 89 dorsal and pectoral origins and a little less than one-fourth of standard length. Nasal rosette round. Three (4) AOp over anal base. Five to 7 supracaudal and 4 to 6 infracaudal luminous glands are evident on specimens of about 20 mm SL. Size: To about 40 mm. Least depth of capture: At surface at night. Distribution: The range of C. breuirostris, known primarily from the northwestern Pacific, extends in a narrow band from about the North Tropical Convergence to the southern bound- ary of the North Pacific Drift (Fig. 74). Discussion C. breuirostris is so very similar to C. nigroocellatus of the North Atlantic Ocean that it may be at best only a subspecies. Until a more detailed comparison is made I feel it best to retain Becker's species. Centrobranchus nigroocellatus (Gunther, 1873) Fig. 76 — Centrobranchus nigroocellatus. From Becker (1964a, p. 59, fig. 24). Description D. 10 (9-11); A. 18 (17-19); P. 15 (14-17); AO 5 (4-7) -H 9 (8-11), total 15 (13-17); vertebrae 36 (35-37) (based on Atlantic specimens). Snout length about equal to least depth of caudal peduncle, over half the orbital diameter. Greatest body depth a little less than one-fourth of standard length. Nasal rosette round. Three or 4 AOp over anal base. Six (5-7) supracaudal and 5 (3-6) infracaudal luminous glands evident on specimens as small as 20 mm. Size: To about 40 mm. Least depth of capture: At surface at night. Distribution: The range of C. nigroocellatus appears to lie in the Indian Ocean, with one occurrence noted in the southwestern Pacific at 29°52' S, 172°00' W (Becker, 1964a). It has not yet been reported from the eastern Pacific (Fig. 74). 90 Centrobranchus choerocephalus Fowler, 1904 Fig. 77 — Centrobranchus choerocephalus. From Becker ( 1964a, p. 62, fig. 25). Description D. 10 (9-11); A. 18 (17-19); P. 15 (14-17); AO 5-6 (4 7) + 10-11 (9-12), total 15-16 (13-18); vertebrae 38-39 (37-40). Nasal rosette oval. Body slender; least depth of caudal peduncle considerably less than orbital diameter or snout length. At least 4 AOp over anal base. Six to 7 supracaudal and 5 (4-6) infracaudal luminous glands evident on specimens of 20 to 25 mm. Size: To about 40 mm. Least depth of capture: At surface at night. Distribution: Centrobranchus choerocephalus, the most abundant, or at least the most collected, species of the genus, appears to have at least two more or less segregated groups separated by about 10° of latitude at the equator, from about 05° N to at least 05° S (Fig. 74). This zone, at least in the eastern Pacific, has been rather well collected, and particularly so in the extreme eastern sector. Except for this break at the equator, the range of the species appears to extend between the North and South Tropical Convergences. The Diaphid Fishes Genera Lobianchia and Diaphus l/n So, j/Q AOai^efior /lO posterior Fig. 78 — Diagram of a fictitious diaphid fish showing the location and terminology of commonly occurring photo- phores. From Nafpaktitis (1968, p. 8, fig. 2). 91 The diaphid fishes, a rather difficult group taxonomically, are still not well understood throughout the world oceans. Although some species are quite distinctive, most are difficult to distinguish, a difficulty due in part to a very extensive overlap in many characters. The number of fin rays and anal photophores (AOa and AOp) are, with few exceptions, rather constant among species. The number of gill rakers and the positions of certain photophores (PLO, VLO, SAOi and SAO3, Pol and Prc4, and the AOa and AOp series) are of greatest use in separating species. However, there is variation in numbers of gill rakers within species, particularly among those of worldwide distribution, and there is some inconstancy in the positioning of the photophores named above. Seldom are the relative positions of the fins of taxonomic value. If only adults or young adults in good condition are considered, the luminous organs of the head (variations of the Dn and Vn organs common to other genera of the family) will in most cases serve to delimit species groups, and some species. But, in some groups there are often distinct differences in these organs between adults and juveniles and between males and females. Unfortunately, these organs are tender and easily damaged or lost. However, despite these obstacles, it is possible to arrange the species into groups (albeit rather broad groups) on the basis of the kind and arrangement of the luminous organs of the head; the principal categories of the key to species used here are based on these arrangements (for adults and young adults only). This was attempted by Fraser-Brunner (1949), who employed four sub- genera, Hyperphotops Fraser-Brunner, 1949; Partthophos Jordan and Hubbs, 1925; Lam- prossa Jordan and Hubbs, 1925; and Diaphus Eigenmann and Eigenmann, 1890. Bolin (1959) segregated into the genus Lobianchia some species formerly placed in sub- genus Hyperphotops, primarily on the basis of the presence of supracaudal and infracaudal luminous glands — glands not present in other diaphid species. Also, Bolin, on the basis of dentition, placed the remaining species in two genera, Aethoprora Goode and Bean, 1896, and Diaphus Eigenmann and Eigenmann, 1890. The genus Diaphus was characterised as having an inner series of broad-based, sharply recurved teeth on the posterior part of the upper jaw. Teeth of the outer series of the upper jaw and dentary of genus Aethoprora were described as small and closely set, with those of the inner series somewhat enlarged and tending to be more widely spaced, particularly on the dentary. The types of luminous organs of the head appear to coincide with the respective types of dentition in that the genus Diaphus (as restricted by Bolin) has the Dn and Vn widely sepa- rated and, in addition, a more or less prominent suborbital organ (So); the genus Aethoprora has a well-defined Dn and often has the Vn elongated and extending upward and contiguous or confluent with Dn, but has no So. Moser and Ahlstrom (1974) supported the concept of three genera by demonstrating that the larvae of Lobianchia, Aethoprora, and Diaphus differ recognizably. However, they re- ported on the larvae of only one species each of the latter plus two genera — Diaphus theta and D. paciftcus (Aethoprora group). Nafpaktitis (1968) suggested that only the two genera Lobianchia and Diaphus be consid- ered valid. His examination of large numbers of specimens of diaphid series revealed that the premaxillary teeth displayed a series of gradually changing shapes and that species with luminous organs of the head that differed considerably from those species assigned to genus Diaphus (as restricted by Bolin) had dentition closely resembling that of that genus. Nafpak- titis concluded, in addition, that although these luminous organs were generally useful in separating species groups, their structure, development, and considerable variation in appear- ance, plus certain instances of striking sexual dimorphism, were at present too poorly under- stood to warrant separation into genera. 1 concur in this opinion. The finding of overlap in types of dentition, the incomplete knowledge of development of luminous organs of the head and transitional states of develop- ment between the two proposed genera, plus the as yet meager (although cogent) evidence of differences in larval types, indicate that more study is needed before adding more confusion to 92 a sufficiently difficult group. Therefore, only the genera Lobianchia and Diaphus are recog- nized herein. The species oi Diaphus treated herein are segregated more or less by the type of luminous organs of the head (see Fig. 83) only as a convenience to the student, and there is no intention to represent a truly phylogenetic relationship. I have seen only adult, or young adult, speci- mens, and information on the development with age of the head organs of the very young of most species must await further study. It is important to remember that the species treated in the following key to identification may not represent the total actually occupying the eastern Pacific Ocean, since the south- central and western portions are still poorly collected. Many of the species were originally described and known only from the Atlantic Ocean, or from the Indo-Pacific region and from near New Zealand. Often these were represented by only a few specimens, frequently in poor condition, and it was not possible to compare specimens from widely separate localities. Thus, there was seldom an indication as to whether those found in the eastern Pacific were different or truly identical with those of distant waters, and, perhaps, were expatriates. An attempt has been made to include species which may conceivably occur in the eastern Pacific, largely because they are known to occur in water masses that impinge on those of the area of study. Predictably, several taxonomic problems were encountered. One that I am presently un- able to solve involves at least seven apparently distinct forms, or species. Four of these conform reasonably well to Brauer's (1906) description and figure of Diaphus fulgens (from the tropical Indian Ocean), and one may be that species; three other forms are very similar to D. rafines- quii (Cocco, 1838), presently known only from the Atlantic Ocean. Two species described by Gilbert (1908) and based on juveniles from near Nukuhiva, Marquesas, Diaphus nanus and D. agassizi, the types respectively 17 and 21 mm long, also present problems. One of the fulgens- like forms may represent D. nanus, but I cannot at all place D. agassizi. Fraser-Brunner (1949) placed/), agassizi in the subgenus Hyperphotops (= Lobianchia), apparently because of the presence of only a Dn, as described and figured by Gilbert. But, as shown by Nafpaktitis (1968), very often diaphid fishes of about 20 mm or less have only the Dn visible, regardless of the ultimate development of other head organs. It is thus quite probable that D. agassizi should not be placed in that group having only a Dn, a character now consid- ered as confined to the genus Lobianchia. Indeed, the patterns of body photophores are quite unlike that of L. gemellarii, L. dofleini, or L. urolampa, although they are basically more like those of the latter species. I have seen no large specimens bearing only a Dn that conform to the description and figure presented by Gilbert ( 1908) for the diminutive holotype ofD. agas- sizi . It is hoped that the obvious shortcomings and inadequacies of this effort on diaphid fishes of the eastern Pacific Ocean will induce others to undertake studies on this very interesting but quite exasperating group of fishes. Lobianchia Gatti, 1903 Five VO, the first 3 usually in an ascending oblique line ( VO2 raised to level of VO:j in one species ). Luminous organs of head limited to a small, inconspicuous Dn. No luminous scales at PLO. A long supracaudal luminous gland present in adult males; a shorter, rather inconspicu- ous infracaudal gland present in adult females. One Pol; 4 Pre. Key to species of Lobianchia la. All upper photophores at or very near lateral line. First 3 VO not in a straight ascending series, VO;. raised to level of VO.,. Only 2 SAO photophores. First AOa highly elevated L. urolampa lb. All photophores well below lateral line. First 3 VO in a straight, ascending series. Three SAO. First AOa not, or but little, elevated 2 93 2a. VLO about midway between pelvic origin and lateral line. Gill rakers 4 + 1 + 10 {Near L. gemellarii) VLO markedly nearer pelvic base than to lateral line. Gill rakers 5 + 1 + 12-14 3 Pol about midway between lateral line and anal base, usually lower. SAO series straight or slightly curved, the convexity directed anterodorsally. Pre evenly spaced, the last some- times a little displaced posteriorly; Prc:,.4 interspace always less than that between Pre,.., L. gemellarii Pol nearer lateral line than to anal base, the distance between the two two to two and one-half times that between Pol and lateral line. SAO in a gentle arc, the convexity directed posteroventrally. Prc3.4 interspace large, usually greater than, or at least equal to, that between Pre,.,-, L. dofleini 2b 3a 3h LobJanchia urolampa (Gilbert and Cramer, 1897) Fig. 79 — Lobianchia urolampa , male, 84.0 mm. Description D. 15; A. 15; P. 14-15; AO 7 -h 6; gill rakers 6 -I- 1 + 13-14, total 20-21; vertebrae 35 (5 specimens). L. urolampa is readily distinguished from other species of the genus by the high positions of the PLO, VLO, SAO:,, and Pol, all at or near lateral line. Other equally distinctive charac- ters are the high and nearly equally elevated VOj and VO3, the highly elevated first and last AOa, and the presence (apparently) of but 2 SAO. None of these characters are present in any other known species o{ Lobianchia. Supracaudal luminous gland rather short, filling half, or slightly more, of upper surface of caudal peduncle; this gland is shorter and much less robust than those of L. gemellarii or L. dofleini; the 5 to 7 individual luminous scales are poorly defined and not delimited by lines of pigment in the five males (69-87 mm) before me. I have seen no females and can offer no information concerning infracaudal luminous glands. L. urolampa was originally figured as having only 2 SAO, but Fraser-Brunner (1949) figured 3. On the 10 sides before me there are but 2 SAO (Fig. 79). The first is almost directly over VO.^ and a little less than midway between there and lateral line; the second is at lateral line and slightly behind a line through V0-, and SAO,. Gilbert and Cramer (1897, PI. 38, fig. 1) show this configuration, but in the text (p. 408) stated "Supraanals 3, forming nearly a right- angled triangle, with one of the spots above the hindmost ventral spot, the second immediately below the lateral line, and the third nearly above the first anterior anal spot." Such a configu- ration as these authors described is unknown in the family Myctophidae, and it would seem more reasonable to consider the posterior "spot" as an elevated AOa rather than a posteriorly displaced SAO. 94 Fraser-Brunner (1949) illustrated a third SAO ( = SAO,) asjust above VO-, and anterior to the middle SAO, the 3 organs closely spaced; an elevated first AOa and the 5 VO are shown in positions similar to those in Fig. 79 above. L. urolampa has no luminous scale at PLO — a finding in agreement with the original description. However, Fraser-Brunner figured this scale. Size: Largest of the five specimens before me, 86 mm. Gilbert and Cramer (1897) listed " — a range for seven specimens of 2 1/2 to 4 1/2 inches." Least depth of capture: Clarke (1973) stated that adults were taken in bottom trawls at depths between 124 and 190 m at night. Clarke also listed juveniles (25-26 mm) take at night from "100?" m, near Hawaii. Distribution: Known principally from the immediate area of the Hawaiian Islands. Lobianchia gemellarii (Cocco, 1838) Fig. 80 — Lobianchia gemellarii, male, 40.2 mm. Description D. 17 (16-18); A. 14 (13-15); P. 11-13; AO 4-5 + 6(5), total 10-11; gill rakers 5 -^ 1 + 12 (11-14), total 18 (17-20); vertebrae 35 (34). The characters given in the keys to L. gemellarii and L. dofleini (see above) are taken largely from Nafpaktitis (1968) and appear adequate for determining the species as found in the eastern Pacific Ocean, except for the following differences: In L. gemellarii from the eastern Pacific, PLO is as much as three times nearer pectoral origin than to lateral line; Pol is occasionally behind, rather than before or over end of anal base; and VLO ranges from about two times nearer pelvic base than to lateral line to about midway between. There also may be a difference in the structure of the infracaudal luminous gland in that females in good condition from the eastern Pacific have but 2 or 3 scales that form a short and broad-armed "Y." Nafpaktitis (1969, p. 14, fig. 4A') figured 6 scales for the North Atlantic form; it may be that some scales in the Pacific form have been lost, as there is some evidence of erosion, but there is no evidence of additional luminous scales on the better specimens. The supracaudal gland of a 30-mm specimen is evident but not fully formed. Size: To about 70 mm (largest of nine specimens). Least depth of capture: Clarke (1973) stated that in nighttime catches, only specimens 25 mm or less were taken above 100 m, those over 40 mm were taken from below 150 m, and substantial catches of larger fishes were made as deep as 300 m. 95 Distribution: The capture localities of L. gemellarii in the eastern Pacific indicate a widespread distribution (Fig. 81), although the captures appear to be sporadic — a cir- cumstance not readily explained. The few occurrences in the southeastern sector (including a possible new form) are bolstered by the taking of 21 specimens (24-59 mm) identified as L. gemellarii in the area of 3r-34° S, 77°-9r W (Craddock and Mead, 1970). Fig. 81— Capture localities for Lobianchia n. sp. ? (solid squares), L. gemellarii (open squares), and L. dofleini (open circles). Discussion Three specimens, two males from the southeastern Pacific and one female from the Indian Ocean, differ from L. gemellarii, as described above, in having VLO midway between lateral line and pelvic base, rather than much nearer the latter, and having 4+1 + 10 gill rakers instead of 5+ 1 + 12 (11-14). The two specimens (48 and 60 mm) from the southeastern Pacific have the supracaudal luminous gland typical of males of L. gemellarii. The Indian Ocean specimen (59 mm) has an infracaudal gland similar to the "Y" of the female from the Pacific Ocean. At present, inadequate material of L. gemellarii, in good condition, is available to deter- mine the limits of variation in numbers of gill rakers and positions of PLO and VLO, or to state whether these specimens are variants or represent an undescribed form. Lobianchia dofleini (Zugmayer, 1911) Description D. 16: A. 13; P. 12-13; AO 5 (4-6), total 10 (9-11); gill rakers 5+1+13 (14), total 19 (20); vertebrae 33-34. This species is basically very similar to L. gemellarii; Pol is nearer lateral line than to end of anal base and lies over or slightly before, but occasionally behind, that base. Last Pre far back on caudal rays. 96 Fig. 82 — Posterior region of Lobianchia dofleini, male, 35.0 mm. Infracaudal luminous glands of females from the eastern Pacific appear to differ consider- ably from those of North Atlantic specimens. Those from the eastern Pacific bear no more than 4 small scales, 2 in line on each side of the median in the space between last AOp and first Pre; this pattern differs notably from the cluster of 7 scales shown for the North Atlantic form by Nafpaktitis (1968, p. 14, fig. 4A). The supracaudal glands of males from both oceans are quite similar. Size: To 48 mm (largest of 60 specimens). Least depth of capture: All specimens before me were taken in tows to 500 m or more. Distribution: This species is apparently confined to the extreme southeastern Pacific Ocean (Fig. 81). I have seen no other specimen among thousands of diaphid fishes from other areas of the Pacific. Craddock and Mead (1970) reported the capture of 120 specimens in the southeastern area at about 31°-34° S, 88°-93° W. Diaphus Eigenmann and Eigenmann, 1890 Aphakic Space Fig. 83 — Head of a diaphid fish showing locations and terminology of characters used in identification. No single species will bear all the characters shown. 97 Always more than 1 luminous organ at orbital margin; these organs are of varied size, shape, and arrangement, and are connected by a varyingly wide band of darkly pigmented tissue. Supracaudal and infracaudal luminous glands absent. A luminous scale of varied size and shape at PLO is present in most species. Five VO, the first 3 in ascending series; 4 Pre. Key to species oi Diaphus in the eastern Pacific Ocean la. So present (Fig. 84A). Ant absent. Inner series of teeth of posterior portion of upper jaw broad-based, the tips sharply recurved 2 Dn-- Dn elongated g^g,, V" Vn (never occurring together) B Dn- Vn- Fig. 84 — Sketches of orbital regions of adult and young-adult diaphid fishes of the eastern Pacific Ocean, showing four combinations of luminous organs and their approximate locations. lb. So absent. Ant absent or present (Fig. 84 B, C, D). Inner series of teeth of upper jaw straight or slightly curved. If (rarely) slightly broad-based and recurved, it is to a much lesser degree than in those species having an So 9 2a. Pupil essentially round, no prominent (aphakic) space between lens and iris. Luminous organs of head small, always well separated 3 2b. Pupil elongated horizontally or vertically, a prominent (aphakic) space usually present anteriorly between lens and pupil (Fig. 83). Luminous organs of head variable in size, not necessarily well separated 4 3a. Dn, Vn, and So small, about equal in size, connected by a thin strand of dark tissue. Body photophores large, very closely spaced, the upper series low on body. SAO series in an 98 oblique line with VO5. Luminous scales at PLO large, the tissue in short wavy lines or convoluted D. anderseni 3b. Dn small but prominent; Vn minute*. So larger than Dn or Vn, very much enlarged in males, wedge-shaped, the apex anteriorly, filling space between upper jaw and orbital margin and extending to about under hind margin of orbit; So of females much shorter than in males, elliptical. SAO, on level of last 2 VO. Luminous scale at PLO small and thin, the tissue appearing as vertical striations D. diadematus* 4a. First AOa not or but very slightly elevated. Posterodorsal margin of operculum moder- ately angulate 5 5a. So behind vertical from posterior margin of pupil. No luminous scale at PLO 6 5b. So before vertical of posterior margin of pupil. Pupil more or less elongated horizontally. Luminous scale at PLO 7 6a. Pupil vertically elongate; a notable space usually present ventrally between lens and iris. Orbit large, 58-60% of upper jaw. So surrounded by and separated from Vn by dark pigment. A large, profusely ramified melanophore immediately posteroventral to So. Body deep, robust, its depth about 34% of SL. Photophores of upper series very low on body. Caudal peduncle short, deep. Vn long, underlying most of orbit, narrow in females, much widened in males; So a small knob at end of Vn D. brachycephalus 6b. Pupil round, no appreciable space ventrally between lens and iris. Orbit about 50% of upper jaw. So not surrounded by or separated from Vn by dark pigment. No large melanophore posteroventral to So. Very similar to D. brachycephalus (Ga) but body less deep and robust, its depth about 22-24% of SL D. richardsoni 7a. Caudal-peduncle length about 22-24% of SL, its depth 48% (44-51% ) of its length. Lumi- nous scale at PLO about half the pupil in size, the tissue in short, wavy lines radiating away from PLO D. theta 7b. Caudal peduncle very short and deep, its length 12-13% of SL, its depth 68% (65-71%') of its length. Luminous scale at PLO half or less the size of pupil, the tissue in short, wavy, laterally directed lines D. longleyi 8a. Posterodorsal margin of opercle notably angulate and recurved. Gill rakers 5-6 +1-1- 12-13; AO 5-6 + 3-4 (rarely 5). Luminous scale at PLO small, the tissue appearing convoluted or granular D. mollis 8b. Posterodorsal margin of operculum only moderately angulate and very little if at all recurved. Gill rakers highly variable in number, totals ranging from 13 to 27. Luminous scale at PLO large and prominent; absent in one form ...D. fulgens-rafinesquii (a complex) 9a. Ant absent (a tiny photophore-like and pigment-ringed luminous dot, present in some species above and often in contact with Dn, is not to be interpreted as an Ant). Pupil essentially round 10 9b. Ant present. Dn and Vncontiguous 25 10a. Dn and Vn widely separated 11 10b. Dn and Vn contiguous or confluent 16 11a. Vn elongated. Dn and Vn widely separated (Fig. 84B) 12 lib. Vn small, not elongated. Dn and Vn widely separated (Fig. 84B) 13 12a. Vn smooth on dorsal surface. Vn very much enlarged in males, wedge-shaped, the apex anteriorly, filling space between upper jaw and orbital margin and extending to about under hind margin of orbit D. diadematus 12b. Dorsal surface of Vn bearing 4 or 5 luminous dots embedded in a heavy streak of dark pigment and protruding into orbital rim. Vn long and slender in females, much more massive in males, extending under much of orbital rim. SAO, on level of last 2 VO. *D. diadematus may be more properly placed in that group having the Dn and Vn widely separated (couplet 111 and connected by a strand of dark tissue bearing one or more dots of luminous tissue. However, one of these dots is often enlarged and may be interpreted as a small Vn, and the larger posterior organ as an So. 99 Luminous scale at PLO about one and one-half to one and three-fourths the size of pupil, the tissue in intermittent, rather horizontal lines D. lutkeni 13a. Dn and Vn both very small, inconspicuous; Vn at anteroventral margin of orbit. PLO near lateral line. AOa, not or but slightly elevated; last AOa often slightly elevated. SAO distinctly angulate; SAO 1.2 interspace half or less that of SAOj..'). Luminous scale at PLO about size of pupil, the tissue in more or less vertical lines D. dumerili 13b. Dn and Vn small but conspicuous, Vn somewhat the larger, more or less rounded, occa- sionally protruding into orbital rim, a little before vertical from hind margin of orbit. ...14 14a. Vn rounded or horizontally elliptical. AOai seldom elevated by more than half its diame- ter above level of AOa^. PLO nearer pectoral origin than to lateral line; VLO midway or lower between pelvic origin and lateral line. SAOs and Pol two to four diameters below lateral line; SAO interspaces nearly equal. No luminous scales at any photophore other than PLO, this scale three to four times larger than PLO, the tissue in wavy, roughly vertical lines D. tennophilus 14b. Vn triangular. First AOa elevated to about level of SAO2 15 15a. Small mounds of pigmented tissue protruding into ventral margin of orbit anterior to Vn. Luminous scales adjacent to PLO, VLO, SAO:i, Pol, and Prc4. Total gill rakers 24-25 (22-26) D.trachops 15b. No small mounds of pigmented tissue anterior to Vn. A luminous scale present only at PLO. Total gill rakers 22 (21-23) D. similis 16a. One or more of the last few AOp elevated, the last usually the highest. PLO and VLO much nearer lateral line than to pectoral and pelvic bases. Pre interspaces increasingly wider. Luminous scale at PLO about the size of pupil, the tissue in short, somewhat vertical lines D. regani 16b. Last few AOp photophoreson same level asothers 17 17a. Total gill rakers 13-14 (4 + 1 + 9 (8) ). PLO below level of VLO and slightly nearer pectoral base than to lateral line; VLO slightly nearer lateral line than to pelvic base. SAO3 well behind a line through the almost vertically placed SAOi.^- Luminous scale at PLO small, 0.50 to 0.75 in pupil, the tissue in wavy or convoluted lines directed posteriorly D. problematic us 17b. Total gill rakers 16 or more 18 18a. SAO., and Pol two or more of their diameters below lateral line 19 18b. SAOii and Pol ator very near lateral line 20 19a. VO:! always below a line through PLO, VLO, and SAO2. SAOi on same level as last 2 VO. Vn of males not extending up behind Dn and displacing it forward. Luminous scales at PLO roughly ovoid horizontally, slightly larger than pupil, the tissue in long, nearly vertical lines D.jenseni 19b. VO., on a line through PLO, VLO, SAO,, and AOa, (AOa, very rarely not elevated). SAO, its diameter above level of last 2 VO. Vn of males with an occasionally isolated lobe extending up behind Dn and displacing it forward; this lobe of Vn then resembles an Ant. Vn of females often not quite contiguous with Dn. Luminous scale at PLO as large as, often slightly larger than, pupil, the tissue in long, nearly vertical lines D. pacificus 20a. Posterodorsal margin of operculum strongly lobed, recurved, weakly serrate in adults. Dn of both sexes large, half or more the vertical diameter of orbit. Body photophores notably small. Head deep, 80-85'7f of its length. Luminous scale at PLO slightly larger than pupil, the tissue convoluted D. lucidus 20b. Posterodorsal margin of operculum not strongly lobed 21 21a. First 3 Pre closely and rather evenly spaced, the fourth widely separated 22 21b. All Pre separated by two or more diameters, the spacing often becoming progressively wider 23 22a. PLO nearer pectoral base than to lateral line; VLO usually nearer lateral line than to pelvic base, but sometimes midway between. SAO2 and AOa, well below a line through PLO and VLO. Dn expanded to over nasal apparatus, particularly in males. Luminous 100 scale at PLO two or three times PLO in size, the tissue in short, irregular, somewhat vertical lines D. malayanus 22b. PLO always, VLO usually, nearer lateral line than to pectoral and pelvic bases. SAO2 and AOa, usually above, rarely on, a line through PLO and VLO. Dn of males much enlarged, that of females small. Luminous scale at PLO somewhat rectangular, about as large as pupil, the tissue convoluted D. garmani 23a. PLO usually much nearer pectoral base than to lateral line; VLO always nearer lateral line than to pelvic base. A line through SAOi.j usually passes before SAO;,. Dn not expanded to over nasal rosette. Anterior end of frontal supraorbital bone produced into a strong, forward-directed spine. Luminous scale at PLO somewhat triangular, half or more the size of orbit, the tissue convoluted near center but in closely spaced, more or less parallel lines near margin D. splendidus 23b. PLO and VLO about on same level, both slightly nearer lateral line than to pectoral and pelvic bases, or about midway between. No AOp over anal base 24 24a. PLO and VLO much nearer lateral line than to pectoral and pelvic bases. AOai often over A0a2. Dn of males (only) expanded to over nasal rosette. Luminous scale at PLO slightly larger than pupil, the tissue in short, nearly vertical lines D. schmidti 24b. PLO and VLO only slightly nearer lateral line than to pectoral and pelvic bases, or about midway between. AOai usually over or distinctly behind AOa^. Luminous scale at PLO triangular, slightly larger than pupil, the tissue in closely spaced, wavy lines radiating away from PLO D. signatus 25a. Ant present. Inner row of teeth of lower jaw much enlarged, curved, rather widely and evenly spaced. PLO a little above level of VLO and nearer lateral line than to pectoral base. VLO slightly nearer pelvic base than to lateral line. SAOa and Pol at lateral line. Pre progressively more widely spaced. Luminous scale at PLO about half the size of pupil, the tissue in long, vertical lines D. fragilis 25b. Inner row of teeth of lower jaw not notably enlarged 26 26a. Head considerably longer than deep 27 26b. Head short, about as deep as long 32 27a. Ant much elongated and narrow, extending back under supraorbital bone to near hind margin of pupil. Dn small; Vn separated from Dn and extending under orbital rim to about midpupil. PLO much nearer pectoral base than to lateral line. VLO about midway between pelvic base and lateral line. Luminous scale at PLO large, roughly triangular, nearly filling space between PLO and pectoral fin, the apex rounded, the tissue finely convoluted D. adenomas 27b. Ant round or somewhat triangular 28 28a. SAO;, and Pol two to threeof their diameters below lateral line 29 28b. SAO3 and Pol at lateraHine 30 29a. Orbit about 3 in upper jaw. Dn small, not extending over nasal apparatus or to near median ethmoid crest. Gill rakers short and heavy, total rakers 19 (18-20). Luminous scale at PLO about half the pupil in size, the tissue convoluted D. coeruleus 29b. Orbit about 2 in upper jaw. Dn large, extending over nasal apparatus nearly to median ethmoid crest. SAOi low, slightly above level of VO5. First AOa elevated to above level of SAO2. Gill rakers long and slender; total rakers 25-26 (24-27). Luminous scale at PLO no more than twice the size of PLO, the tissue in wavy lines radiating from a point on anterior margin of scale D. rolfbolini 30a. Vn elongated posteriorly, extending below hind margin of pupil. PLO much nearer lat- eral line than to pectoral origin. Luminous scale at PLO about half the pupil in size, the tissue nearly horizontally striated, the scale thin and fragile D. chrysorhynchus 30b. Vn not elongated posteriorly but barely extending under anterior margin of pupil. PLO about midway between lateral line and pectoral origin 31 31a. Least depth of caudal peduncle 54% (52-55'7r) of length of peduncle. Body rather robust, its depth at pectoral origin 24% (23-25) of SL. Total gill rakers 28 (26-29). Luminous scale 101 31b. 32a. 32b. at PLO elliptical to triangular in shape, its length slightly greater than diameter of pupil, the tissue nearly vertically striated D. elucens Least depth of caudal peduncle 417c (40-42%) of length of peduncle. Body rather slender, its depth at pectoral origin 20% (19-21) of SL. Total gill rakers 25-26. Luminous scale at PLO vertically elliptical in shape, its length slightly greater than diameter of pupil, the tissue nearly horizontally striated D. gigas Vn not reaching to under orbital rim. SAO3 and Pol several of their diameters below lateral line. PLO and VLO about midway between lateral line and pectoral and pelvic bases. Posterodorsal margin of operculum moderately lobed and recurved. Photophores notably small. Luminous scale at PLO nearly equal to vertical diameter of pupil, the tissue in short, vertical lines D. ostenfeldi Vn greatly elongated to under orbital rim and ending in a distinct knob about under hind margin of pupil. SAO.j and Pol at lateral line. PLO and VLO much nearer lateral line than to pectoral and pelvic origins. Posterodorsal margin of operculum strongly lobed and recurved. Photophores notably small. Luminous scale at PLO about half the pupil in size, the tissue convoluted D. metopoclampus DiaphusdumerJIij (Bleeker, 1856) Fig. 85 — Diaphus dumerilii. female, 58.0 mm. Description The following data are taken from specimens from off Cabo Corrientes, Cuba. D. 14; A. 15 (16); P. 12-13; AO 7 (6) + 5 (6), total 12 (13); gill rakers 6 -I- 1 -I- 14 (six specimens); vertebrae 36 (35-37). Dn and Vn of females small, inconspicuous. Dn of males much enlarged dorsally, and elongated, reaching to about lower margin of nasal apparatus; Vn of males tiny. PLO much nearer lateral line than to pectoral base; VLO about midway between pelvic base and lateral line. First AOa not elevated, last AOa but slightly so. Size: To about 80 mm. Least depth of capture: At surface at night. Distribution: This species was not found among the extensive material examined for this study, and its occurrence in the eastern Pacific is doubtful, although Beebe and Vander Pyl (1944) reported it from off Acapulco, Mexico, and Fowler (1928) reported it from near Hawaii; the type locality is in the Malay Archipelago. Nafpaktitis(1968) reported the species as abundant in the tropical North Atlantic. Diaphus dumerilii is either very rarely taken in the eastern Pacific or the identifications from there are erroneous. 102 Diaphus termophilus (Taning, 1928) Fig. 86 — Diaphus termophilus, female, 48.0 mm. Description D. 13-14; A. 15-16; P. 12-13; AO 5-6 4- 4-5, total 10 (9-11); gill rakers 7 (6-8) + 1 + 12-13 (14), total 20-21 (19-22); vertebrae 35. PLO about over pectoral origin, or slightly behind, and much nearer that origin than to lateral line. VLO variously over bases of inner pelvic rays or on a point between there and base of outer ray. SAO series usually straight, occasionally slightly curved or angulate, and evenly spaced; SAO2.3 interspace usually no more than a half (rarely a full) photophore diameter wider than that between SAO, ;... SAd about half its diameter above level of VO-,. First and last AOa elevated above level of adjacent AOa by about half their diameters, seldom by more. Dn usually smaller than Vn, not deeply embedded. Vn variable in form (see Discussion ); several tiny dots of luminous (?) tissue are lightly embedded in a thin streak of dark tissue anterior to Vn along anteroventral margin of orbit. Luminous scale at PLO small, somewhat elongate, weakly formed, the tissue in almost vertical, slightly wavy lines. Size: To about 50 mm. Least depth of capture: To 100 m at night. Distribution: In the eastern Pacific Ocean D. termophilus appears to be confined to the equatorial region (Fig. 87). Clarke (1973) did not report the species from near Hawaii. Appa- rently D. termophilus occurs near Australia, for J. R. Paxton (personal communication) stated that specimens at the Sydney Museum were D. termophilus rather than the related species D. trachops and D. similis. Discussion Specimens of Diaphus termophilus from the eastern Pacific Ocean agree rather well with the diagnosis of the species given by Nafpaktitis (1968), based on North Atlantic material, except in numbers of gill rakers; that author listed 8 (rarely 9 or 7) + 15 (14-16), total 23-25 (rarely 26). The somewhat higher count of gill rakers for the North Atlantic material may indicate a specific difference, but until further studies are made, the name termophilus is retained for these specimens from the eastern Pacific Ocean. In addition to the possible interocean differences, there is an interesting variation in structure of the Vn in Pacific specimens. Two basic forms of Vn occur: One (Fig. 88, Form A) is rather full bodied and horizontally elliptical, the tissue in rather coarse horizontal striations, the general aspect closely resembling the Vn shown by Nafpaktitis (1968, p. 56, fig. 32). A second type of Vn (Fig. 88, Form B) is vertically elliptical, finely striated horizontally, and does not fill the total space in the outline of the organ, the posterior area usually being covered with a thin layer of reflective tissue. Specimens with the Vn as in Form A were taken in the eastern 103 Fig. 87 — Capture localities in the eastern Pacific Ocean for Diaphus trachops (solid circle), D. similis (open circles), D. termophilus (open and solid triangles — see text), and D. lutkeni (open squares), A locality for D. trachops, near Monterey, California, is not shown. equatorial area, and those of Form B in the more central portion. An insufficient number of specimens in good condition were available to resolve this intriguing problem. FORM A FORM B premaxillary 2 tn m Fig. 88 — Two forms of Vn o( Diaphus termophilus found in the eastern Pacific Ocean. 104 Diaphus similis Wisner, 1974 Fig. 89— Diaphus similis. holotype, 72.2 mm. From Wisner (1974, p. 7, fig. 4). Description D. 14; A. 15-16; P. 12-13 (14); AO 6 (5-7) + 5(4), total 11 (10-12); gill rakers 7 (6-8) -(- 1 + 14 (13-15), total 22 (21-23); vertebrae 35 (34-36). D. similis is very similar to D. trachops. It differs primarily in that Vn is more rounded or vertically elliptical (Fig. 90 B), and the streak of darkly pigmented tissue containing the Fig. 90 — Vn of (A) Diaphus trachops and (B) D. similus. and associated minute dots of whitish tissue embedded in the darkly pigmented tissue at ventral margin of orbit. 105 minute dots of whitish tissue anterior to Vn is not bulged upward above these dots, or at best any bulges are extremely minute and difficult to perceive. Also, D. similis has a scale of luminous tissue only at PLO, and has fewer gill rakers. AOa, is seldom elevated to the level of SAO;;, and the last AOa is somewhat less elevated than that of £>. trachops. Size: To about 72 mm. Least depth of capture: To about 170 m at night. Distribution: D. similis is known only from a small area of the eastern tropical Pacific Ocean bounded by about 04°-10° N, 87°-119° W (Fig. 88, open circles). Diaphus trachops Wisner, 1974 Fig. 91 — Diaphus trachops, holotype, 63.5 mm. From Wisner (1974, p. 5, fig. 2). Description D. 14; A. 15 (14-16); P. 12 (11-13); AO 6 (5-7) + 5-6, total 11 (10-12); gill rakers 8 (7-9) -^ 1 -I- 15-16 (14-17), total 24-25 (22-26); vertebrae 34-35. Dn small, round, deeply recessed. Vn prominent, triangular, about twice as large as Dn and protruding into orbital rim. The luminous tissue of Vn is vertically striated. Anterior to Vn, and embedded in a band of dark tissue, are 4 or 5 minute dots of whitish tissue (probably luminous); the pigmented tissue above these dots bulges upward in small domes that protrude slightly above orbital rim (Fig. 90 A) and are evident in specimens as small as 22 mm, but not in one of 15 mm. These protrusions, although much less prominent, resemble those that project notably from the Vn into the orbital rim o{ Diaphus luetkeni. AOa, elevated to level of SAO2; last AOa elevated to a line through VO3, SAOj, and AOa,. PLO slightly below midway be- tween lateral line and pelvic origin. Small scales of luminous tissues immediately posterior to PLO, VLO, SAO:,, Pol, and Prc4. Size: To about 64 mm. Least depth of capture: To 100 m at night. Distribution: Most specimens have been taken near Oahu, Hawaii (Fig. 87, solid circles). One specimen known from near Monterey, California (not shown in Fig. 87), may be a stray. 106 Diaphus luetkeni (Brauer, 1904) Fig. 92 — Diaphus lutkeni, male, 54.6 mm. Description D. 16; A. 15 (16); P. 11; AO 6 (5-7)+ 5 (4-6), total 11 (10-12); gill rakers 6-7 + 1 -H 14 (13-15), total 22 (20-23); vertebrae 35 (34-36). SAO in a straight or very slightly angulate line, the SAOo.i interspace nearly twice that of SAOi.o. First AOa elevated to about level of SAOj. Dorsal and anal bases overlap considerably. The elongated Vn of females is much narrower than that of males (Fig. 92) but has distinct, though usually smaller, "knobs" protruding into the orbital rim. Size: To about 60 mm. Least depth of capture: To about 90 m at night. Distribution: In the eastern Pacific, D. luetkeni is known only from a rather narrow sector of the tropical area (Fig. 87); it has not been taken in the extreme eastern sector despite considerable collecting effort. Diaphus diadematus Taning, 1932 Fig. 93 — Diaphus diadematus , male, 24.0 mm. 107 Fig. 94 — Diaphus diadematus. (A.) Head of adult female, (B.) Head of adult male. Note pronounced sexual dimorphism. From Taning (1932, p. 137, fig. 9). Description D. 13-14; A. 13-14; P. 10-12; AO 5 -h 5; gill rakers 5 (4) -h 1 -^ 10 (9), total 16 (15); vertebrae 33(34). PLO a little nearer pectoral base than to lateral line and before a vertical from that base; VLO much nearer lateral line than to pelvic base. SAO, on level of last 2 VO; SAO spacing about equal. The first 3 Pre nearly on same level, the third sometimes slightly raised; Prcj usually well separated from the rest and nearer lateral line than to ventral profile of caudal peduncle. The very large Vn of males is immediately diagnostic (Fig. 94 B); the small Vn of females (Fig. 94 A) is ovate and under posterior half of orbit. A streak of dark tissue extends along margin of orbit between Dn and Vn and bears one or more tiny dots of luminous tissue, one of which may be enlarged to resemble a third organ; the posteriormost organ may then erroneously be interpreted as an So. Size: To 33 mm, largest of 28 specimens; it may be a small species. Least depth of capture: To 500 m at night. Distribution: Probably circumglobal, mainly in southern waters. It is also known from the Atlantic and Indian Oceans near South Africa and from the Java Trench and Celebes Sea (06° N). Discussion The placement o{ Diaphus diadematus in the genus appears to depend on the degree of development and prominence of one of the luminous dots between the Dn and Vn. Fraser- Brunner ( 1949) considered such a dot to be a Vn and placed the species in that group having an So; he stated, "Posterior Vn larger than anterior one, the two separate from each other and from Dn." Of the 28 specimens before me, only five have this dot sufficiently developed to be readily visible and subject to misinterpretation; the dot is quite tiny and barely visible on the remaining specimens. Regardless of the degree of development of this luminous dot, I believe the proper place- ment of the species to be nearer Diaphus luetkeni than to those species having abona-fide So, because the elongated Vn of males of D. diadematus is more akin (albeit quite different) to that of D. luetkeni. Also, SAO, is on level of last 2 VO, a character common to D. luetkeni, D. termophilus, D. trachops and D. similis, but not found among those species having an So. 108 Diaphusgarmani Gilbert, 1906 Fig. 95 — Diaphus garmani, female, 51.6 mm. Description D. 15 (14-16); A. 16 (15-17); P. 11 (10-12); AO 7 (6-8) -^ 5 (4-6), total 12 (11-14); gill rakers 7 (6-8)-)- 1 -I- 13 (14), total 20 (19-21); vertebrae 35 (34-36). Pre series not widely spaced; Prc3.4 interspace about twice those between Prc,.2 and Prc-j.a. A small, round luminous organ lies above and slightly behind Dn; this organ is found also in D. problematic us andD. splendidus (following). Dn of males larger and more clearly defined than Dn of females. Vn larger than Dn in females, but of equal size or smaller than Dn in males. Size: To about 55 mm. Least depth of capture: Readily dip-netted at night and taken at 250 m or less in daytime. Nakamura (1970) reported hundreds of thousands ofD. garmani at the surface at night at Christmas Island. Distribution: Known from about 30° S, 80° W, northerly to about Acapulco, Mexico, wes- terly to Hawaii, and toward Japan to about 35°-40° N, 165° E (Fig. 96). Diaphus problematicus Parr, 1928 Fig. 96 — Diaphus problematicus, male, 50.8 mm. 109 Fig. 97— Capture localities in the eastern Pacific Ocean for Diaphus garmani (open trianglesi, D. schmidti (open circles), D.Jenseni (solid squares), and D. matayanus (solid circles). Description D. 16; A. 17; P. 12; AO 6 + 4-5; gill rakers 4+1 + 9(8) (the lowest count of any known diaphici species); vertebrae 35. Only four specimens were available for study; these all had the low gill raker count, but the PLO appears to be higher than that shown by Parr (1928) and by Nafpaktitis (1968) for specimens from the North Atlantic. One large and one small specimen had the SAO^ set behind a line through SAO1.2, a pattern similar to that found in D. splendidus and D. coeruleus. One AOp over anal base. Dn and Vn of about equal size and connected by a thin streak of luminous tissue close to orbital rim; Vn of males somewhat larger than that of females. Size: To about 80 mm. Least depth of capture: To 180 m at night. Distribution: In the eastern Pacific this species is known only from about 06° N to 10° S along 135° W. 110 Diaphus splendidus (Brauer, 1904) Fig. 98 — Diaphus splendidus. male, 84.5 mm. Description D. 14-15; A. 16; P. 12-13; AO 6 (7) + 5-6 (4), total 11 (10-12); gill rakers 5 -^ 1 -H 12 (11), total 18 (17); vertebrae 35-36. Anterior end of supraorbital ridge produced into a prominent, sharp point, a development not known in other diaphid species. If these points are broken off, the blunt, somewhat ragged stubs are diagnostic. SAC^ interspace slightly less than that of SAO2.3. Pre interspaces prog- ressively wider. AOa, at least its diameter before second AOa and often elevated nearly to level of SAO2. Dn and Vn of males a little larger than those of females. Size.- To 90 mm. Least depth of capture: To 90 m at night. Distribution: In the eastern Pacific this species is known only from a few specimens taken in an area from about 08° N to 12° S and 1 19° W to 162° W. . Diaphus schmidtj Tuning, 1932 Fig. 99— Diaphus schmidti. From Taning (1932, p. 139, fig. 11). Description D. 15-16; A. 16; P. 10-11; AO 6 (5-7) + 5 (4-6), total 11 (10-12); gill rakers 5-6 -F H- 12 (11-13), total 18-19 (17-20); vertebrae 35 (34-36). SAO series slightly angulate; the first two SAO in a nearly straight line with VO.-,; SAO2.3 interspace nearly twice that of SAOi.^- A line through PLO-VLO usually passes above SAO2 and AOa,; a line through SAO1.2 passes through or a little behind VO.^ First AOa elevated to nearly over second AOa and about on level of SAO2. Pre interspaces progressively wider. Dn 111 and Vn of females small, about equal in size, confluent behind nasal apparatus; both much enlarged in males, the Dn resembling that of D. malayanus . Eye small, about 5 in head. Size: To about 40 mm. Least depth of capture: To 100 m at night. Distribution: In the central and eastern Pacific Diaphus schmidti has been taken in a rather narrow band extending from Hawaii southeasterly to about 15° S, 104° W (Fig. 97). Its pattern of capture localities is very similar to that oi Diaphus jenseni. The type locality is north of Samoa. Diaphus regani Tuning, 1932 Fig. 100— Diaphus regani. From Tuning (1932, p. 140, fig. 12). Description 0.16(15-17); A. 16-17; P. 10-11; AO 6(5-7) -I- 5-6, total 12 (10-13); gill rakers 7 (8) -(- 1 + 13 (14), total 21 (22); vertebrae 36 (35-37). The elevation of the last few AOp will immediately justify this species. Dn and Vn but little larger in adult males than in adult females. First AOa elevated nearly to level of SAO^ and to nearly over second AOa. SAO series in a very steep line which passes slightly behind VO,. Size: To about 60 mm. Least depth of capture: To 50 m at night. Distribution: Type locality. New Caledonia. In the eastern Pacific, D. regani is known only from the equatorial region south of Hawaii between 150° and 160° W. Diaphus jenseni Tuning, 1932 Fig. 10\— Diaphus jenseni. male, 37.5 mm. 112 Description D. 14-15; A. 14-15; P. 10-11; AO 6 (5-7) + 5 (4-6), total 11(10-12); gill rakers 6 (5) 4- 1 + 13 (14), total 20 (19-21 ); vertebrae 35. PLO much nearer pectoral base than to lateral line; VLO about midway between pelvic base and lateral line. SAO.j one diameter, Pol and upper Pre two diameters, below lateral line. First 3 Pre low and closely spaced, the fourth widely separate and usually much farther back on base of caudal fin. Neither Dn or Vn much enlarged in males. Size: To about 40 mm. Least depth of capture: To 85 m at night. Distribution: In the central and eastern Pacific D.jenseni has been taken only in a rather narrow band extending southeasterly from near the equator at about 165° to 110° W between 10° to 20° S (Fig. 97). Apparently it does not occur north or east of these limits. The type locality is north of New Guinea. Diaphus malayanus Weber, 1913 Fig. 102 — Diaphus malayanus, male. 31.4 mm. Description D. 15 (14-16); A. 15; P. 11 (10-12); AO 6 (5-7) + 4 (5), total 10 (11); gill rakers 6 -^ 1 + 12 (13), total 19 (20); vertebrae 34 (35). PLO and VLO much nearer pectoral and pelvic bases than to lateral line. SAOt. Pol, and upper Pre at lateral line: Prc.j.j interspace equal to or greater than that between Prci and Prcs. SAO in a steeply oblique straight line. AOai elevated to level of SAO2. Size: To 30 mm. Least depth of capture: To 85 m at night. Distribution: In the eastern Pacific, D. malayanus is infrequently taken in equatorial waters between about 105° and 165° W (Fig. 97). The type locality is in Banda Sea. 113 Diaphus pacificus Parr, 1931 Fig. 103 — Diaphus pacificus. male, 31.8 mm. Description D. 14 (13-15); A. 12 (11-13); P. 10 (9); AO 4-5 + 4 (5), total 8-9 (10); gill rakers 7 (6-8) -H 1 + 13 (12-14), total 20 (19-22); vertebrae 32 (31-33). PLO and VLO respectively much nearer pectoral and pelvic bases than to lateral line. SAO3, Pol, and upper Pre two or three diameters below lateral line. First Aoa slightly elevated to about its diameter below level of SAO j; last AOa often slightly elevated. Pre usually evenly spaced, but the Prc3.4 interspace may be a little greater than the rest. Vn larger than Dn, often with a dorsal lobe that extends up behind Dn, particularly in males; this lobe of Vn may then be misinterpreted as an Ant. Luminous scales at PLO large, nearly filling space between PLO and pectoral fin, the tissue in rather straight vertical lines. Size: To about 35 mm. Least depth of capture: To 90 m at night. Distribution: Apparently confined to the eastern tropical Pacific (Fig. 104); it has not been taken elsewhere. Fig. 104 — Capture localities (or Diaphus pacificus. 114 Diaphussignatus Gilbert, 1908 Fig. 105 — Diaphus signatus, male, 49.5 mm. Description D, 15(16):A. 15(16);P. 11-12; A06(7) + 4 (5); gill rakers 6 (7) + 1 + 14 (15); vertebrae 35-36. Body elongate, its depth about 5.5 in SL. SAO3, Pol, and upper Pre at or very near lateral line. SAO2.:, interspace twice that of SAO, .2. SAO series usually straight, forming a line with VO.v First AOa elevated to about over, often distinctly behind, the second. Pre interspaces progressively wider, in a flattened curve, the last nearly over bases of caudal fin rays. Size: To about 60 mm. Least depth of capture: To 90 m at night. Distribution: In the central and eastern Pacific Diaphus signatus is known only from near the equator between about 165° and 134° W, One occurrence is known from about 11° S, 126° W. The type locality is Nukuhiva Island, Marquesas. Diaphus lucidus (Goode and Bean, 1896) Fig. 106 — Diaphus lucidus, male, 74.0 mm. Description D. 18(17-19); A. 17-18; P. 11-12; AO 7 + 5 (4-6), total 12 (11-13); gill rakers 5-6 -H H-11 (10-12), total 18 (16-19); vertebrae 36 (35-37). 115 SAOo..! interspace one and one-half to two times that of SAO,.-; SAO series in a steeply oblique, usually straight line that passes well behind VO,-,. AOa, elevated to about level of SAO^; last AOa but little elevated. Pre interspaces progressively wider, the last 3 in a nearly straight, oblique line. Luminous scale at PLO about three-fourths the vertical diameter of orbit, the tissue convoluted. Dn large, expanded to ethmoidal crest and of about equal size in both sexes; Vn extending posteriorly to under orbital margin and upward to Dn behind nasal apparatus; much of the Vn is covered by a heavy band of dark pigment. Dorsal origin usually somewhat before pelvic origin; bases of dorsal and anal fins and of anal and adipose fins overlapping. Size: To 78 mm in eastern Pacific. A 118-mm specimen has been taken in the southeastern Atlantic Ocean. Least depth of capture: To 175 m at night. Distribution: In the eastern Pacific eight specimens have been taken from an area from 01° S to 16° N and 130° to 137° W; one specimen known from 26° 14.0' N, 141° 34.5' W, and one from 03° 25' N, 126° 00' W. The type locality is in the northeastern Atlantic Ocean. Diaphusfragilis Tuning, 1928 Fig. 107 — Diaphusfragilis, male, 84.0 mm. Description D. 17-18; A. 17 (16-18); P. 11(12); AO 6 -H 5 (4), total 11(10); gill rakers 5-6 + 1 + 12 (11-13), total 19 (18-21); vertebrae 35 (36). Inner row of enlarged, rather widely spaced teeth on the lower jaw are immediately diagnostic of this species, even for specimens £.s small as 20 mm. PLO a little above midway between lateral line and pectoral origin; VLO about midway, occasionally slightly lower, between lateral line and pelvic origin. SAO2.3 interspace about one and one-half times that of SAO, .J. SAO series in a nearly straight, steeply oblique line; SAO., and Pol at lateral line. First and last AOa elevated. V0-, and SAO, ^ form gentle curve. Pre interspaces progressively wider. Opercular margin tapers to sharp point under PLO. Ant of males usually slightly larger and more sharply delineated than that of females. Size: To about 90 mm. Least depth of capture: To 100 m at night. Distribution: Known in eastern Pacific Ocean from about 23° S, 91° W, to the Hawaiian Islands and south to the equator. I have seen two specimens from about 40° N, 164° W (Fig. 108). 116 Fig. 108— Capture localities in the eastern Pacific Ocean for Diaphus fragilis (open trianglesl, D. gigas (solid squares*. D. elucens (open squares), and D. rolfbolini (open circles). Diaphus coeruleus (Klunzinger, 1871) Fig. 109 — Diaphus coeruleus, male. 94.0 mm. Description The only specimens available to me were off South Africa; these provided the following counts: D. 15-16; A. 15-16; P. 11;A0 6+ 5; gill rakers 5-6 + 1 + 12-13, total 19 (18-20); vertebrae 36. 117 Dn somewhat elongate, extending down to level of nasal apparatus; Ant close under the supraorbital ridge, about half the size of Dn; Vn long, extending from nearly under anterior margin of pupil up to and in contact with Dn; anteroventral portion of Vn enlarged, extending out to under the nasal apparatus. A prominent band of dark pigment separates Dn and Vn from the orbital rim. Size: To 140 mm. Least depth of capture: The South Africa specimens, from off Durban, were taken between 500 and 545 m in daylight (Galathea Sta. 197). Distribution: Diaphus coeruleus has not yet been taken from the eastern Pacific Ocean. Known primarily from the Indo-Pacific and western Pacific region and is included here in case it may be taken in the poorly collected west-central portion of the eastern Pacific. Diaphus chrysorhynchus Gilbert and Cramer, 1897 Fig. 110 — Diaphus chrysorhynchus, male, 62.0 ram. Description ■ D. 16-17; A. 16 (15-17); P. 12 (11); AO 6 (7) + 5(4-6), totalll (12); gill rakers 7 + 1 -h 14 (five specimens); vertebrae 35 (34-36). SAO in a steeply oblique line that passes a little behind VO5. SAO2.3 interspace at least twice that of SAO,.-; Pre interspaces progressively wider. The opercular margin tapers to sharp point below PLO. The adipose tissue covering the entire snout appears to be luminous. There is no information available on sexual dimorphism in the luminous organs of the head. All five specimens before me are males. Size: To about 80 mm. Least depth of capture: At surface at night, 500-600 m in daylight. Distribution: Known only from immediate area of Hawaiian Islands, the type locality. Diaphus adenomus Gilbert, 1905 Description D. 15 (14-16); A. 15; P. 11-12;A0 6 + 5-6, total 11-12; gill rakers 5 -^ 1 + 10-11, total 16-17 (Gilbert recorded 5-1- 1-1-13 rakers for the holotype, but I found b + I + 111 vertebrae. PLO and VLO slightly nearer lateral line than to pectoral and pelvic origins. First 3 VO in flatly oblique nearly horizontal line, VO:, about on a line from POj to SAO,. Three SAO in steeply oblique, nearly straight line that passes a little behind VO:,. First AOa elevated to 118 Fig. Ill — Diaphus adenomus, male, 103.7 mm. Fig. 112 — Diaphus adenomus. Head of adult male, 107.5 mm. showing arrangement of luminous organs level midway between SAO1.2. Last few AOa increasingly elevated toward, and about equally spaced with, Pol. Pre increasingly more widely spaced in a gentle arc, the chord of the arc slightly shorter than the AOp-Prc interspace. Vn and Ant ofD. adenomus are unique in that both are much elongated, the latter organ extending back over the orbital rim (Fig. 112); Dn rather small and not deeply recessed. Size: To 131 mm (Gilbert recorded "16 cm"; this may refer to total length). Least depth of capture: All specimens have been taken in hauls near the bottom from about 460 to 640 m. Distribution: Known mainly from Pacific Ocean near Hawaii and off Japan. It has re- cently been taken in the Caribbean Sea and in the Atlantic area near the Bahamas and off Casablanca, Morocco (Nafpaktitis, 1974). Discussion Nafpaktitis (1974), after comparing the holotypes, placed Diaphus anteorbitalis Gilbert (1913) in synonymy with D. adenomous. I concur, having also compared the holotypes. 119 Diaphus gigas Gilbert, 1913 Fig. 113 — Diaphus gigas, male, 44.9 mm. Description D. 16; A. 15; P. 12; AO 6 + 5, total 11; gill rakers 8 (7) + 1 + 16 (15-17), total 25 (23-26); vertebrae 35. PLO below lateral line about one-third the distance between lateral line and pectoral origin; VLO two or three diameters behind a vertical from pelvic origin and about midway between lateral line and level of pelvic base. VLO low, two or more diameters below a line through VLO-SAOj, SAO, its diameter above and behind VO-,; SAO2 about two diameters above, and almost directly over SAO,; SAOa its diameter behind a line through SAO,.-, about two diameters below lateral line and separated from SAO2 by a space about twice that between SAO, 2- First AOa elevated to about its diameter below level of SAO^; last AOa elevated by about two diameters above penultimate AOa, which is level with second, third, and fourth AOa. Pol at least its diameter below lateral line and under anterior position of base of adipose fin. Penultimate AOa-AOp, interspace about equal to that of AOp-Prc. Si^e: The largest of scant study material from the central Pacific Ocean was 57 mm. Gilbert stated the holotype to be "172 mm. in total length, 140 mm. to base of caudal, — " and the largest of two cotypes from Sagami Bay, Japan, as "21 cm." Least depth of capture: To 218 m at night. Distribution: In the eastern Pacific Ocean, known from only four localities (Fig. 108). Type locality is Sagami Bay, Japan, Discussion Diaphus gigas is very closely related to D. elucens in that the SAO.i and the Pol are close to the lateral line, and the preorbital luminous organs are much alike. However, the name gigas is applied here to the few specimens from the north-central Pacific (Fig. 108, solid squares) because they agree well in certain body proportions with the description, and in numbers of gill rakers (8 + 16) given by Gilbert. Body proportions for D. gigas, including those given by Gilbert, are given in Table 19, and are compared with similar data for D. elucens from the central Pacific and northern Atlantic Oceans. In general, D. gigas is more slender than D. elucens and has a shorter and less deep head and a smaller eye. 120 Table 19. Body Proportions for Diaphus gigas and D. elucens from the Pacific Ocean, and for D. elucens from from the North Atlantic Ocean Diaphus gigas Diaphus elucens North Pacific Holotype* Central Pacific North Atlantic** Measurement N = 3 140 mm N = = 10 N = = 44 (49-57 mm) ( 43-56 mm) (21-56 mm) Av. Range Ave. Range Ave. Range Head length 289 272-301 290 322 315-332 333 310-353 Head depth 203 183-213 — 241 234-247 245 231-266 Upper jaw length 210 200-217 195 220 212-235 229 212-257 Orbit length 82 80-85 85 103 95-110 111 102-119 Prepectoral length 288 277-296 — 301 284-312 325 302-353 Prepelvic length 439 426-447 435 453 435-464 459 443-479 Predorsal length 411 389-426 420 425 415-442 432 412-460 Preanal length 626 624-629 635 650 635-666 642 626-664 Preadipose length 796 786-806 800 812 810-820 801 779-819 Caudal peduncle length 225 217-236 — 208 199-218 — — Caudal peduncle depth 94 90-99 85 112 108-116 118 111-129 Dorsal base length 215 197-225 — 229 221-236 232 220-242 Anal base length 179 172-183 — 168 162-179 180 165-192 *Data from Gilbert, 1913. **Data from Nafpaktitis, 1968. Discussion Diaphus elucens may be conspecific with Diaphus perspicillatus (Ogilby, 1898), type local- ity 31° 33' S, 159° 05' E. This species has seldom been reported in the literature, and the available descriptions, including the original, are inadequate; two of the three extent figures (to my knowledge) of the species shown the preorbital organs as only vaguely resembling those of specimens of £>. elucens before me, although the general aspect of the body and the ar- rangement of photophores are similar. Diaphus danae Taning, 1932), type locality: north of New Zealand, was placed in synonymy with D. perspicillatus by Whitley ( 1933: 63, fig. 1 ) and by Fraser-Brunner (1949); although the photophore patterns of these two species are much like that of Z). elucens, the preorbital organs, as delineated, bear only a vague resemblance to those ofD. elucens. The preorbital organs shown by Brauer (1906: 220, fig. 140) fori), elucens also bear no resemblance to those of specimens I have seen, and none at all to those shown by the respective authors for D. danae and D. perspicillatus. Munro (1967: 38, fig. 265) showed the preorbital organs of Z). perspicillatus to be very similar to those of £>. elucens; unfortunately, most body photophores are indistinct in the figure (a dark half-tone) but the overall pattern appears to be like that of D. elucens. Gilbert (1913: 93) indicated that the two species were synonymous, and these similarities lend some credence to that indication. But as the original descriptions of Z). perspicillatus and D. danae did not include numbers of gill rakers, it is not here possible to make further comparisons with D. elucens, or to attempt a synonymy; therefore, until direct comparison of these species is made, the name D. elucens is retained. Diaphus elucens (Brauer, 1904) Description D. 16(15-17); A. 15(16);P. 10-11; AO 6 (5) + 5 (4), total 11 (10); gill rakers 10 (9) (16-19), total 28 (26-29); vertebrae 35 (34). -1-1-1-17 121 Fig. 114 — Diaphus elucens, male, 44.0 mm. SAO in a nearly perpendicular line that passes through or near the vent and far behind VO.^; SAO3 occasionally slightly before a line through SAO,.j. SAO3 and Pol touch lateral line. VLO at least its diameter nearer pelvic base than to lateral line; PLO about two of its diamet- ers nearer lateral line than to pectoral origin. Penultimate AOa-AOpi interspace greater than that of Prc-AOp. Pre interspaces progressively wider. Body proportions (Table 19) are given for D. elucens from the Central Pacific and North Atlantic Oceans. Size: To about 60 mm. Least depth of capture: To 85 m at night. Distribution: In the eastern Pacific Ocean D. elucens is known only from the central region, near and south of Hawaii (Fig. 108). Diaphus rolfbolini Wisner, 1971 Fig. 115— Diaphus rulfhoUni . holotype, 44.5 mm. From Wisner (1971, p. 48, fig. 5). Description D. 15 (14-16); A. 14-15 (16); P. 12 (11-13); AO 6 (5-7) -t- 5 (6), total 11 (10-12); gill rakers 8-9 (10) -H 1 + 16(15-17), total 25-26 (24-27); vertebrae 35 (34-36). Coordinated counts of AO photophores and gill rakers are given in Table 20. All upper photophores well below lateral line. SAO series in a steeply oblique line that passes well behind VO.-,. SAO, about two of its diameters behind aline through SAO, 2; SAOa.a interspace about twice that of SAO,. j. First and last AOa slightly elevated. Last 3 Pre evenly spaced in a straight, rather flatly oblique (approaching horizontal) line. 122 Table 20. Correlated Counts (Both Sides) of AO Photophores and Gill Rakers for diaphus rolfbolini AOp Lower rakers (including central raker) 5 5 6 8 16 17 18 8 4 7 22 5 Aoa 6 59 4 Upper 9 3 16 3 ^ 1 rakers 10 1 — Preorbital area of holotype and several paratypes covered with a viscous, transparent substance that creates a domelike effect. Entire posterior surface of the preorbital area ap- pears to have a highly reflective lining and no doubt glows when the luminous organs are active. There is no appreciable sexual dimorphism in these organs. Size: To about 54 mm. Least depth of capture: Between 50 and 200 m at night and 600 m in daytime (Clarke, 1973). Distribution: Thus far known from the warmer waters of the central Pacific (Fig. 108) between about 14° S, 93° W and 17° N, 154° W and in the western Pacific and Indo-Pacific areas. Discussion Diaphus rolfbolini is closely related to D. effulgens (Goode and Bean, 1896). It differs primarily in having a total of 25-26 (24-27) gill rakers, rather than 20-21 (19-22). Also, it may be a smaller species, as the largest of 87 specimens available was 65 mm. A gravid female of 60 mm was found. Nafpaktitis ( 1968) reported that no gravid females were found among his study material of D. effulgens from the North Atlantic Ocean, and that "At best, female specimens of about 130 mm and males of 85 to 105 mm showed medium-sized, finely granular, flaccid ovaries and large, healthy looking testes, respectively. The species reaches a relatively large size (commonly 120 to 130 mm)." Diaphus ostenfeldi Tuning, 1932 Fig. 116 — Diaphus ostenfeldi, male, 99.3 mm. 123 Description The following counts were taken from two specimens from off South Africa and one from the Indian Ocean (42° 03.8' S, 70° 39.9' E). D. 16; A. 15-16: P. 11-12; AO 7 + 5; gill rakers 9 (8) -I- 1 + 16 (15), total 24-26; lateralline pores 37; vertebrae ?. A large luminous scale at PLO fills the space between PLO and pectoral fin in a 99-mm specimen; about three-fourths of this space is filled in an 84-mm specimen. This luminous scale is composed of short, contiguous, vertically arranged fibers. This distinctive species may be readily recognized (as adults) by the very large Dn, the short, deep head, the highly irregular opercular margin, and the very small photophores. The nearest related form is D. metopoclampus, but the two species are separable on the basis of a great difference in preorbital organs and the higher positions of the SAO3 and Pol of D. metopoclampus, at or near the lateral line. Size: To about 100 mm. Least depth of capture: To 100 m at night in southeastern Pacific Ocean (Craddock and Mead, 1970). Distribution: This species was not among the material examined in this study. Craddock and Mead (1970) reported the capture of 37 specimens (15-73 mm) from eight localities along about 34° Sand between about 76° and 91° W. King and Iversen (1962) reported the species from the region of the Equatorial Countercurrent, but I have not been able to examine the specimen or to confirm the identification. Clarke (1973) did not list this species from the immediate area of Oahu, Hawaii. Diaphus metopoclampus (Cocco, 1829) Fig. 117 — Diaphus metopoclampus, male, 49.4 mm. Description The following data are taken mostly from South African specimens. D. 15;A. 15;P. 10-11; AO 6 (5-7) + 6(5-7), total 12 (11-13); gill rakers 8(7-9) -h 1 -I- 14 (13-15), total 23 (21-25); lateral line pores 36-37; vertebrae ?. As in D. ostenfeldi, the body photophores are notably smaller than in most diaphid species. The short, deep head and the very distinctive preorbital organs, especially the posterior exten- sion of the Vn and its ending in a prominent knob under the latter half of the iris, are like those of no other diaphid fish. Size: To about 75 mm. Lea,st depth of capture: To about 600 m in daytime in the eastern Pacific Ocean and Indo-Pacific area. 124 Distribution: In the eastern Pacific a single specimen (46.3 mm), a male with moderately well-developed testes, is known from about 25° S, 155° W. The species is also known from the North Atlantic Ocean and is common off South Africa. I have examined specimens from the Indian Ocean (25° 24' S, 35° 41' E) and from the Indo-Pacific area (ca 13° N, 111° E). Whitley (1968) did not list the species in his checklist of New Zealand fishes. The Diaphus fulgens-rafinesquii Species Complex in the Pacific Ocean During this study I encountered eight apparently distinct diaphid species that correspond reasonably well to Z)/ap/!t/s/'(//j^e/!s Brauer (1904). One of these forms is almost certainly Diaphus mollis Taning (1928), and three appear to be allied to D. rafinesquii (Cocco, 1838). I believe the remaining four to be most closely related to D. fulgens, but as I am unable to assign any of the four to Brauer's species, I diagnose them only as Forms A, B, C, and D. Similarly, I diagnose the three D. rafinesquii -like forms as Forms R-1, R-2, and R-3. The affinities of the seven presently unassignable forms to described species will be discussed after their diagnoses. The following key will aid in the identification of the Forms. Key to the identification of Forms A, B, C, and D of the Diaphus fulgens complex and Forms R-1, R-2, and R-3 of the D. rafinesquii complex in the Pacific Ocean. la. Total gill rakers 21 or less (rarely 22). The D. fulgens complex 2 lb. Total gill rakers 22 or more. The D. rafinesquii complex 5 2a. Upper gill rakers 3 to 4 3 2b. Upper gill rakers 5 to 6 4 3a. Gill rakers 4 -h 1 + 10 (9-11), total 15 (14-16). No luminous scale at PLO. Enlarged Vn of males in two parts, the anterior the largest Form A 3b. Gill rakers 3-4-1-1 + 9 (8-10), total 14 (13-15). A large luminous scale present at PLO, the tissue in horizontal lines. Enlarged Vn of males undivided Form B 4a. Gill rakers 6 (5) + 1 + 12-13 (14), total 19-20 (18-22). Luminous scale at PLO large, the tissue in straight lines slanting more or less posteroventrally. Enlarged Vn of males undivided. Body photophores small. V0:;.3 interspace 72% (60-86%) of space between VLO andVO, Form C 4b. Gill rakers 5 + 1 + 10-11 (12), total 16-17 (15-18). Luminous scale at PLO large, the tissue in steep, posteroventrally slanting, often nearly vertical lines. VO2-3 interspace 48% (39- 55%) of space between VLO and VOj FormD 5a. Length of orbit 51% (49-56%) of length of upper jaw. Length of anal base 84% (79-93%) of length of dorsal base. VO,..;, interspace 52% (40-60% ) of space between VLO and VO. Form R-2 5b. Length of orbit 46% to 48%- (44-52% ) of length of upper jaw 6 6a. Length of orbit 46% (44-48%) of length of upper jaw. Length of anal base 77% (74-80%) of length of dorsal base. VO2-3 interspace 61% (56-67% ) of space between VLOandVOo Form R-1 6b. Length of orbit 48% (45-52% ) of length of upper jaw. Length of anal base 83% (75-91%) of length of upper jaw. VO,.;, interspace 57% (53-62% ) of space between VLO and VOo (in young fish, 37 to 57 mm) FormR-3 Meristic data for Diaphus mollis. Forms A, B, C and D of the D. fulgens species complex and Forms R-1, R-2 and R-3 of the D. rafinesquii species complex are given in the following tables: Numbers of gill rakers (Table 21 ); correlated counts of AO photophores (Table 22); body proportions for the four forms of the D./"i//^(?ns complex (Table 23); body proportions for the three forms of the D. rafinesquii complex from the North Pacific Ocean and for D. rafinesquii from the North Atlantic Ocean (Table 24). 125 Table 21. Numbers of Gill Rakers for Diaphus mollis from the Pacific Ocean, for Forms A, B, C, and D of the D. fulgens Species Complex in the Eastern and Central Pacific and for Forms R-1, R-2, and R-3 of the D. rafinesquii Secies Complex in the North-Central and Northwestern Pacific Ocean Species or complex Upper rakers D. mollis D. fulgens species complex Form A FormB FormC Form D D. rafinesquii species complex Form R-1 Form R-2 Form R-3 31 16 47 24 11 61 30 3 2 49 13 9 D. mollis D. fulgens species complex Form A Form B FormC FormD D. rafinesquii species complex Form R-1 Form R-2 Form R-3 10 Lower rakers (including central raker) 11 12 13 14 15 16 17 18 19 31 2 27 2 — 15 2 — — — — — 33 — 10 12 1 21 27 19 11 — 4 25 7 14 6 1 D. mollis D. fulgens species complex Form A FormB FormC FormD 13 14 2 13 15 27 2 Total rakers 16 17 19 20 21 22 12 28 26 28 27 D. rafinesquii species complex Form R-1 Form R-2 Form R-3 22 23 24 Total rakers 25 26 27 17 10 2 — 2 2 24 7 9 8 3 1 126 Table 22. Correlated Counts of AO Photophores for Diaphus mollis from the Pacific and Atlantic Oceans, for Forms A, B, C, and D of the Diaphus FULGENS Species Complex and for Forms R-1, R-2, and R-3 of the Diaphus rafinesquii species complex in the eastern and northwestern pacific Ocean, and for D. rafinesquh from the Atlantic Ocean Diaphus mollis (Pacific Ocean) Diaphus mollis* (Atlantic Ocean) AOa AOp 3 4 5 — 2 — 36 — 3 2 — AOa AOp 3 4 5 2 — 240 23 4 8 — AOa Diaphus fulgens species complex, Pacific Ocean Form A FormB AOp 3 4 5 4 — 4 5 5 65 12 6 6 4 — 5 + 4 Both sides of 9 specimens AOa FormC AOp 4 5 6 4 — 3 4 5 9 84 4 6 5 1 — FormD AOa AOp 3 4 5 4 — 2 2 5 4 46 7 6 2 — 1 Diaphus rafinesquii species complex, central and northwestern Pacific Ocean Form R-1 Form R-2 AOp AOp AOa 24 AOa 29 AOa Form R-3 AOp 18 2 D. rafinesquii* (Atlantic Ocean) AOP AOa 3 4 5 — 1 2 4 121 7 4 3 — *Data from Nafpaktitis, 1968. 127 Table 23. Body Proportions for Four Forms of the Diaphus fulgens Species Complex FROM THE Pacific Ocean Form A FormB FormC FormD Measurement N= 12 (23.8-33.0 mm) N = 9 17.7-30.6 mm) N= 12 (27.3-41.8 mm) N= 12 (25.2-35.9 mm) Ave. Range Ave. Range Ave. Range Ave. Range Head length 288 284-295 295 284-300 283 269-300 320 303-336 Head depth 216 211-232 224 216-237 201 186-212 240 224-251 Upper jaw length 177 167-188 184 173-191 162 154-171 199 180-208 Orbit length 110 105-114 115 106-121 103 94-112 119 107-130 Dorsal origin to pelvic origin 228 212-236 228 220-239 210 187-227 240 226-257 Dorsal origin to anal origin 316 291-318 319 307-335 313 304-330 346 316-342 Prepectoral length 278 271-289 296 286-309 280 264-298 322 306-336 Prepelvic length 448 437-459 455 441-477 451 442-468 468 452-484 Preanal length 668 651-683 672 656-683 676 659-696 682 664-696 Predorsal length 484 461-505 467 450-477 463 439-477 487 478-500 Preadipose length 831 821-851 822 806-831 800 784-810 824 805-837 Dorsal base length 183 169-195 189 168-202 183 167-197 181 166-198 Anal base length 145 130-162 139 126-150 136 124-149 140 123-159 Caudal peduncle length 224 216-232 222 212-238 227 203-238 211 197-226 Caudal peduncle depth 108 102-116 106 90-122 102 96-108 109 103-122 Table 24. Body Proportions for Three Forms of a Diaphus rafinesquii-like Species Complex from the Northern Pacific Ocean and for Diaphus rafinesquh FROM the North Atlantic Ocean* D. rafinesquii-like forms, northern Pacific Measurement FormR-1 N= 12 (39.2-60.2 mm) Form R-2 N= 12 (55.8-80.3 mm) Form R-3 N= 11 (37.1-94.0 mm) D. rafinesquii, North Atlantic N = 43 (30.0-73.9 mm) Ave. Range Ave. Range Ave. Range Ave. Range Head length 300 289-310 304 289-311 309 296-324 Head depth 217 205-229 226 216-245 219 213-225 Upper jaw length 201 193-206 211 204-218 207 192-219 Orbit length 104 100-107 96 93-99 100 93-108 Dorsal origin to pelvic origin 213 198-223 230 221-240 223 213-232 Dorsal origin to anal origin 320 292-315 308 290-320 302 291-312 Prepectoral length 297 281-310 305 292-313 308 293-326 Prepelvic length 451 442-469 467 453-480 471 463-493 Preanal length 674 653-695 676 659-689 676 661-686 Predorsal length 472 455-489 466 450-475 466 450-489 Preadipose length 825 814-839 828 819-846 828 811-841 Dorsal base length 174 163-191 197 190-201 187 168-203 Anal base length 144 136-155 151 143-158 157 145-165 Caudal peduncle length 208 196-214 212 208-217 213 198-225 Caudal peduncle depth 99 92-105 104 99-112 103 96-109 314 231 216 112 309 461 660 475 814 186 167 111 306-325 222-243 204-228 105-119 229-322 450-478 640-680 463-489 781-830 175-200 153-179 104-123 *Data from Nafpaktitis, 1968, p 82. 128 Diaphus mollis Taning, 1928 Fig. 118 — Diaphus mollis, male, 55.4 mm. From about 27° N, 155" W. (Photophers retouched). Description D. 12-13; A. 12-13; P. 10-11; AO 5 (4-6) + 4 (3-5), total 9 (10); gill rakers 5-6 + 1 + 12-13 (11), total 18-19 (17-20); vertebrae 33. Numbers of gill rakers (Table 21) and AO photophores (Table 22) are compared with counts for Forms A, B, C, and D of the Diaphus fulgens species complex and for Forms R-1, R-2, and R-3 of the D. rafinesquii species complex of the Pacific Ocean. Posterodorsal margin of operculum sharply angulate and recurved. Origin of dorsal fin about over pelvic origin. Origin of anal fin behind a vertical from end of dorsal base by about 0.75% of the orbital diameter. End of base of adipose fin usually slightly before, occasionally on, a vertical from end of anal base. Pelvic fins extend past anal origin by nearly the length of the pupil in undamaged specimens. Body photophores rather small, often indistinct against the very dark integument nor- mally found on freshly preserved and undamaged specimens. PLO on or very slightly behind a vertical from origin of pectoral fin and above that origin by 39% (35-43% of the distance from it to lateral line. VLO over bases of inner pelvic rays and nearer them by 45% (42-50% ) of the distance to lateral line. VO2.3 interspace 53% (44-64% ) of the space between VLO and VO2 SAO3, Pol, and Prc4 lie about three of their respective diameters below lateral line. SAO series broadly angulate, a line through SAOi.^ passing through or a little before VO.-, and well behind SAO3. SAO^-:! interspace 2.0 to 2.5 times that of SAO,.-. First AOa elevated nearly to level of SAO2 and from 1.5 to 2.0 times its diameter above second AOa. Last AOa seldom elevated by more than its diameter above next to last AOa. Pol about over base of last anal ray. Pre interspaces progressively wider. Vn of males much enlarged and in two parts; a large anterior part of dense, fine-grained tissue, roughly triangular in shape, fills the space between anteroventral orbital margin, premaxillary and nasal apparatus. The posterior part is much smaller and oblong; it appears as a reflective layer thinly covered with luminous tissue; two parts are separated by a promi- nent darkly pigmented streak. The luminous tissue of both parts is easily eroded and lost. The small So barely intrudes into the orbital margin. Vn of females slender, elongate, entire, and also easily lost. Luminous scale at PLO small, two to three times the size of that organ; it is thin and weakly formed, the tissue appearing as granular or convoluted. Size: To about 65 mm. Least depth of capture: D. mollis has been dipnetted once in central Pacific waters; the least depth of tows taking the species is from 0 to 300 m. Distribution: Probably common in warmer waters of Pacific Ocean. I have seen specimens from only one locality of the Indo-Pacific region, south of Mindanao, Philippines (Fig. 119). 129 Fig. 119 — Capture localities in the Pacific Ocean (or Diaphiis mollis (M), Forms A, B, C, and D of the D. fulgeris species complex, and Forms R-1, R-2, and R-3of the D. rafinesquti species complex. Discussion Although the type locality ofDiaphus mollis is in the North Atlantic Ocean, north of the Cape Verde Islands, with some confidence I have applied the name to the Pacific Ocean specimens. The body proportions are extremely similar to those given by Nafpaktitis (1968) for the North Atlantic specimens, as also are the numbers of AO photophores (Table 22) and the general pattern of photophores. However, the total numbers of gill rakers (Table 21 ) average about 2 higher in the Pacific; Nafpaktitis listed 4-5 +1 + 11 (10-12), total 16-17 (rarely 15 or 18) for the North Atlantic specimens. Also, Nafpaktitis (1968, fig. 56) described and figured the Vn of males as entire, although apparently of two contiguous or coalesced parts. Possibly direct comparison of large numbers of specimens from each ocean will show the Pacific form to be distinct. 130 Diaphus fulgens species complex Form Form B Form C Form Fig. 120 — Forms A, B, C, and D of the Diaphus fulgens species complex in the Pacific Ocean. (Photophores retouched in Forms C and D). Form A of Diaphus fulgens species complex Description D. 14 (13); A. 11-12 (13); P. 10; AO 5 (4-6) + 4 (5), total 9-10; gill rakers 4 -h 1 + 10-11, total 15-16, vertebrae 33 (32-34). Posterodorsal margin of operculum smoothly rounded, not recurved. No luminous scale at FLO; despite the very excellent condition of several of the larger specimens, no trace of this scale was found. Body photophores moderately large, those of the AO series separated by no more than their diameters, usually less. FLO about its diameter behind a vertical from origin of pectoral fin and variably above that origin by 33% (26-39% of the distance from it to lateral line. VLO over bases of inner pelvic rays and about 46% (41-52%) of the distance from them to lateral line. SAO.,, Pol, and Prcj below lateral line by about two of 131 their respective diameters. The VO2-3 interspace averages approximately half (53% ) of that between VLO and VO2 but varies from 44% to 64%. A line through SAO, and SAO^ usually passes slightly before, occasionally through, VOs and well behind SAO,,. AOai seldom elevated by more than its diameter (usually half) above AOa^. Last AOa from 1.0 to 1.5 times its diameter above level of next to last AOa. Pol usually under middle of base of adipose fin. Pre interspaces increasingly wider. The much enlarged Vn of males appears as two parts, the posterior part small and ovate to round and separated from a much larger anterior part by a whitish (in preservative) septum. The larger anterior part is rather egg-shaped, apex pointing posteriorly, and fills space be- tween orbital rim, nasal apparatus, and premaxillary. Vn of females small, ovate, and often indistinct. So small and usually well covered with dark tissue and intruding sharply into orbital margin. Teeth of premaxillary small, flattened laterally, and sharply recurved in a forward direc- tion on the posterior portion, but less flattened and are curved posteriorly on the anterior position. Size: To 31 mm. Form A may be a small species, as gravid females of 26 to 30 mm were found. Least depth of capture: To 375 m at night. Distribution: Form A is known only from three localities of the eastern Pacific Ocean (Fig. 1 19); most specimens were taken at about 27° N, 155° W. Form B of Diaphus fulgens species complex Description D. 13-14; A. 12-13; P. 10-11; AO 5 -I- 4, total 9; gill rakers 4 (3) -h 1 -I- 9-10, total 14 (13-15); vertebrae 33 (only eight specimens known). Posterodorsal margin of operculum rounded and only slightly recurved. Body photophores moderately large, those of AO series usually separated by less than their diameters. PLO over or slightly before a vertical from pectoral origin and above it by 35% (30-49% ) of the distance from there to lateral line. VLO over bases of inner rays of pelvic fin and above them by about 44% (38-39% ) of distance to lateral line. VO,.^ interspace 44% (38-54% ) of space between VLO and VOj. A line through SAOi.j passes through or a little before VO.i and well behind SAO.j. SAO.,, Pol, and Pre, below lateral line about three of their respective diameters. First and last AOa photophores about half their diameters above levels of adjacent ones; Pol under end of adipose base. Pre interspaces progressively wider. Luminous scale at PLO large, extending from slightly above PLO nearly to pectoral fin, the tissue arranged in rather coarse horizontal lines. Vn of males large, undivided, somewhat triangular in shape with the apex posteriorly, and filling space between anteroventral margin of orbit, premaxillary, and nasal apparatus. Vn of females much smaller, elliptical, and often indistinct. Teeth of upper and lower jaws similar to those of Form A. Palatine toothless, or one or two teeth present at anterior end. Mesopterygoids sparsely set with small elongate teeth. Size: To 31 mm, largest of eight specimens. Apparently Form B is also a small species; a female of 22 mm was gravid. Least depth of capture: To 580 m at night. Distribution: All eight known specimens taken at about 27° N, 155° W (Fig. 119). 132 Form C of Diaphus fulgens species complex Description D. 13-15; A. 12-13; P. 10-11; AO 5 (4-6) + 5 (4-6), total 10 (9-11); gill rakers 6 (5) + 1 + 13 (12-14), total 19-20 (18-22); vertebrae 34 (33-35). Posterodorsal margin of operculum moderately angulate and recurved. All body photo- phores notably smaller than those of Forms A, B, and D; spaces between those of AO series equal to at least two diameters, often more. PLO slightly behind a vertical from base of upper pectoral ray and above it by 39% (35-46%) of the distance to lateral line. VLO nearly over bases of inner pelvic rays and about midway, 49% (44-53%), between pelvic base and lateral line. SAO3, Pol, and Prcj 1.0 to 1.5 of their diameters below lateral line. VO2.3 interspace 72% (60-86% ) of distance from VLO to VO2, this space notably wider that that of Forms A, B, and D. SAO series somewhat more angulate than in other forms; line through SAO1.2 passes through or slightly before VO-, but far behind SAO3. AOa, 1.5 to 2.0 times its diameter above level of A0a2 and very slightly below a line through VO., and SAO2; last AOa about its diameter above level of the next to last AOa. Pol variably below middle to end of base of adipose fin. Luminous scale at PLO large, about equal to space between PLO and pectoral origin, the tissue in somewhat coarse, straight lines that slant posteroventrally at an angle of 30° to 40° to the horizontal. Vn of males, large, undivided, broadly elliptical in shape but more robust anteriorly, filling space between posteroventral margin of orbit, premaxillary and nasal ap- paratus. Vn of females small, ovate, under anterior portion of pupil. Teeth of upper and lower jaws similar to those of Forms A and B. Palatine teeth absent except for a small clump at anterior end. In adults, the mesopterygoids are sparsely set bucally with elongate teeth but with a narrow row of thick-set similar teeth mesially, the centers often naked or with a few scattered teeth. In sub-adults, the mesopterygoids tend to be more evenly set with small, conical teeth. Size: To about 40 mm. Form C also appears to be a small species; a female of 34.5 mm was fully gravid and one of 28.0 mm had ovaries in an advanced stage of development. Least depth of capture: To 85 m at night. Distribution: Form C appears to be restricted to a narrow band of equatorial water be- tween about 137° and 165° W, although little or no collecting has been done westerly of this area. It is also known from the Indo-Pacific area (Fig. 1 19). Discussion Form C has been taken in greater numbers than any of the other forms. Also, it may be more gregarious, for several tows captured from 20 to 68 specimens each, whereas of the other forms only one to four were taken per tow. Form D of Diaphus fulgens species complex Description D. 13 (12-14); A. 12-13; P. 10-11; AO 5 (4-6) + 4 (3-5), total 9 (8-11); gill rakers 5 + 1 -h 10-11 (12), total 16-17 (15-18); vertebrae 33. Posterodorsal margin of operculum broadly angulate and slightly recurved. Body phosphates moderately large, those of the AO series about one diameter apart. PLO over pectoral origin and nearer it by 35% (29-42%. ) of the distance from them to lateral line. VLO above bases of inner pelvic rays by 39% (36-42%) of the distance from there to lateral line. 133 SAOs, Pol, and Prc4, respectively, two to three of their diameters below lateral line. VO2.3 interspace 48% (39-55% ) of the space between VLO and VO2. SAO series angulate, a line through SAO1.2 usually passing through V0.-„ occasionally before, but well behind SAO3. AOa, from 1.0 to 1.5 diameters above level of AOaj, the succeeding AOa in a straight line ascending dorsally at a slight angle; last AOa nearly its diameter above next to last. Pol about its diameter before a vertical from end of base of adipose fin. Pre interspaces progressively wider. Luminous scale at PLO large, broadly lunate, its length greater than distance from PLO to pectoral origin, the luminous tissue in more or less straight lines that slant posteroventrally at a steep angle, often vertically. Vn of males large, undivided, filling space between postero- ventral margin of orbit, premaxillary and nasal apparatus; an intrusion of non-luminous tissue extends ventrally from orbital rim at about mid-Vn so that the organ may appear divided. Vn of females much smaller and broadly ovate. Teeth of both jaws similar to those of Forms A, B, and C. Palatines toothless except for 1 or 2 occasional small teeth at anterior end. Mesopterygoids sparsely set with small, conical teeth, the centers often toothless. Size: To 38 mm. Form D also appears to be a small species; gravid females were found at lengths of 28 and 32 mm. Least depth of capture: To 50 m at night. Distribution: Form D is known only from the tropical eastern Pacific (Fig. 119). Diaphus rafinesquii species complex in the North Pacific Ocean Form R-l Form R-2 Form R -3 Fig. 121 — Forms R-l, R-2, and R-3 of the Diaphus rafinesquii species complex in the North Pacific Ocean. 134 Form R-1 of the Diaphus rafinesquii species complex in the North Pacific Ocean Description D. 12-13; A. 12-13(11);A0 5 + 4 (5), total 9-10; gill rakers 7 (6-8) + 1 + 15 (14-16), total 23-24 (22-25); vertebrae 33-34. Posterodorsal angle of operculum sharply rounded and slightly but distinctly recurved. Dorsal origin over pelvic origin. Anal origin slightly behind vertical from end of dorsal base. Base of adipose fin over end of anal base. FLO over pectoral origin and about midway between it and lateral line. VLO over bases of inner pelvic rays and midway, or slightly less, from there to lateral line. VO^.s interspace about 61% (57-67%) of space between VLO and VO2. SAO series in a nearly straight, steeply oblique line; SAO2-3 interspace about twice that between SAO1.2. SAO,,, Pol, and Prc^ below lateral line by slightly more than their diameters. First and last AOa elevated about two of their diameters above level of adjacent AOa. Pol about under end of base of adipose fin. Pre interspaces progressively wider, the Prca.^ interspace nearly as wide as that of Prci.3. Vn of males enlarged, somewhat wedge-shaped, the apex posteriorly. A small intrusion of luminous tissue extends slightly into orbital rim. The apex of Vn in larger males is nearly confluent with the small So. Vn of females small, narrow, well separated from the So. Lumi- nous scale at PLO small, weakly formed, scarcely larger than PLO, the tissue convoluted. Teeth of jaws typical of diaphid species bearing an So organ. Palatines with small teeth on only the anterior two-thirds, the posterior third toothless; no enlarged teeth at tips. Vomer heads naked or with very few asperities. Mesopterygoids thickly set with small, sharp teeth. Size: To 65 mm. Least depth of capture: To 200 m at night. Distribution: Form R-1 is known only from a narrow region of the North Pacific Ocean, about 30° to 40° N, 155° W to 165° E (Fig. 119). Form R-2 of the Diaphus rafinesquii species complex in the North Pacific Ocean Description D. 12; A. 12; P. 11-12; AO 5 (6) -t- 5 (4), total 10 (9); gill rakers 8 (7-9) -I- 1 + 16 (15-17), total 25 (23-27); vertebrae 34. Posterodorsal angle of operculum rounded, not recurved. Dorsal origin slightly before a vertical from pelvic organ. Anal origin behind a vertical from end of dorsal base by slightly more than half the length of anal base. End of base of adipose fin distinctly behind a vertical from end of anal base. PLO and VLO respectively a little below midway between origins of pectoral and pelvic fins. SAO:i, Pol, and Prc^ usually about two of their diameters below lateral line. SAO series in a slight but distinct angle, a line through anterior margins of SAOi.^ passing slightly behind SAO-,; S AO2-3 interspace at least twice that of SAO 1 .-,. First AOa elevated one to one and one-half times its diameter above level of second AOa; last AOa elevated by a similar amount. Pol about over base of next to last anal ray and under anterior end of base of adipose fin. Pre interspaces progressively wider. 135 Vn of males enlarged, nearly filling space between orbital rim, premaxillary and nasal apparatus, and almost confluent with So. Vn of females much smaller, elongate, not reaching to So. Luminous scale at PLO large, its length equal to or slightly greater than distance between PLO and pectoral origin, the tissue convoluted. Teeth of jaws as in Form R-1. Palatines very sparsely toothed except for a patch of small teeth at anterior end, these teeth becoming increasingly larger toward the tip. Vomer heads naked. Mesoptergoids thickly set with small, sharp teeth. Size: To 85 mm. Least depth of capture: To 360 m at night. Distribution: Form R-2 is known only from a narrow region of North Pacific Ocean, about 30° to 43° N, 140° W to 170° E. This distribution is very similar to that of Form R-1, and the two have twice been taken sympatrically (Fig. 119). Form R-3 of the Diaphus rafinesquii species complex in the North Pacific Ocean Description D. 13 (12); A. 12-13; P. 11; A0 5(6) + 4 (5), total 9 (10); gill rakers 7-8 -I- 1 + 15-16(14-17); vertebrae 33-34. Posterodorsal angle of operculum rounded, not recurved. Dorsal origin on or slightly behind a vertical from pelvic origin. Anal origin behind a vertical from end of dorsal base by a distance equal to about half the length of anal base. Base of adipose fin distinctly behind a vertical from end of anal base. PLO usually behind, rarely over, pectoral origin and nearer that origin than to lateral line by about three of its diameters. VLO over bases of inner pelvic rays and about midway between them and lateral line. PLO, VLO, and SAO2 on a straight line. VO...3 interspace about 57% (48-66% ) of space between VLO and VO2. SAO.i, Pol, and upper Pre from one to three of their diameters below lateral line. SAO series moderately angulate, a line through SAO1.2 passing through or slightly before VOr, and well behind SAO;,. First and last AOa elevated by one to two of their diameters above adjacent AOa. Pol variably under middle to anterior end ofbase of adipose fin. Prcj distant from Prcn by a space nearly equal to that between Pre, and Prc.^. Vn of males enlarged, undivided, extending from nasal apparatus to and confluent with So in a 94-mm specimen; in a 58-mm specimen the Vn and So are not quite confluent. In smaller males Vn incompletely formed and falling well short of the So. Vn of females elongate and narrow, but no females over 45 mm (based on structure of Vn) were available. Luminous scale at PLO large, about equal in length to distance between PLO and pectoral origin in the largest specimen (94 mm) but about half that length in the 58-mm specimen, the tissue finely convo- luted. Teeth of jaws as in Forms R-1 and R-2. Palatines almost naked except for shorter anterior portion bearing enlarged, backward-curving teeth; a few small teeth scattered sparsely along posterior portion of palatines. Vomer heads naked. Mesopterygoids with a few randomly scat- tered sharp teeth. 136 In young specimens (37-55 mm) the anterior portion of the palatine, and the entire surface of the mesopterygoids, are densely set with minute teeth. Size: To 94 mm. Least depth of capture: The single capture was from 0-880 m at night. Distribution: Form R-3 is known from only one locality in the North Pacific Ocean (Fig. 119). It is probably sympatric with Forms R-1 and R-2. Discussion The difficulty is definitely assigning any of Forms A, B, C, and D to the species described by Brauer (1904, p. 402, fig. 4) and further delineated by Brauer (1906, p. 224, fig. 146) as Myctophum (Nyctophus) fulgens lies in the fact that the species is at present undefinable. Dr. C. Karrer, Zoological Museum, Humboldt University, Berlin, has informed me that the 3.9-cm specimen figured by Brauer is not among the specimens cataloged in that Museum (personal communication). Dr. Karrer kindly provided me with two specimens cataloged as Myctophum (Nyctophus) fulgens, each designated as "Typen." One specimen, 10.0 mm SL, ZMB 17606, from Valdivia Station 228, is of a circumglobal species complex related to Diaphus theta Eigenmann and Eigenmann (1890); the second specimen, 22.0 mm SL (Fig. 122), ZMB 17605, from Valdivia Station 226, probably a female (based on appearance of Vn), is not of the same species described and figured by Brauer. Instead, I believe it may be the same as Form C, diagnosed above in that the VOo.-, interspace is about 60% of the space between VLO and VO-, a value similar to that found for Form C, and higher than for Forms A, B, and D. Also, the numbers of gill rakers, 5 + 1 + 12, agree with the count for Form C (Table 21 ), as does the count of AO photophores, 5 + 5 (Table 22). Also in agreement with the counts for the "Type" of Z). fulgens are those given for Diaphus nanus Gilbert ( 1908, p. 224, pi. 2) described from nera Nukuhiva, Marquesas, 5 + 5(6) AO and 5+13 gill rakers, including all rudiments. Unfortunately, the holotype of D. nanus is only "17 mm long"; Gilbert recorded four paratypes from the same region and stated that "All are smaller than the type." It is possible that Form C, D. nanus and the "Type" of D. fulgens (ZMB 17605) are conspecific. But, if the latter specimen is not of the same species as that described and figured by Brauer, the name fulgens is not available and must remain in doubt until the 3.9-cm specimen is reexamined. The solution to that dilemma is not within the scope of this publication. -p Fig. 122— A specimen, 22.0 mm, ZMB 17065, labeled as "Type" of Myctophum (Nyctophus) fulgens Brauer, 1904. (Photophores retouched). 137 Form A may be related to Diaphus parri Taning (1932) primarily because of the lack of a luminous scale at PLO, although Taning stated "PLO with a very diminutive luminous scale, sometimes not to be seen." This scale was not discussed or illustrated by Nafpaktitis ( 1973 ) in his redescription of Z). parri. The slight elevation of the first AOa is also similar in Form A and in D. parri, but apparently this organ has a consistently higher position in Form A. Nafpak- titis (1973) described the first AOaof D. parri as being very slightly, if at all, raised, whereas in Form A it is at least a half, often a full, diameter above the level of the second AOa. The numbers of AO photophores and gill rakers are very similar in both species. Forms B and D do not readily conform to any known species, or it may be that inadequate data on variation in characters is available for a known related species. The very low numbers of gill rakers of Form B, totalling 14 (13-15) is to my knowledge the lowest of any diaphid species other than the quite unrelated D. problematicus Parr ( 1928). Form D differs from the other three forms primarily in the very steeply slanting, almost vertical lines of the tissue in the large luminous scale at PLO, a structure unlike that of any other diaphid species I have seen. Two other species, Diaphus aliciae and D. kendalli, described by Fowler (1934) from near the Philippines, should also be compared with the Forms A, B, C, and D, and with the ful- gens" of Brauer. However, because of Fowler's inadequate descriptions and illustrations, com- parisons are difficult, but the patterns of the SAO series of Fowlers two species are similar to these forms and to that of fulgens, as delineated by Brauer. Both D. aliciae and D. kendalli are described and figured as having a large Vn. D. aliciae is shown to have a large luminous scale at PLO, but D. kendalli is not; this apparent lack of luminous scale at PLO is a character shared with Form A, but the latter appears to be a much smaller species. Fowler reported a length of 69 mm for the holotype of Z). kendalli, but I found the length to be 59.5 mm SL; both lengths are far in excess of the maximum length found for the diminutive Form A (31 mm). Also, the numbers of gill rakers for D. kendalli are much higher(6 + 1+ 13) than that of Form A (4 + 1 + 10(9-11) ). Fowler recorded 8 + 14rakersfor D. kendalli. Diaphus aliciae and Form C may be conspecific, primarily because of a similarity in numbers of gill rakers and sizes of luminous scales at PLO. I found the gill raker count for the holotype of D. aliciae to be 6 -t- 1 -(- 12 plus 1 "nub" on lower limb, but Fowler recorded 7 + 17. Fowler also reported a length of 53 mm, but I found it to be 42.0 mm SL. I have related Forms R-1, R-2, and R-3 to the Atlantic Ocean species Diaphus raflnesquii (Cocco, 1838) rather than to the D. fulgens complex, because of several similarities. First, the expanded Vn of males and the So organ are very close together, occasionally confluent; this condition is not found in the D. fulgens group. Also, AO photophores (Table 22) and body proportions (Table 24) are very similar. Nafpaktitis (1968) listed the number of gill rakers for D. raftnesquii as 7-8 + 1 + 14-15, total 22-24, a count very similar to those of the three Pacific forms (Table 21), although the latter have somewhat higher counts. Also, they attain a similar size (70 to 94 mm), although these Pacific forms may reach a larger size than D. rafinesquii. Becker (1967) recorded a specimen of 79.5 mm, the largest I have found recorded in the literature, and much larger than the Forms of the Diaphus fulgens complex. Although quite alike in counts and superficial aspect, D. rafinesquii is distinct from these Pacific forms in having a somewhat smaller and differently shaped enlarged Vn in males. Also, the SAO series is straight or but very slightly angulate in D. rafinesquii , and a line through the anterior margins of SAO, and SAO- touches or passes very near the posterior margin of SAO3; in the Pacific forms this condition is approached only in Form R-1. Forms R-1, R-2, and R-3 are also basically similar to Diaphus theta Eigenmann and Eigenmann ( 1890) and may occur sympatrically. However, D. theta is easily separable because of the very low position of the first AOa, usually on the level of adjacent the AOA or, rarely, elevated above that level by more than its diameter, usually only half Also, the SAO series is almost evenly spaced and in a straight line in D. theta, whereas the SAO2-3 interspace is always notably greater than that of SAO1.2 in the three forms in question. 138 DJaphus longleyi (?) Fowler, 1934 Fig. 123 — Diaphus longleyi (?), male, 55.8 mm. Description D. 13 (14); A. 13; P. 10-11; AO 5 (6) + 4 (5), total 9 (10); gill rakers 6 (5-7) + 1 + 12-13 (11-14), total 19-20 ( 18-22); vertebrae 33 (32). Body robust, deepest at pectoral origin. Caudal peduncle short, deep, its depth about 68% of its length. Photophores moderately large, those of AO series averaging about a diameter apart. First AOa not, or but little, elevated; last AOa elevated to about its diameter (often less) above level of penultimate AOa. PLO and VLO a little nearer pectoral and pelvic bases than to lateral line: SAO.t, Pol, and upper Pre three to four diameters below lateral line. SA0_..3 interspace no more than 1.5 times that of SAO i. 2. Posterodorsal margin of operculum mark- edly angulate, often slightly recurved; operculum produced into blunt point at about PLO. Vn of males much expanded anteriorly, reaching to nasal apparatus. Size: To about 55 mm. Least depth of capture: To 200 m at night. Distribution: This species, although described from the Philippines region, has been taken primarily in the southeastern and central Pacific Ocean (Fig. 124). Fig. 124 — Capture localities in the eastern and central Pacific Ocean for Diaphus longleyi, (solid circles), D. brachycephalus (solid squares) and D. andersem (solid triang- les). 139 Discussion The species is provisionally listed as D. longleyi since it compares well with measure- ments and notes made by me of the holotype (USNM 92320). Unfortunately, Fowler's unsatis- factory figure and description are of little use in distinguishing his form from any closely related one. The pattern of distribution suggests that the name longleyi may not apply to these specimens, unless that species is widespread. However, the far western Pacific has been very inadequately collected, and the one capture locality at 170° E on the equator (Fig. 124) strengthens the possibility that the specimens in question may be D. longleyi. Diaphus theta A species complex Eigenmann and Eigenmann, 1890 Fig. 125 — Diaphus theta, male, 52.0 mm. Description The counts below were taken from specimens from off San Diego, California (the type locality). This was done in order to confine the counts to specimens that unquestionably are D. theta (see Discussion ). D. 13 (12-14); A. 13 (14); P. 10 (11); AO 5-6 + 6 (5); total 11 (10) (12 once in 70 sides); gill rakers 6-7 + 1 -H 14 (13-15), total 21-22 (19-23); vertebrae 35 (34-36). PLO and VLO much nearer pectoral and pelvic bases than to lateral line. SAO, Pol, and upper Pre, two to three diameters below lateral line. SAO series usually equally spaced and in line with VO,,; SAO^ often a little behind a line through SAO,.:,; SA02.,i interspace in- frequently slightly greater than that of SAO, .2. First AOa usually on level of adjacent ones but occasionally slightly elevated, though seldom by a full diameter; last 1 or 2 AOa elevated to form a curve with Pol. Pol and last AOa interspace usually a little larger than those between the other AOa. Size: To about 90 mm. Least depth of capture: To 10 m at night, 400 m in daylight. Distribution: This species ranges into the north-central Pacific (Fig. 126), and the num- bers of total gill rakers increase with increasing latitudes; also, the species appears to reach a larger size in northern waters, a 50-mm specimen being uncommon off southern California. Discussion The larger specimens from the northeastern Pacific, with higher total gill raker counts on the average (aboutone raker), appear to represent the form on which Gilbert (1891) based his description of Z). protoculus, herein considered a synonym of D. theta. 140 § i 1 Wj Vm^N^ ^^^^^ ^jj ^ • 5^ f*J^, — % ' 1 "} ^^^h\^ v^'^rw. ■' V 1 '1 1 T^ * 1 \ ZTl # ^ • ■ 1 \ qr Li ■ ^ qi_u ^ — c 1 1 1 )° \] BO' _j - le 0° ■ 1 0° 140° 130" 120" 1 no- 100- 9 ( " Fig. 126- -Capture localities for Diaphus theta in the northeastern Pacific Ocean. Although the name Diaphus theta may properly apply only to specimens from off South- ern California, the name has also been applied to specimens from the eastern Pacific, off Chile (Bussing, 1965). Recently Craddock and Mead (1970) reported the capture of 54 specimens, in 19 collections off Chile from an area roughly bounded by 3r-34° S, 72° -92° W (not included in Fig. 126). These authors correctly placed these specimens in a "Diaphus ^/jeta -complex." This southern complex probably extends across the southern Atlantic; I have seen a few specimens from the central Pacific and from off South Africa. These southern specimens may represent one or more undescribed species. They differ slightly from those from the type locality of D. theta in having somewhat longer and deeper heads and deeper bodies. They have 11 to 12 pectoral rays rather than the 10 (rarely IDof Z). theta, and the AO photophores more commonly number 5-1-5 (rarely 4 or 6), total 10 (rarely 11), rather than the 5 (4-6) -^ 6 (5), total 11 (10-12), of D. theta. Also, there may be differences in size and structure of the luminous scale at PLO; this scale appears to be markedly smaller in the few undamaged southern specimens before me, and the tissue is much more finely convo- luted than in D. theta. I have studied too few specimens from the southern Atlantic Ocean to now attempt a solution to this problem. Diaphus brachycephalus Tuning, 1928 Description D. 12-13; A. 12-13; P. 11-12 (10); AO 5 (4) -f 4 (5), total 9; gill rakers 6(5-7) -H 1 -I- 13 (12-15); total 20-21 (17-23); vertebrae 33 (32-34) (10 specimens). Photophores large, closely spaced, those of the AOp series much less than half a diameter apart and often nearly in contact. V0.-„ SAOi, and SAOj form a flatly oblique, nearly horizon- tal, straight line that passes slightly behind SAO3; SAO1.2 interspace about half that of 141 Fig. 127 — Diaphus brachycephalus. male, 51.2 mm. (Photophores retouched). SAO..-,!. Pre closely spaced in a moderate curve, the Prc.^.^ interspace a little wider than the others. Opercular margin irregular, the lateral portion produced into a blunt point above FLO. Size: To about 45 mm. Least depth of capture: To about 150 m at night. Distribution: Apparently the species is confined to warm waters of both the North Atlantic and Pacific Oceans (Fig. 124). I have seen two specimens from the South Atlantic Ocean (33° 47' S, 15° 47' W). Discussion The 10 specimens before me answer well to the description and figure offered by Nafpak- titis (1968) for specimens from the North Atlantic (the type locality). This species is closely related to D. richardsoni but differs slightly in some body proportions (Table 25) as well as in certain luminous organs, as stated above. Table 25. Body Proportions for Diaphus richardsoni and D. brachycephalus. D. rich ardsoni D. brachycepha \tus Java S. China Sulu South So uth Eastern North Measurement Trench Sea Sea Africa Pacific Atlantic* SL- SL- SL- SL- SL- SL- SL- 31 (21.3- 50.0mm 37.5mm 46.5mm 44.0mm 39.6mm 34.2mm 38.1mm 51.4mm) Head lengtli 320 317 327 311 346 351 .342 353 342-368 Head depth 234 221 219 220 260 264 267 266 252-282 Upper jaw length 212 205 219 207 220 232 226 232 222-239 Orbit length 112 107 106 109 134 133 131 138 130-149 Snout length 56 48 49 55 40 42 47 — Prepectoral length 312 315 327 298 334 339 334 350 337-362 Prepelvic length 500 476 495 479 487 481 467 510 496-521 Preanal length 700 688 697 675 685 692 683 699 680-723 Predorsa! length 500 507 516 515 548 536 525 516 503-531 Preadipose length 842 845 845 850 852 835 838 831 800-844 Dorsal origin to pelvic origin 230 237 219 218 266 269 263 — Dorsal origin to anal origin 320 304 314 298 336 342 334 — Caudal peduncle length 220 189 187 200 189 181 192 — Caudal peduncle depth 118 128 120 102 134 140 131 145 135-158 Dorsal base length 174 176 172 168 194 197 186 195 186-213 Anal base length 166 165 159 155 157 163 152 168 158-181 'Data from Nafpaktitis (1968). 142 Diaphus richardsoni Taning, 1932 Fig. 128 — Diaphus richardsoni, male, 50.0 mm. From the Java Trench. Description The following data are taken from four specimens, one each from Java Trench, South China Sea, Sulu Sea, and off Durban, South Africa. D, 12-13; A. 13; P. 10 (11); AO 5 + 3-4, total 8-9; gill rakers 6 + 1 + 13-14, total 20-21; vertebrae 32. PLO above pectoral origin by about one-third the distance from there to lateral line. VO4 elevated to about level of pectoral origin. VLO slightly behind pelvic origin and nearer to it by about one-third the distance to lateral line. VLO about half its diameter above level of VO.,, a line through these 2 organs passing well above PLO. SAO series very slightly angulate; a line through SAO1.2 passes a little before VO,-, and behind SAO.^. First AOs not elevated; ultimate AOa elevated by about its diameter above penultimate AOa. SAOj and Pol below lateral line by two to three times their diameters. Diaphus richardsoni is closely related to D. brachycephalus . It differs primarily in having no heavily pigmented area around the So, and the Vn of males is much less massive anteriorly than in D. brachycephalus; the Vn of females is similar in the two species. Also, D. richardsoni appears to have the external pore structure of the lateral line less strongly developed. It has a more slender body, as indicated in the body proportions in Table 25. Size: To 57 mm (Holotype). Least depth of capture: To about 200 m at night. Distribution: This species has not yet been reported from the eastern Pacific Ocean, but since the type locality is north of new Guinea (02° 00' N, 138° 22' E), it may occur in the poorly collected southwestern section. Diaphus anderseni Tanmg, 1932 Description D. 13; A. 11-12; P. 10-11 (9); AO 4 (3-5) + 5, total 9 (8-10); gill rakers 5-6 (4) + H- 12 (11-13), total 18-20; vertebrae 33 (32-34). Body photophores large, those of SAO and AO series less than half a diameter apart. PLO before pectoral origin and somewhat nearer it than to lateral line; VLO only two or three of its diameters above pelvic base. Pre closely spaced, in a moderately flat curve. 143 Fig. 129— Diaphus anderseni . From Taning (1932, p. 134, fig. 6). Size: To about 35 mm. Least depth of capture: To about 24 m at night. Distribution: Although the type locality is southwest of Fiji, the species is very common in the northeastern Pacific Ocean (Fig. 124). Notolychnus Fraser-Brunner, 1949 Frontal bones expanded into a small, but conspicuous, median, transparent dome into which the pineal organ extends. Adipose fin far behind end of anal base. Two Pre arranged vertically. Five PO, the third notably, the fourth markedly, elevated. Four VO, the first elevated. VLO, SAO;,, and upper Pol very high, near dorsal profile. Dn present; no Vn. A single deeply set translucent supracaudal luminous gland present in both sexes; no infracaudal glands. Males have a much larger eye and supracaudal gland than do females. Lateral line obsolete. Photophores are easily lost on this diminutive species, but the supracaudal gland, or a portion of it, usually remains. If this gland is also lost, the far-back portion of the adipose fin is diagnostic, as are the low number of pelvic rays (6). A single species is recognized. Notolychnus valdiviae (Brauer, 1904) Fig. 130 — Notolychnus valdiviae (Brauer, 1904). (A.) Adult male (note large eyei, (B.) Dorsal view of male caadal peduncle, (C.l Head of adult female, (D.) Caudal peduncle of adult female, lE). Dorsal view of female caudal peduncle. From Bolin (1946, p. 147, fig. 9i. 144 Description D. 11 (10-12); A. 13 (12-14); P. 13 (12-14); AO 4-5 + 3-4; gill rakers 2 + 1 + 7; vertebrae 29 (27-31). Size: To about 25 mm. Least depth of capture: Clarke (1973) reported that night tows between 80 and 100 m took specimensof less than 15 mm almost entirely, but specimens of 20 mm or more between 115 and 145 m. Distribution: Circumglobal in tropical and temperate waters. Discussion Although Bolin ( 1946) described and figured an infracaudal gland for females from the Indian Ocean (Fig. 130 E), I have been unable to detect a definite gland on any specimen from the eastern Pacific Ocean. However, as this is a very fragile species, it may be that the gland is easily lost. The figure from Bolin was used because no intact specimen was available to me; none had the full complement of photophores, and few had the supracaudal gland intact. Taaningichthys Bolin, 1959 Lateral line poorly developed or obsolete. Snout short and blunt, less than half the orbital diameter; orbit large, usually less than 3.0 in head. A large, opaque, whitish crescent on posterior half of iris. Photophores weakly developed or entirely absent, often lost with the fragile, easily eroded integument. PO 5-7; VO 3-10. A large, pearly white luminous organ set deeply into upper and lower surfaces of the caudal peduncle of both sexes. Three Pre, the first 2 low and closely spaced, the third at lateral line and widely separated from the others. Key to species of Taaningichthys la. Distance from anal origin to end of hypural less than distance from anal origin to upper end of pectoral base. Pectoral fin extending well beyond pelvic base. Five PO; VO 8-10; only 1 SAO, near lateral septum; AO 5-8 -i- 3-5. Supracaudal luminous gland usually less than half the length of infracaudal gland. Scales small, 40-41 along lateral septum; ver- tebrae 49 (39-41) T. minimus lb. Distance from anal origin to end of hypural greater than distance from anal origin to upper end of pectoral base 2 2a. Supracaudal and infracaudal luminous glands about equal in length. Pectoral fin not reaching to pelvic base. Five to 7 PO; VO 2-5; only 1 SAO, high, near lateral septum; AO 2-3 + 1-2. Scales large, 35-36 along lateral septum; vertebrae 35-36 T. bathyphilus 2b. Supracaudal luminous gland half or less the length of infracaudal gland. Pectoral fin reaching to about pelvic base. No photophores on head or body T . paurolychnus Taaningichthys bathyphilus (Taning, 1928) Fig. 131— Taaningichthys halhyphihts^ From Bolin (1959, p. 26. fig. 6) 145 Description D. 13 (12-14); A. 13; P. 13 (12-15); AO 2-3 + 1-2; PO 5-7; VO 2-5; gill rakers 3 + 1 -f- 7 (6-8), total 11 (10-12); vertebrae 35-36. PVO, J in nearly vertical line. VLO much nearer lateral line than to pelvic base. Pre,. 2 interspace small, equal to about one photophore diameter. Size: To 68 mm. Least depth of capture: Clarke (1973, p. 415) reported that T. bathyphilus was taken regularly between 600 and 1000 m and occasionally deeper both day and night. Greatest catches were between 700 and 800 m. It was the only myctophid which definitely did not migrate. Distribution: This species is known from all oceans, but is not common; seldom are more than four taken in one haul. In the eastern Pacific Ocean it has not been taken in the wide area between the tip of Baja California and about 15° S (Fig. 132), perhaps due to the thick layer of oxygen-deficient water underlying the area. Fig. 132— Capture localities in the eastern Pacific Ocean for Tanmngichthys bathyphilus (open circles), T. minimus (closed squares) and T. paurolychnus (open triangles). 146 Taaningichthys minimus (Taning, 1928) Fig. 133 — Taaningichthys minimus. 51.8 mm. Description D. 12 (11-13); A. 13 (12-14); P. 16-17; AO 7 (5-7) + 4 (3-6); PO 5-6; VO 9-10; gill rakers 4-5 -I- 1 -I- 11-12 (10-13), total 16-17 (15-18); vertebrae 40 (39-41). PVOi well behind a vertical from PVO^. VLO midway between pelvic base and lateral line, or slightly nearer the latter. Prci.2 interspace equal to at least two photophore diameters. Size: To about 60 mm. Least depth of capture: Between 0 and 400 m at night, 0 to 800 m in daylight in Hawaiian waters. Clarke (1973) states "Other reports, e.g., Davy (1972), have stated that T. minimus does not migrate, but all night catches in this study were well above the day depth range. Individuals 20-30 mm long were caught between 150 and 250 m at night and larger fish between 200 and 400 m. None were taken in night tows below 475 m." Distribution: As with T. bathyphilus, T. minimus is known from all oceans but is even less frequently taken. In the eastern Pacific it is the least commonly taken of the three species (Fig. 132). Taaningichthys paurolychnus Davy, 1972 Fig. 134 — Taaningichthys paurolychnus, male, 64.5 mm. Description D. 12-13; A. 13 (12-14); P. 14 (13-15); no AO photophores; gill rakers 3-4 +1-1- 10-11 (9-12), total 14-15 ( 13-16); vertebrae 35 (36). No luminous organs or photophores on head or body, other than large supracaudal and infracaudal luminous glands; although species of the genus Taaningichthys are notable for 147 extreme fragility of the photophores, the very excellent condition of several specimens of T. paurolychnus leaves not doubt as to their absence. Size: To 95 mm. Least depth of capture: Between 0 and 1000 m at night. Davy (1972) reported that this species had not been taken above 900 m and that it did not appear to perform daily vertical migrations. Distributions: In the eastern Pacific Ocean (Fig. 132) this species is commonly taken but not in large numbers, no more than two having been taken in one haul. Davy (1972) reported this species from the warmer waters of all oceans. Discussion Aside from the lack of head and body photophores, another striking feature of T. paurolychnus is the presence of a pair of nearly transparent, bony, broad-based, and strongly recurved teeth projecting forward from the tip of each premaxillary (Fig. 135). Similar teeth rarely occur in the species T. bathyphilus and T. minimus, but only a few specimens of each species have been found with one or more teeth remaining, either relatively intact or as stubs. If an entire tooth is missing a pit in the bone will indicate its former presence. The highly vulnerable position of these teeth, at the very tips of the premaxillaries, and their sharply pointed and recurved structure, render them easily snagged and broken by the meshes of nets, or by contact with other organisms during capture. The probably luminous crescent of whitish opaque tissue on the posterior position of the iris (a differentiating character of the genus Taaningichthys) is more pronounced in this species than in others of the genus (Fig. 136). This crescent is barely or not at all visible in Fig. 135 — Ventral view of premaxillary teeth of Taaningichthys paurolychnus. Paired teeth occur at an- teriormost margin of each premaxillary bone. The tooth at left center is intact; the tips of the remaining teeth are missing. The entire tooth is missing on the extreme right (left side of specimen!. 148 A " :irv«3s£^'-77-S5,\r.-r>ir-T7>i:x.j:-ff.-»rrprf*/,ii!;2c^ ^i^ J -i V w4*.'«'-. ' : : :>": ^. it 1 F ■■^^^^^^ Figure 136 — Head of Taaningichthys paurolychnus , 69.0 mm, showing extent of whitish crescent on posterior portion of iris. fresh material, most specimens requiring nearly two hours in preservative (10% formalin) before attaining the maximum state of whiteness. On specimens of T. paurolychnus in excellent condition there is often a domed covering of a transparent, viscous substance over both the supra- and infracaudal luminous glands (Fig. 137). Either this dome is quite fragile or the viscous substance is readily dissolved in preserv- ing fluids (lO'/f formlin followed by 40% isopropyl alcohol) for in several specimens that originally had this structure it is now collapsed. Lampadena Goode and Bean, 1896 Large, very silvery, undivided luminous glands, usually set rather deeply into vertical surfaces of caudal peduncle in both sexes. No crescent of luminous tissue on iris. Vn small, inconspicuous; Dn absent. PO series linear, except in one species in which PO4 is highly elevated. Usually 5 VO, but variably 4 to 6, none markedly elevated. SAO in a steep, slightly angulate line, usually in series with last VO. One Pol; 3 Pre, the upper at end of lateral line. Dorsal and anal fin bases not overlapping; base of adipose fin over or slightly behind end of anal base. Procurrent caudal rays stiff, spine-like. Nafpaktitis and Paxton ( 1968) presented a review of the genus Lampadena from all oceans and included a key to identification of seven species, one new; of these, five are known to occur in the eastern Pacific Ocean, and the other two may eventually be found in the poorly 149 Fig. 137 — Caudal region of Taaningichthys paurolychnuH, 69.0 mm, showing domed covering of the caudal luminous glands. Supracaudal gland is the shorter one. collected southern portion. Krefft (1970), dealing only with Atlantic Ocean material, described a new species, L. pontifex, from the vicinity of Cape Verde Islands, and provided a detailed description and a figure of L. anomala (see Fig. 145). As stated by Nafpaktitis and Paxton (1968), "The genus as a whole is rather uncommon. Examination of many more collections around the world will probably result in an increase in the number of know species in the genus and further elucidate individual patterns of distribu- tion." With this statement in mind it is deemed reasonable to present their key, including all seven species, in anticipation that further collecting effort will indeed show them to occur in the eastern Pacific Ocean. Key to species oi Lampadena la. PO4 abruptly and highly elevated to over or slightly before or behind PO3 and about on level of PVO,, or slightly higher L. luminosa lb. None of the PO abruptly or highly elevated 2 2a. VO plus SAO equals 5 to 6; AOa 3 to 4. Caudal luminous glands rather weakly developed and not set deeply into vertical surfaces of caudal peduncle L. anomala 2b. VO plus SAO equals 7 to 9; AOa 5 to 7. Caudal luminous glands strongly developed and set deeply into vertical surfaces of caudal peduncle 3 3a. Prci.2 interspace equal to, or greater than, three times the diameter of a photophore of this series 4 3b. Prci.j interspace much shorter than three times the diameter of a photophore of this series 5 4a. Last 2 (sometimes 3) AOa entirely behind base of anal fin; 2 AOp; infracaudal luminous gland very long, at least 1.5 times as long as least depth of caudal peduncle, almost twice as long as diameter of eye; crescent-shaped patch of whitish tissue on iris above pupil; pterotic spine directed posteriorly L. chauesi 4b. No AOa behind base of anal fin; 4 to 5 AOp (rarely 3); infracaudal luminous gland shorter than 1.5 times the least depth of caudal peduncle an about 1.5 times as long as diameter of eye; no crescent-shaped patch of whitish tissue on iris above pupil; pterotic spine directed downward and forward (in specimens longer than about 30 mm) L. dea 150 5a. Gill rakers 6-8 + 1 + 12-17; supracaudal gland shorter than infracaudal gland; mesoptery- goid teeth uniformly small 6 5b. Gill rakers 3-5 + 1 + 8-10; supracaudal gland equal in length to or somewhat longer than infracaudal gland; posterior mesopterygoid noticeably enlarged L. urophaos 6a. Distance between posterior end of base of anal fin and anterior margin of infracaudal gland equal to, or slightly greater than, length of this gland. Photophores small; those of the AOa series about one diameter apart (about two diameters in specimens of less than 30 mm). First and usually second AOp in front of infracaudal gland; AOa level; gill rakers 6-7 + 1-1- 12-14, total 19-22 L. speculigera 6b. Distance between posterior end of base of anal fin and anterior margin of infracaudal gland equal to about one-fourth of length of this gland; photophores large. AOa in- terspaces about 1.5 times the diameter of a photophore (less than one diameter in speci- mens less than 30 mm). All AOp well over infracaudal gland; last AOa usually distinctly raised above level of rest of organs of same series; gill rakers 7-8 -I- 1 + 16-17, total 24-26 L. notialis Lampadena luminosa (Garman, 1899) / \ \ 7 Fig. 138 — Lampadena luminosa, 67.4 mm. From Nafpaktitis and Paxton (1968, p. 5, fig. 1). Description D. 15; A. 14 (13-14); P. 16 (15-17); AO 5-6 (7) + 2; Pre 2+1; gill rakers 4+1 + 9 (8-10), total 14 (13-15); PO 5; VO 4-5; vertebrae 36 (37) (8 specimens); lateral line scales 35-37. Pterotic spine prominent, directed posteriorly. Supracaudal and infracaudal luminous glands of about equal length, slightly less than orbital diameter; distance between anterior end of infracaudal gland and posterior end of anal base about equal to or slightly less than length of gland. /ly P SJ2e.- To 150 mm (off Japan). /^ • Least depth of capture: To 60 mm at night and to 555 m in daylight. Clarke (1973) reported "large" fish taken mostly between 150-250 m at night but between 650-750 m in daylight in Hawaiian waters. Distribution: This species has been reported primarily from the warmer waters of the Atlantic and Indian Oceans; one specimen is known to me from the eastern Pacific, 04°56' N, 142°54' W. 151 Lampadena urophaos Paxton, 1963 Fig. 139 — Lampadena urophaoa. male, 112-0 mm. Fig. 140 — Lampadena urophaos. 56-0 mm. From Nafpaktitis and Paxton (1968, p. 8, fig, 2). Description D. 15 (14-16); A. 14 (13); P. 16 (15-17); AO 5 (6) + 2 (3), total 7 (8-9); gill rakers 4 (3-5) + 1 + 8-9 (10), total 13-14 ( 16); PO 5; VO 5 (4-6); Pre 2+1; vertebrae 36 (35). Pterotic spine strong, directed posteriorly and slightly ventrally. Caudal luminous glands about of equal size in small specimens, but supracaudal gland slightly larger in those over 50 mm. Distance from anterior end of infracaudal gland to end of base of anal fin 1.0 to 0.75 times the length of the gland. Size: To 104 mm. Least depth of capture: To 130 m at night. Distribution: L. urophaos occurs between about 25° and 42° N in the eastern Pacific and westward to Hawaii, A possible subspecies occurs in the North Atlantic Ocean. Discussion Maul (1969) described a new subspecies, L. urophaos atlanticus , from the northeastern Atlantic Ocean, He based the distinction on a more posterior position of PVOi (slightly behind, rather than on, a vertical from PVO2); also, the 2 caudal luminous glands were described as equal in length at all sizes of specimens, whereas in the Pacific form the supracaudal gland was somewhat larger in specimens over 50 mm. 152 Photographs of an otolith of L. urophaos (Nafpaktitis and Paxton, 1968) and of L. u. atlanticus (Kotthaus, 1972) show striking dissimilarities that approach the familial level and indicate a possible aberrance in formation or an error. Nafpaktitis (personal communication) has found the more posterior position of PVO, to be inconstant, a significant number of specimens having PVOi directly below PVO^. Thus, in view of this inconstancy, the apparently excessive difference in shapes of otoliths, and an only slight difference in lengths of supracaudal luminous gland with size offish, more study is needed, particularly on otoliths, to validate the subspecific distinction. Pending this study, I retain L. urophaos at the full species level. Lampadena speculigera Goode and Bean, 1896 Fig. 141 — Lampadena speculigera . 66.0 mm. From Nafpaktitis and Paxton (1968, p. ll,fig.3). Description D. 14(13-15); A. 14 (15); P. 14(15); AO 6-7 + 3-4 (5); Pre 2 + 1; PO 5 (6); VO 5 (4-6); gill rakers 6-7 -I- 1 + 12-14, total 19-22; lateral line scales 39-41; vertebrae 38-39 (40) (five specimens). Eye large, 2.7 to 3.2 in head. Opercular margin not pointed but with a shallow indentation about at level of pectoral origin. Pterotic spine strong, straight, directed posterolaterally. Supracaudal luminous gland one-half to two-thirds the length of infracaudal; posterior margin of supracaudal distinctly notched. Distance from end of anal base to anterior end of infracaudal 1 to 1.5 times the length of the gland. Size: To 130 mm. Least depth of capture: To 60 m at night and 100-700 m in daylight. Distribution: In southeastern Pacific off Chile at about 34° S, 73° 30' W. Also known from North Atlantic and southern Indian Oceans, and off New Zealand. 153 Lampadena notialis Nafpaktitis and Paxton, 1968 7 / / Fig. 142— Lampadena notialis. holotype, 66.3 mm. From Nafpaktitis and Paxton (1968, p. 14, fig. 5). Description D. 14; A. 14; P. 14; AO 6 + 3; Pre 2 + 1; PO 5; VO 5 (6); gill rakers 7-8 + 1 + 16-17, total 24-26; lateral line scales 38-39; vertebrae 37-38 (two specimens). Eye large, 2.8 to 3.0 in head. Opercular margin produced into two rounded lobes separated by triangular indentation about at level of PVO2. Pterotic spine directed posterolaterally in young (66 mm) and posteroventrally in mature specimen (105 mm). Supracaudal luminous gland about 0.75 times the length of infraucaudal; infracaudal gland length equal to (in small specimens) or greater than (in large specimens) diameter of eye. Distance between end of anal base and anterior end of infracaudal gland about 0.25 of that gland. Size: To 105 mm. Least depth of capture: To 60 mm at night (28-mm specimen) and to 715 m in daylight (128-mm specimen). Distribution: Known from near New Zealand and Australia, and from Indian Ocean and off the Cape region of South Africa between 40° and 50° S. Lampadena dea Fraser-Brunner, 1949 ^■>f^ ' O oy Fig. 143 — Lampadena dea, 59.0 mm. From Nafpaktitis and Paxton (1968, p. 17, fig. 6). 154 Description D. 14; A. 14 (15); P. 14 (15); AO 6-7 (5) + 4-5 (3); Pre 2+ 1; PO 5; VO 5 (4-6); gill rakers 6 (7) + 1 -H 14 (15), total 21 (22-23); lateral line scales 37-38; vertebrae 37-38 (three specimens). Eye large, 2.9 to 3.3 in head. Opercular margin with a very distinct triangular indentation at level of pectoral origin. Pterotic spine very strong, curved downward and forward in larger specimens, pxisterolaterally in smaller specimens. Supracaudal luminous gland about 0.66 of infracaudal; posterior margin of supracaudal slightly to distinctly notched. Distance between end of anal base and anterior end of in- fracaudal gland less than 0.25 the length of that gland. Size: To 63.5 mm. Least depth of capture: To 150 m at night (21-mm specimen) and between 350 and 2390 m in daylight (64-mm specimen). Distribution: In southern parts of all three oceans between about 20° and 50° S. Lampadena chavesi Collett, 1905 .C^^\:- Fig. 144 — Lampadena chavesi, 54.5 mm. From Nafpaktitis and Paxton (1968, p. 18, fig.7). Description D. 14; A. 13-14 (12); P. 16-17; AO 7 (8) + 2; Pre 2 -f- 1; VO 5 (6); gill rakers 6-7 -t- 1 -F- 13, total 20-21; lateral line scales 38 (39); vertebrae 37-38 (two specimens). Eye large, 2.6 to 3.3 in head. Opercular margin with slight indentation opposite middle of pectoral base. Pterotic spine strong, directed posteriorly. Caudal glands largest and most distinctive of the genus Lampadena ; supracaudal gland bifurcate posteriorly; infracaudal flat in cross section, limited to ventral surface, and not extending down much on sides of peduncle, tapering posteriorly rather than anteriorly (in contrast to all other species of this genus). Distance between end of anal base and anterior margin of infracaudal gland very short, about twice a photophore diameter. Size: To 60 mm. Least depth of capture: To 50 m at night (22 to 24-mm specimens). Distribution: Apparently antitropical; it occurs in North Atlantic and in southern Indian and Pacific Oceans between about 30° and 40° S. Craddock and Mead (1970) reported eight specimens from west of Valparaiso, Chile, between about 88° and 93° W. Lampadena anomala Parr, 1928 Fig. 145— Lampadena anomala, 149.7 mm. From Krefft (1970, p. 282, fig. 4). Description D. 16; A. 13-14; P. 16-18; AO 3-4 + 2; gill rakers 5 -h 1 -^ 11 (10-12), total 17 (16-18); vertebrae 36-38. The following data and description are taken from Nafpaktitis and Paxton (1968) and from Krefft (1970). Photophores smaller than in other species of the genus. VLO nearer lateral line than to pelvic base. Three VO; 3 SAO; 3 AOa, widely separated; 2 AOp, the last over anterior margin of infracaudal luminous gland. Three Pre, the first 2 very close together, the third far distant at end of lateral line. SAOu and Pol about their diameters below lateral line. Supracaudal luminous gland slightly shorter than infracaudal, its length about equal to distance between end of anal base and anterior margin of infracaudal gland. Size: To about 150 mm. Least depth of capture: To 170-330 m at night (Krefft, 1970). Distribution: L. anomala is known primarily from the Atlantic Ocean. Nafpaktitis and Nafpaktitis ( 1969) reported a single, damaged specimen from the western Indian Ocean. A badly damaged specimen, apparently of this species, was taken in the east-central Pacific Ocean at about 05° S, 135° W. Discussion The occurrence of this species in the eastern Pacific Ocean is somewhat questionable. It is based on a badly damaged specimen (ca. 48 mm) that conforms well to the diagnoses given by Nafpaktitis and Paxton (1968) and by Krefft (1970), exceptfor somewhat fewer gill rakers (4 + 1 ^- 9-10, total 14-15). All photophores, except the AO series, are missing in the Pacific specimen, but the weakly formed caudal luminous glands, and the general similarity in counts, indicate at least a close relationship to L. anomala. Dorsadena Coleman and Nafpaktitis, 1972 Basically similar to genus Lampadena in body structure, arrangement of photophores, and size and positions of caudal luminous glands. It differs principally in having an elongate luminous gland covering the dorsal midline immediately in front of the adipose fin; this gland is in addition to the supracaudal and infracaudal glands. Also head, body, anterior portion of caudal fin, and scale pockets along lateral line bear many tiny secondary photophores. Four or 5 Pre, 1 or 2 far above lateral line near bases of dorsal procurrent caudal rays. A single species is known. 156 Dorsadena yaquinae Coleman and Nafpaktitis, 1972 Fig. \46— Dorsadena yaquinae. holotype, 77.0 mm. From Coleman and Nafpaktitis (1972, p. 3, fig. 1). Description As I have seen no study material of this species, the following data are taken entirely from Coleman and Nafpaktitis, 1972. D. 14-15; A. 12-14; P. 15-16; AO 5-7 + 3-5, total 9-11; gill rakers (4) 5 + H- 11, total 17 (16); vertebrae — no data. Dn absent; Vn very small, poorly developed. Body photophores generally small and not well defined (in preserved specimens). PLO slightly before a vertical from pectoral origin. PVO, and PVOj in a near vertical line; PVOj close to middle of pectoral base. PLO, VLO, SA0,-5, and Pol respectively about their diameters below lateral line. Six to 8 PO, variably spaced in a wavy line; 3 to 5 (usually 4) VO, none elevated. SAO series in very wide angle, a line through SAO, and SAO. passing behind SAO^ and near vent. First and last AOa in- terspaces occasionally enlarged; first or last AOa, or both, slightly elevated. Pol under base of adipose fin. Prc,.j interspace less than a photophore diameter; Pre, slightly lower than Prc^; Prc3 well behind a vertical from PrC:.. and at or near end of lateral line; 1 or 2 additional Pre near dorsal procurrent caudal rays. Supracaudal and infracaudal luminous glands small, undivided, equal in size, and ap- posed, their length 1.6 to 2.0 times in orbital length. Each gland framed in dark tissue; most of the luminous tissue is covered posteriorly by a darkly pigmented hood. Next to the dorsally displaced Pre, the most definitive character is an undivided luminous gland about equal to the orbital length, extending from anterior end of base of adipose fin to nearly midway to end of base of dorsal fin, the gland outlined by black pigment with luminous tissue bulging dorsally. Many minute secondary photophores on head, body, and anterior part of caudal fin, and in rather regular vertical patterns on scale pockets along lateral line. Size.- To about 100 mm. Least depth of capture: To 180 m at night. Distribution: Only five specimens known, taken from a small area of the North Pacific Ocean bounded by about 44° to 45° N, 134° to 139° W. Lampanyctodes Fraser-Brunner, 1949 The 8 to 10 procurrent caudal rays are stiff and spine-like. Dn, if present, modified into a thin, elongate patch of luminous tissue between anterior portion of supraorbital bone and orbital margin and extending downward nearly to nasal rosette; Vn round, deeply embedded. PVO, before and nearly level with PVO:. — a condition similar to that found in the primitive 157 Electronini subgenera Protomyctophum and Hierops, and in genera Benthosema and Diogenichthys. Five PO, the third and fifth slightly but distinctly elevated. Five VO, the first 3 successively elevated in a pattern similar to those of the genera Lobianchia and Diaphus; last 2 VO essentially on the same level and well below VO3. One species is recognized. Lampanyctodes hectorisCGiinther, 1876) Fig. 147 — Lampanyctodes hectoris, male, 60.5 mm. Description D. 13-14; A. 15-16 (14-17); P. 13 (12-14); AO 8 (7-9) + 6(4-7), total 13-14 (12-15); gill rakers 10-11 + 1 + 20-21 (19-22), total 30-31 (29-33); vertebrae 37 (36-39). Three SAO in a straight, equally spaced line about in series with VO5. No AOa elevated; 1 Pol; 5 (4-6) Pre; all photophores well below lateral line. Dorsal and anal bases about equal in length. Pupil very small, less than diameter of lens. Size: To about 70 mm. Least depth of capture: To 220 m at night off South Africa. Distribution: This species is known from off South Africa, New Zealand, and Australia, and is probably circumglobal near the southern boundary of the Subtropical Convergence; it has not yet been reported from the eastern Pacific Ocean. Discussion Lampanyctodes hectoris, an infrequently reported species, is poorly described. The de- scription of the type is inadequate in that neither photophores nor luminous glands are men- tioned (Giinther, 1876: 471). Gilchrist (1905), in describing this species as Scopelus argenteus from off South Africa, presented a more complete description. Fraser-Brunner (1949), in characterizing the genus Lampanyctodes , added further details but erred in stating that the procurrent caudal rays were "soft" and spine-like when they are distinctly stiff. He further erred in stating that aside from the small supracaudal and infracaudal luminous glands no luminous glands appeared elsewhere. In addition to the three or four small luminous scales of the caudal glands, weakly de- veloped, small and fragile, luminous scales are below PVO, , posteroventrad to PLO, below VLO, and below most if not all AOa photophores, but apparently not below those of the AOp series. There are also one or two rows of very small luminous scales under most of the Pre photophores. Similar scales are present at bases of most dorsal procurrent caudal rays behind the supracaudal gland, possibly on each scale pocket between end of dorsal base and origin of adipose base, between origin of dorsal base and occipital region of head, and at bases of most dorsal fin rays. Since detailed counts and measurements for L. hectoris are not available in the literature, correlated counts for dorsal and anal fin rays, AO photophores, and gill rakers (Table 26), and a list of body proportions are offered, based on material from near South Africa. 158 Table 26. Correlated Counts of Anal and Dorsal Fin Rays, AO Photophores, and Gill Rakers for Lampanyctodes hectoris from Near South Africa Anal rays 13 14 15 16 17 Dorsal 2 5 4 2 rays 14 — 18 13 1 AOp 5 6 7 3 59 8 AOa 8 1 47 112 3 9 — 7 6 — Lower rakers (including central raker) 19 20 21 22 Upper rakers 10 11 27 5 17 14 The following body proportion of Lampanyctodes hectoris are based on 15 to 17 specimens, 37.5 to 61.9 mm in length. Averages are given first, followed by the range of values in parentheses. Head length 308 (293-326): head depth (on a vertical through angle of jaw) 199 (191-208); orbital diameter 90 (81-99); upper-jaw length 236 (223-251); prepectoral length 320 (302-338); prepelvic length 447 (429-466); preanal length 631 (612-655); predorsal length 449 (432-466); preadipose length 814 (797-828); dorsal origin to pelvic origin 191 (176-204); dorsal origin to anal origin 276 (262-293); caudal peduncle length 201 (187-213); caudal peduncle depth 83 (76-88); dorsal base length 177 (165-187); anal base length 197 ( 180-208). Stenobrachius Eigenmann and Eigenmann, 1890 Vn present, no Dn. SAO in relatively straight line, in line, or nearly so, with last VO. One Pol. POj much elevated; VO level. Supracaudal and infracaudal glands present in both sexes. la. lb. Key to species of Stenobrachius Usually 4 (3-5) VO, the V0,-2 interspace larger than the rest. Usually 4 (3-5) Pre, in even curve. Numbers of SAO variable, usually counted as 3, but 2 or 4 not uncommon. Sup- racaudal gland with 5-8 luminous scales; infracaudal with 7-9 scales, filling entire space. Body moderately robust S.leucopsarus Usually 5, rarely 4, VO; usually 3, rarely 4, Pre. Supracaudal luminous glands 2-4; in- fracaudal glands 5-6, filling only about three-fourths of infracaudal space. Body slender, elongate -S- nannochir nannochir Stenobrachius leucopsarus (Eigenmann and Eigenmann, 1890) Description D. 14 (13-15); A. 15 (14-16); P. 9 (8-10); AO 6 (5-7) + 7 (6-8), total 13 (12-14); gill rakers 5 (6)-^ 1 + 12 (11-13), total 18 (17-19); vertebrae 36 (35-37). Descriptive data, other than that in key to species, is given below in a discussion of differences between S. leucopsarus and its congener S. nannochir . 159 Fig. 148 — Stenobrachius leucopsarus, male, 77.0 mm. Size: To about 90 mm. Least depth of capture: Rarely dipnetted, but commonly taken above 30 m at night. Distribution: S. leucopsarus is confined to the North Pacific cold water areas. It occurs from off Baja California, Mexico (about 29° N, 115° W) northward into Gulf of Alaska and Bering Sea and west to Kamchatka and Kurile Islands (Fig. 149). Capture data from Aron, (1960, Fig. 149, dotted lines) indicate that the species is abundant in northern waters; the solid line enclosing near-shore water off southern California, indicates an area in which hundreds of specimens have been taken. Paucity of capture localities in northwestern Pacific may reflect minimal collecting effort. Fig. 149 — Capture localities for Stenobrachius n. nannochir (large solid circlesi and S. leucopsarus. For this latter species, the heavy curved line off southern California and northern Baja California, Mexico, encloses an area in which many collections (hundreds of specimens) were made. The thin, straight lines indicate the cruise tracks of expeditions reported by Aron (1960), each dot representing at least one capture of this species. The open circles indicate additional captures of S. leucopsarus. 160 Stenobrachius nannochir nannochir (Gilbert, 1890) Fig. 150 — Stenobrachius n. nannochir , female, 107.0 mm. Fig. 151 — Stenobrachius n. nannochir, drawing of specimen in Fig. 150. Description D. 14 (13); A. 15 (14-16); P. 9 (10); AO 7 (6-8); total 13-14 (15); gill rakers 5-6 + 1 + 12 (11-13), total 18-19 (17-20); vertebrae 37 (36-38). Size: To about 110 mm. Least depth of capture: To 300 m in daylight (See Discussion). Distribution: In the eastern Pacific this is a more northern form than S. leucopsarus . Off California it is not taken south of about 40° N; it ranges north into Gulf of Alaska and across the North Pacific (Fig. 149). A subspecies, S. n. laticauda Kulikova (1960), occurs in Okhotsk Sea, but the eastern range of this subspecies, or any overlap in distribution of the two forms, is not known. Discussion S. n. nannochir and its congener S. leucopsarus are somewhat similar and have been confused although they are readily separable. In addition to the principal characters given in the key to species, the following may be of aid in distinguishing between the two; In general, S. leucopsarus has a more robust body; the depth at pectoral origin is 21% of SL, vs about 19% in S. n. nannochir . The eye is slightly smaller and the upper jaw distinctly longer in S. n. nannochir, such that the eye is 30% (28-33% ) of upper jaw vs 38% (34-41% ) in S. leucopsarus . Also, the caudal peduncle is more slender '\nS. n. nannochir , its least depth being 30% (28-33%r ) of its length vs 36% (33-40% ) in S. leucopsarus. In life, and persisting for some time in preservative, the photophores of S. leucopsarus are yellowish-green in color, and those of S. n. nannochir claret. 161 S. n. nannochir is apparently a deeper-living form than S. leucopsarus . Aron (1960) reported many captures of the latter species, but none of the first, in the North Pacific Ocean; most of Aron's sampling was at depths above 225 m at night, with but few to 400 m. Pearcy (1964) reported 2 specimens of S. n. nannochir from 23 tows taken between 0 and 500 m, and 39 specimens from 24 tows taken between 0 and 1000 m, all about 50 mi (80 km) off Newport, Oregon. Parvilux Hubbs and Wisner, 1964 Body elongate, slender, moderately compressed, the musculature rather weak and flaccid as in deep-living lampanyctids. Caudal peduncle moderately deep, about half the greatest depth of body. SOA in straight or slightly angulate oblique line. Procurrent caudal rays stiff and spinelike. Body photophores very small. PO i highly, PO,, slightly, elevated. Upper Pre at lateral line and widely separated from the rest. Pectoral fins very weak and short. Key to species of Parvilux la. Supracaudal and infracaudal glands short, of about 4 luminous scales each. VLO nearer lateral line than to ventral profile. SAO3 over or before a vertical from anal origin P. ingens lb. Supracaudal and infracaudal glands longer, of about 6 or 7 luminous scales each. VLO nearer ventral profile than to lateral line. SAO.t well behind a vertical from anal origin P. boschmai Parvilux ingens Hubbs and Wisner, 1964 Fig. 152 — Parvilux ingens. holotype, 160.0 mm. From Hubbs and Wisner 1964, p. 459, fig. 4). Description D. 14-17; A. 15-18; P. 10-13; AO 6 (5-7^+ 7 (6-8), total 13 (11-15); gill rakers 5 (4-6>f H- 12 (11-14), total 17 (15-19); vertebrae 37 (36-38). PO4 elevated to about level of PVO^; PO.i elevated by about its diameter above level of PO^ and POfi. VLO below lateral line by about one-third of distance from VLO to ventral profile and about over VO,; 3 to 6 VO (usually 4). SAO series slightly angulate, first 2 in line with VO.^, uppermost at lateral line and about over anal origin. AOa series level. AOp and Pre series not continuous. 162 Size: To about 200 mm. Least depth of capture: To 155 m at night. Distribution: This species is apparently confined to northeastern Pacific Ocean. It is pres- ently known from between about 28° and 40° N and seaward to about 130° W (one specimen known from near 41° N, 146' W). It is mostly confined to the California Current. Parvilux boschmai Hubbs and Wisner, 1964 Fig. 153 — Parvilux boschmai. holotype, 113.0 mm. From Hubbs and Wisner (1964, p. 458, fig. 5). Description D. 16-17; A. 17 (16-18); P. 12 (11-13); AO 6 (5-7M- 7 (6-8), total 13 (12-14); gill rakers (4)5 + 1 + (10) 11-12, total 17-18 (one specimen had 4+1 + 10, each side); vertebrae 36-37 (35-38). The species Parvilux boschmai was based on the holotype and only known specimen, but 12 additional specimens (101-126 mm) were available for the present study. PLO, SAO), upper Pol, and Pre touch or are very near lateral line. PO^ high, about on level of pectoral origin and slightly below, rarely on, level of VLO; PO4 usually nearer a vertical from PO.) than from PO.-, but occasionally midway between. VLO midway between, often slightly nearer, lateral line than level of VO, (nearer VOi in one specimen) and usually nearer a vertical from VO, than from VO^. Four VO (holotype has only 3 VO) about equally spaced. SAO series slightly to moderately angulate; SAOj on or a little behind, rarely slightly before, a vertical from VO.-,; SAO- variously somewhat before, on, or behind a vertical from first AOa. First AOa depressed, AOai.o interspace wider than those of remaining AOa. AOp and Pre series usually continuous; Prc^ widely distant from Pre,-}. Dn apparently absent; in the original description it was suggested that the Dn, if present, was represented merely by a streak of silvery tissue, but study of the new material shows this streak to be connective tissue. Vn prominent but often well covered with darkly pigmented tissue. Perhaps the most significant changes in the original description of P. boschmai are an increase from 3 VO to 4 (although holotype has but 3 equally spaced VO) and reduction in length of supracaudal gland; in holotype this gland was 14.2% of standard length but only 8.9% (7.1-11.6%) in the 12 new specimens. Certain body proportions are given below, including those for the holotype; the average value is given first, followed by range in parentheses: Head length 289 (273-310); head depth 155 (151-169); length of orbit 52 (48-60); length of upper jaw 200 (190-210); prepectoral length 288 (274-304); prepelvic length 401 (388-421 ); preanal length 545 (528-582); predorsal length 440 (414-464); preadipose length 791 (778-811); dorsal origin to pelvic origin 169 (147-176); dorsal origin to anal origin 206 (190-223); length of 163 dorsal base 208 (191-223); length of anal base 215 (206-232); length of caudal peduncle 252 (224-270); depth of caudal peduncle 80 (71-88); length of supracaudal luminous gland 89 (71-116); length of infracaudal luminous gland 134 (109-159). Size: To 126 mm. Least depth of capture: To 370 m at night. Distribution: P. boschmai is presently known only from the following five localities in the eastern Pacific Ocean: 02° 09' N, 84° 53' W (holotype), 08° 57' S, 107° 44' 107° 44' W (one specimen), 14° 46' S, 93° 37' W (one specimen), 20° 00' N, 129° 00' W (one specimen) and 11° 49' N, 144° 51' W (nine specimens). Triphoturus Fraser-Brunner, 1949 Five VO, 1 or more highly elevated and displaced forward. SAO markedly angulate. Two Pol. PLO, VLO, SAO.i, and Pol on or a little above lateral line; upper Pre well above and behind end of lateral line. Usually only 3 Pre, separate from AOp. Vn present, Dn absent. Pectoral fins tiny. Key to species of Triphoturus in eastern Pacific Ocean la. VO, and VO^ highly elevated and displaced forward to before verticals from VO2 and VO:j, respectively. PVO, well before vertical from PVO^ T. mexicanus (a complex) lb. Only VO] elevated and displaced forward to before VO.. PVOj almost directly below PVO2 T. nigrescens Triphoturus mexicanus species complex (Gilbert, 1890) Fig. 154 — Triphoturus mexicanus. From Bolin (1939, p. 136, fig. 21J, Description PLO below but nearly touching lateral line; all other upper photophores a little above lateral line. PO4 and SAO,.j about on a straight line that passes well above VO^ and VO3. SAO, well behind a vertical from VO4. Infracaudal luminous gland long, reaching to, or nearly to, end of anal base. The outline sketch (Fig. 154) is representative of all forms, since all are superficially very similar. In the eastern Pacific, two species and a probable subspecies are found, based primarily on numbers of gill rakers and vertebrae (Table 27). Moser and Ahlstrom (1970, p. 114) stated that, based on distinctiveness of the larvae, the southern form is referrable to Triphoturus oculeus (Carman, 1899). 164 Size: To about 70 mm. Least depth of capture: To about 50 m (rarely less) at night. Distribution: The species comples of T. mexicanus extends from about 38°N to 35°S, from off San Francisco, California, to a little south of Valparaiso, Chile (Fig. 156). As indicated (Table 27), the Gulf of California harbors a population that differs significantly from that of the open ocean, extending from near the tip of Baja California Peninsula northward. Moser and Ahlstrom (1970, p. 114) stated that T. oculeus ranged from Panama to Peru. However, T. oculeus ranges somewhat farther to the north and much father south (Fig. 155). Bussing (1965) reported the species from near Valparaiso, Chile, and Craddock and Mead (1970) reported it from there and westward to about 76°W, between about 31° and 35°S. Table 27. Some Meristic Characters of the Two Forms of Triphoturus mexicanus and for t. oculeus. Character Total gill rakers Vertebrae Total AO photophores Dorsal rays Anal rays Pectoral rays T. mexicanus T. oculeus Oceanic form Gulfof S.E. Pacific (ca20°to30°N) California (cal3°Nto35°S) 17(15-18) 18(16-20) 14(11-16) 34(32-36) 32(30-331 34(32-35) 10 ( 9-11) 9( 8-10) 10 ( 8-12) 14(13-16) 13(12-15) 14(12-15) 15(14-17) 15(13-16) 15(14-16) 9 ( 8-10) for all three forms. Triphoturus nigrescens (Brauer, 1904) Fig. 155 — Triphoturus nigrescens, 34.8 mm. Description D. 14 (13-15); A. 17 (16-18); P. 9 (8-10); AO 5 (4) + 6 (5), total 11 (10); gill rakers 3 (2-4) + 1 -H 8 (7-10), total 12 (10-14); vertebrae 33-34. Only upper Pre is above lateral line, all other upper photophores below but touching that line. VO. about on line through PVO., POj, and SAO,... Infracaudal luminous gland short, ending far behind end of anal base. Size: To about 40 mm. Least depth of capture: To 24 m at night. Distribution: In eastern Pacific Ocean T. nigrescens appears to be widely spread between about 30° N and 30° S. It is a warm water species, not taken in California Current system, but rather common in central water masses. It occurs across the Pacific and into the Indo-Pacific 165 Fig. 156 — Capture localities for Tnphoturus mexicanus (solid circles) and T. oculeus (open circles). and Indian Ocean areas. The exact distribution is open to some question because of taxonomic confusion (see Discussion ). Discussion The name T. microchir Gilbert (1913) is herein synonymized with T. nigrescens (Brauer, 1904) as I cannot find any differences that warrant retention of Gilbert's species. I find that all characters overlap completely. These two species appear to have been confused primarily because of Fraser-Brunner's illustrations showing the PO^ to be well above the origin of the pectoral fin in T. nigrescens, as 166 also shown by Brauer, (1906, p. 241, fig. 158), and below that origin in T. microchir, as described, without figure, by Gilbert (1913, p. 101-103). In a total of 150 specimens from the southeastern Pacific and the Indo-Pacific area and South China Sea, I found no PO4 above the level of the pectoral origin; in fact, many were below the level of the bases of lower pectoral rays, or between there and the first ray. Nafpaktitis and Nafpaktitis (1968, p. 57, fig. 70, as T. microchir) showed the PO^ to be no higher than the pectoral origin. Another species, T. micropterus , placed in the genus Triphoturus by Fraser-Brunner (1949), may also be discussed here. It was described and figured by Brauer (1906, p. 239-240, fig. 157) as M. (Lampanyctus) micropterum). Brauer's study material was from the Atlantic Ocean (Gulf of Guinea) and the Indian Ocean (from near Sumatra to near the Seychelles). Brauer gave some body proportions for two specimens, for example 3.1 and 7.2 cm "korper- lange," and stated that the largest specimen was 7.4 cm and the smallest 1.5 cm. It is quite probable that Brauer based his species on a mixed material, for of the large material of the genus Triphoturus before me (excluding species of the rnexicanus complex) the largest speci- men is but 4.0 cm SL. Also, the genus Triphoturus has not been since reported from the Atlantic Ocean. Bolin (1959) did not list the genus from the large Michael Sars collection from the North Atlantic, nor did Becker ( 1967a) from the large material gathered by the R/V PETR LEVEDEV from throughout the Atlantic Ocean. Bolin (unpublished notes) examined a 15.2-mm specimen (Berlin Mus. no. 19375), deter- mined by Brauer to be micropterum, and stated that the specimen differed in several respects from Brauer's figure and description, notably in having only "13 V2" anal rays. Other differ- ences listed by Bolin are: the AOa forms a light arc anteriorly; there are 4 Pre in an even arc with the last interspace markedly enlarged; the AOa-Prc interspace is equal to about half the depth of the caudal peduncle; and there are 5 dorsal and 5 ventral luminous scales before procurrent caudal rays. Bolin further stated that the specimen was in poor condition, and he added a note that the broadness of the pectoral base indicated that it might possibly be a somewhat aberrant juvenile {Lampanyctus) macropterus . In view of Bolin's findings, and the quite large size of at least two specimens of Brauer's type material (72-74 mm), the species micropterus is in some doubt. Holotypes of Gilbert's T. microchir and Brauer's T. nigrescens and T. micropterus must be compared before the taxonomy of these forms is fully understood. Meanwhile it seems best to apply the name nigrescens to at least eastern Pacific material. Lampanyctus Bonaparte, 1840 Upper jaw long, slender, slightly but abruptly expanded posteriorly. No Dn; Vn small; PVOi always well below PVO^. Five PO, the fourth elevated. 4 VO, the second elevated in some species. Two Pol. Four PrC. Scale-like luminous glands on both dorsal and ventral sur- faces of caudal peduncle; some species bear a few similar scales on base of adipose fin. No luminous scales at bases of dorsal, anal, or pectoral fins. One or more primary photophores on cheeks and minute secondary ones on head and body in some species. In the eastern Pacific Ocean, the genus Lampanyctus is reasonably well understood, except for a few troublesome species groups. One group involves L. tenuiformis (Brauer, 1906), L. festivus Taning, 1928, and possibly L. steinbecki Bolin, 1939; the first two species were described respectively from the Indian and Atlantic oceans, but study material is scant and very few specimens have been reported on in detail. L. steinbecki, described from off southern California, is well represented in collections and is herein considered a valid species; however, adequate material of the first two species must be compared with the latter before firm conclu- sions as to synonymy are warranted. A second group involves L. niger (Giinther, 1887) and L. ater Taning, 1928; these species are very similar and are poorly understood in the world oceans. Also, L. achirus Andriashev is quite variable and involves two or more species. 167 In addition to these troublesome groups, there are a few specimens before me, in poor condition, that bear such abnormalities as 5 VO, or the SAO, well behind a vertical from VO4. These specimens, not discussed further, cannot now be properly assigned, because other useful characters are too often eroded away. Also, many specimens, obviously Lampanyctids, are unidentifiable because of severe damage to head and body, or complete denudation — conditions common in the more fragile species. Key to species of Lampanyctus la. Pectoral fin short, weak, narrow-based, or entirely absent. If present, width of the base equal to or less than shortest distance between lower orbital margin and toothed margin of upper jaw. No prominent photophore on cheek, but a small Bu may be present pos- teroventrally just above margin of upper jaw. No luminous gland at base of adipose fin; no minute secondary photophores under scales of body and head 2 lb. Pectoral fin long, broad-based; width of base greater than shortest distance between lower orbital margin and toothed margin of upper jaw. Some species bear 1 or more prominent photophores on cheek, a luminous gland at base of adipose fin, and minute secondary photophores under scales of body and head 7 2a. VLO well below lateral line 3 2b. VLO ator near lateral line 6 3a. SAO, over or slightly before VO4. SAO2 well behind, SAO3 far behind, origin of anal base. Bu present L. idostigma 3b. SAO, about over VOs. SAO-, over or slightly before origin of anal base. Bu present 4 4a. Photophores notably small. SAOj and SAO3 both before anal origin. VLO well above a line from SAO i.^. Bu present L. regalis 4b. Photophores not notably small 5 5a. SAOj about over, SAOs slightly behind, anal origin. VLO on a line from SAO, .2. Bu present. Infracaudal gland with 6 (5-7) luminous scales filling three-fourths or less of infracaudal space L. ritteri 5b. SAOi; well before, SAO.) well behind, anal origin. VLO slighly above line from SAO,.... VO2 slightly but distinctly elevated. Bu present; 8-9 (7-10) luminous scales in in- fracaudal gland filling, or nearly so, infracaudal space L. fernae 6a. Infracaudal gland with 7 to 9 luminous scales. Pectoral fin absent or reduced to a few filamentous rays. SAO,, above third or fourth anal ray. Upper Pol on or slightly behind vertical from base of last anal ray L. achirus (A complex) 6b. Infracaudal gland with 3 to 5 luminous scales. Pectoral fin usually present but small and fragile. SAO,, over origin of anal base. Upper Pol before vertical from base of last anal ray L. niger 7a. No photophores on cheek; no luminous scale at base of adipose fin; no minute secondary photophores on body 8 7b. One or more photophores on cheek; 1 or more luminous scales at base of adipose fin (absent in one species); minute secondary photophores present and more or less prom- inent 17 8a. First 3 Pre in a slightly curved, nearly horizontal line; Prc^ usually widely separate from the rest 9 8b. First 3 Pre not on a nearly horizontal line, last 3 about equally spaced on an oblique, usually straight line; Prc4 not widely separate from the rest 12 9a. Nine to 11 procurrent caudal rays. VO2 elevated but not displaced forward, VO series curved and about equally spaced. AOa series curved. Seven to 8 luminous scales in infracaudal gland L. acanthurus 9b. No more than 8 ventral procurrent caudal rays 10 168 10a. VO and AOa series distinctly curved. VO2 elevated but not displaced forward, VO series about evenly spaced. VLO nearer lateral line than to pelvic base. SAO, slightly above level of SAO2; a line through them passes slightly below VLO and far below PLO. Seven to 9 luminous scales in infracaudal gland L. festivus 10b. VO and AOa series in straight or very slightly curved line 11 11a. SAO, above level of SAOj. VLO much nearer lateral line than to pelvic base. Line through SAO2, SAOi, and VLO passes near PLO. Five to 6 luminous scales in infracaudal gland L. steinbecki 1 lb. SAOi on or below level of SAO^. VLO about midway between lateral line and pelvic base. Line through SAO2, SAO,, and VLO passes far below PLO. Six luminous scales in infracaudal gland L. tenuiformis 12a. VO.j moderately elevated but not displaced forward. VLO about midway between lateral line and pelvic base, slightly above or on a line from PLO to SAO,. SAO, distinctly below level of SAO2. Prcj usually notably well back on bases of caudal rays; Prc3.^ interspace somewhat greater than that between the others L. nobilis 12b. VO2 markedly elevated and displaced forward to near VO, 13 13a. VO2 elevated and displaced forward to before vertical from VO,. VLO at lateral line. Prcj offset posteriorly to below Prc;,. First, third, and fourth Pre form a straight, steeply oblique line. Three or 4 AOp over anal base L. hubbsi 13b. VO2 elevated and displaced forward to slightly behind vertical from VOi. VLO several of its diameters below lateral line 14 14a. Prc2 slightly offset to under or behind Prc.^; first 2 Prc often smaller than last 2. One, rarely 2, AOp over anal base. Seven to 8 luminous scales in infracaudal gland L. macropterus 14b. Prc2 not offset posteriorly, but forms a steeply oblique line with iPrCujnd Prc^ 15 15a. PVO, over or slightly before a vertical from PVO2. Prc2 not offset posteriorly. Two or 3 AOp over anal base. Seven to 9 luminous scales in infracaudal gland L. omostigma 15b. PVOi well behind vertical from PVO2. Infracaudal gland short, with 5 or 6 (4-7) luminous scales, filling no more than 75% (usually much less) of infracaudal space L.parvicauda 16a. AOa series abruptly angulate, not evenly curved. Extra PLO close above and behind origin of pectoral fin 17 16b. AOa series straight or evenly curves; AOa^ and/or AOaa may be slightly depressed. No extra PLO 18 17a. Second to fourth AOa variously and abruptly elevated; first, fifth, and succeeding ones never elevated. Extra PLO near pectoral origin strongly developed. Secondary photo- phores weakly developed, persistant only near lateral line L.jordani 17b. Only A0a2 and AOa:i abruptly elevated (often only slightly so). Extra PLO well de- veloped. Secondary photophores very weakly developed L. simulator 18a. Three to 5 luminous scales in infracaudal gland 19 18b. Seven to 9 luminous scales in infracaudal gland 20 19a. No luminous scale at base of adipose fin. VLO about midway between lateral line and pelvic base. AOa series slightly curved. Secondary photophores well developed. Pectoral fin reaching to about AOa, L.pusillus 19b. Luminous scale present at base of adipose fin 21 20a. Gill rakers 3-4 -1- 1 -1- 8-9. VLO at lateral line. One cheek photophore; secondary photo- phores prominent. SAO, about over VO:,. Pectoral fin long, reaching to Pol L. alatus 20b. Gill rakers 5-7 + 1 + 12-14 L.australis 21a. Gill rakers 6-8 + 1 + 14-18. VLO about midway between lateral line and pelvic base, and behind vertical from VO,,. Secondary photophores weakly developed, persistent only near Lateral line L. macdonaldi 21b. Gill rakers 4-5 -H 1 -I- 9-12. VLO about over midpoint of VO,.,'; interspace. One or 2 cheek photophores 22 169 22a. AOa series in a slighly arched line; AOai.^ interspace wider than others of the series. VLO no higher than midway between pelvic base and lateral line. VLO, SAO,, and SAO^ in nearly straight, horizontal line. Pectoral fin short, reaching to about pelvic base; width of pectoral base 287? (24-31'7f ) of length of orbit. Two photophores on cheek. Secondary photophores well developed. 7 (8-9) luminous scales in infracaudal gland L. iselinoides 22b. VLO above level of SAO, 23 23a. Width of pectoral base 55'7r (50-60'7f ) of length of orbit. Pectoral fin reaching to between A0a2 and AOa.v SAO, above level of SAOj, the 2 usually forming straight line with VLO. A0a2, and often AOa.i, usually depressed below level of adjacent AOa. Two, rarely 1, cheek photophore. Body photophores not unusually small; secondary photophores weakly developed, persistent only near lateral line L. intricarius 23b. Width of pectoral base 39% (35-42%) of length of orbit. Pectoral fin reaching to between VO2 and VO.i. SAO, below level of SAO^, line through them passing far below VLO. A0a2 and A0a3 occasionally depressed below level of adjacent AOa. One, rarely 2, cheek photophores. Body photophores very small; secondary photophores well developed, per- sistent over entire body L. lepidolychnus Lampanyctus ritteri Gilbert, 1915 Fig. 157 — Lampanyctus ntten. male, 108.0 mm. Description D.13 (13-15); A. 18 (17-19); P. 11 (11-12); AO 7 (6-8) -i- 8 (9), total 15 (14-17); gill rakers 4 + 1 + 9 (8-10), total 14 (13-15); vertebrae 36 (35-38). Body moderately robust, its depth at pelvic origin about 18% of SL; caudal peduncle deep, about 10% of SL. Infracaudal luminous gland covering no more than three-fourths (usually less) of the ventral surface of the caudal peduncle. VO; not elevated. VLO on line through SAO, and SAO2 and a little below midway between lateral line and pelvic base. SAO.j well behind from anal origin. Prcj slightly behind vertical from Prcg. Size: To about 120 mm. Least depth of capture: To about 20 m at night. Distribution: Apparently confined to colder waters of the northeastern Pacific (Fig. 158). It ranges from about 25° N off Baja, California, Mexico, to about 46° N off Vancouver Island, Canada. Aron (1960) reported captures as far west as about 146° W. Solitary captures of what 170 appear to be L. ritteri have been made to 153° W at about 37° N. The species has not been reported from outside these limits. Discussion L. ritteri appears to be most closely related to L. fernae. It differs, in part, in certain meristic characters (Table 28) and in having a shorter infracaudal luminous gland and a generally more robust body (Table 29). Table 28. Correlated Counts of Dorsal and Anal Fin Rays, AO Photophores, and Gill Rakers for Lampanyctus fernae and L. ritteri (counts underlined). AOa Upper rakers Anal fin rays 12 16 17 18 19 20 1 2 — Dorsal 13 3 1 85 24 — 1 fin 14 1 4 14 1 15 4 — rays 15 — 3 6 — — AOp 1 22 7 257 2 6 21 9 120 73 39 7 10 Lower rakers (including central raker) 9 10 11 12 13 130' tdO' LiMBERTS ftZlMuTHAL EOUfiL-AREA PRO JEC T lO Fig. 158 — Capture localities for Lampanyctus ritteri (many eastward of curved line), L. fernae (open squares) and L. regalis (open circles). 171 Table 29. Body Proportions for Lampanyctus fernae and L. ritteri. L. fernae L. ritteri Holotype* Paratypes IWpflsurftrn&nt N= 20 N= 18 ^TX^ no LIA ^IXA^AAv SL-76.3mm SL-41-90mm SL-47-98mm Ave. Range Ave. Range Head length 257 250 235-264 286 272-300 Head depth 149 146 130-159 173 162-180 Orbit length 62 61 57-66 65 59-73 Upper jaw length 181 174 154-187 202 194-212 Prepectoral length 266 263 254-275 298 280-312 Prepelvic length 389 387 371-408 413 391-429 Predorsal length 470 461 445-481 475 454-495 Preanal length 539 548 538-562 555 544-566 Preadipose length 786 782 758-806 800 782-813 Dorsal origin to pel' I'ic origin 179 169 159-180 186 169-202 Dorsal origin to ana il origin 199 191 176-201 213 190-226 Dorsal base length 149 152 140-164 167 152-187 Anal base length 214 215 198-229 233 223-255 Caudal peduncle length 245 259 242-280 224 211-245 Caudal peduncle depth 88 84 69-99 105 85-115 Supracaudal gland length 79 80 66-96 55 42-72 Infracaudal gland length 207 207 182-232 126 77-145 "Data from Wisner, 1971. Lampanyctus fernae Wisner, 1971 Fig. 159 — Lampanyctus fernae, holotype, 76.3 mm. From Wisner (1971, p. 50, fig. 6). Description D. 13 (12-14); A. 17 (16-18); P. 13 (12-14); AO 6 (5-7H- 8-9 (7-10), total 14-15 (13-16); gill rakers 4 (5>f \+ 11 (10-13), total 16 (15-18); vertebrae 37 (36-38). Correlated counts of dorsal and anal fin rays, AO photophores and gill rakers (Table 28), and body proportions (Table 29) are given for L. fernae and are compared with similar data for L. ritteri. Size: To about 90 mm. Least depth of capture: To 200 m at night. Distribution: Presently known from a rather restricted area of the North Pacific Ocean, about 40= to 45" N, 135 to 16^ W (Fig. 158). 172 Discussion Lampanyctus fernae is basically similar to L. ritteri (Fig. 157) and has been found so misidentified in some collections of that species. It differs from L. ritteri in having more gill rakers, more scales in the infracaudal luminous gland (this gland longer and reaching to end of anal base instead of but one-half to three-fourths that distance, as in L. ritteri ), a shorter and less deep head, and a generally more slender body. Also, the VO2 is slightly but distinctly elevated, although not displaced forward, and the VLO is notably higher. Prcj lies well behind rather than over or a little before a vertical from Prc:j. Lampanyctus regalis (Gilbert, 1891) Fig. 160 — Lampanyctus regalis, male, 155.0 mm. Description D. 15(14-16); A. 17 (18); P. 13 (14); AO 6 (7)- 8 (7), total 14 (13-15); gill rakers 4+ 1-H 9(8), total 12 (13); vertebrae 37 (36-39). Body moderately robust, very similar to that of L. ritteri. SAO.i about over anal origin; VLO much nearer lateral line than to pelvic base; line through VLO and SAO, passes far below SAO). AOa series often slightly curves. In specimens in excellent condition tiny second- ary photophores can be seen at the posterior border of some scale pockets. Size: To about 165 mm (see Discussion). Least depth of capture: To about 50 m at night. Distribution: From south of Magdalena Bay, Baja California, to off Japan, in the colder waters of the northeastern Pacific (Fig. 158). The density of occurrence in the California area is no doubt the result of a greater number of hauls. Discussion A possible new form, closely related to L. regalis, occurs in near-shore waters off Oregon and perhaps off northern California. Apparently it is a large species, reaching at least 170 mm. It differs from L. regalis in having the following features: D. 17 (16); A. 19 (18); P. 14 (rarely 12 or 13); AO 7 (8) + 8(7), total 15 (14-16); gill rakers 4 (5) + 1 + 10 (11), total 15 (14-16). SAO;i lies over base of third anal ray rather than over anal origin; AOa, is not followed by an enlarged interspace. Only a few specimens have been examined thus far, and more must be studied to determine if these differences are more than just clinal. Lampanyctus idostigma Parr, 1931 Description D. 13 (12); A. 17 (16-18); P. 11-12; AO 5-6 + 6 (5-7), total 11 (10-13); gill rakers4 (5)+ 1 + 10 (9-11), total 15 (14-17); vertebrae 32 (31-33). SAO:) far behind anal origin, over or a little behind A0a2; SAO, over or a little before VO4; SAO2 about over AOa,. VLO about midway between lateral line and pelvic origin. Pre in- terspaces progressively wider; Prc^ about over Pre.). Two or 3 luminous scales in supracaudal 173 Fig. 161 — Lampanyctus idostigma, 82.5 mm. Fig. 162 — Capture localities for Lampanyctus idnstigma (open circles i and L stcinhecki (solid squares); this latter distribution represents only captures in the eastern Pacific Ocean. gland and no more than 3 in infracaudal gland. AOa series level; AOp and Pre series usually continuous. Size: To about 90 mm. Least depth of capture: All tows taking the species were from 0 to 300 m and more. Distribution: Apparently confined to the east of about 135^ W. It has a very large north- south range, but no significant differences could be found between specimens from the ex- tremes of this wide range (some 3300 miles between San Diego, California, and Antofogasta, Chile). 174 Lampanyctus niger (Gunther, 1887) Fig. 163— Lampanyctus niger. holotype, 102.8 mm. BMNH 1887.12.7.219. (An unpublished drawing by Rolf L. Bolin). Fig. 164 — Lampanyctus ater Tuning, 1928, holotype, 89.0 mm. From Dana Sta- tion 1152 I. (An unpublished drawing by Rolf L. Bolin). Description D. 13-14; A. 16 (15-17); P. 10-11; AO 6 (5-7) + 6-7, total 11-12 (14); gill rakers 4-5 + 1 + 10 (9-11), total 15-16 (14-17); vertebrae 35 (34-36). The nominal species L. niger, of worldwide distribution, apparently constitutes a complex of closely related forms, subspecies or species (see Discussion). The following data are taken from specimens from north of Hawaii, that conform reasonably well to the inadequate descrip- tion and figure provided by Giinther and to the above outline sketch by Bolin. Two forms may occur near Hawaii: one form apparently reaches a maximum size of about 80 mm (apparently sexually mature at about 70 mm), the other (based on a very few specimens) reaches about 140 mm. PLO about three times nearer lateral line than to pectoral origin and well forward of vertical from that origin. PO4, SAO,, and SAO2 on a nearly straight, level line. VLO varies from near lateral line to four of its diameters below lateral line and over or slightly behind VOi. Four VO, equally spaced. SAO series strongly angulate; SAO, over a point variously nearer VO2 or VO.-,; SAO2 about over anal origin; SAO3 nearly touching lateral line over a point midway between anal origin and first AOa. AOa series level, the AOi.j interspace often wider than those between remaining AOa. First Pol well behind last AOa; a line through the 2 Pol passes variously through origin or end of base of adipose fin. Pre, and Prc2 very closely spaced and nearly on same level; Prc;, above and behind Prc^ and distant from it by a space three times wider than that of Pre, and Prcj. Prcj on or slightly above lateral line, over, or its diameter behind, vertical from Prc;, and distant from it by twice the Prco .•! interspace. 175 Supracaudal luminous gland short and weak, of 2 or 3 coalesced scales; infracaudal gland more robust, of 3 to 5 overlapping and coalesced scales, its length about equal to or slightly greater than least depth of caudal peduncle. Size: To about 90 mm (see Discussion). Least depth of capture: To about 1000 m at night. Distribution: The nominal species L. niger is worldwide, but at present there is considera- ble doubt as to the correctness of identification. Until a definitive study is made of all forms concerned, the distribution of L. niger (sensu stricto) must remain in question. Discussion Giinther's description oVNannobrachium nigrum ," based on a single damaged specimen, applies to several lampanyctid species in that the body structures received the most discussion. Photophores are described in the following terms: "The eye-like phosphorescent organs are small and arranged very much in the same manner as in Scopelus engraulis, but owing to the condition of the specimens no exact description of their number can be given. A long, linear, glandular organ of white colour occupies the back and opposite side of the posterior half of the caudal peduncle." Unfortunately, this account of the photophores is useless in defining L. niger. because Sopelus engraulis belongs to the genus Diaphus, as shown by the description and figure provided by Giinther (1963 reprint: p. 197, pi. LI, fig. C). Tuning (1928) described Lampanyctus ater as new; Bolin (1959) expressed doubt that L. ater was specifically distinct from L. niger and stated that fishes of this group were variable in the numbers of infracaudal glands, those from the southern hemisphere and East Indian region having fewer glands than those from the North Atlantic Ocean. It is of interest that Bolin's figure (above) of the holotype of L. niger differs from that shown by Giinther (Plate LII, fig. b, Report on the deep-sea fishes) in that Bolin shows SAO] to be nearly over VOj rather than over VO.j, as shown in Giinther's and subsequent illustrations of the species. (Bolin had included with the drawing the statement "no trace of pectorals left"). Possibly this discrepancy was due to the poor condition of the specimen, but in his personal notes Bolin has stated that in specimens from the South Atlantic Ocean VLO was more nearly over VOj than over VO3. At least two forms of this niger-ater (?) complex are found in the eastern and central Pacific Ocean. Aside from the probable difference in maximum sizes, the smaller form has VLO very near lateral line and a gill raker count of 5 + 1 + 11-13; in the larger form VLO is several of its diameters below lateral line, and the rakers number 4-1-1-1- 9-10. Much more study on specimens in good condition from all oceans, and a careful examina- tion of the holotype of L. niger must be accomplished before this problem is solved. Lampanyctus achirus Andriashev, 1962 Species Complex Fig. 165 — Lampanyctus achirus, holotype, 124.0 mm. From Andriashev (1962, p. 257, fig. 27). 176 B Fig. 166— (A.) Lampanyctus achirus (?), From 12°15' S, 77°48' W; iB. ) Lampanytus achirus (n.sp. ?), 48.0 mm. From about 27° N, 155° W. Description Counts for specimens basically referrable to L. achirus from four areas of the eastern Pacific Ocean and from off South Africa are presented in the following tables: Dorsal and anal fin rays (Table 30), AO photophores (Table 31), gill rakers (Table 32), and vertebrae (Table 33). Table 30. Numbers of Dorsal and Anal Fin Rays of the Lampanyctus achirus Species Complex from Four Areas of the Eastern Pacific Ocean and from Near South Africa. Area Dorsal fin rays Anal fin rays 13 14 15 16 17 15 16 17 le 19 20 Southeastern Pacific 64''-46° S 34°-03° S Northeastern Pacific 19°32° N, 118°-133° W 19°-26° N, ca 155° W Near South Africa 4 20 19 6 - 3 16 33 2 15 1 — 4 26 3 _ 8 13 6 — 5 16 20 2 8 16 3 — 6 11 15 3 Table 31. Numbers of AO Photophores of the Lampanyctus achirus Species Complex from Four Areas of the Eastern Pacific Ocean and from Near South Af- rica. Area AOa photophores AOp photophores Southeastern Pacific 64°-46'' S* 34°-03° S* 56 27 20 5 23 72 1 10 177 Northeastern Pacific 19° -32° N, 18 6 118°-133° W 19°-26° N, 28 38 ca 155° W Near South Africa — 4 3 26 13 18 34 11 Total AO photophores 11 12 13 14 15 16 Southeastern Pacific 64°-46° S* 34°-03° S* Northeastern Pacific 19°-32° N, 118°-133° W 19°-26° N, ca 155° W Near South Africa - — — 6 46 - 2 15 17 3 3 18 3 — — 6 49 18 2 _ 14 *Counts for AOp photophores include those of Bussing (1965). Table 32. Numbers of Gill Rakers of the Lampanyctus achirus Species Complex FROM Four Areas of the Eastern Pacific Ocean and from Near South Af- rica. Upper rakers Lower rakers (central raker included) rtrea 4 5 6 Southeastern Pacific 64°-46° S* — 18 46 34°-03° S* — 95 3 Northeastern Pacific 19°-32° N, 48 2 — 118°-133° W 19°-26° N, 61 1 — ca 155° W Near South Africa 11 8 1 10 11 12 13 14 8 31 43 32 77 3 50 — — 57 3 _ 11 Total gill rakers 14 15 16 17 19 20 Southeastern Pacific 64°-46° S 34'-03° S Northeastern Pacific 19°-32° N, 118°-133° W 19°-26° N, ca 155° W Near South Africa — — 7 17 1 18 73 6 48 2 — — 28 4 _ _ 31 10 'Counts for lower gill rakers include those of Bussing (1965) 178 Table 33. Numbers of Vertebrae of the Lampanyctus achirus Species Complex from THE Eastern Pacific Ocean and from Near South Africa. Vertebrae 33 34 35 36 37 Southeastern Pacific 64°-46'' S* 34°-03° S* Northeastern Pacific 19° -32° N, 118°-133° W 19°-26° N, ca 155° W Near South Africa — — 6 15 - — 1 18 — 27 28 18 2 10 1 — 4 12 2 *Counts include those of Bussing (1965). Pectoral fins usually absent, or when present are reduced to a few extremely vestigial rays. PLO and VLO two or three of their diameters below lateral line. PLO well forward of a line through the two vertically arranged PVO. PVO,.o interspace from 0.75 to 1.0 in vertical diameter of orbit; the highly elevated PO4 and upper PVO about on same level. P04 on or slightly behind vertical from PO,^ SAO series in obtuse angle of about 140°, SAI, on or a little above level of SAO^,, the latter over or slightly before origin of anal fin or variously father back to over bases of second to fifth anal rays (see Discussion). SAO1.2 interspace from 1.5 to 2.0 times that of SAOl,.,]. Upper Pol and SAO.) on or very near lateral line. Prc4 about on or slightly above lateral line and on, before, or behind vertical from Prca (see Discussion ). Supracaudal luminous gland short (2 to 5 scales); infracaudal gland variable in numbers of scales, with 7 to 10 in far southern waters but only 3 to 5 off Chile and Peru (34° to 03° S) and in northeastern Pacific. Size: To about 155 mm in the southeastern, to about 70 mm in the northeastern, Pacific Ocean. Least depth of capture: To about 300 m at night in northeastern area. All captures in southeastern area, and off South Africa, were from tows with open nets to deeper than 300 m. Distribution: Probably circumglobal in far southern seas. Andriashev's type material of L. achirus (12 specimens) was taken in an area of the southeastern Pacific and southwestern Atlantic Ocean from 58° to 64° S, 61° to 135° W. Specimens conforming well to the diagnosis of L. achirus have been taken off Chile and Peru and in the northeastern Pacific between 19° and 32° N, 118° and 133° W, and in the north-central Pacific between 19° and 27° N, along about 155° W. The species also occurs off South Africa and in the southeastern Atlantic at about 30° S, 05° W. There are no records of capture in the eastern Pacific between about 03° S and 19° N; also no captures are recorded from between the two northeastern areas. Discussion In the eastern Pacific Ocean throughout the nearly 5800-mile south-to-north range of these fishes without pectoral fins there are some interesting variations in meristic characters and body proportions that may indicate possible speciation. Meristic characters are invariably somewhat higher in far southern waters but grade more or less smoothly to lower in the north; this is apparent in numbers of dorsal and anal fin rays (Table 30), AO photophores (Table 31), gill rakers (Table 32), and vertebrae (Table 33). Variability also occurs in the general robust- ness of the body; specimens from between 64° and 46° S, and from the northeastern Pacific, have a somewhat more slender body form than those from between 34° S and 03° S, as illus- trated by Bussing (1965, p. 204, fig. 7). This difference in body form between the Peruvian and northeastern specimens is also shown in Figures 165 and 166, above. 179 Table 34. Body Proportions for the Lampanyctus achirus Species Complex from off South Africa and from the Southeastern and Northeastern Pacific Ocean. South Africa Southeastern Northeastern Pacific Pacific Measurement n= 10 N= 20 N= 27 (58-140 mm) (84-145 mm) (42-68 1 mm) Ave. Range Ave. Range Ave. Range Head length 265 253-284 274 261-289 277 265-286 Head depth 168 156-182 175 162-184 162 152-176 Upper jaw length 201 186-216 201 188-211 205 197-215 Orbit length 55 49-61 51 44-61 64 49-74 Prepelvic length 412 399-423 403 389-418 407 398-417 Preanal length 561 530-581 534 521-550 563 541-582 Predorsal length 500 462-533 460 437-477 483 457-505 Preadipose length 815 789-837 803 790-820 817 797-832 Dorsal origin to pelvic origin 169 146-191 197 178-218 178 160-193 Dorsal origin to anal origin 184 173-199 222 214-226 198 174-215 Dorsal base length 189 176-203 199 181-216 189 180-198 Anal base length 231 206-247 247 229-265 243 229-259 Caudal peduncle length 214 199-241 218 201-233 216 192-239 Caudal peduncle depth 79 66-85 98 90-104 76 68-90 Supracaudal gland length 154 142-181 137 105-195 76 62-87 Body proportions (Table 34) are given for specimens of the L. achirus complex from near South Africa and from the southwestern and northeastern Pacific Ocean. Lampanyctus achirus was described and figured as having SAO^. slightly before a vertical from origin of anal fin but this character is highly variable througout the range. In 83% of the legible specimens (a total of 70 sides) from between 64° S and 46° S, SAOj was beofre or on a vertical from origin of anal fin, and over bases of second or third anal ray in 17% of the sides. In specimens from between 34° S and 03° S, SAO^ was somewhat more posteriorly placed; of 56 sides only about 12% of SAO^ were before or over anal origin, but 68% were over bases of second or third rays, and 20% were over bases of fourth or fifth rays. On 51 sides from the northeastern Pacific, SAO2 had, on the average, an even more posterior position; SAO^ was not observed to occur before a vertical from anal origin and was over that origin in only 6% of the sides; SAO2 was over bases of second or third rays in 34% of the sides, and over bases of fourth or fifth rays in 60%. In the few legible specimens from off South Africa (15 sides) SAO2 was over or slightly before anal origin in 66% of the sides, and over bases of second or third rays in 34%. The position of Prc^ relative to PrC;, also is variable throughout the range of the L. achirus complex. In specimens from 64' to 46° S, Prc4 is predominantly on (few slightly before or behind) a vertical from Prc^; in specimens from 34° to 03° S, Prc4 is before, rarely on or behind, a vertical from Pre.). In specimens from the northeastern Pacific, Prc^ is nearly always behind, often by at least two diameters, the vertical from Prc.j and is rarely on or before it. Since the achirus-hke form was first reported from the northeastern Pacific (Berry and Perkins, 1966), it has been thought to be specifically distinct. But as the above data indicate, the intergrading of the various meristic characters between the southeastern and northeast- ern forms and the variability in positions of SAO2 and Prcj suggests caution in regarding the northeastern form as a separate species. However, I believe it may prove to be distinct because of the consistently more posterior position of Prc4 and the much smaller size. Examination of ovaries of specimens 58 to 65 mm revealed well developed, though still immature, ova, an indication that this northeastern form may be fully adult at the largest known size of about 70 mm. 180 Lampanyctus steinbecki Bolin, 1939 Fig. 167 — Lampanyctus steinbecki, holotype, 35.5. mm. From Bolin (1939, p. 140, fig. 23). Description D. 12-13 (14); A. 17-18 (16-19); P. 14 (13-15); AO 6(5-7) -l- 7 (6-8), total 12-13 (14); gill rakers 3-4 -H 1 + 9 (8-10), total 13 (12-14); vertebrae 35 (34-36). SAOi well above level of SAOj, a line through them passing through or near VLO and PLO. VLO below lateral line by about one-third the distance from there to pelvic base. VO2 often slightly elevated by about half its diameter above the rest. AOa series usually slightly curved. Deviations of VOj and AOa are not always evident in smaller specimens (30 mm and less). Infracaudal gland with 5 or 6 luminous scales covering about three-fourths ventral surface of caudal peduncle. Size: To 80 mm. Least depth of capture: To about 300 m at night. Distribution: Apparently widespread in eastern Pacific Ocean (Fig. 162). Insufficient col- lecting has been done westerly and southwesterly of the depicted range to be certain of its occurrence in those areas. Whitley ( 1968) did not include the species in his list of fishes from New Zealand. L. steinbecki has been reported from the Indian Ocean (see Discussion). Discussion Nafpaktitis and Nafpaktitis (1969) applied the name L. steinbecki to specimens from the western Indian Ocean, stating that they agreed very well w^ith Bolin's original description. However, these authors listed counts that differ somewhat from those of eastern Pacific speci- mens: D. 12; A. 16 (15-17); P. 13-14; AO 4-5 (6) + 5-6 (7), total 9-11 (12); gill rakers 3 + 1 -H 8 (7). Also, these authors showed the VLO to be somewhat nearer lateral line than in eastern Pacific specimens. These differences indicate a probability that two distinct species may be involved. How- ever, at present there are insufficient data to warrant specific separation. Lampanyctus tenuiformis-festivus species complex Bolin (1959), in a discussion of Lampanyctus festivus (Tuning, 1928) from the North Atlantic Ocean, stated that the species was possibly conspecific with L. tenuiformis (Brauer, 1906), L. bensoni (Fowler, 1934), and L. steinbecki Bolin (1939), but offered neither illustra- tions nor criteria for separating the forms. Nafpaktitis and Nafpaktitis ( 1969) discussed and illustrated all except L. bensoni and offered a few characters for distinguishing between L. tenuiformis and L. festivus; Bolin (personal communication) also provided characters for separating the latter two species. Data from these investigators are combined in Table 35 and are compared with similar data from specimens provisionally identified as L. tenuiformis from 181 Table 35. Some Characters Reported as Useful in Distinguishing Between Lam- panyctus tenuiformis and l. festivus from the indian and atlantic Oceans Compared with a Form Provisionally Identified as L. tenuiformis FROM THE Pacific Ocean. L. tenuiformis* (Indian Ocean) A. 18 P. 14 A06 + 7 L. festivus** (Atlantic Ocean) A. 19-20 P. 16(15-17) AO 7 -I- 8-9 L. tenuiformis (?) (Pacific Ocean) A. 17-18 P. 14(13-15) A06 + 7 6 scales in infracaudal gland, filling four-fifths of infracaudal space VO series in a straight line AOa series in a straight line SAOi and SAO2 on same level SAOi before vertical from VO3 PO4 slightly above level of lower end of Pectoral base Line SAO, ;. passes slightly below pectoral base 8 (7-10) scales in infracaudal gland, filling all the space VO series curved AOa series slightly curved SAOi below level of SAO2 SAOi directly over VO3 PO4 about on level of upper end of pectoral base Line SAO|.; passes slightly above pectoral base 5-8 scales in infracaudal gland, filling two-thirds to all the space VO series usually curved, often straight in specimens of less than 50 mm AOa series slightly curved SAOi on or below level ofSAOi SAOi before vertical from VO3 PO4 slightly above level of lower end of pectoral base Line SAO,.j passes var- iously near upper and lower ends of pectoral base *Data from one specimen (85 mm) reported by Nafpaktitis and Nafpaktitis, 1969. **Data from holotype (101 mm) reported by Nafpaktitis and Nafpaktitis, 1969, and from three specimens (35-68 mm) reported by Bolin, 1959. the Pacific Ocean. L. steinbecki is herein regarded as a valid species; L. bensoni is not dis- cussed. The following key will be of aid in separating L. steinbecki (from the eastern Pacific Ocean) from L. tenuiformis and L. festivus. la. A line through SAO, 2 passes through or near VLO and/or PLO. SAO, over VOn and well above level of SAO2. VO and AOa series slightly but distinctly curved, often nearly straight in specimens of 25 mm or less L. steinbecki lb. A line through SAOi. 2 passes variously near upper or lower ends of pectoral base 2 2a. VO and AOa series not curved. SAOi slightly below level of SAO2 and directly over VO3. A line through SAO, .2 passes near lower end of pectoral base L. tenuiformis 2b. VO and AOa series slightly but distinctly curved. SAO, about on level of SAO^ and before vertical from VO.j. A line through SAO ,.2 passes through or slightly above upper end of pectoral base L. festivus 182 Lampanyctus tenuiformis (?) (Brauer, 1906) Fig. 168 — Lampanyctus tenuiformis (?), female, 110.0 mm. From the southeastern Pacific Ocean, 02°31' S, 137°04' W. Description D. 13-14; A. 17-18; P. 14 (13-15); AO 6-7 -I- 6-7, total 13 (12-14); gill rakers 4 (5) -(- 1 -I- 9 (10-11), total (see discussion); vertebrae 36 (37). PLO two to three of its diameters below lateral line; SAO.j, Pol, and Prcj touching lateral line. VLO about over base of inner pelvic ray and slightly nearer lateral line than to pelvic base. Line through PLO and VLO passes through or very near SAO,. Line through SAO3 and SAO2 passes through or slightly behind VO4. Size: To 115 mm. Least depth of capture: To 300 m at night. Distribution: Apparently widespread in the eastern Pacific Ocean (Fig. 169) but, as few specimens have been taken, it may be either uncommon or somehow unavailable to capture gear. Discussion Two possibly distinct forms of the provisional species are evident. Eight of the eleven specimens showed little variation in numbers of gill rakers, all having 4+1 + 9, except one which had 5 + 1 + 9 on the right side. Also, in these specimens the Prc-j.^ interspace was notably greater than that between Prciand Prc:). Three of the eleven specimens (in three collections from the northeastei'n Pacific, enclosed by dashed line in Fig. 169) differed in that the Pre.!., interspace was equal to or slightly les than that of Prci.j. The number of gill rakers was also higher, 5 + 1 + 10-11; one specimen (of two), totally denuded, had 4+1 + 9 rakers, whereas the other (all photophores present) had 5 + 1+10; the respective sizes were 38 and 48 mm. Based on criteria given in Table 35 and in the foregoing key, specimens conforming strictly to either L. tenuiformis or L. festivus were not found in the eastern Pacific Ocean; however, 11 specimens (9 collections) in good condition, from widely scattered areas of the Pacific (Fig. 169), have characters that are presumed to differentiate L. tenuiformis and L. festivus (Table 35). It may be that these Pacific specimens represent a new species, but because of the paucity of information on either L. tenuiformis or L. festivus they may also merely reflect an unknown variation in these species. Therefore, until further study the older name, tenuiformis, is provisionally applied to the Pacific forms. However, as the western and southern areas of the eastern Pacific Ocean are inadequately collected it is possible that the forms from the Indian Ocean, identified as L. tenuiformis and L. festivus by Nafpaktitis and Nafpaktitis (1969, p. 48, figs. 57, 58) may eventually be found in these marginal areas. Therefore, the figures provided by these authors for the two species are reproduced here (Figs. 170 and 171). 183 Fig. 169 — Capture localities for specimens tentatively assigned to Lampanyctus tenutformis but having characters reported as useful in separating the nominal species L. tenuiformis and L. festwus. Fig. 170 — Lanxpanyctus tenutformis. 85.0 mm. From Nafpaktitis and Nafpaktitis (1969, p. 48, fig. 571. 184 Fig. ni~Lampanyctus festivus. holotype, 101.0 mm. From Nafpaktitis and Nafpaktitis (1969, p. 58. fig. 48). Lampanyctus acanthurus Wisner, 1974 Fig. 172 — Lapmanyclus acanthurus. holotype, male, 93.3 mm. From Wisner (1974, p. 37, fig. 8). Description D. 13 (14); A. 17 (16-18); AO 6 (5) + 7 (8), total 13 (12-14); gill rakers 5 (6) + 1 -^ 10 (9-11), total 16 (15-18); vertebrae 36. Particularly diagnostic of this species is the high number of procurrent caudal rays, 9 (8-10) above and 10 (11) below, a number higher than found in any other species of the genus. PLO, SAO,, upper Pol, and Pre one or two of their diameters below lateral line; PLO about three of its diameters before a vertical from origin of pectoral fin. VLO slightly nearer lateral line than to base of pelvic fin and on or very near a line from PLO to SAO,. VO series curved; VO2 elevated at least its diameter above levels of VO, and VO3. SAO, usually above level of SAO2 and on or a little before vertical from VO^; SAOj about over anal origin; SAO.1 slightly behind vertical from first AOa; a line through SAOa and SAOj passes through or a little behind VO^. AOa series curved, AOa, depressed and AOa^ raised by about three diameters. All AOp behind anal base; AOp and Pre series continuous. Pre .3.4 interspace about equal to that be- tween Prci.3; Prc^ slightly behind vertical from Prc3. Supracaudal luminous gland very short, of about 2 coalesced scales; infracaudal gland long, of 7 (6-8) overlapping, noncoalesced scales. Size: To 112 mm (largest of 21 specimens). Least depth of capture: To 800 m at night. Distribution: Most specimens were taken about 600 mi (960 km) north of Hawaii (27° to 31° N,155° W); two specimens known from about 350 mi (560 km) west of Point Conception, California. Discussion L. acanthurus appears to be most closely related to the poorly understood nominal species L. tenuiformis and L. festivus, discussed above. 185 Lampanyctus nobilis Tuning, 1928 Fig. 173 — Lampanyctus nobilis, 86.2 mm. Description D. 14-15; A. 18 (17-19); P. 14(13); AO 6 (5-7) + 9 (8-10), total 15 (14-16); gill rakers3 (4)+ 1 + 9 (8-10), total 13 (12-14); vertebrae 38 (37-39). This species may be easily recognized by the rather far back position of last Pre, over bases of caudal rays, and by the slightly but distinctly elevated VO^, which is not displaced forward toward VO,, the VO series remaining about equally spaced. In general, a line through SAO^ and SAO:, passes a little before VOj, and PVO, and PVO,. are in oblique line with PO2. The Prc-AOp interspace is either distinct or not present (this character appears variable). Supracaudal gland has 4 to 5, infracaudal gland 10 to 11, well developed luminous scales, the latter filling the infracaudal space. Size: To about 100 mm. Least depth of capture: Between 100 and 200 m at night. Distribution: In the eastern Pacific this species is known only from the Hawaiian area. It appears to occur in warm waters of all oceans. Lampanyctus macropterus (Brauer, 1904) Fig. 174 — Lampanyctus macropterus, 45.0 mm. From Nafpaktitis and Nafpaktitis (1969. p. 50, fig. 61). Description D. 13-15; A. 18-19; P. 14 (13-15); AO 6 (5-7) + 9 (8-10), total 15 (13-16); gill rakers 3-1- 1 + 9 (8-10), total 13 (12-14); vertebrae 38 (37-39). VO2 elevated and displaced forward to about its diameter behind vertical from posterior margin of V0|, but never to over or before VO,. AOa series notably curved; AOa..^ interspace about twice as large as others. First 2 Pre often closely spaced and slightly smaller than last 2; 186 second, third, and last Pre form a slight curve, the concavity facing posteriorly (Fig. 174). Supracaudal gland with 3 to 4, infracaudal gland with 6 to 8, small but well developed luminous scales, the latter filling at least three-fourths of ventral surface of caudal peduncle (Fig. 174). Size: To about 60 mm. Least depth of capture: To 70 m at night. Distribution: All known eastern Pacific specimens are from near Hawaii. Discussion The Lampanyctus macropter us -like forms from the eastern-central Pacific Ocean appa- rently represent a species complex, or the species is highly variable in its arrangement of Pre photophores. Although basically similar to the pattern of Pre shown in Fig. 174, the first two Pre of the few central Pacific specimens available to me are much larger and more widely spaced. In most respects I can find no differences between the specimens before me and the figure and descriptions offered by Nafpaktitis and Nafpaktitis (1969, p. 50, fig. 61). All have the VLO well below instead of at the lateral line; most of the AOa series appeared to be arched. Because of the position of VO^ behind VOi,and not before it as in L. hubbsi, the name macropterus is given to these specimens. Unfortunately, the specimens are not in good condi- tion. Several have the Prearranged as in L. hubbsi, but with the VO^ elevated asinL. macropterus. Much more study is needed for this species group. Because the species L. macropterus (Brauer, 1904) and L. nobilis Tuning, 1928, have been confused, the following nomenclatorial history of the two is offered. Brauer (1904, p. 404, fig. 5) described and figured Myctophum (Lampanyctus) macropterum. Brauer (1906, p. 249, textfigs. 166-167) offered a more detailed account (with two figures) of this species, but apparently he had mixed material. Brauer reproduced the 1904 figure of L. macropterus (1906, p. 250, textfig. 166) again under that name, but he also showed what he presumed to be variations in the position of the VO. and of Pre patterns in textfig. 167. In this figure the VOj is shown to be directly over the VOj and the second Pre offset posteriorly so that instead of Prc2,\PrC3, and Prcj, Pre,, Prc;), and Prcj are in an oblique line as in textfig. 166. The VLO is not shown in textfig. 167. Brauer's textfig. 166 shows the VLO to be well below the lateral line but much nearer it than to the pelvic origin, and the VO- as distinctly elevated but displaced forward only to about its diameter behind a vertical from the VO,; the AOa series is markedly curved, and the AOp-Pre series is continuous. Nafpaktitis and Nafpaktitis (1969, p. 50, fig. 61) offered a figure (Fig. 174) for L. macropterus that is basically similar to that of Brauer's textfig. 166 but has the Prc series much like that shown by Brauer's in textfig. 167, except that the first two Pre are shown to be very small and close together. The confusion of L. macropterus with L. nobilis is largely the result of two actions by Parr (1928, p. Ill, fig. 20) in which he published a figure asL. macropterus that closely resembled Brauer's (1906) textfig. 166, the major difference being a lesser elevation of the VO2 with no forward displacement. Then Parr ( 193 1 , p. 29, fig. 1 1 ) offered a figure of L. nobilis that differed from his figure of L. macropterus partly in that the AOa series was shown to be level. He stated that this figure was verified by Tuning to be that of nobilis by direct comparison with the type. Without mention of depicted difference in curvature of the AOa series, Parr ( 1931 ) placed his 1928 version of L. macropterus in the synonymy of L. nobilis. Nafpaktitis and Nafpaktitis (1969, p. 49, fig. 59) presented a figure of the holotype of L. nobilis (53.5 mm, DANA Station 1185 XI, 17° 41' N, 60° 58" W) showing the AOa series to be markedly curved anteriorly. Thus, this figure is more similar to Parr's 1928 illustration of L. macropterus than to his 1931 illustration of L. nobilis. 187 Lampanyctus parvicauda Parr, 1931 Fig. 175 — Lampanyctus parvicauda, 62.1 mm. From Wisner (1963a, p. 17, fig. 3). Description D. 14 (13-15); A. 18 (17-20); P. 13 (12-15); AO 5 (4-6) + 9 (7-11), total 13-14 (12-16); gill rakers 3 (4) -I- 1 -h 9 (8-10), total 13 (12-14); vertebrae 36-37 (35-38). PLO and VLO slightly below, SAO3 and upper Pol touching, lateral line. VO^ elevated and displaced forward to just behind vertical from VO,, but never to over or before it. AOa series strongly curved, the photophores about evenly spaced. Last 3 Pre evenly spaced in straight, steeply oblique line. Usually 3 AOpover anal base. Infracaudal gland short, with about 5 (4-7) luminous scales. Pectoral fin short, barely reaching to vent. Size: To about 110 mm. Least depth of capture: At surface at night. Distribution: May be confined to warmer waters of eastern Pacific Ocean between about 20° N and 15° S (Fig. 176). It has been taken in southern part of Gulf of California. It is not i \ -U^ —r ^ jx\> 4 \ tlu;\ V^ 7^ \ \ \* \ \ li. ft. y^ nt * »,,_ +1 c 44 *1 — — r • UJ'^ -i j t 1 • ■•-■H ^ 1 0 160» ' 1 jO° fto" «^30° 120° 1 110° 100°. „ ■i^ i * x ■ t 1 1 • • ~r~M k u 1 ^ r~~~i—^ * 1 I l~ — T — ""/-—!_/ / 1 1 1 1 /• /i / r—Lj / //Y '^ 1 i i^ ^ , / / f- A- ~i S/ -^ / r > H Fig. 176 — Capture localities for Lampanyctus omostigma (X), L. parvicauda (solid circles! andL. hubbsi (solid triangles). 188 commonly taken in eastern central Pacific west of 150° W, but whether because of nonoccur- rence or lack of collecting effort is not known. Lampanyctus omostigma Gilbert, 1908 Fig. 177 — Lampanyctus omostigma, 60.0 mm. From Wisner (1963a, p. 17, fig. 2). Description D. 14 (13-15); A. 18 (16-20); P. 13 (12-14); AO 5 (4)6 + 8-9 (7-10), total 13-14 (12-15); gill rakers 4 (3-5) + 1 + 10-11 (9-12), total 15-16 (13-18); vertebrae 36 (35-38). PLO and VLO slightly below, SAOn and upper Pol touching, lateral line. VO^ elevated and displaced forward to at least its diameter before a vertical from VO,. AOa series about evenly spaced, markedly curved. Last 3 Pre evenly spaced in a straight, steeply oblique line. Two or three AOp over anal base. Pectoral fin usually reaches to about middle of AOa series. In- fracaudal gland with 8(7-9) luminous scales, nearly filling infracaudal space. Size: To about 65 mm. Least depth of capture: At surface at night. Distribution: L. omostigma appears to have distribution very similar to that of L. par- vicauda (Fig. 176). It is sparsely collected in the central Pacific, but the reason for the paucity of occurrence is not clear. Lampanyctus hubbsi Wisner, 1963 Fig. 178 — Lampanvctus hubbsi. holotype, 54.0 mm. From Wisner (1963a, p. 17, fig. 1). 189 Description D. 14 (21-15); A. 20 (18-21); P. 13-14 (12-15); AO 5 (4-6) + 11 (9-12), total 15-16 (14-17); gill rakers 4 (3-5) + 1 + 10-11 (9-12), total 16 (15-17); vertebrae 37-38 (39). PLO several of its diameters below lateral line; VLO, SAO;,, and upper Pol and Pre at lateral line. VO2 elevated and displaced forward to about its diameter before VOi. AOa evently spaced in marked curve. Prc^. notably offset behind line through Pre,, Prc;,, and Prc^. Usually 4 AOp over anal base. Infracaudal gland with 8 (7-9) luminous scales, nearly filling infracaudal space. Pectoral fin reaches to Pol. Size: To about 80 mm. Least depth of capture: Taken only in hauls from 0-2000 m. Distribution: L. hubbsi may be confined to the east-central portion of the equatorial region of the Pacific Ocean (Fig. 176). The pattern of distribution reflects the track of the expedition that captured the study specimens. The species is infrequently taken, with no more than eight specimens in one haul. Lampanyctus jordani Gilbert, 1913 Fig. 179 — Lampanyctus jordani , 113.0 mm. From Wisner (1970b, p. 421, fig. 1). Description Principal dorsal rays 11 (10-12); A. 18 (17-20); P. 16 (14-17); AO 7 (6-8) + 9 (7-10), total 16 (14-18); gill rakers 6 (5-7) + 1 + 14-15 (13-16), total 22-23 (20-24); vertebrae 39 (38-40). The abruptly elevated A0a2, AOa,.;, and often A0a4 (Fig. 179), and the extra photophore close above pectoral origin, will, in combination, immediately identify this species. Also, the pectoral fins are not as long or broad-based as in most of the species having tiny secondary body photophores. PO4 elevated high, about on line through PVO,, VLO, and SAOi.j. Size: To about 115 mm in northeastern Pacific; lengths of 140 mm reported from Okhotsk Sea. Least depth of capture: To 200 m at night. It has been taken at surface at night once, by dipnet and surface light. Distribution: All known capture localities oiL. jordani are shown in Fig. 180 (solid circles). The one occurrence off Santa Catalina Island, Southern California (an adult, 116 mm) no doubt represents a stray. The species has not before been taken to the east or south of the depicted range. Localities shown in Fig. 180 (solid circles) include those of various authors, as listed by Wisner (1970b, fig. 2). 190 50° W0° !30' 120° 110° 100° 90° 80° Fig. 180 — Capture localities for Lampanyctusjordani (solid circles) and L. simulator (open triangles). Lampanyctus simulator Wisner, 1971 Fig. 181 — Lampanyctus simulator, holotype. female, 73.3 mm. From Wisner (1971. p. 52, fig. 7). Description D. 13 (12-14); A. 18 (17); P. 12-13; AO 6 (5-7) + 8 (7), total 14 (13-15); gill rakers 5 (4) + 1 -H 11-12, total 17-18 ( 16); vertebrae 36 (35-37). Correlated counts of AO photophores and of gill rakers are given in Table 36 and are compared with similar counts for L.jordani. Lampanyctus simulator is similar to L.jordani, primarily because of the extra-pectoral photophore just above and behind origin of pectoral base (an organ previously thought unique to L.jordani ). Also, the second and third AOa photophores are often slightly elevated in a weak imitation of the much greater elevation of these two organs in L.jordani, as delineated by Wisner (1970b). Other similarities and differences are discussed below. Size: To about 95 mm. Least depth of capture: To 200 m at night. Distribution: L. simulator is thus far known from only 13 specimens from a restricted area 191 Table 36. Correlated Counts of AO Photophores and Gill Rakers for Lampanyctus jordani and l. simulator (counts underlined). AOp 5 7 8 9 10 — 3 — — 6 2 14 10 9 AOa 7 2 111 93 41 8 — 8 14 2 Lower gill rakers (including raker at angle) 4 12 13 14 15 16 17 1 1 — — — — Upper 5 8 12 — 1 — — gill rakers 6 — — 15 21 4 — 7 — — 8 45 40 3 of the North Pacific Ocean between about 35' and 4CP N (Fig. 180). The distribution is similar to that of L. fernae (Fig. 158) but appears to extend farther westward; one specimen was taken near Japan. Discussion Although L. simulator is superficially similar to L.jordani, the two species differ notably in numbers of gill rakers (Table 36) and in several body proportions (Table 37), the former being a more slender fish. L. simulator has a higher number of both upper and lower gill rakers, with little or no overlap. In nearly all the body proportions given in Table 37, those of Table 37. Body Proportions for Lampanyctus simulator and L. jordani. L. simulator L jordani* Holotype Paratypes n= 12 N=22 Measurement SL— 73.3mm SL— 41-94 mm SL- -52-108 mm Head length 267 271 257-288 290 272-309 Head depth 154 155 152-167 181 166-191 Orbit length 59 61 56-67 66 580-80 Interorbital width 79 71 66-82 86 78-95 Upper jaw length 190 182 186-203 215 204-231 Body depth at pelvic origin 161 164 144-176 190 175-210 Prepectoral length 281 283 27.5-295 308 290-325 Prepelvic length 396 397 378-412 427 402-463 Predorsal length 453 457 442-469 464 437-494 Preanal length 565 554 541-590 590 561-615 Preadipose length 787 787 776-800 798 785-818 Dorsal origin to pelvic origin 199 185 169-200 205 186-223 Dorsal origin to anal origin 229 213 201-229 243 226-260 Dorsal base length 171 152 141-171 151 134-171 Anal base length 237 230 222-251 214 197-237 Pectoral fin length 105 106 89-120 281 259-300 Pelvic fin length — 141 128-154 173 159-188 Caudal peduncle length 221 232 217-245 228 210-248 Caudal peduncle depth 105 95 85-105 104 96-119 Infracaudal gland length 162 174 166-189 177 163-182 *These data are from a combination of specimens from the northeastern and northwestern Pacific Ocean (Wisner, 1970b). 192 L.jordani have higher values than those of L. simulator, although often with considerable overlap; those proportions showing no overlap are the upper-jaw length and pectoral and pelvic-fin lengths. Lampanyctus australis Taning, 1932 Fig. 182 — Lampanyctus australis , 99.0 mm. (Photophores retouched). Description D. 13; A. 17-18; P. 14 (13-15); AO 7 (7-8) -i- 7-8, total 14 (15); gill rakers 6 (5) -h 1 -f- 13 (14) total 20 (19-21); vertebrae 36 (35). This species is easily distinguished by the single, prominent cheek photophore, by the VLO close to lateral line, by the very long pectoral fin which reaches nearly to the Pol, and by the very few (3-5) luminous scales in the infracaudal gland. Upper Pre over or slightly before vertical from next lowest; Pre and AOp continuous. Size: To 102 mm. Least depth of capture: To 100 m at night. Distribution: L. australis is common and circumglobal in the southern hemisphere. In the eastern Pacific, it is known from off Chile (30° to 45° S, 72° to 80° W) (Craddock and Mead, 1970; Bussing, 1965). Discussion A related species, Lampanyctus alatus Goode and Bean, 1896, is superficially very similar to L. australis and the two have been confused by various authors. L. alatus is a smaller species, seldom attaining 50 mm SL and it differs further in having fewer gill rakers (3-4 + I + 8-10, total 12-15). In the Pacific Ocean L. alatus is known only from the northern Indo-Pacific region and from near Taiwan. It is common in the Atlantic, Indian and western Pacific Oceans between latitudes of about 36° N and 37° S (Bolin, 1959). 193 Lampanyctus pusillus (Johnson, 1890) Fig. 183 — Lampanyctus pusillus, 34.5 mm. From Nafpaktitis and Nafpaktitis (1969, p. 54, fig. 66). Description D. 12-13; A. 14-15: P. 13-14; AO 5 (4) -h 5-6, total 10 (9-11); gill rakers 3+1-1-8 (9), total 12(13). AOa but slightly curved; the space between first 2 AOa notably wider than these between the rest. Prc^ distinctly before vertical from Prc:,. Caudal luminous glands small and weakly formed, with 2 to 4 scales in supracaudal and 3 to 5 in infracaudal glands. Size: To about 40 mm. Least depth of capture: To 70 m at night. Distribution: In the eastern Pacific, it is known only from off Chile (Bussing, 1965; Crad- dock and Mead, 1970) between about 29° and 34° S, 73° and 93° W. It is also known from the southern Indian and North and South Atlantic Oceans. Discussion This species is superficially similar to both L. alatus and L. australis but is readily separable by the absence of a luminous scale at the base of the adipose fin and by the low position of VLO, about midway between base of pelvic fin and lateral line. Lampanyctus iselinoides Bussing, 1965 Fig. 184 — Lampanyctus iselinoides, 97.2 mm. (Photophores retouched). 194 Description D. 13 (12-14); A. 17 (16-18); P. 11 (10-12); AO 7 (6-8) + 7 (8), total 14 (13-16); gill rakers 4 (5)+ 1 +11 (10-12), total 16 (15-18); vertebrae 36 (35-37). Two prominent photophores on middle of cheek, well separated and on a line about paral- lel with upper jaw. Anal origin about under beginning of last third of dorsal base. Prominent secondary photophores on each scale pocket. Last 3 Pre in oblique line, the last (uppermost) on level of lateral line at bases of caudal rays; Prc3.4 interspace slightly greater than the rest; Pre and AOp continuous. AOa level, the space between the first 2 notably greater than those between the rest. Infracaudal gland with 7 (8-9) luminous scales filling ventral surface of caudal peduncle; supracaudal gland small, the scales varying in number from 3 to 4. Luminous gland at base of adipose fin with 1 to 4 luminous scales. Size: To about 100 mm. Least depth of capture: To 70 m at night. Distribution: Known only from the southeastern Pacific Ocean off Chile, from about 21° to 48° S, 71° to 82° W. Lampanyctus intricarius Taning, 1928 Fig. 185— Lampanyctus intricarius. male, 107.5 mm. From the southeastern Pacific Ocean, near Valparaiso, Chile. Description D. 14-15; A. 18-19; P. 14 (13-15); AO 8-9 (10) + 8-9 (10), total 17 (16-19); gill rakers 4 -t- 1 -I- 9 (10), total 14 (15); vertebrae 39 (38-40). Body proportions are given in Table 38 and are compared with similar data for a related species, L. lepidolychnus . PLO below lateral line, about one-third the distance from there to pectoral origin. PV0,.2 interspace about half that of PLO-PVO.. PLO and PVO,.- form straight, posteriorly slanting line that passes slightly before PO^. P04 elevated to about level of middle of pectoral base, or slightly lower, and to almost directly over PO:,. VLO over or slightly behind pelvic origin and slightly above midway between that origin and lateral line. SAO, on level of or slightly higher than SAO,, and about over midpoint between V0,..3 interspace. SAO, . . interspace nearly one and one-half times that of SAOo.,. A line through SAO,. > passes slightly behind VO,. SAO, about over anus; SAO., slightly before or behind vertical from AOa,. The 2 Pol and last AOa form line that passes variously through, before, or slightly behind end of base of adipose fin. AOa-AOp interspace equal to about half least depth of caudal peduncle and considerably greater than space between Prc3.4. First 3 Pre equally spaced in curve; Prcj at end of lateral line and separate from Prcj by space only little less than that between Pre, and PrCj. Size: To about 155 mm. Least depth of capture: To 70 m at night, off Chile. 195 Table 38. Body Pro'^ortions for Lampanyctus intricarius, from off the Pacific Coast of Chile, and for L. lepidolychnus, from the Southern Oceans. L. intricarius L . lepidolychnus* N = 25 N = = 20 Measurement (63-170 mm) (58-115 mm) Ave. Range Ave. Range Head length 287 278-297 259 247-271 Head depth 164 153-177 145 139-157 Orbit length 62 56-68 59 50-67 Upperjaw length 207 212-218 184 178-196 Prepectoral length 303 293-315 278 271-288 Prepelvic length 418 402-430 396 380-409 Preanal length 566 548-580 560 552-578 Predorsal length 465 451-475 462 452-473 Preadipose length 791 777-804 802 787-809 Dorsal origin to pelvic origin 183 163-198 190 174-200 Dorsal origin to anal origin 220 210-233 223 215-235 Caudal peduncle length 222 213-237 214 204-225 Caudal peduncle depth 96 82-111 106 100-114 Dorsal base length 157 146-165 176 171-184 Anal base length 226 209-245 246 231-252 *0f the 20 specimens of L. lepidolychnus, 10 were from off South Africa, 3 each from the southwestern Atlantic and south-central Pacific Oceans, and 4 from the southern Indian Ocean. Distribution: In the eastern Pacific Ocean, L. intricarius is known primarily from off Valparaiso, Chile (Bussing, 1965, and Craddock and Mead, 1970), and northward to 2ri6' S, 71°09' W. I have seen one specimen ( 142 mm) from between New Zealand and Chatham Island. It is also known from the North Atlantic and southern Indian Oceans. Discussion Lampanyctus intricarius is very similar to L. lepidolychnus; this relationship will be discussed in the following account of that species. Lampanyctus lepidolychnus Becker, 1967 Fig. 186 — Lampanyctus lepidolychnus, female, 103.0 mm. From the southeastern At- lantic Ocean, 36°51' S, 12°43' E. Description D. 15(14-16); A. 19-20; P. 12 (11-13); AO 9 (8-10) -h 8 (7-9), total 16)17 (18); gill rakers 4 (3) + 1 + 10(9-11), total 15(14-16); vertebrae 37-38. Body proportions are given in Table 38 and are compared with similar data for a related species, L. intricarius. 196 PLO below lateral line by one-third to one-fourth the distance from there to pectoral origin. PVO,., interspace about half that of PLO-VPO,.. PLO and PVO, ^ form straight, posteriorly slanting line that passes slightly before POo. PO4 elevated to about level of middle of pectoral base, or somewhat lower, and to its diameter behind a vertical from PO:). VLO about midway between lateral line and pelvic base and about over middle of that base. SAOi below level of SAO2 and about over midpoint of VOj.n interspace, often slightly nearer to VO.j. SAO1.2 interspace about one and one-half times that of SAO2.3. A line through SAOm; passes through or below PO4; a line through SAO^ .) passes slightly behind VO4. SAO^ about over anus; SAO,, slightly behind vertical from AOa, and over bases of third or fourth anal rays. A line through the 2 Pol passes slightly behind last AOa. AOa-AOp interspace slightly less than half least depth of caudal peduncle and about equal to that between Pre,..!. AOp continuous with Pre. First 3 Pre equally spaced in curve; Prc4 at or above lateral line and separate from Prc3 by a space about a third greater than that between Pre, and Pre,;. Stze.TollOmm. Least depth of capture: To 200 m at night off South Africa. Distribution: L. lepidolychnus appears to occur circumglobally in southern waters, proba- bly below 30° S. It is known from off South Africa and Argentina and from south-central Pacific and Indian Oceans. It has not yet been reported from the southeastern Pacific, off Chile, where the related species, L. intricarius, is moderately abundant. Discussion Lampanyctus lepidolychnus and L. intricarius are very similar. They may be confused primarily because of the similarity in positions of the depressed AOaa photophores. However, in addition to those characters given above, and the few differences in body proportions (Table 38), the two species differ somewhat in the percentage values of depth to length of the caudal peduncle: 49% (45-57% ) for L. lepidolychnus, vs 43% (36-48% ) for L. intricarius. Also, the color (in preservative) of the latter species is a light to medium brown, whereas the former is very dark. Other characters useful in distinguishing between L. lepidolychnus and L. intricarius are given in Table 39. Table 39. Some Characters Useful in Distinguishing Between Lampanyctus lepidolychnus and l. intricarius. L. lepidolychnus L. intricarius SAOi below level of SAO2 AOa-AOp interspace slightly less than half least depth of caudal peduncle and about equal to that of Pre,., Pre .I.J interspace slightly less than that of Pre,.;, Least depth of caudal peduncle 49% (45-57% ) of length of peduncle Color in preservative very dark SAOi on or above level of SAO2 AOa-AOp interspace about as in L. lepidolychnus but much greater than that of Prc.,.j Prcj., interspace about one-third greater than that of Pre,.., Least depth of caudal peduncle 43% (36-48%) of length of peduncle Color in preservative light to medium brown. L. lepidolychnus is also somewhat similar to L. iselinoides but differs in part in that the pectoral fin of the latter is much shorter (scarcely reaching to pelvic origin), and the length of the pectoral base averages 28% (24-31%) of the length of the orbit. The percentage values for depth to length of caudal peduncle are higher in L. iselinoides — 43% (40-46% ). Also, this latter species has 2 cheek photophores, rather than 1, and the last 3 Pre are in a straight, oblique line, rather than in a curve as in L. intricarius . 197 Lampanyctus macdonaldi (Goode and Bean, 1896) Fig. 187 — Lampanyctus macdonaldi , female, 117.0 mm. Description D. 14-15; A. 18; P. 12 (11); AO 7 (6-8) + 7 (6-8), total 14 (13-15); gill rakers 8 (9) + 1 -I- 17 (16-18), total 26 (25-27); vertebrae 36 (seven specimens). PLO below lateral line about a third the distance to pectoral origin; VLO usually slightly nearer lateral line than to pelvic origin and slightly before vertical from that origin. Line through SA0|.2 and VLO passes through or somewhat below PLO; SAOi slightly behind vertical from VO., and usually slightly above level of SAO^. AOa series evenly spaced and occasionally very slightly curved, or AOa, slightly depressed. No AOp over anal base. Pre and AOp often continuous; upper Pre at end of lateral line and distant from closely spaced first 3. The luminous scale before adipose base is weakly developed and easily lost; 2 to 4 weak luminous scales in supracaudal gland, 7 to 9 in infracaudal, the latter usually extending to near base of last anal ray. Size: To 117 mm in eastern Pacific; Bolin (1959) listed 135 mm for a specimen from the North Atlantic. Least depth of capture: To 1200 m at night off Chile. Bolin reported captures with 1000 m of wire out in the North Atlantic. Distribution: Probably circumglobal in southern seas. It is also known from the North Atlantic Ocean, but has not been reported from the South Atlantic. In the South Pacific Ocean, it is known from off Valparaiso, Chile (Craddock and Mead, 19701, to Kermedec Islands and southeast of South Island, New Zealand. I have seen one specimen (115 mm) from about 42° S, 71° E in the Indian Ocean. Discussion L. macdonaldi is superficially similar to L. iselinoides (see above) but differs in having no secondary body photophores and in having about 10 more total gill rakers, 26 (25-27) vs 16 (15-18). At present there is no distributional evidence to link the North Atlantic population of L. macdonaldi (reported by Bolin, 1959) with that of the southern oceans. Data from the seven specimens available to me from the South Pacific agree well with that given by Bolin, except, perhaps, in numbers ofgill rakers; Bolin reported 7 (6-8) + 1 + 16 (14-18), total 24 (21-26) (about 2 fewer rakers). Bolinichthys Paxton, 1972 Body moderately robust, head rather short and deep. PO.i slightly, PO^ highly, elevated, the remaining 3 in more or less straight, descending series. SAO series moderately angulate. 3 Pre, first 2 near ventral caudal rays, third above lateral line and well behind vertical from second. PLO, SAO,,, upper Pol, and Prc;, above lateral line. Crescent of whitish tissue on 198 posterior half of iris. Small scales of luminous tissue at bases of dorsal, anal, and pelvic fins, and near base of pectoral fin in one species. Key to species ofBolinichthys in the eastern Pacific Ocean la. VLO far below lateral line, only slightly above midway between there and pelvic base. VOj only slightly elevated, far below level of lower end of pectoral base. No luminous tissue on head or at bases of dorsal and pelvic fins B. supralateralis lb. VLO touching or very near lateral line. VO^ much elevated, about on level of lower end of pectoral base. Luminous tissue on head and at pelvic base 2 2a. Luminous patches present above pectoral origin and below PVO,; 2 to 5 luminous scales at bases of anterior rays of dorsal and anal fins. Infracaudal luminous gland reaches to or beyond last AOp. VLO two or three of its diameters below lateral line B. photothorax 2b. No luminous patches above pectoral origin or below PVOi. One (usually) or 2 (rarely 3) luminous scales at bases of dorsal and anal rays. Infracaudal luminous gland seldom reaches to (never beyond) last AOp. VLO on lateral line B. longipes The genus Bolinichthys was separated from the genus Lepidophanes Fraser-Brunner, (1949) by Paxton (1972) primarily on the basis of characters stated in the "Key to Genera of Family Myctophidae." Paxton's justifiable action restricted the genus Lepidophanes to two known species, L. guntheri (Goode and Bean, 1896) and L. gaussi (Brauer, 1906); neither has been reported from the Pacific Ocean. Bolin (1959) reduced all species now referrable to the genus Bolinichthys to synonyms of Bolinichthys pyrsobolus (Alcock, 1890). However, the time-honored name pyrso6o/us will not be used here for any of the eastern Pacific species of the genus Bolinichthys for a number of reasons. Alcock described Scopelus pyrsobolus from the Indian Ocean, based on a single, damaged female. The inadequate description and figure pertain in part to all subsequently described species oi Bolinichthys. No luminous organs were shown in the figure, and Alcock stated only that, "The luminous organs have been too much damaged for description: two series, traversing the ventral half of the body on each side, still remain; two long luminous organs occupy respectively the mid-dorsal and mid-ventral line close to the base of the caudal." The "long" caudal organs may have been only a subjective interpretation by Alcock, for the accompanying outline sketch shows the gland is short and much more like that oi Bolinichthys than of Lepidophanes (the latter genus having long supracaudal glands). Despite these in- adequacies in description by Alcock, all eastern Pacific specimens have heretofore been re- ferred to "pyrsobolus." Nafpaktitis and Nafpaktitis (1969), reporting on western Indian Ocean material, could not reconcile any of their specimens with Alcock's description and figure and chose to refer them to two species more adequately described and illustrated, Bolinichthys longipes (Brauer, 1906) and B. photothorax (Parr, 1928), and to describe a new species, "Lepidophanes" indicus. This choice is followed herein. 199 Bolinichthys supralateralis (Parr, 1928) .-^•^ Fig. 188 — Bolinichthys supralateralis. female, 60.2 mm. From near Hawaii. Description D. 13 (12); A. 14 (13-15); P. 12-13; AO 5-6 + 4 (3-5), total 9-10; gill rakers 5 (6) + 1 + 11 (10-12), total 16 (15-17); vertebrae 34 (rarely 33). Frequency distributions for the above characters are given in Table 40 and are compared with those for B. photothorax and B. longipes. Table 40. Numbers of Fin Rays, AO Photophores, Gill Rakers, and Vertebrae for Bolinichthys supralateralis, B. photothorax, and B. longipes from the Eastern Pacific Ocean. Dorsal rays Species 11 12 13 14 15 B. supralateralis B. photothorax B. longipes 3 1 17 20 23 3 — Anal rays 11 12 13 14 15 B supralateralis B. photothorax B. longipes — — 8 2 11 21 21 8 1 1 1 Pectoral rays 11 12 13 14 15 B. supralateralis B . photothorax B. longipes — 5 8 10 12 23 21 8 7 AOa photoph lores ' 2 3 4 5 6 7 B. supralateralis B. photothorax B. longipes 7 4 130 53 131 8 10 6 20 2 — AOp photoph lores 2 3 4 5 6 7 B. supralateralis B. photothorax B. longipes — 6 18 21 4 13 225 45 28 11 200 (Table 40 cont'd.) B. supralateralis B.photothorax B. longipes 17 Total AO photophores 10 111 10 4 132 18 53 14 11 12 Upper gill rakers B. supralateralis B. photothorax B. longipes 23 32 57 3 25 B. supralateralis B. photothorax B. longipes 11 Lower gill rakers 12 13 14 15 19 2 24 5 19 34 16 5 14 16 17 B. supralateralis B. photothorax B. longipes 16 Total gill rakers 17 18 19 20 16 3 25 14 29 16 5 21 22 12 B. supralateralis B. photothorax B. longipes 32 10 Vertebrae 33 34 35 36 2 1 61 12 4 34 20 4 PLO, SAO3, Pol, and Prcn distinctly above lateral line. PVO1.2 often form a straight, nearly vertical line that passes through or slightly behind PO2. PO4 elevated to about level of PVOi. VO2 and VO3 nearly on same level. VLO slightly above midway between pelvic base and lateral line. VO.^, SAO,, and SAO^ in an oblique, nearly straight line that passes well behind SAO3. Small photophores behind orbital rim and tiny ones on scale pockets, present in the other two species of Bolinichthys in the eastern Pacific Ocean, are either absent or very weakly developed; on only 1 of 15 specimens was a very small postorbital organ present, but on no specimen was a tiny organ evident on any scale pocket. However, the integument of all specimens was somewhat eroded. No luminous tissue below PVOi , between pectoral origin and lateral line or at bases of dorsal and pelvic fins; 3 or 4 small luminous scales present anteriorly on base of anal fin, beginning at about fourth ray. Supracaudal luminous gland short, of 2 (rarely 3) scales; infracaudal gland of 3 to 5 scales that reach to below last or next to last AOp. Pectoral fins all broken in specimens at hand, but Parr (1928) reported this fin to be "very long, reaching beyond middle of anal fin." Body proportions are given in Table 41 and are compared with similar data for B. photo- thorax and B. longipes. Size: To 84 mm. Least depth of capture: Clarke (1973, Table 1 ) listed depths of 95 to 225 m at night and 490 to 690 m in daytime tows near Hawaii. Distribution: In the eastern Pacific Ocean, the species is known only from near Hawaii. I have also examined specimens from off the northeastern tip of Luzon, Philippines, and from about 10° N, 96° E in the Indian Ocean. 201 Table 41. Body Proportions for 10 Specimens Each of Bolinichthys supralateralis, b. photothorax, and b. longipes from the eastern pacific ocean. B. supralateralis B. photothorax S. longipes Measurement SL— 45.2-84.6 mm SL— 35. 2-66.8 mm SL— 33. 1-47. 1mm Ave. Range Ave. Range Ave. Range Head length 355 346-364 328 308-338 334 320-346 Head depth 239 226-255 203 192-214 220 202-230 Orbit length 111 106-113 114 105-120 111 103-121 Upper jaw length 228 216-238 199 191-208 197 188-214 Prepectoral length 349 338-361 335 332-339 337 321-349 Prepelvic length 464 450-480 447 435-461 467 449-484 Predorsal length 483 467-489 472 462-486 486 472-500 Preanal length 646 626-655 636 620-645 652 646-660 Preadipose length 823 813-843 800 785-816 822 813-839 Dorsal origin to pelvic origin 230 222-239 202 189-223 219 204-237 Dorsal origin to anal origin 279 273-287 274 264-288 281 264-296 Dorsal base length 148 140-154 154 140-160 155 144-164 Anal base length 176 163-184 182 160-207 181 175-189 Caudal peduncle length 197 189-206 205 189-221 191 176-204 Caudal peduncle depth 90 86-94 96 86-106 93 85-100 Discussion Dr. R. K. Johnson, Chicago Natural History Museum, has evidence (personal communica- tion) that specimens referable to B. supralateralis from the central and western Pacific Ocean and Indo-pacific areas may represent an undescribed species. Bolinichthys photothorax (Parr, 1928) Fig. 189 — Bolinichthhys photothorax , female, 67.0 mm. From the central tropical Pacific Ocean. (Photophores retouched). Description D. 13 (12-14); A. 14 (15); P. 14 (13-15, rarely 16); AO 6 (5-7) + 4(3-6), total 10 (9-11); gill rakers 5 (4-6)-)- 1 + 13-15 (12-16), total 18-20 (17-22); vertebrae 35 (34-36). Frequency dis- tribution for the above characters are given in Table 40 and are compared with those for B. supralateralis and B. longipes. Pectoral fin long, fragile, reaching to Pol. PO^ elevated to about level of base of lower pectoral ray; PO3 elevated to at least its diameter above a line through upper margins of PO- and PO-,. VO4 elevated to about level of P04 and SAO,, the remaining VO in descending series. 202 Supracaudal luminous glands with 2 or 3 scales; infracaudal gland with 3 or 4, the latter extending to below (usually slightly beyond) the last, and occasionally to next to last AOp. Patterns of luminous organs of the head in eastern Pacific forms (Fig. 190) are quite similar to those shown by Nafpaktitis and Nafpaktitis (1969, p. 61, fig. 73A) for Indian Ocean specimens. Fig. 190 — Luminous gland on heads of Boltmchthys photothorax: (A) male, 48.0 mm, (B) female, 52.0 mm; and of S. longipes: (C ) male, 34.0 mm, (D ) female, 33.0 mm. Body proportions are given in Table 41 and are compared with similar data for B. sup- ralateralis and B. longipes. Size: To 68 mm. Depth of capture and distribution will be discussed under B. longipes. 203 Bolinjchthys longipes (Brauer, 1906) Fig. 191 — Bolinichthys longipes, male, 45.0 mm. From the eastern tropical Pacific Ocean, (photophores retouched). Description D. 12-13 (rarely 11); A. 14 (13-15); P. 12-13; AO 5 (4-6) -I- 3-4 (2-5), total 8-9 (7-10); gill rakers 5 (4) -h 1 -^ 12-13 (11-14), total 17-18 (16-19); vertebrae 33-34 (32-35). Frequency distributions of the above characters are given in Table 40 and are compared with those for B. supralateralis and B. photothorax . Bolinichthys longipes is basically similar to B. photothorax, differing primarily as stated in key to species. Also, the pectoral fins may not reach quite as great a length, the longest (apparently intact) reaching to about AOan rather than to Pol. In general, depth of head and body is somewhat greater in B. longipes. Body proportions are given in Table 41 and are compared with similar date for B. supralateralis and B. photothorax . The pattern of luminous organs of the head (Fig. 190) is similar to that shown for this species from the western Indian Ocean by Nafpaktitis and Nafpaktitis (1969), particularly in males; these authors stated that only traces of luminous tissue were found on females from that area, but in females from the eastern Pacific Ocean these patches were very well de- veloped anteriorly but to a lesser degree posteriorly. Size: To 49 mm. Least depth of capture: Clarke (1973, Table 1) listed depths of 50 to 150 m in nighttime, and 525 to 725 m in daytime tows (few specimens taken at less than 625 m). Distribution: In the eastern Pacific Ocean B. longipes and B. photothorax occupy the same waters, but for reasons not clear the latter is not commonly taken; both species are occasion- ally taken in one haul. Their distribution appears to be limited to warmer waters, for much collecting has been done north and southeast of the area shown in Fig. 192 without taking either species. Insufficient collecting has been done west and southwest of the area to permit firm statements as to their occurrence there. Whitley ( 1968) did not list any species of Bolinichthys in his checklist of New Zealand fishes. Discussion On the basis of size alone, it is probable that either B. supralateralis or B. photothorax are synonymous with Alcock's pyrsobolus. Alcock (1890) stated the size of the holotype ofpyr- snbolus to be "3V2 inches without caudal" (about 78 mm). The 10 specimens of B. supralateralis from the Indian Ocean examined by me ranged from 51 to 64 mm. Of the three species from the Indian Ocean discussed by Nafpaktitis and Nafpaktitis ( 1969), the largest of 60 specimens of B. photothorax was 60 mm, the largest of 1267 B. longipes was 45 mm, and of 18 B. indicus, 37.5 mm. In the eastern Pacific area, the largest of 15 B. supralateralis was 84 mm, and of 103 B. photothorax, 68 mm; of hundreds of B. longipes none exceeded 47 mm. Thus, only B. supralateralis and B. photothorax (or B. blacki (Fowler, 1934, "length 80 mm"), an Indo-Pacific form not considered here) approach the size (ca 78 mm) recorded for the holotype of B. pyr- sobolus. 204 -J! 1 I 1 \ \^ ^ o\ \_ "v V ~\ i V ^ ^ ^ / ' \°\ 1 • *. 0 " 0 \\ \^ s ^ o <^ 1 0 1 \c • (« °n ^1 o D J 1 o 90° o>^ 0 170° Q "^ 0" ' 150° ^"i O ,3'o° ° 12Si ° 1 '^ TO° 9 100° 0 o o o" o *■ ) 0 o .1 1 .. 0 r / m j li M //^p° I 1 1 4^ \ 1 / T~T- ~j— ■f- r~i ^ 7/ 7~ A -LI Fig. 192 — Capture localities in the eastern Pacific Ocean for Bolinichthys photothorax (solid circles) and fi. longipes (open circles). Ceratoscopelus Giinther, 1864 Very similar to genus Bolinichthys but first 4 PO on same level; only P0-, elevated. Five VO, not on same level. Palatine teeth in single series, the anterior few slightly enlarged. No Dn; Vn small, rounded. PLO, SAO3, upper Pol and Pre below but touching lateral line; VLO about midway between pelvic origin and lateral line. Numerous patches of luminous tissue (scales) occur along dorsal and ventral midlines and on other parts of the body but are easily lost; most persistent is the Y-shaped series of scales between pelvic and anal fins and those along base of anal fin and in caudal luminous glands. There are at least two forms in the eastern and central Pacific Ocean that conform to the above diagnosis. As presently understood, these forms are separable only by the presence or absence of some luminous scales on head and body, and, possibly, the extension of these scales along the secondary (procurre^t) caudal rays. Unfortunately, as some luminous scales are easily lost, only specimens in good condition may be properly allocated; given such specimens, the following key will aid in determining two basic forms. Key to species of Ceratoscopelus la. Prominent patches of luminous tissue over each eye (supraorbital luminous gland). Pec- toral fin seldom reaching past AOa^. No luminous scales between PVOi.j and PO2-3 over PO4, or over anus. Luminous scales on caudal peduncle usually not extending beyond vertical from Pre. C.townsendi lb. No supraorbital luminous gland. Pectoral fin usually reaching AOa:j or AOa^. Luminous scales present between PVO,.. and PO:;;), over POj, and over anus. Luminous scales on caudal peduncle extending to or beyond a vertical from Prca or Prc4 C. warmingii 205 Ceratoscopelus townsendi (Eigenmann and Eigenmann, 1889) Fig. 193 — Ceratoscopelus townsendi, male, 43.0 mm. From Nafpaktitis and Nafpak- titis(1969, p. 67, fig. 78). Description D. 14(13-15); A. 13-14; P. 13-14; AO 6 (5-7) + 6 (5), total 11 (10-12); gill rakers 4 (5) -I- 1 + 10 (9-11), total 15 (14-16); vertebrae 36 (35-38). SAO series in a very slight angle, often nearly straight; anterior margin of SAO^ usually touches a line through posterior margins of SAO,. o. A line through SAO> ..) passes through or slightly before V0.-„ occasionally through VOj. AOar usually below level of others; AOai.^ interspace often slightly greater than others of series. Last AOa often slightly elevated and appearing in series with Pol. Lower Pol over or slightly before end of anal base. All AOp behind end of anal base. First 3 Pre closely spaced, their interspaces slightly but progressively wider, the space between Prc.3.4 nearly as great as that between Pre 1-3. A large and easily lost supraorbital luminous organ lies over each eye (Fig. 193), more massive and robust in males. A small luminous scale present between PLO and pectoral origin, and 2 or 3 scale in area between P0,.2 and PVO|. A row of several luminous scales occurs before dorsal fin, on each side of the fin, and between end of dorsal fin and origin of adipose fin; these scales are also easily lost. Size: To about 60 mm. Least depth of capture: Paxton (1967a) reported captures between 0 and 20 m at night and 500 and 800 m in daylight in the San Pedro Basin, southern California. Distribution: C. townsendi may be restricted to northeastern Pacific Ocean (Fig. 194), but see discussion of its systematic and spatial relationships to C. warmingii. Ceratoscopelus warmingii (Lutken, 1892) Description D. 14 (13-15); A. 14 (13-16); P. 14 (13-15); AO 6 (5-7) + 5 (4-6), total 11 (10-13); gill rakers 4 (5)-h 1 + 10(9-11), total 15 (14-16); vertebrae 36 (35-38). C. warmingii very similar to C townsendi, differing principally as diagnosed in the key to species. In addition, in C. warmingii angulation of SAO series is often such that a line through SAO]. 2 passes well before VO^ rather than well behind or (rarely) through. SAO:) appears to be more often slightly behind vertical from origin of anal fin rather than over or slightly before that origin as in C. townsendi. However, there is considerable variation and slight overlap in these characters within and between the two species. 206 Fig. 194 — Capture localities in the eastern Pacific Ocean for the Ceratoscopelus townsendi-warmingii species complex. The heavy line indicates the probable western limit of C townsendi. The solid circles south and west of the heavy line indicate speci- mens not completely representative of either C. warmingii or C. townsendi . The number- als at certain localities indicate the Pre photophore to which luminous scales extend. The letter B indicates specimens found to have black pigment at tips of one or more luminous scales of the body. Size: Commonly to 75 mm in east-central Pacific; Craddock and Mead (1970) reported a 93-mm specimen (as C. townsendi from off Chile at about 34° S, 85° W. Least depth of capture: To 100 m at night. Distribution: C. warmingii may be widely distributed in the Atlantic, Indian, and perhaps Pacific Oceans (Fig. 194). Additional specimens, determined as C. townsendi, have been re- ported by the following authors: Andriashev (1962) reported ajuvenile taken at 64° 36' S, 108° 52' W, and a 79.5-mm specimen at 600 m (960 km) south of Easter Island. This latter speci- men, as figured by Andriashev (p. 261, fig. 28) agrees well with the figure of C. warmingii by 207 Fig. 195 — Ceratoscopelus warmingii. female, 58.0 mm. From Nafpaktitis and Nafpak- titis(1969, p. 64, fig. 76). Nafpaktitis and Nafpaktitis (1969) (Fig. 195). Craddock and Mead ( 1970) reported capture of 163 specimens (21-93 mm) from west of Valparaiso, Chile, in the areaof about 3r-33° S, 77°-92°W( 16 collections). As noted for other myctophid fishes, individuals o{ Ceratoscopelus appear to avoid, or are rarely taken, in the eastern tropical Pacific over much of the area of oxygen-deficient water (Fig. 194). Discussion C. warmingii described from the North Atlantic Ocean, has been regarded by most au- thors as a synonym of C townsendi , described from Cortez Bank, near San Diego, California, in the northeastern Pacific Ocean. Nafpaktitis and Nafpaktitis (1969) reported the capture of many specimens of the genus Ceratoscopelus from the western Indian Ocean, and stated that these specimens were generally very similar to specimens of C. warmingii from the North Atlantic and that a direct comparison of the two forms with C. townsendi from the northeast- ern Pacific Ocean revealed the principal differences stated in the above key to species. They further stated, "Prior to the development of the supraorbital gland (individuals smaller than about 27 mm), or in cases of poorly preserved specimens (supraorbital glands rubbed off), it is difficult to distinguish C. townsendi from C. warmingii. Minor differences which, considered together, may help distinguish the young and poorly preserved adults of the two species include: series of luminous scales along the bases of the caudal procurrent rays often extending to vertical through Prc4 in C. warmingii (the character does not apply to populations from equatorial Atlantic waters), not reaching vertical through Prca in C. townsendi; pectoral fin extending to the fourth AOa in C. warmingii, not reaching the second AOa in C. townsendi; absence of luminous tissue between PVOi and PVO2, anterodorsad to PO3 and PO4, above the base of ventral fin and over the origin of the anal fin in C. townsendi." On the basis of the presence or absence of the supraorbital tissue these authors concluded that C. townsendi was limited to the northeastern Pacific (Fig. 194), and that C. warmingii was widely distributed in the Atlantic, Indian, and probably South Pacific Oceans. In regard to this sole criterion, it would seem that these authors were correct. I have found specimens having supraorbital luminous patches only among those captured at localities east of the heavy line shown in Fig. 194, draw roughly parallel to the coast of North America. No sup- raorbital luminous tissue was found on any specimen from elsewhere in the Pacific Ocean; many were in such excellent condition that it could only be concluded that such tissue was never present. However, the other critera offered by Nafpaktitis and Nafpaktitis ( 1969) for separating the two species appear to be of questionable value. In the northernmost portion of the area of C. townsendi, off North America (Fig. 194), I found some specimens bearing supraorbital luminous tissue to have pectoral fins reaching to or beyond AOaa, and luminous scales reach- ing to under or beyond Prc;,. Also, an occasional specimen had luminous scales in the areas of 208 the PO and PV0,-2, as shown for C. warmingii (Fig. 194). The criteria were also quite variable in specimens from other parts of the eastern Pacific — specimens in excellent condition and without supraorbital luminous tissue. In many, the pectoral fins reached no further than to AOa,., but in others to A0a4; also, particularly in the Hawaiian area, the luminous scales under the Pre reached only to Vvc^ and Prcg, but on an occasionaly specimen to Prc^. A previously unreported character was found in specimens from the central and south- eastern Pacific Ocean. A cap of black pigment covered the posterior portions of the luminous scales above the pectoral fin, at PVO, and PVO,, at PO3 and PO4, above the pelvic origin, at the posterior ends of the ventral "Y," above the anus, and at least on the last few scales below the Pre series. These black-tipped luminous scales have thus far been found only on males from near Juan Fernandez Island, Chile, and between there and Hawaii (indicated by "B" in Fig. 194); none of these specimens, all in excellent condition, bore supraorbital luminous tissue, and on most the luminous scales extended to under Prc4. Thus, from the above findings, it is possible that C. townsendi is confined to the extreme northeastern Pacific Ocean. Whether or not only C. warmingii or one or more closely related species, occupies the rest of the eastern Pacific, or the entire ocean, must await detailed studies on extensive material in good condition. As no very highly significant differences in counts and body proportions were found between the two species, any valid differences may well depend on number and kind of luminous scales on the body. Becker and Borodulina (1968) placed C. warmingii in the synonymy of C. townsendi and concluded that the world population of the latter was variable. They also reported that only specimens from the northeastern Pacific Ocean bore luminous tissue interorbitally. Gymnoscopelus Giinther, 1873 Body elongate, moderately deep. Dn and Vn well developed. PO 5 or 6; P04 not elevated. 5 or 6 VO. First AOa always strongly elevated. No supracaudal or infracaudal luminous glands. Body with variously arranged specks and small irregularly shaped patches of luminous tissue, all highly deciduous, often in longitudinal rows. Pre varying in number from 4 to 9. Both PVO below pectoral origin, except in subgenus Nasolychnus. Smith (1933) erected the subgenus Nasolychnus to contain at least two species of Gvw- noscopelus which had the upper PVO well above the pectoral origin. Andriashev (1962) revised the genus Gymnoscopelus, largely from material collected by the Russian vessels OBJ and SLAVA in far southern seas. The following key, data, and illustrations are derived mainly from that revision. The portion for the subgenus Nasolychnus was communicated to Andriashev by Rolf L. Bolin. Key to species of Gymnoscopelus la. Upper PVO below level of pectoral origin. Lower PVO always behind vertical from upper PVO Subgenus Gymnoscopelus 2 lb. Upper PVO well above level of pectoral origin. Lower PVO almost vertically below upper PVO Subgenus Nasolychnus 5 2a. PLO midway between lateral line and pectoral origin 3 2b. PLO nearer lateral line than to pectoral origin 4 3a. Caudal peduncle longer than upper jaw. VLO nearer pelvic origin than to lateral line. Six to 9 Pre, the series usually continuous with AOp G. (G.) nicholsi 3b. Caudal peduncle shorter than upper jaw. VLO about midway between lateral line and pelvic origin. Four to 5 Pre, the series continuous with AOp G. (G.) opisthopterus 4a. Pre 7, the series not continuous with AOp. Total AO 17-19; total gill rakers 21-24 G (G.) bolini 4b. Pre 4 to 5, the series continuous with AOp. Total AO 18-21; total gill rakers 23-25 (22- 26) G- (G.) braueri 209 5a. Dorsal rays 16-18, always fewer rays than in anal; A. 20; P. 13; AO 11+7; gill rakers 7-9 + 1 + 17-19, total 26-28; Pre 3+1, the upper widely separate and elevated; Pre separate from AOp. Scale margins with a few blunt projections G. (N.) fraseri 5b. Dorsal rays 18-20, always with more rays than in anal; A. 18; P. 13-14; AO 8-9 + 8-9; gill rakers 9-10 + 1 + 19-22, total 29-33; vertebrae 42. Pre 5 (4?), the last widely separate and elevated; Pre separate from AOp G. (N.) piabilis Gymnoscopelus (Gymnoscopelus) nichoisi (Gilbert, 1911) Fig. 196 — Gymoscopelus (G.) nichoisi, 141.0 mm. From Andriashev (1962, p. 270, fig. 32). Description D. 18 (17-19); A. 19-20; P. 13-14; AO 10 (9-11) + 7 (6-9), total 17-18 (19); gill rakers 10-11 + 1 + 21-24, total 32-36; vertebrae 43-44 (42-45). Photophores relatively large, light in color. PLO about midway between lateral line and pectoral origin; VLO 1.0 to 1.5 times nearer pelvic origin than to lateral line. A line through PV0,.2 passes well behind PO^, nearly through PO.^. Six PO, the last notably elevated, the rest on same level; 5 (4 or 6) VO, none elevated. SAO series straight or in slightly obtuse angle. SAOi.2 interspace slightly less than that of SA02..i. SAO, nearly on level of last VO. AOp-Prc series usually continuous, except when 9 Pre are present. Size: To 148 mm. Least depth of capture: No information. Distribution: Antarctic waters of Pacific and Indian Oceans (about 62° to 70° S). Gymnoscopelus (Gymnoscopelus) bolini Andriashev, 1962 Description Two specimens reported by Andriashev ( 1962, p. 272), the holotype (46.0 mm) and paratype (33.0 mm). The counts are given in that order. D. 19, 21; A. 21, 21; P. about 13; AO 10 + 7-6, 12-10 + 7 (6?); gill rakers 6 + 1 + 14, 7 + 1 + 16, total 21-24; vertebrae 43. PLO nearer lateral line than to pectoral origin; VLO midway between lateral line and pelvic origin. A line through PVOi.j passes through PO2. Five PO, the last elevated. Five VO, 210 Fig. 197— Gymnoscopelus (G.I bolini. holotype, 46.0 mm. From Andriashev (1962, p. 273, fig. 34). none elevated. SAO series in nearly vertical, straight or slightly angulate line; SAO, .2 in- terspace about half that of SAO,...). AOp-Prc series well separated; 7 Pre, equally spaced in very slight curve, nearly horizontal. Size: To 46 mm, largest of two specimens. Least depth of capture: The two specimens taken with 4700 and 4200 m of wire out, rGSDGctivGlv. Distribution: The holotype was taken at 47°2r S, 160°05' W, paratype at 53°0r S, 109°30' W. Gymnoscopelus (Gymnoscopelus) braueri (Lonnberg, 1905) Fig. \%%— Gymnoscopelus (G.) brauen. 110.0 mm. From Andriashev (1962, p. 265, fig. 29) 211 Description D. 16 (14-17); A. 18 (17-19); P. 13-14; AO 10 (9-11) + 9-10 (8-11), total 19-20 (18-21); gill rakers 6-7 + 1 -^ 15-17 (18), total 23-24 (22-26); vertebrae 42-43 (41-44). PLO nearer lateral line than to pectoral origin; VLO midway between lateral line and pelvic origin. A line through PVO,.j passes through PO^... PO:i and P0-, slightly elevated, the rest on same level. SAO series in nearly straight, vertical line; SAO, over anus; SAO;) its diameter below lateral line. SAOi.j interspace a little smaller than that of SAO^.;). AOp-Prc series usually continuous. Pre pattern 3 + 1 or 4 -i- 1, rarely 2 -t- 1 or 5 -I- 1. Size: To 133 mm. (Norman, 1937). Least depth of capture: Andriashev recorded a capture at not over 100-150 m at negative temperatures (time not stated). Distribution: Known from Drake Strait and southern Pacific and Indian Oceans south of the Antarctic Convergence. Gymnoscopelus (Gymnoscopelus) opisthopterus Fraser-Brunner, 1949 Fig. 199 — Gymnoscopelus (G.) opisthopterus, 111.0 mm. From Andriashev (1962, p. 269, fig. 31). Description Counts from two specimens, holotype included. D. 15; A. 16-17; P. 14-15; AO 9-10 + 7-8; total 17-18; gill rakers 8 -I- l-i- 19, total 28; vertebrae 43. Photophores small, dim, often difficult to distinguish from small specks of luminous tissue on body. PLO about midway between lateral line and pectoral origin; VLO about midway between pelvic origin and lateral line. A line through PVOi.j passes through or slightly behind PO2 Six PO, nearly on same level; 5 VO, the middle 3 slightly raised above level of first and last. SAO series in a very obtuse angle; SAOi over anus and its diameter above level of last VO. SAO.) 1.0 to 1.5 times its diameter below lateral line. SAO^ :i interspace nearly twice that of SAOi.j. AOp-Prc series continuous; Pre pattern 3 -1- 1 or 5 in a continuous curve (the only available specimen was damaged caudally). Si2e.Tolll.0mm. Least depth of capture: 0 to 500 and 900 m (two captures). Distribution: Presently known only from southern Indian Ocean (60°-50° S). 212 Gymnoscopelus (Nasolychnus) fraseri Fraser-Brunner, 1931 Fig. 200 — Gymnoscopelus IN. I fraseri, holotype, 63.0 mm. From Fraser-Brunner (1931,p. 224, fig. 4). Description The following counts are taken from both Fraser-Brunner (1931) and Andriashev (1962). D. 16-18; A. 20; P. 13; AO 10 + 7; gill rakers 7-9-^1 + 17-19, total 26-28. No data available on numbers of vertebrae or scales in lateral line. {Note: Fraser-Brunner listed 20 rays in both the dorsal and anal fins. ) The following description is taken from Fraser-Brunner (1931). PLO much nearer lateral line than to pectoral origin; VLO midway between lateral line and pelvic origin. PLO and PVOi.2 form a nearly vertical line. Five PO, only the last elevated; 5 VO, none elevated. SAO series in a nearly vertical, straight line; SAO, only slightly above level of last VO; SAO3 1.0 to 1.5 diameters below lateral line. AOp-Prc series well separated. Pre 3+1, the last widely separate and elevated. Size: Only two sizes given, that of holotype and 6.95 mm for a questionable specimen reported by Andriashev. Least depth of capture: A specimen from Antarctic waters, provisionally identified as G. (N.) fraseri by Andriashev, was taken at surface at night; others from 0 to 1000 m. Distribution: Taken mostly in Antarctic waters, but the holotype was taken in Gulf of Guinea at 03°18' S, 05°17' E. Gymnoscopelus (Nasolychnus) piabilis (Whitley, 1931) Description D. 18-19; A. 18; P. 13-14; AO 7-8 + 8-9, total 15-17; gill rakers 9-10 + 1 + 18-19, total 28-30; vertebrae 42. (Note: In a key to identification of G. fraseri and G. piabilis (communi- cated to Andriashev by Bolin) the gill rakers for G. piabilis were given as 9-10 + 1 + 19-22, total 29-33.) PLO less than its diameter below lateral line; PLO and PVO1.2 in a nearly straight line inclined somewhat forward. VLO midway between lateral line and pelvic origin. Five PO, the last slightly elevated; 5 VO, the last slightly below level of rest. SAO series almost equally spaced in a nearly vertical, slightly angulate line; SAO, a little above level of last VO; SAO,^ its diameter below lateral line. Pre 3 (4?) + 1, the last widely separate and elevated. Size: To 122 mm. Least depth of capture: No information. The holotype was found stranded on a beach at Macquarie Island (Whitley, 1931). Distribution: Poorly known; mostly taken in Antarctic waters. 213 Fig. 201 — Gymnoscopelus (N). piabilis, female, 122.0 mm. From Andriahsev (1962, p. 276, fig. 35). Lampichthys Fraser-Brunner, 1949 Upper PVO at least two of its diameters above pectoral origin. Five PO, only the last slightly elevated; 5 VO, the series curved. Dn and Vn present. Four to 6 photophores on cheek; small scales of luminous tissue on various parts of body, easily lost. A tiny secondary photo- phore present on hind margin of each scale pocket of body. Three Pol, forming a right-angled triangle. Caudal luminous glands small, inconspicuous, 1 or 2 scales in each. Body elongate, deepest at dorsal origin; caudal peduncle deep, slightly more than half the greatest depth of body. Nine dorsal, eleven ventral, procurrent caudal rays. Dorsal base much shorter than anal base. A single species recognized. Lampichthys procerus (Brauer, 1904) Fig. 202 — Lampichthys procerus, 93.0 mm. The luminous scales on the body represent those found on several specimens. Description D. 17 ( 16-18); A. 22 (21-23); P. 11-13; AO 8-9 + 8-9, total 16-18; gill rakers 5 + 1 + 13-14, total 19-20; vertebrae 40-41. 214 Dn elongate, extending over entire upper margin of orbit; Vn small, rounded and hidden at about level of lower margin of nasal rosette. Three or 4 photophores in a row on cheek before preopercular ridge, 2 or 3 randomly placed between there and orbital rim. PLO well before vertical from pectoral origin and 2 or 3 of its diameters below lateral line. PLO and PV0,.2 form posteriorly slanting straight line, PO^ often on this line. VLO 3 or 4 of its diameters below lateral line. SAO3 and the 2 horizontal Pol at or very near lateral line. SAO series in a wide angle (ca 140°). SAO, high on body, slightly less than midway between ventral profile and lateral line. SAO1.2 interspace about one-third less than that of SAOj.i. The 3 Pol form nearly right-angled triangle, first 2 in a nearly horizontal row near lateral line, a third Pol almost directly below, often its diameter before, the anteriormost of the upper two. Pre 3+1, the first 3 closely spaced and nearly on same level, the upper much elevated and distant by a space one and one-half times as great as that between first and third Pre. Size: To about 100 mm. Least depth of capture: To 200 m at night in the eastern Pacific Ocean. Distribution: L. procerus is known from the southwestern Atlantic and southeastern Pacific Oceans. In the latter region, it has been taken primarily in the Peru Current from about 07° to 35° S, and to 85° W. Becker, 1967, did not report the species from among the large VITIAZ collections from the southwestern Pacific Ocean. Discussion Lampichthys rectangularis Fraser-Brunner, 1949 (p. 1103, fig. 14) is herein regarded as a synonym of L. procerus, as there appears to be insufficient evident to warrant retention of both species. Fraser-Brunner stated that the principal differences lay in the arrangement of the PVO, the lower position of VLO, the more posterior Pol, the fourth cheek photophore, and the much more elongate form of L. rectangularis. However, he recognized that these differences could be attributable to the large discrepancy in sizes of the specimens compared (22.3 mm vs 76 mm). Bussing (1965, p. 209, fig. 10) showed the number of cheek photophores to vary from 3 to 5 in specimens from off Chile. Notoscopelus Giinther, 1864 Doral base notably longer than anal base; anal base beginning under last third of dorsal. Upper PVO well above, lower PVO at lower end of, pectoral base. Two Pol (rarely 1 or 3) in horizontal line. Pre 2 + 2 or 2 -1- 1. Ventral proeurrent caudal rays 12 or 13. Small patches of luminous tissue, easily lost, are variously located on body and below some photophores. A single species in eastern Pacific Ocean. Notoscopelus resplendens (Richardson, 1844) Fig. 203 — Notoscopelus resplendens, 78.1 mm. The luminous scales of the body repre- sent those of several specimens. 215 Description D. 22 (21-23); A. 19 (18-20); P. 12 (11-13); AO 8-9 + 5 (4), total 13-14; gill rakers 6 (7) + 1 -H 13 (12-14), total 20 (19-22); vertebrae 37 (35-38), Dn somewhat elongate along anterodorsal margin of orbit; Vn tiny, often hidden in pig- mented tissue, slightly below level of nasal apparatus. A thin streak of whitish tissue is present on iris above ventral margin of orbit. Only the last PO and VO are slightly elevated. AOa series curved anteriorly; last AOa slightly elevated. AOa-AOp interspace usually some- what greater than half the least depth of caudal peduncle. Pre 2 + 1 in all eastern Pacific specimens. Supracaudal luminous gland long, of 8-10 scales, filling space between base of adipose fin and first procurrent caudal ray. No infracaudal gland. Small paired luminous scales over bases of procurrent caudal rays. The patches of luminous tissue (Fig. 203, dotted lines) are a compos- ite of several specimens in good condition. There was no indication that in life each scale bore a luminous patch. Size: To about 80 mm. Least depth of capture: To 200 m at night in eastern Pacific. In the North Atlantic, it has been taken at night between 0 and 30 m. Distribution: Known primarily from near-shore waters, possibly due to greater collecting effort, in eastern Pacific between Southern California and Chile (35° N to 33° S). Scattered collections from near Hawaii and from 37° N, 140° W indicate that it may also range into midocean. Aron (1960) reported "Notoscopelus elongatus" from the north-central Pacific, but I have not seen these specimens. Discussion Bolin (1959) revised the genus and restricted A'^. elongatus to the inner Mediterranean Sea. According to Bolin's data, all specimens from the eastern Pacific examined by me, were N . resplendens. A far western form, N.japonicus, has strongly dentate scales. Matsubara (1938) recorded "N. resplendens" from off Japan, but did not mention body scales; he listed 8-9 -l- 16-17 gill rakers — well above the number for A^. resplendens. Also, Matsubara gave the size as up to 153 mm "body length." None of the material before me exceeded 75 mm. Body proportions for A^. resplendens from the eastern Pacific Ocean (Table 42) are com- pared with similar data given by Bolin (1939, p. 152, as A^. elongatus ). Bolin's data were based on two large specimens (110 and 113.5 mm) from Misaki Sea, Japan. These data differ sig- nificantly from those of A^. notoscopelus from the eastern Pacific. Table 42. Body Proportions for Notoscopelus resplendens from the Eastern Pacific Ocean, and for Two Specimens Identified by Bolin (1939) as A''. elongatus from off Japan. Measurement N. resplendens N= 12 (35.2-78.1 mm) Ave. Range 303 290-320 187 177-195 75 67-83 219 206-231 311 296-329 426 410-436 578 571-592 425 414-440 806 792-813 202 190-212 270 254-284 309 296-323 N. elongatus 110.0 mm 113.5 mm Head length Head depth Orbit length Upper jaw length Prepectoral length Prepelvic length Preanal length Predorsal length Preadipose length Dorsal origin to pelvic origin Dorsal origin to anal origin Dorsal base length 264 58 189 273 413 574 393 786 141 236 266 266 61 195 278 414 587 423 837 156 251 268 216 Anal base length Caudal peduncle length Caudal peduncle depth Pectoral fin length Pelvic fin length Supracaudal gland length Table 42 (Continued) 224 214-233 214 200-236 99 88-106 118 84-135 148 138-160 138 122-161 210 76 211 90 Hintonia Fraser-Brunner, 1949 Body robust and heavy; head deep, about 1.4 in its length; caudal peduncle short and deep, its depth about half its length. Dorsal base longer than anal base, anal about 1.4 in dorsal. Six PO, only the last slightly elevated; 5 VO, the series curved; VO2 much elevated, the last three in descending series. Photophores weakly developed and inconspicuous but not notably small, often not formed on specimens less than 25 mm. A small patch of luminous tissue present on most scale pockets and at many photophores. Two Pol. Pre 6 (5-7 ), last 2 widely separate from rest. Secondary (procurrent) caudal rays numerous, stiff and spine-like, 10 (9-11) dorsally and 12-13 (11-14) ventrally. A single species recognized. Hintonia candens Fraser-Brunner, 1949 Fig. 204 — Hintonia candens, female, 110.0 mm. Fig. 205 — Hintonia candenn, holotype, 78.3 mm. From an unpublished drawing by Rolf L. Bolin. 217 Description D. 15 (14-16); A. 13-14 (12); P. 13-14; AO 6-7 + 5-6 (7), total (11-13, rarely 14); gill rakers 6-7 + 1 + 12(10-13), total 18-19 (17-21); vertebrae 38 (37-39). Correlated counts of AO photophores and of gill rakers are given in Table 43. Table 43. Correlated Counts of AO Photophores and Gill Rakers for Hintonia can- dens. AOp AOa ^ 21 23 2 8 20 2 Lower rakers (including central raker) 11 12 13 14 Upper 6 rakers 7 30 23 1 4 11 2 Characters given for the genus will also serve for the species. Fraser-Brunner ( 1949) provided a moderately detailed description of the holotype of//, candens. Rolf L. Bolin pre- pared a considerably more detailed description of the holotype (unpublished) and kindly made it available to me. As H. candens is poorly known, and as the two descriptions differ somewhat (see Discussion), it seems advisable to present Bolin's description verbatim. Description of the holotype of Hintonia candens, 78.3 mm (Fig. 205) in the British Museum, Natural History, taken at Discovery Station 1774 in the southeastern Atlantic Ocean between 41°50.0' S, 00°01.7' E and 45°54.3' S, 00°03.3' E, between 400 and 650 m: Body heavy, robust throughout. Snout rather pointed, markedly protruding, mouth definitely inferior, lower jaw somewhat shorter than upper, slightly included. Maxillary not expanded posteriorly, ending in a rounded point, bent slightly downward, extending about 1.1 orbital diameters behind orbit, about 0.4 of its length lying behind a perpendicu- lar to mouth drawn through posterior margin of orbit. Premaxillary and dentary with narrow bands of cardiform teeth, the inner ones somewhat enlarged in the premaxillary and developed into quite heavy canine-like structures on the dentaries. Palatine teeth in a single series, about equal in size to the outer teeth of the jaw. No teeth on vomer. Pterygoid teeth rather widely scattered, the dorsal ones much enlarged as in Lampadena. Opercular margin ending in a somewhat pointed flap, its upper portion bearing a feebly ctenoid lobe. Gill rakers moderately long but rather heavy, this posterior surfaces con- spicuously toothed. Origin of dorsal about midway between snout and AOp,. Anal origin slightly behind end of dorsal base. Adipose fin slightly behind end of anal base. Pectoral base on a vertical midway between snout and anus. Fin broken, probably extending to, or slightly beyond, ventral base. Ventral base slightly posterior to dorsal origin, fin extending about to VO.v Body scales in general cycloid, those of the lateral line somewhat cremate and displaying a deep posterior notch. A moderately prominent Dn under anterior portion of frontal margin. A very deeply embedded Vn appears to be present. OPi deeply embedded opposite lower end of premaxil- lary. Op2 slightly larger than adjacent body organs, somewhat above end of premaxillary. A rather well developed Bu about on level of lower orbital margin and somewhat behind the eye. PLO almost directly over the base of upper pectoral ray and about midway between it and lateral line. PVO, somewhat in advance of upper part of lower end of pectoral base. PVO2 immediately below and in front of lower end of pectoral base. Six PO. 218 The first pair about under posterior end of PVOo, rather close together. Second to fifth pairs somewhat more widely divergent, forming equally spaced and roughly parallel straight lines from ventral view. PO,i widely divergent, located somewhat more than an organ diameter in front of base of outer pectoral ray. Five VO. VO, rather close together, posteromesad to inner ventral ray. VO2 markedly elevated forming, with the next two organs, evenly spaced descending or convergent lines. VO, and VO.-, about as widely spaced from midline as VO,. VO,^ just anterolaterad to anus. Three SAO forming an evenly spaced, almost straight and strongly oblique, isolated series. SAO, very slightly behind, or even over, V0:„ about twice as close to lateral line as to anal base. Seven AOa forming a continuous sigmoid curve with the Pol. AOa, slightly elevated, separated from second by a somewhat enlarged interspace. Second to fifth organs forming a slightly curved line, the concavity directed upward, penultimate and ultimate organs progres- sively elevated toward the Pol, which lies about on the vertical of the end of the adipose base and is markedly closer to lateral line than to ventral body margin. Five AOp, evenly spaced in a straight series. Pre 3 + 2 or 4 + 2, separated from last AOp by an interspace equal to about 0.4 depth of caudal peduncle. The first three or four Pre very closely spaced, the last interspace markedly larger and the penultimate one larger still, the final organ lying somewhat behind end of hypural and somewhat more than its own diameter below lateral line. Well developed luminous organs displaying a somewhat spongy character are widely scattered over the head and the body. Particularly well defined or prominent ones occur below the lower PVO, Bu, VLO, each of the SAO and in the interorbital space. No indication of any well defined glands among the procurrent rays of the caudal fin. The body of this fish has very much the same general character as that of many large lampa- denas. That is, where the scales are lost a pale pinky grey area is surrounded by a broad brownish band marking the scale pockets and giving the entire fish a lattice work appear- ance. Probably in life a luminous gland was borne on the posterior part of every scale pocket. Bolin did not mention a Ce photophore, but Fraser-Brunner did. On the several specimens in excellent condition before me, what may be interpreted as a Ce lies just above the anterod- rosal insertion of the operculum and about over PO,; this organ, however, is very similar to the small, weakly formed and easily lost patches of luminous tissue present on most scale pockets; it is differentiated primarily in having a very narrow black margin not visible on other patches. Also, Bolin did not mention the VLO, where Fraser-Brunner did, correctly located it about midway between lateral line and pelvic base. A character not mentioned by either author is that the photophore are mostly kidney-shaped, the concavity directed downward; the ventral margins are usually more heavily bordered by dark pigment than the upper margins. Although Bolin considered only 1 Pol to be present, Fraser-Brunner interpreted two; the latter opinion is herein accepted. The arrangement of the 2 Pol is variable; usually they are in a straight, oblique line with the elevated last, or last 2, AOa; occasionally PoU is either slightly behind that line but above the level of Pol, or is on the line and slightly below the level ofPoh. The pectoral fin of a few specimens (43-49 mm) reached to SAO,, but on one larger specimen (86 mm) it reached only to VO2. Unbroken pectoral fins of larger fishes did not extend beyond VO,, usually to about over pelvic base. Size: To about 120 mm. Least depth of capture: To 200 m at night. Distribution: Probably occurs circumglobally in a restricted area between about 40° and 50° S (Fig. 206). The hiatus in distribution in the southern Atlantic and Indian Oceans is no doubt due to lack of collecting effort in those areas. All but two collections shown in Fig. 206 were taken by the USNS ELTANIN during the United States Antarctic Research Program of 219 Fig. 206 — Capture localities for Hintonia candens. the National Science Foundation; exceptions are the holotype and a specimen taken by Scripps Expedition Lusiad at about 49''26' S, 132°18' E. Discussion There appear to be distinct differences in the rate of growth with size (or age) in certain parts of the body in Hintonia candens. Although isometry is indicated for most of the charac- ters given in Table 44, allometry is also indicated in that the smaller sizes tend to have higher values for thousandths of standard lengths (with no overlap), the values decreasing with increasing size offish; this is true for the lengths of the head and upper jaw, and the prepec- toral, prepelvic, and predorsal lengths. Conversely, the depth of the caudal peduncle appears to be relatively greater in smaller than in larger specimens. An unusual, and not readily explained, curvature of the vertebral column, determined by X-ray, occurred in about 29%> of the specimens. This curvature (Fig. 207) appears not to be a result of distortion during preservation, for several specimens having a distinct bend in the body in the area of the curvature shown in Fig. 207 were manually straightened and pinned to a paraflfm block and X-rayed; the curvature of the vertebral column persisted. Similar vari- ously pronounced curvatures of the vertebral column were found in the remaining specimens, although some of the bodies were somewhat bent. As the figure of the holotype, drawn by Bolin (Fig. 205), shows a distinct bend in the body, the vertebrae column is probably also curved. 220 Table 44. Body Proportions for 15 Specimens in Each of Four Size-Classes of Hin- tonia can dens. Measurement SL— 20-30 mm SI^-40-50 mm SL- -51-60 mm SL— 70-1 18 mm Ave. Range Ave. Range Ave. Range Ave. Range Head length 327 320-342 326 314-339 309 288-319 290 280-308 Head depth 225 219-230 222 210-230 216 208-226 216 206-238 Upper jaw length 232 222-247 226 211-239 215 198-225 202 192-217 Snout length 80 70-89 69 62-78 64 52-74 59 51-75 Orbit length 87 76-94 88 79-97 83 75-90 82 73-89 Interorbital width 112 101-128 123 118-129 120 107-127 116 110-124 Prepectoral length 344 333-361 336 323-346 324 309-341 312 300-328 Prepelvic length 475 462-486 464 452-474 466 435-483 447 433-461 Preanal length 642 630-656 635 622-657 639 621-656 630 608-657 Predorsal length 473 467-483 450 433-469 444 436-456 435 421-455 Preadipose length 805 792-828 793 785-802 789 777-805 785 772-807 Dorsal to pelvic origins 213 203-221 197 178-210 196 182-218 217 201-245 Dorsal to anal origins 292 282-302 291 278-307 296 281-311 313 301-339 Caudal peduncle length 245 238-259 243 236-261 242 227-254 264 251-289 Caudal peduncle depth 102 92-110 107 92-121 113 104-121 126 112-143 Dorsal base length 201 189-217 193 179-202 197 191-205 211 186-219 Anal base length 145 136-154 138 123-153 133 129-151 144 135-160 Fig. 207 — Radiograph oi Hintonia candens showing curvature of verteb- ral column. Scopelopsis Brauer, 1906 Dorsal and anal bases long, nearly one-third of standard length, about equal in length. Pectoral short, reaching but little beyond pelvic origin, rather heavy and broad-based. Dn and Vn present. Dn small, round, prominent; immediately below and in contact with Dn is a larger patch of luminous tissue; Vn large, deeply buried. Small secondary photophores, heavyily margined in black, on head and body at bases of dorsal and anal fins and extending along rays of all fins, probably to the tips, where they appear on a very thin, easily lost integument covering the rays. These small photophores (luminous dots) on head and body are often expanded and may be confused with the primary ones. The only valid criteria for separating the two is that scales overlying the primary series have the characteristic lens-like modification (Tuning, 1932), but scales over the secondary dots do not. Scales of lateral line with dentate margins, those of rest of body smooth-edged. Body color very dark brown in preservative. A single species is recognized. 221 Scopelopsis multipunctatus Brauer, 1906 Fig. 208 — Scopelopsis multipunctatus, 51.8 mm. The principal photophores represent those found on several specimens. The tiny secondary photophores, present on each scale pocket of head and body, are shown only on the midbody. Description D. 22 (21-23); A. 24 (23-25); P. 10-11; 5 PO and 5 VO, none elevated; 2 or 3 Pol, horizon- tally arranged; 4 to 6 Pre, the last elevated and widely separate from the rest. AO difficult to perceive but appear to range from 7 to 10 + 5 to 6; gill rakers 8 (7-9) +1 + 16 (15-17), total 24-25 (23-26); vertebrae 38 (37-40). The drawing in Fig. 208 is a composite of observations from several specimens and is intended only to show the general pattern of the primary photophores (small open circles); the secondary dots are shown only for the midregion (tiny solid dots). Unfortunately, the body scales are very deciduous, and fully, or even mostly, scaled specimens are rare. When most or all scales are lost it is not always possible to distinguish between primary and secondary photophores. Nafpaktitis and Nafpaktitis (1969) stated that they were unable to substantiate Fraser-Brunner's ( 1949, p. 1098) distinction of "primary" and "secondary" photophores; how- ever, that distinction is supported herein (see diagnosis of the genus). Supracaudal luminous gland long and broad, with 6 or 7 overlapping, roughly triangular plates. An infracaudal luminous gland may not be present, or not in the usual position, but on an occasional specimen two small patches of luminous tissue may be found along bases of anteriormost ventral procurrent caudal rays. Supracaudal glands begin to develop on speci- mens of about 55 mm. Size: To about 76 mm. Least depth of capture: It has been taken off Peru at night with as little as 350 m of wire out. Distribution: Circumglobal in southern seas. It is plentiful off South Africa, New Zealand, and in the southern Indian Ocean. In the eastern Pacific, occasional specimens have been taken as far north as 15° S in the Peru Current and may be migrants, or expatriates, moving north with this cold current. It has been taken at about 25° S, 155° W in mid-Pacific. Discussion Despite the not insignificant literature on this species, only Brauer's original account offers body proportions, and for only one specimen. Therefore, I present the following mor- phometric data based on 15 specimens, 25.5 to 76.7 mm, taken off South Africa and Chile. The average value is given first, followed by the range in values in parentheses: Head length 293 (262-325); head depth 187 ( 160-208); orbit length 67 (55-751; upper jaw length 218 (202-238); prepectoral length 299 (276-321); prepelvic length 368 (345-384); predor- sal length 416 (395-451 ); preanal length 508 (491-524); preadipose length 802 (781-823); dorsal 222 origin to pelvic origin 224 ( 195-230); dorsal origin to anal origin 237 (223-256); dorsal base length 300 (286-327); anal base length 309 (290-328); caudal peduncle length 203 (187-217); caudal peduncle depth 84 (77-93). The tips of all pectoral and pelvic fins were broken but reached nearly to origin of anal fin in a few specimens. 223 REFERENCES Alcock, a. 1890. On the bathybial fishes collected in the Bay of Bengal during the season 1889-90. Ann. Mag. Natr. Hist., London (ser. 6). 6: 197-222. Alverson, F. G. 1961. Daylight occurrence of myctophid fishes off the coast of Central America. Pacific Sci., 15 (3): 483. 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