vE.W'D Contents August 31, 1995. Editorial. A Contribution to the Natural Classification of Lower and Middle Cambrian Arthropods: Food Gathering and Feeding Mec hanisms . E. L. Bousfield The Amphipod Superfamily Pontoporeioidea on the Pacific Coast of North America. II. Family Haustoriidae. Genus Eohaustorius J. L. Barnard: Systematics and Distrihutional Ecology. E. L. Bousfield and Phillip M. Hoover The Amphipod Family Pleustidae on the Pacific Coast of North America. Part III. Subfamilies Parapleustinae, Dactylopleustinae, and Pleusirinae: Systematics and Distributional Ecology. E. L. Bousfield and E. A. Hendrycks Additions to Amphipacifica Vol. I (4). Eusiridae. Cataloguing data. 35. 1 National Library of Canada ISSN No. 1 1 89-9905 ESTACION Maz, A POSTAL 81 1 82000 NIOfL U N A M Slr^TALOA, AMPHIPACIFICA JOURNAL OF SYSTEMATIC BIOLOGY Volume II, Number 1 August 31, 1995 AMPHIPACIFICA, Journal of Systematic Biology (ISSN No. 1 189-9905) is published quarterly by Amphipacifica Research Publications, 61 1-548 Dallas Rd., Victoria, B. C., Canada, V8V 1B3. Annual subscription rates are $40. US or $50. Canadian funds. DEDICATION The Journal AMPHIPACIFICA is dedicated to the promotion of systematic biology and to the conservation of Earth’s natural resources. Cover design: Adapted from the title page of S. J. Holmes (1904). “Amphipod Crustaceans of the Expedition.” Harriman Alaska Expedition, pages 233-244. AMPHIPACIFICA VOL. H NO. 1. AUG. 31, 1995. EdISt@iro§ill „ Since completion of the first volume of Amphipacifica last spring, we have continued to receive expressions of both satisfaction and criticism concerning the quality of its content and editorial format. The commentary came from a wide spectrum of readers including: MarkCostello, Dublin, Ireland; Larry Hamblin, Romford, U. K.; Pierre Noel, Universite de Paris, France; John Holsinger, Norfolk, VA.; Patricia McLaughlin, Anacortes, WA; Valerie MacDonald, West Saamch, Charles Low, Victoria, and Cas Lindsey, Vancouver, B . C. Jim Lowry, Australian Museum, Sydney, has pointed out a problem in one of early phoxocephalid plates that requires clarification. Niel Bruce, University of Copenhagen Museum, Denmark, has detected a number of editorial oversights in previous numbers that we have attempted to correct in this issue. Changes include a repositioning of the pagination and running head, more restricted use of underlining, oversize letters, and boldface type, and reduced use of abbreviations in the references. More careful attention has been given the alignment of type in parallel columns, and to consistency in labeling of illustrations. We welcome your further suggestions for improvement. As the scope of the journal expands, we encourage exchange advertising with other journals of systematic biol- ogy, and with societies and agencies concerned with conser- vation of natural resources. We welcome submissions of medium to large systematic studies, and also shorter research papers and review articles that involve some aspect of aquatic biology and/or environmental concern. Although the journal emphasizes systematic research on aquatic invertebrate faunas of the North Pacific, as noted previously, publication criteria extend to other biomes (including terrestrial), other biotas (including vertebrates and fossil animals) and other regions (including the North Atlantic). ' The first paper of this issue is a contribution to the re- classification of arthropods and arthropod-like animals, based on feeding and food-gathering mechanisms. Arthropod-like fossil animals of the Burgess Shale formation flourished in ancient Paleozoic seas some 520 million years ago. As a result of later orogenic processes, exquisitely preserved fossilized remains of these early crustacean and arachnid- like animals can be recovered from Middle Cambrian sedimentary rocks now situated at altitudes of about 1.5 km a.s.l. This study outlines possible phyletic relationships of known fossil species within two major groups of arthropods. These are defined as the uniantennates, including the aquatic Paleozoic trilobites and modem terrestrial arachnids, and the biantennates that encompass the mainly aquatic crustaceans, and modem terrestrial myriapod and hexapods. This enorm- ous assemblage of joint-legged animals, comprising well over one million described species, fossil and recent, has been encompassed within a phyletic subdivision of only 9 superclasses and 29 classes. Quite remarkably, the total known Cambrian arthropod fauna of less than 100 fossil species, all aquatic, represents 6 of the superclasses and 14 of the classes, whereas the Recent arthropod fauna of over 1 one million described species, both aquatic and terrestrial, is contained in only 4 superclasses and 15 classes. Thus, the contention of Stephen J. Gould, set forth in his popular book "Wonderful Life" (1989), that the Cambrian fauna exhibited greater disparity (diversity at high taxonomic level) than at any other time in animal evolutionary history, finds strong support in the present analysis. The second paper in the series treats the sy stematics and distributional ecology of North Pacific members of amphipod family Haustoriidae. Among macro-cmstaceans, haustoriids are one of the most highly modified for a free-burrowing life style. The family is most diverse within the western North Atlantic region, especially along the sandy estuarine coastline of southeastern United States. However, one genus, Eohaust- orius, has penetrated the North Pacific and is now nearly equally speciose along Asiatic and North American coastlines. Its subtidal species occur throughout the Pacfic Rim region. However, intertidal species are apparently absent from corresponding Asiatic shores. There, winter conditions are severe, accompanied by sub- freezing temperature and shore icing; in summer, species of the competing fossorial talit- roidean family Dogielinotidae dominate intertidally. Along corresponding North American Pacific sandy shores, how- ever, winter conditions are relatively mild, shore icing is lacking and, in summer, only one species of intertidal dogiel- inotid occurs, and only along the open coast of Washington and Oregon states. Their infaunal densities, ease of collect- ing, and sensitivity to inimical substances, render certain species of Eohaustorius suitable for bioassay monitoring and testing of marine sediment toxicity. The final paper is a continuation of a series of revision- ary studies on the relatively primitive, benthic, gammaridean amphipod family Pleustidae. Member species are mainly micro-carnivores and commensals within marine commun- ities of sessile invertebrates and attached plants. Subfamilies Parapleustinae, Pleusirinae, and Dactylopleustinae, investigated here, are almost wholly endemic to the North Pacific Brim region. Of the 32 known species combined, all but two occur nowhere else. The North Pacific marine shelf is characterized by long-term stability of associated biotic communities, and equable marine climates. These factors, presumably operating throughout the evolutionary devel- opment of the three pleustid subfamilies, are considered primary in dampening evolutionary thrust in other directions. In summary, a remarkable feature of these three papers is the coincidental stratigraphic range of the marine animals encompassed, from the subtidal to the ocean abyss on the one hand, and from the supralittoral zone to high interior mountain slopes of British Columbia on the other. With respect to the article on Cadborosaurus that ap- peared in the special supplementary issue of Amphipacifica, Vol. I, commentary pro and con has been received. A few excerpts are as follows: "You may have created some controversy with "Caddy" but . . you'll have provided some foundation for its recognition and study" (Dale Calder letter, June 19). "I was most impressed by . . . the paper on AMPHIPACIFICA VOL. H NO. 1. AUG. 31, 1995. 2 AMFEIP ACIFICA: PERSONAE NOVAE. . . Cadborosarusu willsi . . . and I should like to distribute it among our subscribers (Jon Downes, Centre for Fortean Zoology, U. K.). " . . You were right in publishing. Perhaps, some day, it might prevent another "Kermode" . . (who make) hasty, often erroneous identifications" (Earl Godfrey, Ottawa). The popularized version entitled "Cadborosaurus, survivor from the deep", Horsdal & Schubart, publishers, Victoria, 1 34 pp.. May, 1985, was "read with much interest" by several subscribers and friends, including Ian McTaggart Cowan, Victoria. Concerning this matter, the resignations of dissenting editorial associates of this journal, Craig Staude and Phil Lambert, have been accepted, regretfully. We are greatly indebted to Craig and Phil for their editorial help with previous regular issues of the journal, and wish them well in furthering their invertebrate research objectives. The authors of the research paper on Cadborosaurus did not refer to a paper by Peter Scott and Robert Rines in Nature, 258: 466-468, 1975, in which the Loch Ness phe- nomenon was newly described as Nessiteras rhombopteryx. Their reconstruction, based on fixed demersal strobe flash Marianne Wilkinson, B.A. (Eng), Associate Editor, has had a varied background in the field of communication and education. She has served as a high school teacher, news reporter, freelance writer, designer, and photographer. Fol- lowing a four-year stint as a humour columnist, she becaame publisher and editor-in-chief of British Columbia's "Island Life" Magazine. Her avocational interests include writing, archeology, paleontology, and the outdoors, and is avid about flying. Phillip M. Hoover, BSc., majored in biology at the University of Victoria, with emphasis on marine pollution biology and invertebrate taxonomy. During studies for the MSc degree in biology, he served as a teaching and research assistant in the laboratory of Dr. Derek V. Ellis with whom he co-authored studies on the impact and recovery of marine benthos in mine tailing wastes. Phil recently completed stud- ies on the systematics of North American Pacific marine amphipods of families Haustoriidae, Amphilochidae, and Corophiidae, the first of which appears in this issue. Production of this issue benefits greatly from the experienced editorial services of Tara Steigenberger, former assistant editor. Royal British Columbia Museum, Victoria. photographs of a partial body, neck and supposed hind flipper, portrays a thick-bodied, long-tailed animal with two pairs of large flippers. Such is quite unlike Cadborosaurus willsi, and the names are thus very probably not synonymous. Regretably , the Loch Ness specimen was not "in hand" at any time and, in our view, the photographs are not sufficiently distinct or complete to form the basis for a reasonably accur- ate interpretation of the animal’s external morphology. The difficulty of research here cannot be overestimated. Acquiring a further large specimen for detailed morphologi- cal study is very unlikely, but a small juvenile might again be captured alive and its behaviour studied in a marine aquarium. Despite several recent sightings in waters of the Saanich pen- insula, May - August, 1995, neither video footage nor photo- graphic "still" shots of this species at the water surface were obtained. However, these new sightings, made independ- ently, some by two or more observers simultaneously, in- cluding one from a large deep freshwater lake not far from Victoria, further support the reality and recurring predict- ability of this large, anadromous, vertebrate species. AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 3 A CONTRIBUTION TO THE NATURAL CLASSIFICATION OF LOWER AND MIDDLE CAMBRIAN ARTHROPODS: FOOD-GATHERING AND FEEDING MECHANISMS. ABSTRACT by E. L. Bousfield, Research Associate Royal Ontario Museum, Toronto, Canada MSS 2C6 The classification of arthropods and arthropodlike invertebrates of Lower and Middle Cambrian strata is currently in a state of flux. Reanalysis of these early arthropods, however, indicates that a more widely acceptable basis for their natural classification might emphasize mechanisms of food gathering and feeding. Moreover, such mechanisms are usually readily determinable in both fossil and living specimens. This study employs a relatively broad definition of the term “arthropod”, and utilizes most higher classificatory names of the arthropod literature, but with reorganized emphasis. The views of Gould (1989) and Briggs et al. (1993) concerning high-level taxonomic diversity (disparity) of Lower and Middle Cambrian arthropods ( sensu Walcott, 1912) are generally supported. However, these taxa have all been classified previously within accepted arthropod subcategories and none is considered new at the level of phylum or subphylum. Although the present analysis suggests plausible evolutionary pathways for food-gathering and feeding mechanisms in uniantennate (i.e., chelicerate) lineages, and possibly in biantennate (i.e., crustacean, myriapod and hexapod) arthropods, incorporation of these ideas within a suggested formal classification awaits broader acceptance among current workers. INTRODUCTION Arthropods are a major component of a fauna that, dur- ing the Cambrian Period, attained what has been described by Gould (1989) as a "maximum disparity of animal life". This concept, of broad morphological diversity at high tax- onomic level (here defined as subclass or higher, or undeter- mined), has been questioned in detail by several (e.g., Ridley (1990, 1993; Briggs et al. (1992), but ably defended by Gould (1993) and Foot & Gould (1992). Thus, disparity of arthropods and arthropod-like forms does not appear to have been greater in Cambrian than in Recent times, whatever classifications are consulted or methodologies used (Wills et al., 1994). However, in proportion to the small number (< 1 00) of Cambrian arthropod species recorded to date, from a half dozen or so major fossil sites world- wide, the percent- age of high-level taxa that they represent is very much higher than that of comparable samples of Recent faunas. If considerations are restricted to aquatic faunas only, the percentage difference is even higher. Whatever the magni- tude of these differences, however, the Cambrian Period can fairly be viewed as ^ period of arthropod evolutionary "explosion". Cambrian arthropods are mostly unlike living repre- sentatives of the phylum, and therefore difficult to classify on existing natural bases. One of the richest arthropod as- semblages, of about 35 species, has been described from Middle Cambrian Burgess Shale deposits in Yoho National Park, British Columbia (Conway Morris & Whittington, 1985). General and popularized treatments of that fauna, by Gould (1989) and Briggs et al. (1993), have summarized the original work of Charles Walcott (1912), and the subsequent careful descriptive treatments by Whittington (1971, 1975), Bruton (1981), Briggs (1979, 1981); Briggs & Whittington (1983, 1987), Collins (1987a, b), Collins & Rudkin (1981), Conway Morris (1986) and others. Their work has made possible the present re-analysis of the etaly arthropod fauna for which the author feels most grateful. Previous work has revealed a plethora of Cambrian tax- onomic oddities several of which, according to Gould (1989), may require new higher classification, even at the level of phylum. Gould accepted, justifiably, the morphological interpretations of the aforementioned principal workers in this unfolding paleontological drama. Recent field work, especially in the Chengjiang region of southern China (Hou et al . 1991), and in Greenland (Conway Morris et al . 1987), has yielded many more important new taxa (e.g., by Hou, 1987 a, b; Hou & Bergstrom, 1991; Chen, etal. 1994). During his relatively brief two-year book-compilation period, Gould (1989) touched on the initial papers by Hou; however, he did not reference other pertinent works of group specialists (e.g. of Bergstrom, 1986; Schram, 1986; Dahl, 1984, 1987) that embody alternative and possibly more plausible classifica- tions and evolutionary starting points, as suggested by the writer (Bousfield, 1987), for some of the major Burgess arthropod groups. Some reviewers (e.g., Fortey, 1989) have pointed to papers on cladistic classificatory methodology (e.g., Briggs & Fortey, 1989) that do provide credible, but not entirely correct, classifications of some of the enigmatic groups contributing to Gould’s high disparity levels. Delle Cave & Simonetta (1991) analyzed previous stud- ies in a well illustrated and comprehensive account of early Paleozoic arthropods. They emphasized the importance of functionality, specially the the role of feeding appendages in the evolution of arthropod morphotypes. For the most part, their taxonomic groupings and evolutionary charts bring perceptive and cohesive insight to some mini-groups (e.g., trilobitomorphs, the Sanctacaris problem, and the Scanian larval stages), and stress the need for authors to name new taxa, whatever the later higher categories might be. How- ever, they did not differentiate between food gathering and feeding (masticatory) roles and, as summarized in their AMPHIPACIFICA VOL. II. NO. 1 AUG. 31, 1995 4 Table IV, apparently missed the significance of relationships within the Dicephaiosomala and the overall relationships between anomalocarids and primitive trilobitomorph as- semblages (which they did recognize) such as the Yohoiida and Leanchoiliida. Briggs et al (1993) continued with a conservative classification of early arthropods (p. 6) in which several previous higher taxa were not recognized and the anomalocarids omitted entirely. Whatever the merits or weaknesses of these various treatments, collectively they underscore the state of flux that presently characterizes early arthropod classification. The purpose of this paper is to provide a classification that reflects more closely the actual degree of biological disparity and the major evolutionary themes within the Cambrian arthropod fauna. It also attempts to reveal, in more detail than previously, the relationship between form and food-gathering and feeding functions in selected Lower and Middle Cambrian arthropods and their descendent groups. ACKNOWLEDGEMENTS This study has taken place during a 10-year association with Dr Desmond E. Collins at the Royal Ontario Museum (ROM), Toronto, for whose tactful guidance and perceptive stimulus the writer is most grateful Dr David Rudkin (ROM), Derek Briggs (University of Bristol, U.K.), Jan Bergstrom (Natural History Museum, Sweden), Jarmila Kuk- alova-Peck (Carleton University, Ottawa), Frederick R. Schram (Institute of Taxonomic Studies, Netherlands) and several others, have directly or indirectly provided helpful input to the text. Earlier drafts of the text have been helpfully reviewed by C.R.Harington and Stephen Cumbaa (Canadian Musem of Nature (CMN), Ottawa), Murray Copeland and T. E. Bolton (Geological Survey of Canada (GSC), Ottawa), and A. L. Hamilton (Biosystematics, Agriculture Canada). Lisa Bohach (Earth & Ocean Sciences, University of Victoria) has provided perceptive commentary and editorial services, and references not previously available to the author. In the preparation of composite illustrations here I have been privileged to adapt, with warmest appreciation, the or- iginal text illustrations of D. E. G. Briggs, H. B. Whittington, D. E. Collins, F. R. Schram, X. Hou, L. Delle Cave, A. Simonetta, and several other primary sources. In parallel to the present study, Professor Edward Laidlaw Smith, San Francisco, CA, has combined and collated pre- vious arthropod categories in a detailed phyletic classific- ation of arthropods (Atlas of Insect Anatomy, unpublished). Since this study has resulted in some similar classificatory conclusions. Dr Smith has generously permitted detailed reference to and use of updated non-insect arrangements in this text, for which I am most grateful. SYSTEMATIC PREAMBLE The term “arthropod” is here defined as an invertebrate having an externally segmented body that bears one or more pairs of j ointed appendages. The body consists of head and trunk regions, of which the latter may be tagmatized or sub- divided into thorax and abdomen, mesosome and metasome, pygidium and/or telson, according to the taxonomic group. In primitive aquatic arthropods, the head always bears an acronal segment (first, or protocerebral somite) that is always pre-oral in position, having sensory organelles but no jointed limbs. The first true head segment (second or deutocerebral somite) is limb bearing, and usually pre-oral in active life stages. The head may also encompass up to five (rarely six) additional limb-bearing segments, the first of which (third or tritocerebral somite) may appear pre-oral in position. The post-oral appendages of head and trunk are primitively or embryologically biramous, the segments of which are exter- nally chitinized, sclerotized or mineralized. The inner ramus is usually locomotory, food gathering or masticatory, and the outer ramus usually respiratory in function. Growth pro- ceeds by moulting of the ectoderm (ecdysis). Following Bergstrom (1986, 1987) and Chen et al. (1994), true arthro- pods here embrace the primitive Cambrian dicephalosomatid genera Anomalocaris, Opabinia, Cassubia and close rela- tives. However, contrary to the views of Snodgrass (1956) and Manton (1977), true arthropods do not include the Tardigrada nor the Onycophora in which the body is not externally segmented and the post-oral limbs, although dactylate (clawed), are not jointed nor biramous. The Middle Cambrian macro-arthropod fauna is charac- terized by a high percentage of primitive body forms that, superficially, appear to be intermediate between true worms (phylum Annelida) and higher groups of aquatic arthropods such as the Chelicerata and Crustacea. Paradoxically per- haps, some of these early forms (e.g., Opabinia) show a remarkably high degree of specialization of body form and function that tends to mask their true phyletic affinities. In adult stages of some primitive modem arthropods (e.g., Remipedia) and larval stages of cirripedes, phosphatocopine ostracods and skaracarids, the acronal segment bears conspic- uous frontal organs or frontal filaments of presumed sens- ory function, and/or a median naupliar eye (Schram, 1986). The acronal somite is especially well developed in skaracarid crustacean larvae (e.g., Martinssonia Muller & Walossek, 1986). However, in arachnids, myriapods and hexopods, the acron is considered embryonic and fused with the second head somite in active hfe stages (Savory, 1964). The first tme head segment (second somite) of arthro- pods bears one pair of limbs, of 1-14 basic segments, that is embryonically uniramous and pre-oral. These limbs may be stout, the segments spinose or toothed, or apically pincer- like and raptorial in function, as in chelicerates and their presumed precursors. However, more often they are filamentous and sensory in function, as in the "antennae" of trilobites, and the antennules of crustaceans and their pre- sumed ancestors, and marrellomorphs. In some Cambrian arthropods (Q.g., LeanchoiliaX the appendage appears distally multi-flagellate. In higher cmstaceans (Malacostraca), the antennules are often secondarily biramous (e.g., in Eumalacostraca), and occasionally triramous (in Stom- atopoda). In myriapods and insects, the antennae are AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 uniramous, filamentous and sensory. In no instance, however, are these appendages gnathobasic. The third head somite (rarely lacking except in a few Cambrian species such as Opabinia and Sidneyia) bears a pair of limbs homologous with the antennae of crustaceans and early biantennate arthropods. These limbs, homologous also with the pedipalps of chelicerates and pycnogonids, may be uniramous or, as in the intercalary (supralingual) segment of myriapods and hexapods, vestigial or essentially lacking. In primitive arachnids and early precursors, and in larval stages of crustaceans, limbs of the third head somite are masticatory as well as locomotory and/or respiratory in function. Thus, as will be demonstrated in Cambrian aquatic arthropods (below), the evolutionary trend in func- tioning of the first two pairs of appendages in arthropods progresses from food gathering and mastication, to food sensing and tactilility. The head segment and limb homologies employed in this study, and suggested classification (pp. 23-27), conform with classical concepts of arthropod head structure, innerva- tion and embryology (e.g., of Borradaile & Potts, 1941; Savoiy, 1964; Bergstrom, 1979). Kukalova-Peck (1987) and Smith (1990) have fused the acronal segment of hexa- pods with the labrum to form the clypeolabral, or first (protocerebral) somite which, in Upper Carboniferous monurans, appears basolaterally segmented. The second head somite remains the antennal (deutocerebral) somite, homologous with the antennular somite of crustaceans. However, Smith (loc. cit.) has suggested that the chelicerae of arachnids originate on the third (tritocerebral, supralingual) somite, and the pedipalps on the fourth or mandibular seg- ment, resulting in eight prosomal somites, one more than the normal maximum recognized by all other authors. In Cambrian arthropods, the anterior portion of the gut is typically deflexed and the mouth usually opens ventrally on the head. In a few groups, however, (e.g., Jianfengia, Sanctacaris) the mouth appears to open apically or frontally (Hou, 1987a, Biiggs & Collins, 1988). Body segmentation may not always be externally visible, especially in larval forms, or in highly modified adults (e.g., some internal parasites). Paired limbs of the trunk are primarily biramous, but may be secondarily uniramous. The branches may be variously modified, unsegmented, or lacking (e.g., in early growth stages and in adults of various taxonomic groups). Thus, in a biramous limb, the outer branch may be lightly chitinized and flaplike (unsegmented) in swinuning forms or, when the outer is respiratory in function, the inner branch may be fully segmented, leglike, and heavily calcified or mineralized, especially in heavy bodied benthic forms. As noted above, some post-oral paired appendages may be gnathobasic wherein the coxa and/or adjacent segments are medially toothed, or the entire limb reduced and modified as a specialized mouthpart (e.g., mandible or maxilla). Such feeding appendages are tagmatized as part of the cephalon. Morphological differences between major groups of arthropods are fully as great as between accepted subphyla 5 and classes within other major phyla (e.g., as between chitons and cephalopods within phylum Mollusca). In Lower Cambrian to Lower Ordovician times (530-500 m.y.b.p.), major groups of arthropods having modem repre- sentatives (e.g., Chelicerata, Crustacea) were then in what might be termed a primordial or early state of evolution or, in the case of Myriapoda and Hexapoda, unrecognized as such. Thus, true crustaceans were represented in the Cambrian fossil record only by the Maxillopoda (Ostracoda, Cirripedia, and skaracarid larval forms) (see Schram, 1986 in part; Dahl 1984, 1987). Members of the Aglaspida (Upper Cambrian) were considered by Bergstrom (1979) to be early chelicerates but Briggs et al. (1978) demonstrated the filamentous nature of the "chelicerae" and removed the Aglaspidida from the merostomes. The earliest chelicerates are Chasmataspis, or perhaps Triopus, from the Lower Ordovician (Fig. 8). Other major arthropod groups (e.g. Myriapoda, Hexapoda) were recognizable in late Silurian and early Devonian times, when freshwater and terrestrial fossils deposits were first identiifed. PREVIOUS CLASSIFICATIONS Several different classifications of Cambrian macro- arthropods have been proposed, four of which are presented in Table 1. The 17 sample species listed here were classified initially by Walcott (1912) who “shoehorned” them (fide Gould, 1989) into a relatively few existing crustacean and arachnid subcategories (Column 1). Over the next 75 years the species were classified variously by Stdrmer (1959), Sharov (1966) and Bergstrom (1979), and incorporated by Edward Laidlaw Smith in a forthcoming “Atlas of the Insecta”, communicated to the writer, with kind permission, for comparative purposes here (Column 4). Despite previous designations, Gould (1989) regarded these forms as highly distinctive, belonging to two new phyla; 12 unique arthropods; one chelicerate arthropod; one trilobite; and one malacost- racan (Column 2). Briggs et al.( 1993) had retreated into a somewhat similar conservative listing of Cambrian arthropods, a list that did not include Opabinia, and other dicephalosomatid forms (Column 3). The E. L. Smith listing (Column 4) would place 15 of Gould's new or unique taxa within long-established classes of crustaceans, trilobitoids, protochelicerates, and chelicerates, five of them more or less within Walcott's original categories. However, as we may note in the following text, Smith's placement of Marrella mdBranchiocaris within the protochelicerates, and Odaraia andCanadaspis within the Crustacea, is inter- preted otherwise here. Mechanisms of food-pgathering and feeding. In assessing the overall legitimacy of these classifications, we might conclude that, under the circumstances of the relatively limited systematic knowledge of his day, Charles Walcott was remarkably perceptive in much of his classifi- cation. Although thereticenceofGouldandBriggstorefine AMPHIPACMCA VOL. 11. NO. 1 AUG. 31, 1995 6 TABLE L THE CLASSIFICATORY STATUS OF SOME BURGESS SHALE FOSSIL GENERA Genus Name Higher category by Author Walcott (1912) Gould (1989) Briggs et al (1993) E.L.Siiiith C'Atlas" prep)* Marrella (Wale.) near Trilobita unique Arthropod Protochelicerata Stormer, 1944 arthropod (primitive) CL. Marrellidea Walcott 1912 Yohoia (Wale.) branchiopod unique Arthropod Protochelicerata Stprmer, 1944 crustacean arthropod (other) CL. Yohoiidea Henriksen 1928 Opabinia (Wale.) branchiopod new Unassigned Protochelicerata Stprmer, 1944 crustacean phylum Invertebrate CL. Probosciferidea Sharov 1966 Burgessia (Wale.) branchiopod unique Arthropod Trilobitoidea St0rmer, 1955 crustacean arthropod (other) 0. Nectaspida Raymond, 1920 Branchiocaris (Wale.) malacostracan unique Arthropod Protochelicerata St0rmer 1944 crustacean arthropod (primitive) CL. Branchicaridea Canadaspis (Wale.) phyllocaridan malac- Crustacea Crustacea Pennant 1777 crustacean ostracan CL. Branchiopoda Latr. 1817 Naraoia (Wale.) branchiopod soft-bodied Trilobita Trilobitoidea St0rmer, 1955 crustacean trilobite 0. Nectaspida Raymond 1920 Odaraia (Wale.) malacostracan unique Crustacea Crustacea Pennant 1777 arthropod CL Pranchiopoda Latreille, 1817 Sidneyia (Wale.) merostome unique Arthropod Protochelicerata St0rmer 1944 arthropod (other) CL. Sidneyiidea Walcott, 1912 Malaria (Wale.) merostome unique Arthropod Trilobitoidea St0rmer, 1955 arthropod (other) incertae sedis Habelia (Wale.) merostome unique Arthropod Trilobitoidea Stprmer, 1955 arthropod (other) incertae sedis Actaeus (Wale.) unknown unique Arthropod Protochelicerata St0rmer, 1944 arthropod (other) CL. Leancholiidea Raymond! Alalcomanaeus (W.) unknown unique Arthropod Protochelicerata St0rmer, 1944 arthropod (other) CL. Leanchoiliidea Raymond! Emeraldella (Wale.) merostome unique Arthropod Protochelicerata St0rmer, 1944 arthropod (other) CL. Emeraldellidea Raymond! Leanchoilia (Wale.) branchiopod unique Arthropod Protochelicerata St0rmer, 1944 crustacean arthropod (other) CL. Leanchoiliidea Raymond! Sanctacaris (Briggs & N/A chelicerate Chelicerata Chelicerata Heymons 1901 Collins) arthropod Arachnida Lamarck, 1801 Anomalocaris (Wale.) branchiopod new Unassigned Protochelicerata St0rmer, 1944 -1- Laggania phylum Invertebrate CL. Anomalocaridea Raymond! + Peytoia + appendage F ^ Selected names with permission of E. L. Smith (references not detailed here); ! - Raymond, 1935. the classification with new terminology is to some extent justified, Smith's listing of previous formal categories indi- cates that their reticence does not provide a helpful solution to the problem. The need seems greatest for more careful and more rigorous definition of existing categories, based on principles of functional morphology where possible, and a resort to new categories when existing or redefined catego- ries prove inadequate. As Gould (per Schram, 1990) reminds us, errors and oversights of the past are part of the process of getting the probably correct answer, and so provide a prime stimulus for the present undertaking. Gould (1989) noted that previous workers on Cambrian arthropods seemed reasonably confident of their classifica- tion of the most primitive forms, e.g., the Onycophora, and the presumably most advanced major taxon, the Trilobita. However, they seemed less certain of other arthropods variously attributed to the Crustacea (ie. Canadaspidida, Branchiocarida) or having only general similarities with the Trilobita. The greatest difficulties were encountered with forms having both annelid-like and arthropod-like features (e.g. Anomalocaris, Opabinia). Charles Walcott (1912) utilized subcategories of extant arthropod groups (e.g., Branchiopoda, Ostracoda -t- Merostomata). St0rmer(1944, 1959) proposed new “catch-all” categories (e.g., Trilobit- oidea) for many enigmatic forms. These classifications utilized standard character states such as body tagmatization, number of paired head (or head shield) appendages, types of appendages (biramous, gnathobasic, gill-like) and larval biology, to the hmit of existing knowledge, but did not emphasize fimctionahty or possible behavioural significance. AMPHIPACIFICA VOL. U. NO. 1 AUG. 31, 1995 7 Bergstrom (1979, et seq.) employed the term “Schizoramia” to encompass all Trilobitomorpha (Trilobita, Merostomatoidea, and Chelicerata). These are characterized by primitively biramous trunk limbs of which the endopod is gnathobasic, and the exopod bears lamellar spines. The enigmatic genus Emeraldella, having gnathobasic post-oral legs, was included here, as well as the Marrellomorpha, but the latter group primarily lacks gnathobasic limbs. The Pycnogonida (Pantopoda) was not related to any particular arthropod group. Commendably, Bergstrom relegated binia and Anomalocaris to the status of a “pre-arthropod” stock, but later (1986, 1987) decided they were indeed arthropods, a view now firmly supported by the recent work of Chen eLal (1994). However, Bergstrom employed the term Uniramia to encompass both the soft-bodied, externally annulated onychophorans, and the hard-bodied, externally segmented myriapods and hexapods having whole-limb jaws. This concept is now proving flawed and untenable as a category of natural classification (see Kukalova-Peck, 1992). Onychophorans, early forms of which did exist in Cambrian seas, resemble the Tardigrada in having shaft-like, primitively uniramous limbs and pharyngeal teeth or spines, whereas myriapods and insects have segmented, primitively biramous limbs, and mouthparts modified from biramous limbs. Furthermore, Bergstrom’s doubts that biramous and mandibulate crustaceans arose from the same gnathobasic limb stock as hexapods are not supported here nor by some other workers (e.g., Kukalova-Peck, 1987). Imperfect fossilization has so far prevented determination of the precise nature of locomotory limbs of dicephalosomatids However, such is not here considered a major impediment to phyletic implications of the better preserved, clearly "arthropodized" feeding appendages of the head region, nor overall relation- ships with confirmed early biramous arthropod groups. In assessing the impact of feeding processes on the evolution of body form in arthropods, a definition of terms is prerequisite. The entire feeding process encompasses food-gathering and food-consumption mechanisms. The food-gathering mechanism is the process by which food items are entrapped and brought to the mouth region. The food-consumption (feeding) mechanism is the process of mastication, the external means by which food items are rendered suitable for entry into the digestive tract proper. Basic types of feeding processes of arthropods and their presumed antecedents are illustrated in Fig. 1. In errant poly chaete worms (Q.g.^Nereis, Vefit/iej), a taxonomic group "classically” presumed ancestral to the arthropods, the head consists of a prostomium and usually a peristomial segment bearing food-sensing tentacles. No paired limbs, segmented or otherwise, are involved in food gathering or in food mastication; these processes are entirely pharyngeal (Fig. lA). The mechanism consists of an eversible pharyngeal proboscis, the everted distal end of which is armed with strong teeth or “jaws” by means of which the food material (prey organism) is captured and killed. As the proboscis retracts, it re-inverts, taking in the prey and partly macerating it by means of other teeth lining the pharynx wall. The food is then passed rearward to the digestive gut proper. No true arthropods conform with this category. In very primitive uniantennate arthropods, (e.g., Anomalocaris, Fig. IB . 1 ), food is gathered by the large, spin- ose and multi-segmented, pre-oral paired appendages. These capture and transfer prey organisms posteriorly to the mouth region that opens immediately behind the first true head segment. The actual feeding mechanism, however, remains entirely pharyngeal; no paired mouthparts or leg gnathobases are present, although in the related Opabinia regalis (Fig. 1B.2), some prey items may be partly macerated by the pre- oral clawed appendage. In the anomalocarids, food is initi- ally macerated by means of peribuccal teeth, and/or stout teeth or spines lining the anterior walls of the pharynx, as in some polychaetes. This feeding process is analogous, or perhaps even homologus, to mechanisms elsewhere among living arthropods in the pycnogonids, and among other invertebrates in the cephalopod molluscs (Borradaile & Potts, 1941). In cephalopods, the “head-foot” appendages (tentacles) grip, but do not masticate, the prey by means of specialized suckers, rather than spines; modified anterior pharyngeal teeth, the horny beaks, and smaller radular teeth masticate the prey items just inside the mouth entrance. In more advanced uniantennates (e.g. in chelicerates. Fig. 1C), food gathering is also the prime function of post- oral head (prosomal) appendages, and/or the cheliform pair of pre-oral appendages. In primitive aquatic chelicerates (e.g., merostomes), the food is first macerated externally by means of a grinding action of the gnathobasic coxae of the paired head and/or trunk appendages. In more advanced terrestrial arachnids that secondarily lack leg gnathobases, the killing bite and maceration of the prey is performed by the distally clawed first post-oral appendages, the pedipalps and/ or the pre-oral chelicerae (Savory, 1964). Within advanced biantennate (mandibulate) arthropods (e.g., malacostracan crustaceans. Fig. ID), the pre-oral and first post-oral appendages are flagellar and food-sensing. Food is gathered mainly by the anterior trunk (thoracic) limbs. Swimming, and often respiratory functions may be relegated to the posterior trunk (abdominal) limbs. Food is macerated by specialized post-oral limbs of the head region, the mandibulate mouthparts. Other branches or lobes of post-oral head appendages may serve in locomotion, and/or respiration, especially in adults of more primitive groups (e.g., cephalocaridans) and in larval stages of advanced forms. Food mastication may also become the primary func- tion of one to three pairs of anterior trunk limbs, serving as maxillipeds (e.g., in Decapoda), or as gnathopods (e.g., in Amphipoda). In their larval stages (e.g., nauplii, metanauplii) the biramous first post-oral appendage (antenna 2) usually retains a function in food gathering and mastication, as well as locomotion (Schram, 1986). AMPHIPACMCA VOL. D. NO. 1 AUG. 31, 1995 8 oc;ipitot onttnnoi RAPTORIAL TEETH (JAWS) PARAGNATHS (LATERAL TEETH) A. PHARYNGEAL PRE-ORAL HEAD LIMB (CHELICERA) RAPTORIAL PRE-ORAL LIMB RAPTORIAL "CLAW" (FUSED PRE-ORAL HEAD LIMBSl -ORAL HEAD LIMBS (MOUTH - PARTS) POST-ORAL HEAD LIMBS (GNATHOBASIC) Limulus C. CHELICERATE PRE-ORAL GNATHOBASIC POST-ORAL TRUNK LIMBS ( GILL BOOKS ) GILL BOOKS ANUS ANUS PLEOPODS ANUS TELSON ■ Orconectes D. ANTENNAL PRE-ORAL MANCHBULATE POST-ORAL FIG. 1. BASIC TYPES OF FOOD-GATHERING AND FEEDING MECHANISMS IN AQUATIC ARTHRO PODS. A. Polychaete (ancestral). B. Primitive uniantennate arthropod. C. Advanced uniantennate arthropod D. Advanced biantennate arthropod AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 9 TABLE II. SELECTED GENERA OF CAMB RIAN UNIANTENNATE ARTHROPODS CATEGORIZED BY FOOD- GATHERING AND FEEDING MECHANISMS SEGMENTED LIMBS LACKING 1 . SEGM ENTED PRE-AND POST-ORAL LIMBS II. PRE-ORAL LIMBS RAPTORIAL Ml PRE-ORAL LIMBS TRANSITIONAL IV. PRE-ORAL LIMBS FILAMENTOUS V. PRE-ORAL LIMBS CHELICERATE PHARYNGEAL MASTICATION PHARYNGEAL MASTICATION TRANSITIONAL PHARYNGEAL MASTICATION GNATHOBASIC MASTICATION GNATHOBASIC MASTICATION POLYCHAETA TARDIGRADA ONYCHOPHORA Halluctgonia AyshaaSa ENDOPODS LOBATE OR SMOOTH Anomalocaris Laggania Opabinia t Tulllmonstrum Casaubla Jianfengia Yohoia ENDOPODS SPINOSE Leanohollla Acanthomaridlon Actaeus Alalcomanaeua Sldneyla Burgessia Molaria Habelia Tegopelte Naraola TRILOBITA Sanctacaris Emeraldella Aglaapis Chaamataapla t MEROSTOMATA t EURYPTERIDA t 8CORPIONIDA t PYCNOGONIDA? t Ordovician and later Selected uniantennate arthropods of the early Paleozoic are grouped according to categories of food gathering and feeding outlined in Table II. As noted previously, unassisted pharyngeal feeding typifies polychaetes and pararthropods such as the tardigrades and onychophorans (Column I). The dicephalosomatid arthropods (Column II) utilize only rap- torial pre-oral appendages in food gathering and/or prelimi- nary food mastication. They feed in an essentially similar pharyngeal manner, except that the mouth opening is deflexed ventrally in anomalocarids and proboscoideans, and opens anteriorly (or nearly so) in Yohoiida (Hou, 1987a). In prim- itive trilobitomorphs, the Leanchoiliidacea (Column III), the post-oral head and trunk limbs appear capable of capturing and holding food items but feeding is still essentially pharyn- geal. In the advanced species Alalcomenaeus, post-oral limbs are essentially gnathobasic (Delle Cave & Simonetta, 1991). In advanced trilobitoideans, includin Sidneyia, the Burgessiida, trilobites, Emeraldellida and Sanctacarida (Col- umn IV), the pre-oral appendages become essentially singly filamentous in form and presumably chemosensory and thigmotactic in function. The post-oral head and trunk limbs become fully gnathobasic (although remaining biramous) and presumably assisted in both food capture and food mastication. The chelicerates are a final stage in the uni- antennate feeding series (Column V). The raptorial pre-oral limbs are reduced to two to four segmented chelicerae, and the post-oral head limbs are fully gnathobasic and essentially uniramous. Both types of head appendages may assist in food gathering and food maceration, especially in the terres- trial arachnid subgroups. The anterior post-oral trunk limbs are essentially uniramous; the endopod is lost, but the exopod remains functional in respiration. This tabular arrangement of taxa according to feeding style parallels an increasing evolutionary sophistication of head and trunk segmentation, and form and function of their appendages as detailed in pages 11-14. It also matches the ? Head limbs not gnathobasic fossil track record of the uniantennate groups (Table V, p. 28). Thus, the most primitive feeding styles, as in the dicephalosomatids, persisted little beyond the Cambrian Period and not beyond the Palaeozoic Era. By contrast, the most advanced uniantennate feeding types expanded into the chelicerate taxa of Ordovician and later periods, including the remarkably diverse terrestrial arachnids of Tertiary and Recent times. Evolution of Post-oral Limb Morphology The changing structure of the post-oral head and trunk appendages of uniantennate arthropods is depicted in greater detail in Figure 2. Within the Dicephalosomatida, the Anomalocarida and Probosciferida were equipped with pairs of closely approximated paddlelike plates on each side, not clearly joined at the base, and perhaps not technically, even if functionally, forming a biramous limb. The upper plate (in Opabinm, Fig. 2B, C) was fringed with lateral lamellae, presumably respiratory in function. The head of Opabinia (2B, C; 7C.l)lacked post-oral plates, but the three pairs of post-oral head plates in Anomalocaris (Fig. 2 A) are consid- ered homologus with the trunk plates. In Cassubia (Fig. 3), considered here (and by Smith, "Atlas" unpubl.) as a benthic anomalocarid with relatively short stout pre-oral limbs, the head may be two segmented. Trace elements alongside the trunk may be ambulatory endopods of the posterior head and/ or anterior trunk segments. In Yohoiida, including the multi- segmented Jianfengia from the Lower Cambrian of China (Fig. 7G), the head bore 3 pairs of post-oral appendages of which the endopod was 7-segmented, cylindrical, and pre- sumably ambulatory. The limbs were not demonstrably gnathobasic, but the ectoderm was sclerotized or mineralized, with a gill-like exopod, much as in a trunk limb of the biantennate genus Marrella (Fig. 2D). An exopod was present andfoliaceous in head limbs of the ^longnt^ Jianfengia AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 10 FIG. 2. BILOBATE AND BIRAMOUS POST-ORAL (HEAD AND TRUNK) LIMBS OF PRIMITIVE ARTHROPODS OF THE EARLY PALEOZOIC ERA. A. Anomalocaris (section) B. Opabinia (dorsal) C. Opabinia (lateral) D. Marre(&i(trunk section) E. ( post-oral section) F. L. (trunk section) G. Sidneyia (post -oral section) H. TnorlArus (trunk limb) J. LimulusQeRl) AMPHIPACIFICA VOL. D. NO. 1 AUG. 31, 1995 11 but apparently lacking in those of the relatively short-bodied and more advanced Yohoia. Trunk limb exopods were broad, as in the trilobitomorph Leanchoilia (Fig. 2E, F), and margins setose, as in Sanctacaris (Fig. 6). At least the first pair, and possibly up to 1 0 pairs, of anterior trunk limbs bore a cylindrical ambulatory endopod. Within the primitive transitional trilobitomorphs, in- cluding the Leanchoiliidacea and Actaeida (Figs. 2E, F), the 3 pairs of post-oral head limbs, and all trunk limbs, developed strong spines on the inner margins of the segments of the endopod. The spines were presumably used in grasping and holding prey organisms, much in the manner of the thoracic leg spines of eusirid amphipods and adult dragonflies. In more advanced groups of trilobitoids, the post-oral hmbs of head and trunk became fully gnathobasic, in which strong teeth or spinose processes developed on the proximal (coxal and basal segments) of the endopod. The distal claws of the endopods functioned in seizing, and the gnathobases in killing and masticating, prey items prior to transfer to the mouth proper. In Sidneyia (Fig. 5D), the head lacked post- oral limbs but the anterior four pair of trunk limbs were strongly gnathobasic and uniramous, the remaining trunk limbs biramous. In Burgessiida and in the Trilobita proper (Fig. 2H), the 3 pairs of post-oral head limbs remained fully biramous and multifunctional. The outer ramus bore numer- ous respiratory lamellar spines. In the Emeraldellida, includ- ing Emeraldella (Figs. 6E, 7M) and Sanctacaris (Figs. 6, 7L) the anterior two trunk segments became fused to the head, resulting in 5 pairs of post-oral head appendages. As the locomotory and respiratory functions decreased and rapto- rial and masticatory functions of the head limbs increased, the endopods became more powerfully raptorial and gnathobasic, whereas the exopods became vestigial, as in Sanctacaris. In the aquatic chelicerates, the merostomes (e.g. Limulus, Fig. 2J), the head region similarly bear five pairs of strongly gnathobasic, ambulatory and essentially uniramous limbs. However, the pre-oral limbs of merostomes are chelicerate, not filamentous, and derived from very different ancestral uniantennates (seepage 12). In all but the most prinutive aquatic merostomes, the trunk endopods lost their ambulatory function and disappeared, whereas the anterior pairs of trunk exopods remained functional in the form of book gills and, in terrestrial derivatives, book lungs. In the above evolutionary sequences, the development of gnathobasic limbs may have been a consequence of im- proved efficiency in exploiting, as food, hard-shelled prey living in soft bottom sediments. The feeding style of Limulus still follows this original primitive pattern. Evolution of Food-Gathering Appendages Within uniantennate arthropods, the morphological and functional forms of pre-oral food-gathering and food-sens- ing appendages may be linked in possible evolutionary path- ways (Fig. 3). The presumed ancestral form of this cephalopod-style food-gathering mechanism is the large multi-segmented raptoral form typical of species of Anomalo- caris (Figs. 3A, D). Despite anomalies of fossil limb pre- servation, the primary plane of motion is presumed to be essentially vertical. The paired limbs combined, nearly in parallel, to form a raptorial basket in which prey organs were captured and killed by the daggerlike posterior (inner) mar- ginal spines (Collins, 1987). The food items were then transferred posteriorly, by deflexion and retraction of limbs, to the masticatory buccopharyngeal teeth of the mouth region. This plane of action contrasts with the nearly horizontal or oblique position of the natatory trunk limbs or lateral lobes of epi-benthic animals. In benthic species, in which the endopods of post-oral head and trunk limbs were mainly ambulatory and vertical in position, the pre-oral appendages were essentially co-planal. In "Laggania "-like animals (Table I - A. nathorsti group), with 11 -segmented limbs, the posterior marginal spines were exceptionally long and strong, as if utilized in raking or digging in soft sediments (Fig. 3D). If the plane of action is rotated to the horizontal, the paired limb spines come into opposition as a prey-capturing and killing mechanism. In this manner, and through prolon- gation of the head region into a long flexible annulated pro- boscis, the terminal raptorial claw of ^the free-swimming Opabinia can be derived (Fig. 3B; Bousfield & Collins, in preparation). The paired spines on each side are 14 in number, as in Anomalocaris canadensis. The distal five of these are longer and more steeply oblique and probably served in prey capture, whereas the proximal nine pairs are stouter, shorter, and more perpendicular and may have served in holding, crushing, and possibly preliminary mas- tication. The form and function of the claw is analogous to a modern pair of pliers. However, it was probably activated by a combination of muscular and hydrodynamic processes. The transfer of food material rearwards to the mouth by the proboscis was probably similar to the action of an elephant’s flexible trunk. The proboscis does not contain the anterior gut, as proposed by Sharov (1966) (per Callahan, 1979). In a much more highly modified Upper Carboniferous, internally segmented, squidlike counterpart, Tullimonstrum gregarium, described in detail by Johnson & Richardson, 1969 (Fig. 7C.2), the terminal claw was more slender, and the spines, 13- 14 in number on each side, were minute (Fig. 3C). Prey items were probably small and soft-bodied, possibly free-swimming plankters, or worms or insect larvae extracted from tubes in soft bottom sediments. In a Lower Cambrian benthic species, Cassubia infra- cambriensis (Lendzion, 1975), the number of pre-oral limb segments was reduced to 7, and segments 2-5 had large medial spinose processes (Fig. 3E). Regrettably, the plane of motion is not precisely determinable from the single in- complete fossil specimen. In a direction presumably leading to the chelicerates, the pre-oral appendage of the protochelicerates Jianfengia and Yohoia was reduced to 3-4 segments, the outermost being double-spined and movably pincering upon the inner marginal spine of segment 2 (Fig. 3F). Limb orientation was in a vertical plane and the movable distal spine had been AMPHIPACIFICA VOL. 11. NO. 1 AUG. 31, 1995 12 FIG. 3. PLAUSIBLE EVOLUTIONARY SCENARIOS IN THE PRE-ORAL APPENDAGE OF UNIANTENNATE ARTHROPODS (from Gould (1989) and various sources) A. D. Anomalocaris spp. ( Hypothetical Ancestrai type) Raptorial proboscoid line B. Opabima C. Tullimomtrum (Carboniferous) Raptorial chelicerate line £. Cassubia F. Yohoia tenuis Gl. Limulus (late Palaeo 2 oic) Sensory flagellar line H. LeanchoiUa J. Actaeus K. Emeraldella rotated to the lower or inner side, as in limuloids and phal- angiate arachnids (Fig. 3G1). In eurypterids, scorpions, and pedipalpate arachnids (including spiders), however, the move- able segment is on the upper or outer side of the limb (Fig. 3G2). A major link in the presumed lineage from Yohoia to merostomatid arachnids is not confirmed from the fossil record, viz., a yohoiid-like pre-oral appendage on a broad- ened head of 5 post-oral segments. A further evolutionary thrust of the pre-oral uniantennate limb resulted in a filamentous sensory flagellum, repre- sented in early stages by the form of the 7-segmented "great appendage" of LeanchoiUa (Fig. 3H). The inner marginal AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 13 FIG. 4. PROPOSED HOMOLOGIES BETWEEN PRE-ORAL APPENDAGES OF MIDDLE CAMBRIAN TRILOBrrOMORPH UNIANTENN AXES AND ANTENNULES OF CRUSTACEAN fCIRRIPEDE AND ASCOTHORACID) BIANTENNATE ARTHROPODS (A,B,C after Gould, 1989 ; D, E, F after Schram, 1986) spines of segments 3-4 and the terminal spine of segment 7 were apparently modified as a multi-segmented whip-like flagellum, whereas those of segments 5 and 6 were reduced to short stubs. In Actaeus (Fig. 7E.3), segments 3 and 4 remained flagellated, but 5-7 were much shortened, and bore short spine-like processes. In Sanctacaris, segment 3 (?) was short-flagellate and (4?) 5-7 terminated in a star-hke cluster of spines (Fig. 4C; 6D). Derivation of a 3-segmented chelicera from such an appendage would seem improbable. The simple elongate flagellar state is attained in Alalcomeneus (Fig. 7E.4), Emeraldella (Fig. 3K) and in most other trilobitoids, including the Burgessiida and the Trilobita (Fig. 5E, F). This analysis concludes that, in some evolutionary lines within uniantennate arthropods, the pre-oral appendage was initially a raptorial food gathering apparatus that secondarily became flagelliform. These morphotypes, including the trilobites, did not persist beyond the Paleozoic Era. In the evolution of primitive merostomes (e.g. Chasmataspis), a filiform antenna is unlikely to have disappeared, and a cheliform appendage suddenly appeared, as Bergstrom (1979) proposed for early chelicerates. The pre-oral appendage was already semi-cheliform in the proposed ancestral Yohoia. The trend from raptorial to sensory flagellar condition within the Trilobitoidea, rather than the reverse, is accompanied by parallel evolutionary trends in cephahzation of the head, gnathobasic development of ambulatory limbs, rearward shift of respiratory limbs, and in other major character states within component major sub-taxa (p. 22). Within biantennate arthropods, however, the evolution- ary picture is different. As revealed by the limited early fossil record, and the ontogeny of larval stages of extant and fossil forms, the pre-oral appendage appears to been filiform thoughout, with few exceptions, as noted on page 14). The flagellate form has also persisted, with little change, in the myriapod and hexapod taxa that have dominated terrestrial environments since the close of the Paleozoic Era (Delle Cave & Simonetta, 1991). Possible Homologies in Pre-oral Appendages of Uniantennate and Biantennate Arthropods. As noted above, the significance of the first pre-oral appendage as a mechanism of food detection, food gathering, and general feeding style is basic in the Arthropoda. Both the organelles of the acron (e. g., frontal filaments, naupliar eyes) and the pre-oral first segmented head appendage are presumed sensors of environmental conditions and food sources. In uniantennates, the primary role ofthe latter was food gathering, a raptorial function that was retained in the AMPHIPACIFICA VOL. II. NO. 1 AUG. 31, 1995 14 single successful line of uniantennate evolution, the Chelicerata. In the biantennates, however, the appendage was primarily sensory, at an early stage, and remained so throughout evolutionary history of all major subgroups. A comparison of pre-oral limbs of selected primitive morpho- types of both uni- and bi-antennates is pertinent (Fig. 4). In the primitive trilobitomorphs, the pre-oral appendage passes through several stages of reduction of accessory flagella and sensory organelles (Figs. 4A, B, C). leading to the simple elongate flagellar condition of the Trilobita and Emeraldellida. In a few primitive maxillopodan crustaceans with specialized life styles, however, the appendages devel- oped correspondingly specialized sensory and raptorial func- tions. In cirripedes, the antennules are natatory in naupliar and metanaupliar larvae (Fig. 4D), but become organs of site selection and attachment in the cyprid larvae of sessile, shell- burrowing and parasitic forms, the Thoracica, Acrothoracica, and Rhizocephalia respectively (Glenner&Hoeg, 1995)(Fig. 4E). These 4-segmented antennules bear aperhaps superficial but remarkable similarity, and almost certainly homologous relationship to, the pre-oral appendage of the primitive trilobitoiduniantennates, (Fig. 4B), andSanctacaris (Fig. 4C). However, in the ascothoracidan biantennates, parasitic on echinoderm and anthozoan coelenterates, the antennule is raptorial in the cyprid and adult stages (Fig. 4F). The term- inal two segments of the 4-segmented appendage, reminis- cent of Yohoia (Fig. 3F), form a subchela for attachment to the host, or removal of pieces of the host tissue as food. Perhaps a more precise concept of the pre-oral append- ages of long extinct uniantennates of the Cambrian Period might be derived through closer study of the antennules of these very primitive extant crustacean biantennates. The Pre-oral Appendage of Trilobitoid Uniantennates, The general external morphology of selected tiilob- itomorph uniantennates is shown in Fig. 5. In Burgessia (Fig. 5 A), Molaria (Fig. 5B) andHabelia (Fig. 5C), the head comprises four segments (five somites) which, in Burgessia, subtends a broad carapace covering the trunk segments. The post-oral appendages are ambulatory, those of the trunk also respiratory. The trunk terminates in a spikelike telson, similar to that of the merostomatid chelicerates, and suggests a strongly benthic life style. In Sidneyia (Fig. 5D), the head is only 2-segmented, but the anterior four trunk segments bear uniramous, powerfully gnathobasic limbs that are effec- tively part of the cephalic masticatory complex. The posterior 3 trunk segments are free and bear a broad, flabellate telson, evidence that Sidneyia was a powerfully swimming benthic and epibenthic predator. In the trilobites, [e.g., Naraoia , a "soft trilobite" (Fig. 5E), and Olenoides, a primitive true trilobite (Fig. 5F)], the head is also 4- segmented, with 3 pairs of post-oral ambula- tory, respiratory, and masticatory head limbs, and 11+ pairs of similar trunk limbs. However, trilobites differ from Bur- gessiida in having a broad depressed head shield and trunk, the latter ending in a short pygidium or tail region of a variable number of segments. Both groups represent middle stages in cephalization of anterior trunk limbs. Sanctacaris On the basis of five well-preserved specimens from the Stephen Formation, near to but slightly younger than the Burgess Shale quarry, Briggs and Collins (1988) described a large carnivorous arthropod, Sanctacaris uncata, that they assigned to subphylum Chelicerata (Fig. 6). The broad head bears large eyes and six pairs of biramous appendages, the first five of which form a raptorial array of segmented, spinose and gnathobasic endopods with simple short antennalike exopods. The outer ramus of the sixth limb is also filamentous, but the inner ramus is short, terminating in a firinge of starlike radiating spines. The mouth is located anteriorly, presumably in a narrow gap between the first limb bases. The broad trunk is 11 -segmented, the posterior bearing a paddle-shaped telson, the anterior 10 each bearing paired biramous lim bs of which the exopod is large, flabellate, and natatory-respiratory in function. The inner ramus is slender, multi-segmented, and presumably ambulatory; marginal spines and/or gnathobases were not demonstrable. However, another interpretation is utilized here. The biramous "sixth" appendage (Fig. 6D), bears a striking resemblance to the "transitional" pre-oral limb of Actaeus, with its star-shaped accessory flagellum (Fig. 5B), but unlike the raptorial condition in Yohoiida (Fig. 3F; 7D) or the chelicerate condition in arachnids (Fig. 6F). Furthermore it arises near the eye, in a typically pre-oral position. The five pairs of raptorial head limbs of Sanctacaris have apparently been displaced forward beneath the head to form a raptorial "basket", immediately beneath the mouth. These limbs, although non-ambulatory, appear to be homologous with the five pairs of post-oral head limbs of Emeraldella (Fig. 6E). The latter has a single filamentous pre-oral flagellum that is apparently homologous with the short biramous "antenna" of Sanctacaris, In Emeraldella also, the post-oral head limbs are similar to the trunk limbs in being strongly ambu- latory as well as gnathobasic. On this interpretation, and in agreement with Delle Cave & Simonetta (1991), Sanctacaris is removed from the Chel- icerata and placed in Class Emeraldellacea within the revised superclass Trilobitoidea (Table ni,p. 24). Sanctacaris thus stands as a unique, relatively advanced, but apparently short- lived, sideline of Cambrian uniantennate evolution. AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 15 FIG. 5. CAMBRIAN ARTHROPODS: WITH GNATHOBASIC LIMBS AND FILAMENTOUS PRE-ORAL APPENDAGES (variously from Gould (1989) and Briggs et al (1993) Evolutionary Pathways in Uniantennate Arthropods Plausible evolutionary pathways within uniantennate arthropods of the Cambrian period that led to more highly evolved trilobitoid and chelicerate faunas of the middle and late Paleozoic are summarized in Fig. 7 (p. 17). The chart embodies information provided in Table I, and figures 2, 3, 5 & 6 especially. The degree of morphological evolution and specialization of feeding style is represented by four blocks or zones, proceeding along the X-axis, from the most primitive (pharyngeal feeding) on the left, through a narrow transitional band in the middle, to limb gnathobasic and limb masticatory feeding types on the right. Of these, the chelic- erate form on the extreme upper right is the most advanced. The Y-axis represents a generalized, rather than definitive, time scale. As noted previously, the most primitive and presumably ancestral uniantennate arthropod of the late Precambrian, Vendian, and Early Cambrian Periods was a member of the predatory and pharyngeal-feeding Anomalocarida, illus- trated on the lower left. These large-eyed animals possessed a short head (2-4 somites), and a multisegmented body with bilobate lateral pleurae or biramous ambulatory and respiratory paired appendages. In a cephalopodlike feeding AMPHIPACIFICA VOL. D. NO. 1 AUG. 31, 1995 16 FIG. 6. EXTERNAL MORPHOLOGY OF SANCTACARIS (modified from Briggs & Collins, 1988) A. Life-like Reconstruction. B. Dorsal View. C. Head region (MAG. X), D. Pre-oral appendage (X) E. (Inset). Head appendages of Emeraldella (ventral view) F. L/mu/us Left chelicera G. Cassubia Left Pre-oral Appendage. style, paired raptorial pre-oral head appendages apparently captured and transported food to the mouth region where it was masticated and ingested without post-oral limb assist- ance. Within the Anomalocarida per se . development of a benthic life style was accompanied by reduced segmentation but stronger armature, possibly partly fossorial in function, of the pre-oral raptorial limbs (e.g., 'm"Laggania" - type fossils (Table I) and in Cassubia Lendzion, 1977, centre line). Of the three proposed evolutionary offshots from the Anomalocarida, the epibenthic probosciferidans (on the left) developed a very specialized food capturing mechanism, similar in function to the hetercotyl arms of cephalopods, but found nowhere else among the arthropods. It consisted of horizontally opposing limbs fused together in a claw-like appendage that was activated by a flexible proboscoid ex- tension of the anterior head region. Its movements were pre- sumably triangulated and co-ordinated by widely set pairs of stalked compound eyes. The small size of this "proboscis", and lack of peribuccal or pharyngeal teeth, indicate that the prey organisms were very probably small and soft-bodied. Cladistic presentation of relationships of Tullimonst- rum by Beall (1991 ) may be a case of "bending the facts" to fit theoretical models. None of his cladograms provides close relationships between Tullimonstrum and other major invertebrate groups, and each cladogram contradicts rel- ationships depicted by the others. The "re-interpreted" ani- mal appears unfunctional (e. g., a vertical tail on a depressed trunk) and inconsistent with the taxonomic details of Rich- ardson (1966) and Johnson & Richardson ( 1969) that resulted AMPHIPACIFICA VOL. n. NO. 1 AUG. 31, 1995 17 o Il I t53 ^ I ,« a, is^.i tfa K th .r 2 ^ ''® 25 s A S s § e 3 & .2 £3 ‘g ri -2 © » CO Z 2 et l> i l-s-rfl'S d « ||.SW| iH ^ .£ , U'C »J J no. 7. RELATIONSHIPS OF CAMBRUN UNIANTENNATE ATHROPODS BASED ON FEEDING MECHANISMS AMPHIPACIFICA VOL. n. NO. 1 AUG. 31, 1995 18 from careful observations on numerous specimens. A more successful evolutionary experiment typifies the mostly benthic trilobitoid line to the right. In it, the pre-oral limb lost its raptorial function and became flagelliform, multi-segmented, and presumably mainly sensory and perhaps tactile in function. Simultaneously, the post-oral head and trunk limbs developed a linear gnathobasic endopod which, through various degrees of cephalization of anterior trunk segments, formed a masticatory feeding field of 2-5 pairs of post-oral head appendages. Remarkably, the species of Leanchoiliidea (including Acanthomeridion from Chengjiang deposits) sit squarely in the transitional zone of both pre- and post-oral limb evolution. Alalcomenaeus, having the most advanced, mono-filamentous pre-oral appendage, also has nearly fully gnathobasic post-oral appendages (Delle Cave & Simonetta, 1991). Of the flagellated trilobitoids with 3 post-oral head segments, the "spike-telsonic" group (centre right) encom- passed the Habelia subgroup having armoured processiferous bodies and short antenna. The associated Molaria, also having filamentous antenna and only three post-oral head segments, is an unlikely precursors of the chelicerates, as proposed by Delle Cave and Simonetta (1991, Chart II). Trilobitoideans withpygidial (non telsonic) abdomens (lower right) included narrow-bodied "idotheid" or "asellid" isopod- like forms such as Mollisonia and Urokodia that may have occupied algal substrates. They also included broad, flat- bodied, fossorial types with protective exoskeletal armour, leading to their only successful subgroup, the trilobites, that di versed in the later Paleozoic times. The trilobitoids include the Eraeraldellidacea that have 5 post-oral head segments and a spike-like telson (upper right). The group here includes the aglaspids, thought to possess chelicerae prior to the work of Briggs et al (1978). Aglaspids "straddle" the Upper Cambrian- Lower Ordovician boundary. The Devonian Cheloniellon may be a distant descendent of the main line of Emeraldellidea. As mentioned above, a carnivorous form with paddle-like telson, Sancta- caris, is considered an early offshoot of this same line. This species has 5 distinct post-oral head segments, each with bi- ramous paired raptorial limbs. Sidneyia has no post-oral head limbs but the first four trunk limbs are uniramous (lacking gills), strongly gnathobasic and form, effectively, a post-oral masticatory field of four segments. Sidneyia is here regarded as a very early (relict) stage of cephalization of ant- erior trunk appendages, and had a separate origin (Fig. 7K). The most successful anomalocarid offshoot is here believed to be the Jianfengia- Yohoia line, to the upper right of Fig. 7. The post-oral head limbs, in the process of losing respiratory exopods, were already ambulatory and transitional in form. Although the pre-oral head limbs remained rapto- rial, their reduced size and segmentation and subcheliform appearance are plausible precursors to the fully chelicerate condition found in the most primitive arachnids, the mero- stomes, of the Lower Ordovician (upper right). However, the viability of this proposed evolutionary connection awaits discovery of a broadly flat-bodied fossil having transitional masticatory post-oral head and trunk limbs and a more clearly cheliform (rather than geniculate) pre-oral append- age. Triopus (Fig. 7P.1) may approach that predicted form but its appendages are poorly known. Chasmataspis (Fig. 7P2) is the most primitive Lower Ordovician undoubted chelicerate, leading to the eurypterids. Although not completely understood (Bergstrom, 1979), Chasmataspis has 5 post-oral head segments and 12 trunk segments. The total is one more than the combined number of post-oral segments of the presumed ancestral Yohoia. The Euthycarcinoidea Enigma The enigmatic group of aquatic arthropods classified as Euthycarcinoidea, is based on a half-dozen limnic (?) species that existed from Carboniferous to Triassic time. Bergstrom (1979) summarized information on theTriassic generaEwr/iy- carcinus and Synaustrus, and Schram and Emerson (1991) utilized the upper Carboniferous genera Pieckoxerxes and Kottixerxes in developing their newly proposed Arthropod Pattern Theory (Fig. 8). The broad head shield is typically composed of 3 somites including an eye-bearing acron, an anterior procephalon with a single pair of filamentous anten- nae, and a posterior gnathocephalon bearing a set of mandi- ble-like appendages and on which the mouth opens ventrally . The broadened trunk is divided into an anterior (thoracic) region of diplo- or triplo- segments each bearing paired uniramous limbs, and a posterior narrower and limbless abdomen that terminates in a spikelike telson. According to Schram & Emerson (loc. cit.), the possession of uniramous limbs and diplosegments may link these animals to the ancestry of the terrestrial myriapods and hexapods (Uniramia of Manton, 1972). On the other hand, the overall appearance of euthycarcinoideans is grossly similar to some uniantennate arthropods having 3-6 head segments, and filamentous pre-oral limbs, e.g., Leanchoilia, Habelia, and Emeraldella. However, unlike the uniantennates, the trunk endopods are filamentous, multisegmented, and lack rapto- rial spines, gnathobases, and/or terminal claws. The leg seg- ments bear slender posterior marginal spines that are possi- bly of both natatory and respiratory support function, and in that respect resemble the exopods of some uniantennate arthropods (e.g., of Trilobitoidea). The Lower Cambrian Chengjiang fossil deposits in Yunnan region, South China, discovered in 1984, contain a number of very primitive arthropods yet imperfectly known, and mostly not included here. However, one of these, Fuxianhuia protensa Hou, 1987b, is remarkably similar in overall form to the euthycarcinoideans (above, and figs. 8A, 9) as detailed recently by Chen et al. (1995) (Fig. 8 A-H). The body consists of a short, broad, head shield and an elongate trunk region. The latter is divided into a thorax of 17 broad, depressed, limb-bearing segments, and an abdomen of 14 narrower and more cylindrical, legless segments, the last bearing a prominent telson spine. The head bears an anterior pair of large stalked eyes, a pair of filamentous pre-oral appendages (antennules) on somite 2 and, ventrally on AMPHIPACIFICA VOL. U. NO. 1 AUG. 31. 1995 19 anteroveniral eye-bearing plate ederite FIG. 8. EUTHYCARCINOIDEA: Fuxianhuia protensa Hou, 1987 (Middle Cambrian) A. Dorsal reconstruction Head shield B., C. ventral reconstr. D. dorsal reconstr. E. Sutehelate head appendage F. Abdomen, ventral G. Abdomen (ventral X. 1987; showily limbs) H. Pieckoxerxes piekoae K. Kottixerxes glotiosus (A. B - after Hou. D-G (after Chen et al, 1995) H, L. (after Schram & Emerson, 1991). J, K, Euthycarcinus Aerr/m (after Bergstrdm, 1979), AMPHIPACIFICA VOL. II. NO. 1 AUG. 31, 1995 20 somite 3, a pair of subchelate raptorial limbs, presumably arising on either of side of the mouth. These superficially resemble the raptorial head limbs of the uniantennate arthro- pod Cheloniellon, the raptorial maxillae of remipede crus- taceans, and the raptorial first thoracic limbs of belostomatid hemipteran insects. However, they are unlike the paired palpless mandiblelike structure of the mouth region ascribed to a few specimens of Euthycarcinus (Bergstrom, 1979). In other details, however, the similarity of Fuxianhuia to euthycarcinoideans is remarkably close. The trunk limbs are biramous, with thin plate-like exopods, but the endopods are cylindrical, multisegmented, and lack terminal claws. These endopods are also similar to the multisegmented, basally shafted rami of larval skaracarids of the Cambrian "Orsten" fauna (Fig. 9, part). The limbless abdomen is found elsewhere in most maxillopodan crustaceans (e.g., several Skaracarida, Cirripedia, Copepoda, etc., and the Cephalocarida) as well as some phyllocaridans and phyllopod biantennates. The incomplete basal fusion of the trunk exopods and endopods is reminiscent of the lateral lobe-like paired flaps or limbs of the primitive dicephalosomatid uniantennates. Modem aquatic predators with "jacknife" raptorial limbs (above) are all free-swimming pelagic preda- tors, perhaps indicating a similar life style in euthycarcinids. In summary, Fuxianhuia bears some similarity to nearly every major group of arthropods of the Lower and Middle Cambrian Period but does not conform completely with any . In the very primitive structure of his head and locomotory limbs, and multi- segmented body, it is close to a model arthropod ancestral type (e.g., of Snodgrass, 1956). How- ever, the presence of two pairs of pre-oral head limbs, the first of which is filamentous and the second raptorial, is similar to the situation in crustaceans and some phyllocaridans, and thus essentially biantennate. This feature, along with the multisegmented, elawless endopods of the thoracic region, justify its inclusion within the class Euthycarcinoidea. Its other members are of more recent geological age, but sufficiently distinct to justify erection of the primitive sub- class Fuxianhuiacea (Table IV, p. 27). Evolutionary Relationships in Aquatic Biantennates A recapitulation of plausible evolutionary pathways within early aquatic biantennate arthropods is sketched in Fig. 9. On the left of the chart are connectives for two genera of skaracarid crustacean larval forms, a phosphotocopine ostracod, and a thecostracan cyprid, that represent the primi- tive evolutionary phases of skaracarid, ostracod and cirripedian maxillopodans of Cambrian times. Their primi- tive character states included the shaftlike form of the basal portion of the post-oral head limb endopods, the unbossed condition of their ramal spines and setae, and the multi- segmented rami that are found variously in early naupliar stages of Copepoda, Cirripedia, and other extant maxillopod- an crustacean subgroups. The systematics and evolutionary history of maxillopodan crustaceans are relatively well known (e.g., in Schram, 1986), and are not discussed further here. In the centre are the euthycarcinoideans of which Fuxianhuia from the Lower Cambrian is here designated the the most primitive member. The Upper Carboniferous and Triassic members are shorter-bodied, with diplo- and triplo- trunk segments, uniramus limbs, and may be ancestral to groups with the Myriapoda. However, further evidence from Silurian and Devonian representatives is needed to clarify such a phylogeny. To the centre right are connectives between the three subclasses of biantennates recognized here within a revised and restricted definition of Latreille's original crustacean class Phyllopoda (p. 26). These Cambrian groups resemble extant branchiopodan and leptostracan crustaceans, at least superficially, and may have had a late Precambiian or Vendian common ancestor. The branchiocarids and odaraiatids were regarded as unique arthropods and/or crus- taceans by Briggs (1976, 1981). However, they differ from true crustaceans in the 3- segmented head structure (lack of clearly defined maxillae and maxillary segments) and the carapace is mandibular rather than maxillary in origin. Although Schram (1986), following Briggs (1978), assigned the Canadaspida to Malacostracan subclass Phyllocarida, Dahl (1984, 1987) convincingly demonstrated primary dif- ferences of tagmatization, total number of body segments, position and form of the presumed mandible, limb structure and other anomalous features that, under existing defini- tions, remove the Canadaspida from the Phyllocarida, and the true Crustacea. In Fig. 9, lower right, are the marrellomorphs. These represent one of the few aquatic biantennate arthropods with qualifications for direct ancestry to the myriapods and hexa- pods, its leg features postulated by Kukalova-Peck (1992). Thus, marrellomorphs are biantennate and the head limbs possibly mandibulate, but not ambulatory-gnathobasic. They are mainly benthic in life style and the anterior limbs are apparently double-clawed, suited to walking or crawling over firm substrates. They also possess similar body tagmatization and limb structure, and the telson is minute or lacking. The leglike maxillary and labial palps of an Upper Carboniferous monuran wingless insect (Fig. 9) are remarkably similar in form to the endopods of the ambulatory head limbs of the Devonian marrellomorphs Mimetaster and Vachonisia (Stiirmer & Bergstrom, 1976). Loss of the second head segment and its antennalike pre-oral limbs in myriapods and hexapods accords with overall evolutionary trend to reduction of limbs and accessory lobes that accompany a shift from aquatic to terrestrial life style. In air, gravitational effects on limb structure are more signifi- cant; two pairs of sensory limbs would thus appear to be mechanically unwieldy and functionally unnecessary. Phylogenetic Tree of the Arthropoda An annotated classification of uniantennate and biantennate arthropods is presented in Tables III (p. 25) and IV (p. 27) respectively, the number of higher categories of which are summarized in Table V (p. 29). Hypothetical AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 21 FIG. 9. PHYLETIC LINKAGES WITHIN BI ANTENNATE ARTHROPODS S 2 OF THE PALEOZOIC ERA relationships of the major genera of the Cambrian Period to each other and to other major groups of arthropods over the 600+ million year geological and evolutionary time scale are summarized in the accompanying chart (Fig. 10, p. 23). Phyletic relationships may be presented in a number of graphical ways, including cladograms (e.g. Briggs & Fortey 1989), following an earlier attempt by Briggs (1983). Those authors (1989) utilized 26 characters and corresponding character states in deriving an arrangement in which the biantennate branchiopods clustered near the base, the trilobites at the advanced end, and various trilobitoideans and arachnids at intermediate levels of the evolutionary AMPHIPACMCA VOL. 11. NO. 1 AUG. 31, 1995 22 scale. Whereas this scheme has an overall plausibility, it is limited in detail by the omission of dicephalosomatid arthro- pods or other related outgroup taxon, by other possibilities in the ordering of some character states, and by weaknesses inherent in cladistic analyses generally (see Gosliner and Ghiseln, 1984). In view of limitations of cladistic methodology at this stage of knowledge, the writer finds merit in modifications of the simple phyletic tree arrangements of Delle Cave & Simonetta (1991), for various early arthropod subgroups, as outlined here in Fig. 10. The hypothetical " tree" com- mences somewhere within late Precambrian times, in con- formity with the views of Dzik & Knimbiegel (1989). Thus, representatives of tardigrade and onychophoran pararthropods and both uniantennate and biantennate arthropods were already present in the earliest (Lower Cambrian) fossil deposits (Dzik &Lendzion, 1988). Also, protarthropods (e.g Xenusia) and some antennognath arthropods (e.g., Spriggina, Praecambridium) are also known from Ediacrian and V end- ian fossil deposits (Delle Cave & Simonetta, 1991). The earliest and morphologically most primitive uniantennulate subgroup of Cambrian times is here consid- ered to be the dicephalosomatids (p. 25). The primitive ano- malocarids did not suri ve the Cambrian and the more advanced probosciferans lasted only until the Upper Carboniferous. The Yohoiida, possibly on a direct ancestral line with the chelicerates, also became extinct in the Cambrian. Not yet discovered, however, is a theoretical Cambrian fossil form having a 6-segmented head, transitional post-oral mastica- tory limbs, and fully cheliceriform pre-oral appendages that might directly link the group with the chasmataspids and primitive aquatic arachnids of Ordovician and later periods. Of the aquatic merostomes, the eurypterids diversified dur- ing the mid Paleozoic but became extinct prior to the Mesozoic, and few relict limulids are the only modem survivors of those primitive aquatic chelicerates. The Trilobitoidea embodied various combinations of head and trunk segments having filiform, sensory pre-oral appendages and raptorial, gnathobasic, post-oral feeding and ambulatory limbs. Several of these, including early trilobites (e.g., olenellids) apparently became extinct during the Cambrian, although the Emeraldellidea persisted until the Devonian (e.g., Chelionellon). The more advanced trilobites became the single most speciose and diverse group of aquatic uniantennates during the early Paleozoic. They apparently survived longer than any other other arthropod group having only 4 head segments, but were gone by the beginning of the Mesozoic. The paleohistory of the biantennates is less clear. Prim- itive biantennates, the euthycarcinoids, marrellomorphs and phyllopods occurred, even abundantly, in the Cambrian. However, the inarrellomophs survived only until the Upper Paleozoic, and the euthycarcinoids to the Triassic. As noted on page 1 8, the marrellomorphs provide a plausible (but not confirmed) aquatic ancestor to the terrestrial myriapods and hexapods whose fossil records commenced in the lower Devonian and upper Silurian periods. Kukalova-Peck (1992) has provided convincing evidence that the myriapod and hexapods could not have originated from the Xenusian- onycophoran line of "uniramians", a conclusion supported by the present study. The fossil record of early cmstaceans is uneven, but little doubt exists, especially as result of remarkable new micro-fossils in the Swedish ’Orsten’ deposits, revealed by Walossek & Muller (1989), that the maxillopodans were a very diverse biantennate group by Middle and Upper Cam- brian times. Maxillopodans continued to exploit aquatic niches and food resources in which small size, free-swim- ming metamorphic developmental stages, and filter-feeding mechanisms are advantageous. The somewhat larger Branchiopoda, by developing a resting egg stage, have managed to survive, mainly in temporary freshwater habi- tats, over a comparable time frame. Their non-palpar mandible, even in early naupliar stages (Sanders, 1963), may indicate an early link with the Phyllopoda. There is little basis for a direct phyletic link with the trilobitoideans, as studied by Hessler & Newman (1975). With respect to the Cephalocarida and the Remipedia, crustacean classes discovered only during the later half of this century, their body and limb structures are more primitive than most other maxillopodans, and certainly the malacost- . racans (Schram, 1986). Despite their problematical late Paleozoic (or non-existant) fossil records, an early Paleozoic origin for both groups is a reasonable expectation. The Malacostraca may be considered the dominant and most diverse crustacean class of Recent times (Bousfield & Conlan, 1990). Transfer of the orders Canadaspida and Branchiocarida from the Crustacea to the phyllopod Bi- antennata (p. 25), leaves the Upper Devonian protoglyphaeid reptantian Palaeopalaemon newberryi as the earliest con- firmed malaeostracan fossil record (Schram, 1986). How- ever, the relatively plesiomorphic body segmentation and limb structure of the Leptostraca (sensu strictu), as well as the Hoplocarida and Syncarida, would suggest a somewhat earlier beginning for the malacostracans, possibly during the Silurian or late Ordovician. THE CAMBRIAN ARTHROPOD FAUNA: EVOLU- TIONARY TRENDS, Early trends in the direction of morphological and be- havioural evolution in arthropods, revealed by Burgess Shale and other Cambrian faunal assemblages, are summarized as follows: (1) Within uniantennate arthropods, the ancestral pharyn- geal and peribuccal feeding methodology was replaced by a masticatory assemblage of post-oral gnathobasic limbs of the head region. The taxonomic series of Anomalocaris, Leanchoilia and Emeraldella represents this transformat- ional process. (2) Also within the uniantennates, the primitively large raptorial food-gathering limbs of the pre-oral head region gave rise to short, paired cheliform and chiefly masticatory appendages within the higher (terrestrial) Chelicerata. The AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 23 -LOG T 1 M E LO o LO CO o CM to u> SCALE (M. Y. B. P.) o c.|mesoz FIG. 10. U. PAL. L. PAL CAMBRIAN PHYLOGENETIC TREE OF THE ARTHROPODA PRECAMBR. no. 10. PHYLOGENETIC TREE OF THE ARTHROPODA. EMPHASIZING THE MIDDLE CAMBRIAN FAUNA (Based parti}' «■ Schram (1986) and Boosfield & Coalan (1990) AMPHIPACIFICA VOL. II. NO. 1 AUG. 31, 1995 24 taxonomic sequence of Artoma/ocam, Yohoia, Chasmataspis, and the Scorpionida illustrates this evolutionary sequence. (3) Other types of pre-oral limb development that involved an opposing limb raptorial mechanism on the one hand, and a filamentous sensory structure on the other, did not survive the close of the Paleozoic Era. (4) The cephalization, or incorporation of masticatory limbs of anterior trunk segments into the head shield, of both uni- and bi-antennate arthropods, proceeded most rapidly during the Cambrian Period. Such a rapid evolutionary process in major taxonomic features may prove to be a direct example of punctuated equilibrium proposed by Eldridge & Gould (1972). However, few aquatic taxa with only 2-4 head somites (e.g., a few Probosciferida, Marrellomorpha) sur- vived beyond the Cambrian, although the euthycarcinoids persisted until the Triassic; some with five somites (e.g., Trilobita) reached the late Paleozoic; whereas groups with 6- 7 head somites (e.g. Crustacea, Chelicerata) extended into Mesozoic and Recent times. (5) Primitively shaftlike and elongate trunk limbs became increasingly distinctly segmented, chitinized, and shortened, especially in benthic forms. A series of forms within the crustacean order Skaracarida (e.g. Data, Bredocaris, and Oleandocaris), the phosphatocopine ostracods, and the naupliar-metanaupliar stages of other maxillopodan crustaceans, illustrate such transformation. (6) The dorsal shield arises from the first head segment (pre- oral carapace) in primitive, pharyngeal -feeding arthropods. In more advanced, limb-masticatory arthropods (e.g., mandib- ulates) the carapace (secondarily bivalved) arises from the posterior segment of the head shield that is mandibular in phyllopods and typically maxillary in crustaceans. (7) With respect to the natatory function of limbs, swimming appendages occur in both post-oral head and trunkregions of very early uniantennates, and larval stages of more advanced arthropods. Coincident with tagmatization of the trunk into thorax and abdomen, and the "cephalization" of feeding limbs in higher taxa, swimming, and respiratory, functions shifted posteriorly from head to thorax and finally to abdo- men, as in stomatopods, isopods, and other Malacostraca. (8) Evolution of the terrestrial myriapods and hexapods from presumed aquatic ancestors apparently involved loss of the second pre-oral head segment and its antennate appendages. In the aquatic environment, those limbs are functionally sensory (see Callahan, 1979), locomotory, or even food gathering. In the terrestrial environment, such limbs presumably became duplicative and mechanically unwieldy, and followed into oblivion the original prothoracic wings of insects. Similarly, in peracaridan crustaceans that have become secondarily terrestrial (e.g., talitrid amphipods, oniscoidean isopods), one of the sensory antennal pairs (first, antennules) has become very much reduced or vestigial, with only one pair (second, antennal) remaining effectively functional. In similar vein, an alternative functional evolution of the head appendages of myriapods and hexapods would countenance die fusion of the first pre-oral limbs to the labrum to form the clypeo-lahrum, and the second pair of head appendages, equivalent to the second antennae of crustaceans, have become the monofilamentous antennae of the hexapods. However, embryological and/or paleohistorical (fossil) evidence for such a proposal has not yet been demonstrated. In summary, in the most successful arthropod groups of modem times, the head shield encompasses anterior limbs of the primordial tmnk region, limbs that assist in food capture and mastication. Body tagmatization has become pro- nounced, and swimming, ambulatory and respiratory func- tions are relegated increasingly to thoracic and abdominal limbs (see also Schram, 1986). In higher cmstaceans (malacostracans), thoracic limbs have become uniramous, cheliform and versatile, and the antennules secondarily bi- or tri-ramous and sensory. In higher arachnids, however (e.g. , pedipalpids and phalangids), the prosomal limb gnathobases have become secondarily lost, but feeding mechanisms remain primitive in the retention of chelicerate pre-oral limbs and a suctorial pharynx. In tracheates, the exopods of trunk limbs have been lost. In hexapods, the abdominal limbs have become vestigial or lost entirely, and exites of limbs have secondarily become gills and/or trachaeae in the abdomen, and trachaeae and/or wings in the thorax (see Kukalova-Peck, 1987,1 992). Such fundamental morpho- logical changes in arthropod body form have unquestionably contributed vitally to the ability of modem groups to utilize the diverse organic and plant-related food resources that have evolved mainly in terrestrial habitats, and mainly since the late Paleozoic Era. Source references for taxonomic andclassificatory names and time-scale occurrences in following Tables III-V are: E. L. Smith - unpublished MS "Atlas of Insect Morphology"; L. Stprmer (1959) - in Treatise on Invertebrate Paleontology ; J Bergstrom (1979) - "Morphology of Fossil Arthropods"; S. J. Gould (1989) - "Wonderful Life" & source materials; D.E.G. Briggs et al. (1993) - "The Burgess Shale fauna" and source material; L. Delle Cave & A. M. Simonetta (1991)- "Early Palaeozoic Arthropods"; T. Savory (1964) - "Arach- nids"; F. R. Schram (1986) - "Crustacea"; and numerous other source papers inducting arthropod sections in "Synop- sis and Classification of Living organisms", McGraw Hill, 1982. A database for analysis of the paleohistorical occurence of major taxonomic groups is given in Table V (p. 28). Some taxonomic names, especially those relatively recently pub- lished or not sufficiently well described (e.g., Wapria Walcott, 1912) have been omitted from the lists and the analysis. A complete bibliography of citations of taxonomic names is not included in the references here, but may be found in the Zoological Record or other basic reference texts for the taxa, author names and dates concerned. AMPHIPACIFICA VOL. II. NO. 1 AUG. 31, 1995 25 TABLE ni. SUGGESTED NATURAL CLASSIFICATION OF AQUATIC, ESPECIALLY EARLY PALEOZOIC, ARTHROPODA BASED ON FOOD-GATHERING AND FEEDING MECHANISMS. PHYLUM ARTHROPODA I. INFRAPHYLUM UNIANTENNATA, new name (= MANDIBULOPODA E. L. Smith ’Atlas ”) One pair of positionally and embryonically pre-oral head limbs; trunk limbs often gnathobasic. tSUPERCLASS DICEPHALOSOMATA Sharov, 1966 (L. Camb. - U. Carb) Pre-oral limbs raptorial, non cheliform, 4-14 segments; post-oral limbs non food-gathering; feeding pharyn- geal, assisted by pre-oral limbs; trunk 12+ segmented, pygidial?; limbs locomotory, respiratory; aquatic. tCLASS ANOMALOCARIDEA Raymond, 1935 (L. - M. Camb.) Pre-oral limbs paired, 7-14 segmented; 1-3 post-oral head segments; peribuccal teeth present. tSUBCLASS ANOMALOCARIDATA new (L. - M. Camb) Pre-oral limbs 1 1-14-segmented; 3 post-oral head segments; trunk limbs natatory tOrder Anomalocarida Raymond, 1935 (Anomalocaris Whiteaves, 1892; ?Hurdia Walcott 19121 tSUBCLASS CASSUBIATA new (L. Camb) Pre-oral limbs 7-segmented; 1? post-oral head segment; anterior trunk limbs ambulatory? tOrder Cassubiida new {Cassubia Lendzion, 1977) tCLASS PROTOCHELICERATA Strmer, 1944, revised and restricted (L. - M. Camb.)0 Pre-oral limbs paired, semi-chelicerate, 4-5 segmented; 3 pairs post-oral, biramous ambulatory head limbs. tSUBCLASS YOHOIIDACEA Henriksen 1928, new status (L. - M. Camb) Trunk limbs biramous, natatory, respiratory. tSuperorder Yohoiidea Henriksen 1928 tOrder Jianfengiida new (Jianfengia Hou, 1987) (L. Camb) tOrder Yohoiida Henriksen 1928 (Yohoia Walcott, 1912) (M. Camb) tCLASS PROBOSCIFERIDEA Sharov, 1966 emend (M. Camb - U. Carb) Pre-oral limbs fused to clawlike (14- segmented) jaws on anterior proboscis; post-oral head segments and peribuccal teeth lacking. tSUBCLASS OPABINIIDACEA Stprmer, 1944 (M. Camb) tOrder Opabiniida St0nner, 1944 (Opabinia Walcott, 1912-, ?Kerygmachela Conway Morris etaK 1987) tSUBCLASS TULLIMONSTRIDEA E. L. Smith "Atlas" (U. Carb) tOrder TuUimonstrida (Tullimonstrum Richardson, 1966) tSUPERCLASS TRILOBITOMORPHA Stprmer, 1944, restricted status (L. Camb. - M. Perm.) Pre-oral limbs filamentous, non raptorial; post-oral head limbs and trunk limbs normally biramous, endopods modified for food-gathering and/or feeding. tCLASS (SUBCLASS) LEANCHOILIIDACEA Raymond, 1953, new status (L. - U. Camb.) 2-3 pairs post-oral, spinose (or weakly gnathobasic) transitional head limbs; trunk limb endopods transitional; telson large. tSuperorder Leanchofliidea Raymond, 1935 Head with 2 post-oral segments; pre-oral limbs multi-flagellate; eyes lacking. tOrder LeanchoBuda (L^awc/wi/ia Walcott, \9\2\ Acanthomeridion Hou, Chen &Lu, 1989 ) tSuperorder Alalcomenaeidea Simonetta, 1970 Head with 3 post-oral segments; pre-oral limbs bi-flagellate or with accessory lobe; eyes present tOrder Actaeida {Actaeus Simonetta, 1970) tOrder Alalcomenaeida {Alalcomenaeus Simonetta, 1970; tCLASS (SUBCLASS) SIDNEYIDEA Walcott, 1911, new status (M. Camb.) Uc^ng post-oral head segment(s) or limbs; trunk not trilobate, limbs gnathobasic; telson flabellate tOrder Limulavida Walcott, 1911. {Sidney ia^^\co% 1911) (S«rarmcerc«^ - a larval stage?) tCLASS TRILOBITOIDEA Stprmer, 1955, restricted (L. Camb. - U. Perm.) 3 pairs of post-oral gnathobasic, masticatory head limbs; trunk limbs biramous, endopods gnathobasic. AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 26 fSUBCLASS BURGESSIDEA Walcott, 1912 (L. - M. Camb) Trunk lacking lateral pleurae, limbs biramous; tail region with spikelike telson. tOrder Burgessiida Walcott, 1912 {Burgessia Walcott, 1912) tOrder Molariida Walcott, 1912 {Molaria Walcott, 1912; Emeraldoides Simonetta, 1964) fOrder Habeliida Simonetta & delle Cave 1972 {Habelia Walcott, 1912; Thelxiopa; Economocaris) TRILOBITOIDEA INCERTAE SEDIS Tontoia Walcott, 1912. Nathorstia Walcott, \9\2\Retifacies Hou, Chen & Lu, 1989; Koumaia Hou, 1987; Rhombicalvaria. Hou, 1987; Helmetia Walcott, \9\lMollisonia Walcott, \9\2\Urokodia Hou, Chen & Lu, 1989; Corcorania Jell, 1980; Serracaris Briggs, 1978? tSUBCLASS TRILOBITA Walch, 1771 (L. Camb - U. Perm) Trunk segments typically with lateral pleurae (trilobate); tail region pygidial. tSuperorder Eotrilobitacea Whittington, 1977 (L. - M. Camb) tOrder Nectaspida Raymond, 1920 {Naraoia Walcott, 1912) (Inch Liwia & Tegopelte, L. Camb) tSuperorder Trilobitacea Walch 1771 (L. Camb - M. Perm) tOrder Agnostida Kobayashi 1935 tOrder Redlichiida Richter, 1933 tOrder Corynexochida Kobayashi, 1935 tOrder Ptychopariida Swinnerton 1915 tOrder Phacopida Salter, 1964 tOrder Lichida Moore, 1959 tOrder Odontopleurida Whittington, 1959 tCLASS EMERALDELLIDEA Raymond, 1935 (M. Camb. - L. Dev.) 5 pairs of post-oral, gnathobasic, masticatory head limbs; trunk limbs biramous, endopods ambulatory. tSUBCLASS SANCTICARIDEA E. L. Smith "Atlas" (M. Camb) Pre-oral limb biramous; post-oral head limbs raptorial, unlike ambulatory trunk limbs; telson flabellate. tOrder Sanctacarida E. L. Smith "Atlas" {Sanctacaris Briggs & Collins, 1988 [=Utahcaris orion Con- way Morris & Robison, 1988]). tSUBCLASS EMERALDELLACEA Raymond, 1935 (M. Camb - L. Dev) Pre-oral limb uniramous, filiform; post-oral head and trunk limbs ambulatory and raptorial; telson a spike tOrder Emeraldellida Simonetta & Della Cave, 1975, revised {Emeraldella Walcott, 1912) tOrder Cheloniellonida Brioli, 1933 {Cheloniellon Broili, 1932) (L. Dev) tOrder Aglaspida (Walcott, 1911) {Aglaspis Hall, 1862, revised Briggs et al, 1978) (L. Ord) Inclusions: Aglaspella, Beckwithia, Palaeomerus; Borchgrevinkium; Palaeoniscus, Kodymirus? Strabops? SUPERCLASS CHELICERATA Heymons 1901 (L. Ord - R) Pre-oral limb chelicerate, 3- (occasionally 2- or 4-) segmented; 5 (6) pairs of uniramous post-oral head limbs; trunk limbs uniramous, respiratory. CLASS MEROSTOMATA Dana, 1852 (L. Ord - R) Post-oral head limbs gnathobasic, first pair undifferentiated; trunk limbs reduced to book gills; aquatic. SUBCLASS XIPHOSURA Latreille 1802 (L. Ord -R) Pre- and post-abdomen strongly differentiated; one pair of compound eyes. Superorder Chasmataspididea Caster & Brooks, 1956, revised status (L. Ord - Dev) Post-abdomen 9-segmented; pre-abdomen 3-segmented? Order Chasmataspidida Caster & Brooks, 1950 (L. Ord-Sil) (Chasmataspis, Pseudoniscus) Order Diploaspidida Caster & Brooks, 1956 revised status (Dev) {Diploaspis, Heteroaspis) Superorder Xiphosuridea Latreille, 1802 (U. Sil. - R) Post-abdomen 1 -3-segmented; pre-abdomen 7(8)-segmented. tOrder Triopida Packard, 1886 (L. Ord) {Triopus ) tOrder Synxiphosurina Packard, 1886 (inch Weinbergina) (6 pairs post-oral head limbs) Order Limulina Richter & Richter, 1929 (Carb - R) {Limulus L. 1787; + Euproops (Carb)) AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 27 fSUBCLASS EURYPTERIDA Burmeister, 1843 (L. Ord - Perm) Pre and post-abdomen not strongly demarcated; 2 pairs compound eyes tOrder Eurypterida Burmeister, 1843 (Eurypterus) tOrder Pterygota Clarke & Rudemann, 1912 CLASS ARACHNIDA Lamarck 1801 (Ord. - R) Post-oral head limbs (secondarily) non-gnathobasic, first often differentiated as pedipalps; feeding chelicerate; anterior trunk limbs forming book lungs or lacking; terrestrial SUBCLASS SCORPINIATA Latreille, 1817 (Sil - R) Order Scorpionida Latreille 1806 (Sil - R) SUBCLASS PEDIPALPATA Latreille 1906 (M. Dev - R) Order Palpigradida Thorell, 1881 (Jur - R) Order Schizomida Petrunkevitch, 1945 (U. Tert - R) Order Uropygida Thorell, 1882 (U. Carb - R) Order Amblypygida Thorell 1883 (U. Carb - R) Order Aranaea Clerck, 1757 (U. Carb - R) tOrder Trigonotarbita Petrunkevitch, 1949 (M. Dev - U. Carb) SUBCLASS PHALANGIATA Leach, 1915 (U. Carb - R) Order Solfugida Leach 1815 (U. Carb - R) Order Acarida Nitzsch 1818 (M. Dev - R) Order Ricinulida Thorell, 1 892 (U. Carb - R) Order Opilionida Sundevall 1833 (U. Carb - R) Order Pseudoscorpiooida Latreille, 1817 (Olig. - R) CLASS PYCNOGONIDA Latreille, 1910 (L. Dev - R) Post-oral head limbs non-gnathobasic, first differentiated as pedipalps; feeding pharyngeal, pre-oral limb assisted; aquatic. tSUBCLASS PALAEOPYCNOGONIDA E. L. Smith Atlas (L. Dev) tOrder Palaeoisopida Hedgepeth, 1978 (Palaeoisopus Broili, 1928) tOrder Palaeopantopoda Broili, 1930 (Palaeopantopus Broili, 1928) SUBCLASS PODOSOMATA Leach, 1813 (L. Dev - R) Order Pantopoda Gerstaeker, 1963 {Pycnogonum littorale L.) TABLE IV. SUGGESTED NATURAL CLASSIFICATION OF BUNTENNATE ARTHROPODS 2. INFRAPHYLUM BIANTENNATA Bergstrom, 1979 revised (= MANDIBULATA Clairville, 1798) Head with acron and 2 pairs of positionally pre-oral limbs, 2nd pair embryonically post-oral, biramous- 3rd (when present) mandibulate; trunk limbs not gnathobasic. tSOTERCLASS EUTHYCARCINOMORPHA Handlirsch, 1914, revised status (L. Camb. - Trias) Head 2(3)-segmented; head shield not maxillary; trunk tagmatized; thoracic limbs primitively biramous endopods slender, multi-segmented, lacking terminal claws; abdomen limbless, with telson.. tCLASS EUTHYCARCINOIDEA Handlirsch, 1914 (L. Camb - U. Trias) With the characters of the superclass. tSUBCLASS FUXIANHUIATA new (L. Camb) multi-segmented, segments simple, each with one pair of biramous limbs; telson short. tOrder Fuxianhuiida new (Fuxianhuia protensa Hou, 1987) INCERTA SEDIS: Chengjiangocaris longiformis Hou & Bergstiom, 1991. tSUBCLASS EUTHYCARCINATA Handlirsch, 1914. (U. Carb - Trias) Trunk with few (<20) diplo- and/or triplo- segments; trunk limbs uniramous, two per diplo- segment; telson elongate. tOrder Sottixeriformes Schram & Rolfe, 1982 (Pieckoxerxes piekoae Starobogatov, 1988) tOrder Euthycarciniformes Schram & Rolfe, 1982 (Kottixerxes gloriosus Starobogotov, 1988) AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 28 fSUPERCLASS MARRELLOMORPHA Walcott, 1912, new status (M. Camb - L. Dev) Head 2-4- segmented; head shield spinose or bivalved, not maxillary; mandible, endopod leglike; trunk not tagmatized; trunk limbs undifferentiated, endopods strongly leglike, ambulatory, exceeds narrowly lamellate. tCLASS MARRELLIDEA Walcott, 1912 (M. Camb - L. Dev) Head 2-3 segmented; head shield with paired spines; telson minute. tSUBCLASS MARRELLATA Walcott, 1912 (M. Camb) Head 2-segmented; first post-oral head limbs antenna-like, t Order Marrellida Walcott, 1912 (Marre/la Walcott, 1912) tSUBCLASS MIMETASTERATA E. L. Smith "Atlas” (L. Dev) Head 3-segmented; first post-oral head limbs leg-like, tOrder Mimetasterida {Mimetaster Gurich, 1931) fCLASS ACERCOSTRACA Lehmann, 1955 (L. Dev) Head 4-segmented; head shield with carapace. tSUBCLASS VACHONISIATA E. L. Smith "Atlas" (L. Dev) Post-oral limbs 3 & 4 leglike, weakly gnathobasic. tOrder Vachonisiida new (Vachonisia Lehmann, 1955) tSUPERCLASS PHYLLOPODA Latreille, 1825 revised, restricted (M. Camb - L Ord) Head 3-segmented; head shield bivalved, not maxillary; mandible masticatory, not leglike or palpate; trunk 15+ segmented, weakly tagmatized; endopods weakly leglike, exopods broadly lamellate (phyllopodous). tCLASS BRANCHIOCARroEA E. L. Smith "Atlas" (M. Camb) Head 3-segmented; trunk segments numerous (20+), with similar phyllopodous limbs. tSUBCLASS BRANCHIOCARATA E. L. Smith "Atlas" (M. Camb) First two pairs of head appendage prominent, 2nd pair cheliform?; carapace normal; tail region bifid. tOrder Branchiocarida E. L. Smith "Atlas" (Branchiocaris Briggs, 1976) tSUBCLASS ODARAIATA Simonetta & Delle Cave, 1975 (M. Camb) Pre-oral appendages minute, linear?; carapace tubular; tail region trifid. tOrder Odaraiida Simonetta & Delle Cave, 1975 {Odaraia Walcott, 1912) tCLASS (SUBCLASS) CANADASPIDIDEA Novoshilov, 1960 (M. Camb - L, Ord) Head appearing indistinctly 5-segmented, posterior 2 pairs of limbs similar to trunk limbs; trunk 15-segmented, posterior 7 segments lacking paired appendages. tOrder Canadaspidida (Canadaspis Novoshilov, 1960; Perspicaris Briggs, l911\?Rhebachiella kinnekullensis Muller 1983 (larval stages) ?Order Hymenostraca Rolfe, 1969 {Hymenocaris Salter, 1853) (M. Camb - L. Ord) SUPERCLASS CRUSTACEA Pennant, 1777 (after Schram, 1986) (M. Camb - R) Head with pre-oral antenna and 4 post-oral limbs, first antennalike, 2-4 (including mandible) masticatory; head shield maxillary; trunk often tagmatized, limbs often differentiated, specialized; telson present. CLASS (SUBCLASS) REMIPEDU Yager, 1981 (M. Dev - R) tOrder Enantiopoda Birshtein, 1960 (Tesnusocaris Brooks, 1955) (M. Dev) Order Nectiopoda Schram, 1986 {SpeleonectesYdigQX, 1981) (R) CLASS BRANCHIOPODA Latreille, 1817 (L. Dev - R) SUBCLASS SARSOSTRACA Tasch, 1969 (M. Dev - R) tOrder Lipostraca Scourfield, 1926 (M. Dev) Order Anostraca Sars, 1867 (L. Dev - R) SUBCLASS CALMANOSTRACA Tasch, 1969 (M. Dev. - R) Order Notostraca Sars, 1867 (L. Dev - R) AMPHIPACIFICA VOL. II. NO. 1 AUG. 31, 1995 29 Order Kazacharthraca Novozhilov, 1957 (L. Jur) Order Conchostraca Sars, 1867 (L. Dev - R) Order Cladocera Latreille, 1829 (Perm-R) CLASS (SUBCLASS) CEPHALOCARIDA Sanders. 1955 (R) Order Brachypoda Birshtein, 1960 (Hutchinsoniella Sanders, 1955) CLASS MAXILLOPODA Dahl, 1956 (L. Camb - R) tSUBCLASS SKARACARIDA Muller, 1983 (M. Camb - U. Camb)) Order Skaracarida Muller, 1983. Skara annulata Muller, 1983) (several other, mostly larval genera e.g., Dala, Walossekia, Oelandocaris, Bredocaris, SUBCLASS OSTRACODA Latreille, 1836 (L. Camb - R) fOrder Bradoriidae Matthew, 1902 t Order Phosphatocopida K. J. Muller, 1964 (L. Camb. - L. Ord) tOrder Leperditicopida Scott, 1961 (U. Camb - U. Dev) fOrder Palaeocopida Henningsmoen, 1953 (L. Ord - Trias) Order Halocyprida Dana 1852 (Sil - R) Order Platycopida Sars 1866 (L. Ord - R) Order Cladocopida Sars 1866 (Ord - R) Order Myodicopida Sars, 1966 (Ord - R) Order Podocopida Sars, 1866 (Sil - R) SUBCLASS THECOSTRACA Gruvel, 1905 (M. Camb - R) Order Facetotecta Gruvel, 1905 Order Rhizocephala F. Muller, 1862 Order Ascothoracida LacazcrDuthiers, 1880 Order Cirripedia Burmeister, 1834 (M. Camb - R) SUBCLASS TANTULOCARIDA Boxshall & Lincoln, 1983 (R) Order Tantulocaridida Boxshall & Lincoln, 1983 SUBCLASS COPEPODA Milne-Edwards, 1840 (Cret - R) Order Calanoida Sars, 1903 Order Harpacticoida Sars, 1903 Order Cyclopoida Burmeister, 1834 Order Misophrioida Gurney, 1933 Order Monstrilloida Sars, 1903 Order Siphonostomatoida Thorell, 1859 emend Sars 1918 Order Poecilostomatoida Thorell 1 859 SUBCLASS LINGULATULIDA Frolich, 1789 (=Pentastomatida Rudolphi 1819) (R) Order Cephalobaeniuda Heymons & Vitzthum, 1936 Order Porocephalida Heymons & Vitzthem, 1936 tCLASS (SUBCLASS) THYLACOCEPHALA Pinna, Arduini et al. 1982. (Camb? L. Sil - Cen) tOrder Concavicarida Briggs & Rolfe, 1983 (L. Sil - Cen) tOrder Conchyliocarida Secretan, 1983 (Camb? - Jur) CLASS MALACOSTRACA Latreille 1806 (Dev - R) SUBCLASS PHYLLOCARIDA Packard, 1879 emended (Dev - R) tOrder Archaeostraca Claus, 1888 tOrder Hoplostraca Schram, 1973 Order Leptostraca Claus, 1880 (see also Dahl, 1984) SUBCLASS HOPLOCARIDA Caiman 1904 (U. Dev - R) tOrder Aeschronectida Schram, 1969 (Carb) tOrder Palaeostomatopoda Brooks, 1955 (U. Dev - L. Carb) Order Stomatopoda Latreille, 1817 (Carb-R) SUBCLASS EUMALACOSTRACA Grobben, 1892 (modified from Schram, 1986) (U. Dev - R) Superorder Syncarida Packard, 1885 (U. Carb - R) tOrder Palaeocaridacea Brooks, 1962 AMPHIPACinCA VOL. H. NO. 1 AUG. 31, 1995 30 Order Anaspidacea Caiman, 1904 Order Bathynellacea Chappuis, 1915 Order Stygocaridacea Noodt ,1964 fSuperorder Belotelsonidea Schram, 1981 tSuperorder Waterstonellidea Schram, 1981 fSuperorder Eocaridacea Brooks, 1962 Superorder Thermosbaenacea Monod, 1927 Superorder Mysidacea Boas, 1883 Order Lophogastrida Boas, 1883 fOrder Pygocephalomorpha Beurlen, 1930 Order Mysida Boas 1883 Superorder Amphipoda Latreille, 1916 Superorder Hemicaridea Schram, 1981 emended Order Spelaeogriphacea Gordon, 1957 Order Mictacea Bowman et al. 1985 Order Cumacea Kroyer, 1846 Order Tanaidacea Dana, 1853 Superorder Isopoda Latreille, 1817 Superorder Eucarida Caiman, 1904 Order Euphausiacea Dana, 1862 Order Amphionidacea Williamson, 1973 Order Decapoda Latreille, 1803 SUPERCLASS MYRIAPODA Latreille, 1796 (Sil - R) (Essentially terrestrial; not detailed here) Head with embryonic acron, pre-oral antenna, 5 post-oral pairs of masticatory limbs (1st post-oral embry- onic); trunk not tagmatized, with more than 20 pairs of ambulatory limbs, ending in telson. CLASS SYMPHYLA Ruder, 1880 (1 subclass) (Olig-R) CLASS CHILOPODA Latreille, 1802 (2 subclasses) (M. Dev - R) CLASS PAUROPODA Lubbock, 1866 (1 subclass) (R) CLASS DIPLOPODA Gervais, 1844 (3 subclasses) (Sil - R) fCLASS ARTHROPLEURIDEA Zittel, 1848 (1 subclass)(L. Dev - U. Carb) SUPERCLASS HEXAPODA (L. Dev. - R.) (Essentially terrestrial; not detailed here) Head with acron + pre-oral antenna, 4 post-oral pairs masticatory limbs (1st post-oral embryonic, 2nd mand- ibulate; trunk tagmatized; thorax with 3, abdomen with 11 (max.) pairs ambulatory limbs; telson embryonic. CLASS PARINSECTA (2 Subclasses: CoUembola, Protura) (L. Dev - R) CLASS INSECTA (2 Subclasses Entognatha, Ectognatha) (U. Carb - R). TABLE V. NUMBERS OF fflGHER ARTHROPOD TAXA SINCE CAMBRIAN TIMES. P E R I O D ARTHROPOD INFRAPHYLA I CAMBRIAN (545-495 mybp) II LATE PALEO- ZOIC (-300 mybp) ni TERTIARY- RECENT (0-30 mybp) IV TOTALS SPCL. CL. SBCL. SPCL. CL. SBCL. SPCL. CL. SBCL SPCL. CL. SBCL. UNIANTENNATA 2 8 11 3 5 8 1 3 5 3 10 18 BIANTENNATA 4 6 9 5 11 24 3 12 24 6 18 34 TOTAL ARTHROPODA 6 14 20 8 16 32 4 15 29 9 28 52 AMPHIPACIFICA VOL. H. NO. 1 AUG. 31, 1995 31 Arthropod Diversity and Evolutionary Trends Table V summarizes (from Tables m & IV) the number of higher arthropod taxonomic categories, recognized here at superclass (SPCL), class (CL) and subclass (SBCL) levels, that are represented by known genera and species of the Cambrian, late Paleozoic and Tertiary-Recent Periods. Analysis of the changing numbers with geological time re- veals interesting and perhaps significant evolutionary trends . Despite the very great difference in numbers of species known for each of the three time-scale samplings (Cambrian ~102 species; Late Paleozoic- ~10 "^-i-species; Tertiary-Re- cent — 10 ^ + species), the numbers of higher taxa are of comparable orders of magnitude for all categories. In the 600-million-year time span since the presumed dawn of arthropod life (Ediacrian, Vendian), we here categorize only 9 superclasses, 28 classes and 52 subclasses to encompass the entire known fauna, past and present, of well over one million described species (Table V, Col. IV, bottom row). Fully one- third of the early subclasses is known from only 1- 10 species, a fact suggesting the likelihood of further new discoveries, at that level or higher, among incompletely described or totally new fossil material. Only one of the 9 superclasses (Crustacea), one of the 28 classes (Maxillopoda) and only two of the 52 subclasses (Ostracoda, Thecostraca) have actually been recorded throughout this immense paleontological range. To this meager total we might add the Chelicerata but it is presently confirmed not earlier than Lower Ordovician. However, further analysis of Paleozoic fossil material is expected to extend the time range of extinct species forwards, and recent species (especially minute, soft-bodied forms), backwards in time. Thus, the morph- ologically primitive Remipedia and Cephalocarida may have originated during Cambrian times, despite their very limited or non-existent fossil records (see Hessler, 1984). Aquatic larval stages of some other classes of Crustacea and of the merostomatid uniantennates (e.g., phyllocarid and trilobite larvae, respectively), tend to recapitulate adult mor- phology of extinct, but related, Cambrian categories. Thus, by the Cambrian Period, 67 % (6/9) of the super- classes, but only -50% (14/28) of the classes and -38% (20/ 52) of the subclasses had evolved. By the late Paleozoic, perhaps the heyday of arthropod evolution generally, nearly all (8/9) the superclasses, and -60% (16/28; and 32/52) of all classes and subclasses were represented. Today, however, scarcely half (4/9 and 15/28) the superclasses and classes persist, and the percentage of subclasses, 56% (29/52), has also dropped slightly. If trends are analysed according to infraphylum for each time interval, for the uniantennates the percentages were highest during the Cambrian, with 33% (2/6) of the superclasses, 57% (8/14) of the classes, and 55% (1 1/20) of the subclasses. However, the group decreased markedly in importance by the late Paleozoic (only 37% of superclasses, -3 1% of classes, and -25% of subclasses), and is lowest to- day (25% of superclasses, -20% of classes, and only -17% of subclasses). By contrast, the biantennates increased steadily from lowest values in the Cambrian (67% of super- classes, 43% of classes and 45% of subclasses), through the late Paleozoic (63% of superclasses, -70% of classes, and -67% of subclasses), to maximum dominance today (75% of superclasses, -80% of classes, and -83% of subclasses). These changes in relative numbers of the two arthropod infraphyla may reflect the impact of the evolution of vascular plants during Silurian-Devonian and later periods (Kukalova- Peck, 1987). That event provided an enormous new food resource in both aquatic and terrestrial environments. These nutrients could be exploited by the omnivorous aquatic crustaceans and terrestrial myriapods and hexapods by direct adaptation and diversification of feeding morphology and style (as in malacostracan crustaceans, and winged insects). By contrast, the uniantennates were more or less “locked into” their mainly carnivorous, and some detritivorous life styles; they could take only indirect advantage of this food resource, and only by developing new predatory morph- ologies and life styles, especially within the terrestrial environment. They are now a secondary part of the terrestrial, and a minute relict part of the aquatic, arthropod fauna. With respect to the level of arthropod disparity during Cambrian times, the positions of both Gould (1989) and proponents to the contrary (e.g., Ridley, 1993; Wills et al. 1994) receive support from the present analysis. Thus, of 9 "all-time" arthropod superclasses, 7 (including Chelicerata) were represented in Cambrian and Lower Ordovician fau- nas, but only 4 are represented in the Recent fauna. Espe- cially remarkable is the fact that Cambrian arthropods were entirely aquatic, and were represented by less than 100 species from a very limited series of marine habitats. The two superclasses missing from the Cambrian record, the Myriapoda and the Hexapoda, are both essentially terres- trial. Thus, if only aquatic faunas are considered, the disparity level of Cambrian arthropods is more than 3 times greater (7 vs. 2 superclasses) than today. On the other hand, at class level, disparity levels are similar ( 14 vs. 15), and at subclass level, the Recent arthropod fauna is about 50% richer (29 vs. 20). Furthermore, all of the arthropod, or arthropodlike, species of the Burgess Shale, designated by Gould (1989) and Briggs et al. (1993) as new (or probably new) at phylum and/or infraphylum levels, can be adequately encompassed within existing class and/or superclass categories. Thus, it is concluded here that, during the entire evolu- tionary history of the Arthropoda, disparity levels were at or near maximum during the Cambrian Period. Such a high level, close to the starting point of the arthropod fossil rec- ord, is consistent with the probable correctness of the evol- utionary theory of punctuated equilibrium (Eldridge & Gould, 1972). 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Basic Arthropodan Stock. Pergamon Press, New York. 267 pp. Smith, E. L., 1990. An arthropod morphologist looks at six hundred million years of chelicerate evolution. Amer. Arachn. Soc., 14th Ann. Conf., Ottawa, 1990. Abstract. Snodgrass, R.E., 1956. Crustacean Metamorphosis. Smiths. Misc. Coll. 131(10): 78 pp., 28 figs. St0rmer,L., 1944. On the relationships and phylogeny of the fossil and Recent Arachnomorpha. Skr. Nor. Vidensk. Akad. Oslo I: Matemat. Naturvidensk. Klasse 5:1-58. , 1959. Trilobitoidea. In R. C. Moore (ed.). Treatise on Invertebrate Paleontology. Part O. Arthro- ropoda. I. pp. 23-37. Sturmer, W., & Bergstrom, J., 1976. The arthropods Mim- etaster ^n^Vachsonisia from Devonian shale. Palaeont. Zeitschr. 50(1/2): 1-112. Walcott, C. D., 1 9 12. Middle Cambrian Branchiopoda, Mal- acostiaca, Trilobita, and Merostomata. Cambrian Geol- ogy and Paleontology n. Smithsonian Misc. Coll. 57: 145 - 228. AMPHIPACIFICA VOL. U. NO. 1 AUG. 31, 1995 34 Walossek D., and K. L. Muller, 1989. A second type of A- nauplius from the Upper Cambrian ‘Orsten’ of Sweden Lethaia22: 302-306. Whittington, H.B., 1971. RQdQSchp\ion of Marrellasplend- ens (Tiilobitoidea) from the Burgess Shale, Middle Cambrian, British Columbia. Geol. Surv. Can. Bull. 209: 1-24. , 1975. The enigmatic animal Opabinia regalis, Middle Cambrian, Burgess Shale, British Col- umbia. Phil. Trans. Roy. Soc. London B 271; 1-43. , & D. E. G. Briggs, 1985. The largest Cambrian animal, Anomalocaris, Burgess Shale, Brit- ish Columbia. Phil. Trans. Roy. Soc. B 309: 569-609. Wills, M. A., D. E. G. Briggs, & R. A. Fortey, 1994. Dispar- ity as an evolutionary index: a comparison of Cambrian and Recent arthropods. Paleobiology 20(2): 93-130. OpaBiniaTyttBs WaCcott MiddCe CamBrianJArtfiropod (SdananneCofBns UCustration, modified from Qotdd, 1S8S) AMPHIPACinCA VOL. 11 NO. 1, AUG. 31, 1995 35 THE AMPHffOD SUPERFAMILY PONTOPOREIOIDEA ON THE PACIFIC COAST OF NORTH AMERICA. I. FAMILY HAUSTORHDAE. GENUS EOHAUSTORIUS J. L. BARNARD: SYSTEMATICS AND DISTRIBUTIONAL ECOLOGY ABSTRACT by E. L. Bousfield^ and Phillip Hoover^ On the Pacific coast of North America, from the Bering Sea to Southern California, the free-burrowing gammaridean amphipod family Haustoriidae is represented by six species of Eohaustorius Barnard, 1957. On the Asiatic Pacific coast six species, all subtidal, have now been described. A single northern subtidal species, E. eous, connects the two faunas in the Bering Sea region. This paper describes E. bamardi, new species, from off Pt. Conception, California, and provides re- descriptions, keys and new distributional information for Eohaustorius eous (Guijanova, 1951), E. estuarius Bosworth, 1973, £. sawyeri Bosworth, 1973, E. brevicuspis Bosworth, 1973, E. sencillus Barnard, 1962 and E. washingtonianus (Thorsteinson, 1941). Material ascribed to the latter species from the northwestern Pacific region by Gurjanova (1962) is herewith redescribed as E. gurjanovae, new species. Subtidal material from South Korea is described as E. longicarpus, new species. The species of Eohaustorius are morphologically variable throughout their ranges, especially E. washingtonianus, but variation is not considered of species or subspecies value. Cluster analysis reveals three main subgroupings, none very closely inter- or intra-related, viz: a North American endemic group of E. washingtonianus Barnard, E. brevicuspis Bosworth and E. bamardi, new species; an Asiatic Pacific group of E. cheliferus Bulcheva, E. subulicolus Hirayama and E. robustus Gurjanova; and a northern relatively primitive core group of E. eous (Guijanova), E. sawyeri Bosworth, E. gurjanovae, new species, E. estuarius Bosworth, E. longicarpus, new species, and E. sencillus Barnard. The Asiatic species have relatively restricted distributions and none is intertidal. This hiatus results presumably from competition with intertidal members of amphipod family Dogiehnotidae dominant in that region, and from severe physical factors in winter of low intertidal temperatures and ice scour. On the North American Pacific coast, however, all species have relatively wide geographical ranges, and four species are intertidal. There, only one species of Dogiehnotidae, Proboscinotus loquax, provides intertidal competition, and the climate is equable year-round winter ice scour is .lacking. The genus Eohaustorius is sufficiently similar to North American Atlantic haustorinid genera as to preclude separate evolution from a pontoporeiid ancestor and thereby render polyphyletic the family Haustoriidae. However, the genus Eohaustorius is cold-temperate, and the Atlantic-endemic genera are warm-temperate, in biogeographical affinities. Eohaustorius is closest morphologically to the Atlantic sub- tidal genus Pseudohaustorius, thereby raising the possibility that during early Miocene times, prior to emerg- ence of the isthmus of Panama, a common ancestor connected the two groups via a southern marine waterway. INTRODUCTION The superfaimly Pontoporeioidea is a relatively small group of fossorial amphipods, whose marine members are foundmainly in sedimentary substrata along holarctic shores. Members of the primitive family Pontoporeiidae tend to be arctic and sub-arctic in distribution, with a significant com- ponent confined to glacial relict freshwater lakes of North America and northwestern Eurasia (Bousfield, 1987). By contrast, members of the advanced and highly specialized family Haustoriidae are marine and estuarine and occur mainly along warm-temperate and boreal coastlines of the North Atlantic and North Pacific regions (Bousfield, 1965; 1970, 1973). On the Pacific coast of North America, family Pontoporeiidae is sparsely represented (Bousfield, in prep: Priscillina and Monoporeia in the Bering Sea, Pontoporeia in glacial Qords, and Diporeia in a few post-glacial lake basins). However, owing mainly to the work of Thorsteinson T (1941), Gurjanova (1951, 1962), Barnard (1957, 1962), Bosworth (1973) and Coyle & Mueller (1981), the family Haustoriidae is known to be moderately speciose in shallow, high energy coastal marine waters from the Bering Sea coast of Alaska to southern California. The genus is well represented in coastal waters of Korea and Japan (Ishimarus, 1994), and along the Russian coast north to the Bering Sea region, but not in Arctic waters. Within the North Pacific region generally, the family Haustoriidae is represented only by the single genus, Eohaustorius Barnard, 1957. Some seven species of this genus have been recorded from the North American Pacific coast and another five from the Pacific coast of Russia and the Japan Sea (including Korea). The genus is distinct from the North Atlantic complex (with the European species Haustorius arenarius (Slabber) as type) in having peraeopods 3 and 4 unlike in size and form, and telson lobes widely sep- arated on the dorsum of urosome 6, among other differences . Research Associate, Royal Ontario Museum, Toronto, Ontario. M5S 2C6. Research and Teaching Assistant, Department of Biology, University of Victoria, Victoria, B. C. V8W 2Y2. AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 36 This study treats the systematics and distributional ecol- ogy of species of the genus Eohaustorius in North Pacific coastal marine region, and emphasizes the North American Pacifica fauna. Species of Eohaustorius have proven useful as indicators of sediment quality (see Bousfield, 1991; Mcleay et al. (1990); Yeeetal. 1992). Acknowledgements. The present North American haustoriid material was accumulated mainly as a result of National Museum, now Canadian Museum of Nature (CMN), field expeditions, conducted by one of us (ELB) and colleagues, during the period 1955-1980. Complete lists of stations, pertinent data and acknowledgement of field assistance are provided elsewhere (Bousfield, 1958, 1963, 1 968 ; Bousfield & McAllister, 1 962; and Bousfield & Jarrett, 1981). Additional material was provided by Drs Peter Slattery, Moss Landing, California; Charles O' Clair, Auke Bay, Alaska; Kathleen Conlan CMN, Ottawa, and McLeay Associates, West Vancouver. The authors are most grateful for use of the laboratory facilites of Dr D. V. Ellis, University of Victoria, and for the use of collections and facilities of the CMN in Ottawa. The authors are indebted to Dr Weldon S. Bosworth for his pioneering work on much of this material in 1973-4, and for his unpublished commentary and distributional informa- tion. Susan Laurie-Bourque very capably assisted in preparation of the line drawings. Marjorie A. Bousfield provided translations of pertinent Russian literature. The illustrative work was supported under a research divisional grant of the Royal Ontario Museum, Toronto. SYSTEMATICS Haustoriidae Stebbing Haustoriidae Stebbing, 1906: 118. — Guijanova, 1951:328; 1962: 395.— Bousfield, 1965: 165 (part); 1973: 99 (part); 1982: 259. — Barnard and Drummond, 1982: 136. — Hirayama, 1985: 395. — Barnard & Karaman, 1991: 357. Taxonomic commentary. B amard and Karaman (1991) have provided a simplified key to genera of Haustoriidae (sensu strictu). With respect to superfamily classification, Barnard & Karaman (loc. cit.) have continued recognition of family Haustoriidae as the type of superfamily Haustorioidea, proposed initially by Barnard & Drummond (1982). As shown by Bousfield (1982b, 1990) and Bousfield & Shih (1994), the Bamardian concept (of Haustorioidea) includes most members of family Urothoidae and other superficially and convergently similar families. The latter groups are phyletically more correctly placed within superfamily Phoxocephaloidea (e.g., Bousfield 1982, 1990; and Schram, 1 986). In all major character states, family Haustoriidae is most clearly related to members of family Pontoporeiidae, and thus phyletically assignable to the superfamily which the latter typifies, the Pontoporeioidea. As shown above (Bousfield, loc . cit.), these major pontoporeioidean character states of Haustoriidae, especially of its most primitive genus Protohaustorius, include its short broad, weakly rostrate head, "pseudorostrate" paired peduncles of antenna 1 , weakly (or non-) dactylate peraeopods and maxilliped, lack of coxal gill on peraeopod 7, unique form of the pleopods (lacking clothespin spines), strongly deflexed urosome, and the holarctic (non-antipodean) distribution of nearly all member species. The character states of the Pontoporeioidea, especially the phyletically significant antennal calceoli, are basically gammaroidean and not phoxocephaloidean or crangonyctoidean in form. Eohaustorius J. L. Barnard Eohaustorius J. L. Barnard, 1957: 81. — Gurjanova, 1962: 400.— Bousfield, 1970: 150.— Bosworth, 1973: 160.— Barn- ard, 1975: 348 (key). — Hirayama, 1985: 43. — Barnard & Karaman, 1991: 361. — Ishimaru, 1994: 64. Type species. Haustorius washingtonianus Thorsteinson, 1941, original designation. Component species. E. tandeensis Dang, 1968; E. subulicolus Hirayama, 1985; E. cheliferus (Bulycheva, 1952); E. eous (Guijanova, 1951); £. robustus (Gurjanova, 1953; E. sawyeri Bosworth, 1973; E. brevicuspis Bosworth, 1973; E. estuarius Bosworth, 1973; E. longicarpus, new species; E. gurjanovae, new species; E. sencillus Barnard, 1962; E. bamardi, new species. Diagnosis. Body short, broad. Head broad; rostrum short, acute. Pigmented eyes essentially lacking. Antennal, flagellum 5-segmented; accessory flagellum 2-segmented, attached subapically to peduncular segment 3, bearing aesthetascs. Antenna 2, peduncle 4 broadly lobate and strongly setose behind; peduncle 5 broad, not lobate behind; flagellum 4-5 segmented. Upper lip rounded. Lower lip, inner lobes with short proximal processes. Mandible, molar strong triturative; incisor acute; palp segment 3 with few (5-15) inner marginal comb spines. Maxilla 1 lacking accessory basal baler lobe; inner plate with single apical seta; outer plate with 8-9 apical spines. Maxilla 2, outer plate little larger than inner, not lunate inform; innerplate with weak facial setae. Maxilliped, inner plate with 2 apical spines; outer plate very large, exceeding palp segment 2; palp segment 3 clavate, not genic- ulate. Coxal plates 1 & 2 small, 3 & 4 squarish below. Gnathopod 1, segment 3 very short; segment 5 relatively short, deep; segment 6 medially deepest. Gnathopod 2, segment 3 very short; segment 5 with postero-distal cluster of specialized spines; segment 6 short, medially swollen, arcuate, produced beneath minute dactyl to form a microchela . AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 37 KEY TO NORTH PACIFIC SPECIES OF EOHAUSTORIUS 1. Pleon plate 3 strongly produced behind into a recurved hooklike process; peraeopod 4, hind lobe of segment 5 elongate, slender, length 4-5 X width (depth); uropod 3, inner ramus with single small inner marginal seta; Asiatic coast £. subulicolus (p. 42) — Pleon plate 3, hind process nearly straight, if hooked, not recurved; peraeopod 4, segment 5, hind lobe shorter, deeper, length less than 2 X depth; uropod 3, inner margin with 2-6 setae 2. 2. Peraeopod 6, segment 4 tall, length 2X width, with 5-6 groups of facial spines (in addition to marginal spines); basis slender, distinctly narrower than length (depth), subovate; uropod 1, hind margin of inner ramus with 2 single setae; gnathopod 1, dactyl, body large, length > nail (unguis) 3. —Peraeopod 6, segment 4 subtriangular, widest distally, length < 2X width; basis as broader or broader than length; gnathopod 1, dactyl, nail longer than body 4 . 3. Antennae 1 & 2, flagella 5-segmented; peraeopod 4, hind lobe elongate, ~2 X depth; abdominal side plate 3, apex abruptly upturned, minutely split-tipped E. longicarpus (p. 56) —Antenna 1 & 2, flagella 3-segmented; peraeopod 4, segment 5, hind lobe short, length not greater than depth; abdominal side plate 3, hind process straight or apex slightly upturned E. sencillus (p. 44) 4. Peraeopod 4, segment 5, posterior lobe, distal margin with spine cluster; peraeopod 6, segment 4 with lower facial row of 2-3 spine groups; peraeopod 6, segment 5 with posterior marginal spine^roup . . 7. Peraeopod 4, segment 5, distal lobe base, smooth; peraeopod 6, segment 4 with at least one other spine cluster above lower row; peraeopod 6, segment 5 lacking posterior marginal spines 5. 5. Peraeopod 7, basis, hind margin proximally with strong cusp or tooth; pleon plate 3 produced, poster- iorly as weak tooth £ washingtonianus (p. 50) Peraeopod 7, basis hind marginal tooth weak or rounded; pleon plate 3, process strong 6. 6. Peraeopod 7, basis wider than deep, hind cusp rounded; maxilliped palp, segment 3 strongly broadened distally, width = 3/4 length e. brevicuspis (p. 50) Peraeopod 7, basis not wider than deep, hind cusp acute; maxilliped palp, segment 3 normal, length ~2X bamardi (p. 54) 7. Peraeopod 4, segment 5, hind lobe strongly produced, width of segment 2 X depth (length); peraeopod 7, segment 6 with 2 posterior marginal groups of spines; gnathopod 2, basis, hind margin with distal setae only cheliferus (p. 55) — Peraeopod 4, segment 5, hind lobe normal, width about equal to length; peraeopod 7, segment 6 with 3-4 posterior marginal spines groups; gnathopod 2, basis, hind margin setose throughout 8. 8. Peraeopod 5, segment 4 widest distally, 2X length; pleon plate 3, postero-dorsal process large, strongly overhanging urosome; uropod 3, inner ramus with 2-3 marginal setae E. sawyeri (p. 44) Peraeopod 5, segment 4 less broad, ~ 1.5X length; pleon overhang normal, little or not exceeding side plate process; uropod 3, inner ramus with 5 marginal setae 9 9. Peraeopod 7, segment 6 with 2 groups of posterior marginal spine groups; coxae 3 & 4 antero-distal mar- gins rounded Eestuarius (p. 40) Peraeopod 7, segment 6 with 3-4 posterior marginal spine groups; coxae 3 & 4 squarish 10. 10. Peraeopod 5, segment 6 with 1 group of anterior marginal spines; pleon plate 3 , hind process, apex slightly upturned; peraeopod 4, segments 5 & 6 lacking anterior marginal spines; peraeopod 7, basis veiy broad, exceeding length £ (p 43 ^ —Peraeopod 5, segment 6 with 2 groups anterior marginal spines; pleon plate 3 hind process straight; per- aeopod 4, segment 5 & 6 with anterior marginal spines; peraeopod 7, basis not wider than deep . . .\ 1 1. AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 38 11. Peraeopod 7, segment 6 with 4 posterior marginal spines; basis lacking posterior cusp; mandibular palp segment 3 with 14-15 posterior marginal comb spines E. eous (p. 38) — Peraeopod 7, segment 6 with 3 posterior marginal spines; basis with rounded posterior proximal cusp; mandibular palp segment 3 with 8-9 posterior marginal comb spines E. gurjanovae (p. 47) Peraeopod 3, segment 4 short, triangular; 5 weakly lob- ate behind; 6 small, margins spinose, not setose. Peraeopod 4 smaller and unlike peraeopod 3 in form; segment 3 very short, 4 little broadened, 5 strongly produced and spinose behind; 6 slender, distally spinose and setose. Peraeopod 5, basis broad, hind margin setose, with proximal cusp; segments 4-6 not broader than long, outer face with spine clusters . Peraeopod 6 longest; basis medium broad, hind margin setose, with proximal cusp; segment 4 often longer than broad; segment 5 broader than long, with prominent antero-distal process and distal marginal notch; segment 6, some distal spines split-tipped. Peraeopod 7, basis very broad hind margin nearly bare, proximal cusp low or lacking; segment 4 broad, triangular; segment 5 broad. Pleon segment 3 strongly deflexed posteriorly, postero- distal lobe strong, overhanging urosome. Pleon plate 3, hind comer acutely produced. Pleopods powerful; peduncle short, broad; outer ramus 10-16 segmented, inner shorter, with proximal baso-medial lobe. Urosome short, lacking antero-distal lappet. Uropod 1, rami cylindrical, inner ramus with posterior marginal setae only. Urosome 2 short, not occluded dorsally. Uropod 2, rami heavily setose, subequal. Uropod 3, rami short, <2X peduncle, terminal segment variable. Telson lobes widely separated at base; each with dorso-lateral marginal setae, and single apical penicillate seta. Coxal gills saclike, on peraeopods 2-6. Brood plates relatively narrow, elongate. Distribution. Member species are endemic to the North Pacific coastal shelf regions of eastern Asia, and North America, from the Bering Sea to Vietnam in the west, and in the east, south to Baja California. Taxonomic commentary. Eohaustorius is distinct from North American Atlantic genera in the unlike form of peraeopods 3 & 4 and the widely separated telson lobes. However, in the short antennal flagella, form of the lower lip, maxilla 1 & 2, maxilliped, processiferous pleon plate 3, and setose telson, it more closely resembles the warm-temperate North Atlantic genus Pseudohaustorius (Fig. 2, p. 41) than the type genus Haustorius (Fig. 2.2). Such basic similarities suggest a former ancestral link with the diverse Atlantic haustoriid complex via the submerged Panama isthmus (Bousfield, 1970) (see also pp. 61-62). Eohaustorius eous (Gurjanova) 40) plumose setae; segment 5 medium broad, widest distally; flagellar segment 1 with postero-distal setal cluster. Mandible, palp segment 3 with 14-15 posterior mar- ginal comb spines. Maxilla 2, inner plate with distinct facial row of 6-7 plumose setae. Maxilliped, outer plate medium; palp segment 2, inner lobe large, broad, reaching almost to tip of narrowly clavate segment 3. Coxae 1 & 2. Gnathopod 1 , segment 5 relatively short, deep; segment 6 medium, arcuate. Gnathopod 2, hind margin long-setose; segment 5 slender, shallow, distal spines slender. Peraeopod 3, coxa squarish; segment 4 short, distally broad; segment 5 strongly setose proximally; segment 6 AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 39 FIG. 1. Eohaustorius eous. (Gurjanova). Female ov. (5.0 mm). Bering Sea, Alaska. Slattery coU. ovate, margins spinose. Peraeopod 4, segment 4 with 23 posterior marginal setae; segment 4 hind lobe short, distally broad, truncate, anterior margin with 1 stout spine group; segment 6 slender, with 21 anterior marginal spine group. Peraeopod 5, basis broadly ovate, hind margin com- pletely lined with setae; segment 4 short, uniformly broad; facial spine clusters strong; segment 5 medium, not wider than long, facial spine clusters strong; segment 6 broadest medially, anterior margin with 2 spine clusters, posterior margin with 2 single spines. Peraeopod 6, basis medium, hind margin setose throughout; segment 4 elongate, with 3- 4 facial spine clusters; segment 5 broadest distally, with 2 weak facial spine groups, 4-5 inner distal and 5-6 outer distal marginal spines; antero-distal emargination medium deep; segment 6 relatively long and slender, with 4-5 clusters of mixed long and short spines. Peraeopod 7, basis broad, hind margin distally narrowing and lined with medium setae; segment 4 slightly wider than long, anterior margin with 3 spine clusters, posterior margin lined with long setae; seg- ment 5 squarish, anterior margin with 1 cluster of long spines; segment 6 little broadened, anterior margin with 1, and posterior margin with 4, clusters of medium spines. Pleopods, basis stout, broad, outer margin strongly plumose-setose; outer ramus 15-segmented, inner 12-seg- AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 40 FIG. 2 Eohaustorius eous (Gurjanova) Female ov. (6.0 mm). East coast Kamchatka peninsula. (after Gurjanova, 1962) merited. Pleon plate 3, hind comer strongly produced, nearly straight, acute. Uropod 1, peduncle, outer margin with 4- 5 slender spines; inner ramus, posterior margin with short spines. Uropod 3, outer ramus, terminal segment short (<1/ 2 proximal segment); inner ramus, inner margin with 3 plumose setae. Telson lobes short, slender, with 12 dorso-distal setae. from the northern Sea of Okhtosk, illustrated in Guijanova (loc. cit., fig. 1 36B2) is here considered a variant on the main theme from the Kamchatka pensinsula andBering Searegions. Eohaustorius estuarius Bos worth (Figs. 4) Distribution. Eastern Kamchatka & Bering Sea, 20-40 m; western Bering Sea, subtidally to 25 m. Not taken in southeastern Alaska despite apparently suitable habitat (e.g. , Glacier Bay) where E. washingtonianus was dominant. Eohaustorius estuarius Bosworth, 1973: 253, fig. 2 im. — Staude, 1987: 372 (key), 383 , fig. 18.11 .—Barnard & Kara- man, 1991: 363. Material examined. 10 lots containing 158 specimens: BRITISH COLUMBIA. Taxonomic commentary. E. eous is a relatively primi- tive species, showing several plesiomorphic character states in common with the N. America estarine species E. estuarius. It is not closely related to E. robustus, differing in the character states noted in the key and on p. 37. The material Queen Charlotte Islands, ELB Stns., July-Aug., 1957 (~10 specimens at 3 stations, verified by W. Bosworth, 1973): H8a (Delkatla Slough) - 3 females; HIO (New Masset) - 1 female; W 1 (north end Lepas Bay) - 8 males 1 2 females, 6 im. Vancouver I., northend, ELB Stns., 1959: 012, AhousBay, AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 41 FIG. 3. Pseudohaustorius caroliniensis Bousfield. Female (7.6 mm), lateral view; mouthparts, telson 2. Haustorius canadensis Bousfield. Female (12.0 mm), mouthparts, telson. (after Bousfield, 1973). Vargas I. - 3 males, 1 fern, 1 im; Stn. 013, Yarksis, Vargas I. - 4 males, 5 females, 1 im. Central Vancouver I., ELB Stns.,1955: PI, Clayoquot I. - 1 female, 1 im; P6a, southeast end Wickaninnish Bay - 1 1 males, 26 females. ELB Stns., July, 1970: P701, south end Long Beach, in surf-exposed sand at freshwater beach seep, LW level - 1 female ov. (5.0 mm), (slide mount) (fig’d specimen), + 17 males, 33 females, CMN Cat. no. NMCC 199 1-1229; P708, Pachena Bay, mouth of estuary - numerous specimens. WASHINGTON. OREGON. ELB Stn. W34, Crescent Beach, east end, near creek mouth- 1 female (4.8 mm), slide mount, -i-12 other females, 5 males, CMN Cat. no. NMCC- 1992- 1255; Stn. W41. Sooes estuary, near mouth, in steep sand banks - 1 im. Diagnosis. Female (5.0 mm): Head, rostrum medium; eyes small, weakly pigmented. Antenna 1, peduncle 2, anterior margin setose nearly to base. Antenna 2, peduncular segment 4, postero-distal lobe large, posterior margin with 25+ plumose setae; segment 5 distally broadest; flagellar segment 1 with distal plumose seta. Mandible, palp segment 3 , inner (posterior) margin with 10-12 marginal comb spines, outer margin with 5-6 mediums etae. Maxilla 2, inner plate with strong facial row of setae. Maxilliped, inner plate tall, slender; outer plate broad, distally truncate; palp segment 2, inner lobe long narrow, reaching tip of broadly expanded palp segment 3. Gnathopod 1, basis, anterior margin weakly setose throughout; carpus short, deep; dactyl, nail long. Gnathopod 2, carpus relatively short and deep, with sub-apical postero- distal cluster of slender spines. Peraeopod 3, coxae expanded anteriorly, basis with antero-distal cluster of setae. Peraeopod 4, segment 4 with 2 posterior marginal plumose setae; segment 5, hind lobe medium, proximal margin with a few setae, anterior margin with strong oblique spine row, hind margin truncate, spinose; segment 6 medium, little broadened distally, with single oblique anterior marginal spine group. Peraeopod 5, coxal hind margin strongly setose; basis medium, hind margin proximally setose; segment 4 rela- tively short, broad, facial spine groups strong; segment 5 shorter than broad, facial spines strong; segment 6 broadest medially, with2 anterior marginal spine groups, hind margin with single spine cluster. Peraeopod 6, basis medium, hind margin distally bare; segment 4 relatively short, broadest distally, with 4 weak facial groups of spines; segment 5 AMPHIPACMCA VOL. 11 NO. 1, AUG. 31, 1995 42 FIG, 4, Eohaustorius estuarius Bosworth, Female ov (5.0 mm) Long Beach, V. L, B. C. (partly after Bosworth, 1973) broader than deep, with 2 small facial clusters of spines, 3- 4 spines along inner distal margin, and 9-10 spines along outer distal margin; segment 6 with 6-7 posterior marginal clusters of short and long spines. Peraeopod 7, basis broadly expanded, lacking proximal basal cusp, hind margin nearly bare; segment 4 short, very broad distally, anterior margin with 2 spine clusters, posterior margin lined with plumose setae throughout; segment 5 short, broader than deep, with 2 anterior marginal spine clusters; segment 6 broad, anterior margin strongly convex with single cluster of strong spines, posterior margin with 2 spine clusters. Pleopods normal for the genus. Pleon plate 3, hind comer strongly produced, straight, acute. Uropod 3 rami relatively short, <2X peduncle; outer ramus medium; inner ramus with few inner marginal seta. Telson lobes medium broad, regularly setose. Distribution. Common in freshwater intertidal seeps and rills over open and/or protected sand beaches, from Central California north through Oregon, Washington, and British Columbia to Dixon Entrance; not yet taken in south- eastern Alaska. Taxonomic commentary. As noted elsewhere (p. 59), this specis shows mainly plesiomorphic character states. It is a member of the E. eous subgroup and similar to E. gurjanovae of the Asiatic North Pacific region.. Eohaustorius subuUcolus Hirayama (Fig. 5) Eohaustorius subulicolaRiTSiy ama, 1985: 43, figs. 155-157. Eohaustorius subulicolusBamaid&Karaman, 1991: 463. — Ishimaru,1994: 64. Diagnosis. Male (2.25 mm): Head, rostmm short, de- curved. Pigmented eyes lacking. Antenna 1, accessory flag- ellum medially inserted on peduncular segment 3. Antenna 2, peduncular segment 4, antero-distal lobe shallow; hind margin with few (~17) plumose setae; segment 5 of medium width; flagellar segment 1 with single large postero-distal seta. Mandibular palp, segment 3 with few (4-5) comb spines. Maxilla 1, outer plate with 8 apical spines. Maxilla 2, inner plate with 6-7 submarginal facial row of setae. Maxilliped, AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 43 FIG. 5. Eohaustorius subulicolus Hirayama. Male palp segment 3 narrowly clavate; outer plate narrow. Coxa 1 vestigial; coxa 2 small rounded below, hind mar- gin with single seta. Gnathopod 1 , segment 5 short and deep; segment 5 slender. Gnathopod 2, basis with ~5 hind mar- ginal setae; segment 5 with 5 distally spoon-shaped spines. Peraeopod 3, basis, hind margin with distal setae only; segment 5, hind margin lacking proximal setae; segment 6 narrow. Peraeopod 4, coxa slender smoothly convex in front; basis hind margin bare; segment 4 with 4 posterior marginal setae; segment 5 (carpus), posterior lobe slender acute, lacking spines; segment 6 slender, with apical spine(s) only. Peraeopod 5, basis, posterior margin setose throughout; segment 4 narrow, longer than broad, facial spines medium; segment 5 slender; segment 6 slender, with single anterior marginal spine. Peraeopod 6, basis, hind margin setose throughout; segment 4 little broadened, facial spines lack- ing; segment 5 broadest distally, lacking facial spines, distal margin with a few spines near hinge; segment 6, postero- distally with slender split-tipped spines and long setae. Per- aeopod 7, basis lacking proximal cusp, hind margin straight. (2.25 mm). Tomioka Bay. (after Hirayama, 1985). nearly bare; segment 4 slender, hind margin nearly bare; segment 5 as long as broad, anterior margin with 3-4 slender spine groups; segment 6 slender with single anterior mar- ginal spine cluster and elongate pectinate apical spines. Pleopods, peduncle small; rami slender, outer ramus 9- 10-segmented. Pleon plate 3, hind corner strongly produced, hooklike, extending well beyond postero-dorsal process. Uropod 1, rami with apical spines and setae. Uropod 3, rami slender; inner ramus lacking inner marginal setae; outer ramus, terminal segment strong (> 2/3 inner segment). Telson lobes slender, marginal setae few. Distribution. Tomioka Bay, Japan; subtidal. Taxonomic commentary. Eohaustorius subulicolus is distinctive on the basis of reduction of some character states, and special development of others. Hirayama (1985) des- cribed the species from the type male and four additional specimens. He noted its general resemblance to F. cheliferus. but E. subulicolus may qualify for separate subgeneric status. AMPHIPACMCA VOL. 11 NO. 1, AUG. 31, 1995 44 Eohaustorius sawyeri, Bos worth (Fig. 6) Eohaustorius sawyeri Bosworth, 1973: 257, fig. la-e. — Austin, 1985: 607. — Staude, 1987: 383, 372 (key). — Barnard & Karaman, 1991: 363. Material examined. Six lots containing 37 specimens (both sexes and subadults), from 4 localities in British Col- umbia, and two in California: BRITISH COLUMBIA. Vancouver I., southern end: Off Long Beach, V. I., 22 m, P. Slattery Stn., 1982 - 3 males, CMN Cat. no. NMCC1991- 1219. ELB Stn. P21a, Trevor Channel, off Bordelais I., 44 m, fine sand, Aug. 9, 1975 - 1 female (3.2 mm) (slide mount) (figured specimen) , CMN Cat. no . NMCC 1991-1227; Ibid . , Stn. B9c, off Second beach, 20-25 m, medium sand, June 28, 1976 - 1 female; ELB Stn. H41, Jordan R., black silty sand, LW, July 27, 1964 - female ov (5.2 mm). CALIFORNIA Off Marine Laboratory, Moss Landing, 2 m sand, P. Slattery coll., June 1, 1982 - 2 males, 7 females, CMN Cat. no. NMCC1991-i240; Ibiil. 12 m, July 1, 1982 - 5 males, 8 females, CMN Cat. no. NMC1991-1239. Diagnosis. Female im. (3.2 mm.): Head, rostrum. Eyes whitish, not pigmented. Antenna 1, peduncle 2, anterior margin weakly setose, singly inserted. Antenna 2, peduncle 4, postero-distal lobe medium, posterior margin with 30+ plumose setae, antero-distal lobe strong, extending >2/3 length of segment 5; segment 5 relatively shallow; basal flagellar segment with 3-4 distal plumose seta. Mandible, palp segment 3 with 8-11 posterior marginal comb spines. Maxilla 1, palp stout, proximal segment short (< 1/2 segment 2). Maxilla 2, inner plate, facial setae submar- ginal. Maxilliped, outer plate medium; palp segment 2, inner lobe narrow, shorter than medium-large segment 3. Gnathopod 1, coxa subquadrate; basis broadened medi- ally, anterior margin smooth distally; segment 5 elongate, medium deep; segment 6, thick (deep). Gnathopod 2, basis, anterior margin smooth; segment 5 slender, lower margin straight. Peraeopod 3, coxa 3 subquadrate; segment 4 short, very broad distally; segment 5 deep, with antero-proximal in- vagination, hind margin proximally setose; segment 6 large, lozenge-shaped, margins slender- spinose. Peraeopod 4, seg- ment 4 with 4 postero-marginal setae; anterior margin with distal spine group; segment 5, anterior margin with fan- wise spine row, hind lobe short, postero-proximal margin with 2 spine clusters; segment 6 stout, broadening distally, with 2 anterior and 2 posterior marginal spine clusters. Peraeopod 5, basis broadly ovate, hind margin nearly bare distally; segment 4 short, strongly broadest distally, facial spines strong; segment 5 expanding distally, longer than broad, facial spines strong; segment 6 broad, apex truncate, anterior margin with 1, posterior margin with 3 spine clusters. Peraeopod 6, basis medium broad, hind margin lightly setose proximally; segment 4 long, broadest distally, with several strong facial spine clusters; segment 5 broadening distally, with 2 strong facial spine clusters antero- distal margin with 12-15 spines, excavation shallow; seg- ment 6 slender, with 4-5 posterior marginal spine clusters. Peraeopod 7, posterior margin of coxa broadly acute; basis broad, convex hind margin distally with a few short setae, lacking proximal cusp; segment 4 short, broadest distally, hind margin setose; segment 5 broader than deep, anterior margin with single spine group, antero-distal free margin broad, lined with spines, postero-distal angle with long heavy spine; segment 6 broad, anterior margin with 1, post- erior margin with 3-4 stout spine groups. Pleopods, peduncle short broad, outer margin strongly plumose- setose; outer ramus 16-segmented, inner ramus 13- segmented. Pleon plate 3, hind corner moderately produced, acute, strongly overhung by, and much shorter than, postero- dorsal process of pleosome 3. Uropod 1, peduncle, outer margin with 3-4 slender spines, distal spine cluster medium; inner ramus posteriorly setose; outer ramus narrow, apex sub-acute. Uropod 3, outer ramus slightly the longer, terminal segment medium; inner ramus lacking inner marginal setae. Telson lobes short, broad, with few dorso-distal setae. Distribution. A southern species, abundant along coasts of California and Oregon, diminishing in Washington, and barely entering British Columbia. Occurs along outer surf- exposed sand beaches, from MLW to shallow subtidally. Taxonomic Commentary. The large female specimen from Jordan R. exhibited a very broad segment 6, and heavy facial spines on segments 4 & 5 of peraeopods 5 and 6. Eohaustorius sencillus J. L. Barnard (Fig. 7) Eohaustorius sencillus Barnard, 1962: 249, figs 1, 2. — Bos- worth, 1973: 8 (key). — Barnard, 1975, fig. 44. — Barnard & Karaman, 1891: 363. Material examined. Mile buoy, off Moss Landing, California, 20 m sand, P. Slattery coll., Feb. 24, 1971 - 1 female (slide mount) (figured specimen), CMN Cat. no. NMCC1991-1241; 13 additional females, 2 males. Diagnosis. Female (3.5 mm): Head, rostrum short. Pigmented eyes lacking. Antenna 1 , peduncular segment 2, anterior margin weakly setose, bare proximally. Antenna 2, peduncular segment 4 relatively short and deep, postero- distal lobe medium, hind margin with 25-30 plumose setae; segment 5 as deep as long; basal flagellar segment postero- distally with 4-5 long setae. Mandible, palp segment 3 slender, with 7 posterior marginal comb spines. Maxillae undescribed. Maxilliped, outer plate broad; palp segment 2, medial lobe large, broad, shorter than moderately broadened terminal segment. . AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 45 FIG, 6. Eohaustortus sawyeri Bosworth, 1973. Female ov ( 3.2 mm ). Off Long Beach, V.I., B.C. Coxae 1 & 2 squarish below. Gnathopod 1 , basis with 7-8 posterior marginal setae; segment 5 medium, deep, convex below; segment 6 sharply broadest medially; dactyl, unguis large, heavy. Gnathopod 2, basis lined posteriorly with longish setae; segment 5 slender, strongly setose; postero-distal spines few, weak; segment 6 slender, regular. Peraeopod 3, coxa deep, sublunate; segment 4 medium broad distally, hind margin with 7-9 setae; segment 5 rela- tively shallow, anterior margin bare, not emarginate proxi- mally, lower margin proximally setose; segment 6 lenticular. margins slender spinose. Peraeopod 4, segment 4 relatively large, hind margin convex, with 2-3 long setae, anterior margin with weak oblique spine row; segment 5, with weak anterior oblique spine row, posterior lobe medium, rounded behind, with 2 weak postero-proximal spine groups; seg- ment 6 slender, with anterior marginal spine cluster, and 2 postero-distal single marginal spines. Peraeopod 5, basis ovate, hind margin lacking distal setae; segment 4 not broader than deep, parallel-sided, facial spine groups weak; segment 4 relatively small, not wider AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 46 FIG 7. Eohaustonus sen ciUus Barnard, 1962. Female (3.5 mm). Off Moss La nding, California. than deep facial spine groups weak; segm ent 6 not br^- Pleon plate 3. hind comer acutely produced, short Up ened, anterior and posterior margins each with 2 single directly beneath dorsal we^ Tne; snines anex narrowly truncate, weakly spinose. outer margin nearly bare, distal spine cluster weak, inner Peraeopodb coxa narrow, deep; basis relatively little broad- ramuswealdysetosepostenorly;outerramus,postenormM- Ined h^d margin with proxLal setae only; segment 4 gin with slender spines. Uropod 3 rami ^ donaate broadest medially, with 6 small facial spine clus- -2X peduncle; outerramus,ternmn^ segment very short ( 36 H- j 32 ® 30 O) 28 UJ < 26 So 24 22 FIG. 16. PHENOGRAM OF NORTH PACIFIC SPECIES OF EOHAUSTORIUS* abcdefghjklm cc LU I- o < cr < X o Q UJ X < Q. 20 18 16 14 12 10 8 "r 13 "T" 20 I I 17 13 "T- 14 "T" 13 16 -T" 15 23 "r 16 SPECIES A subulicofus B cheliferus C robustus D gurjanoyae E eetuarius F ecus G H J K L M "r 16 sawyer/ longicarpus senci/lus wastiingtonianua brevicuspis barnardi 22 P.-A. INDEX 75 >- X < 50 CO 25 * except. E. tandeensis Dang, 1968 cusp on the posterior margin of the basis of peraeopod 7, one spine cluster on the postero-distal margin of segment 5 of peraeopod 4, and a relatively large maxilliped palp segment 3. The core eous group shows mainly plesiomorphic char- acter states, including a relatively elongate, facially and marginally spinose, segment 4 of peraeopod 6 that typifies most Atlantic genera of haustoriinids. E. sencillus is uniquely advanced in its very short antennal flagella, enlarged dactyl of gnathopod 1, and short maxilliped palp segment 3. All in all, few species pairings exhibit greater than 75% similarity and none is closely related, suggesting long peri- ods of isolation and limited gene flow between populations. The relatively primitive nature of intertidal vs. subtidal spec- ies of Eohaustorius is consistent with similar trends in other regional fossorial amphipods (e.g, Jarrett & Bousfield, 1 994a). Biogeographical Considerations The subregional occurrence of species of Eohaustorius is provided in Table II. Of the twelve species considered here, five are endemic to Asiatic North Pacific shores, and six to the North American coast. Only one species, E. eous, occurs in both continental waters, and only in the Bering Sea region. In the Asiatic region, E. robustus and E. cheliferus are confined mainly to the Sea of Okhotsk and Kamchatka regions whereas E. gurjanovae, E. longicarpus and £. sub- ulicolus have been recorded exclusively or mainly from southern Sakhalin Island and the Sea of Japan. In the more southerly region, these haustoriid species overlap distri- butionally, in similar sedimentary habitats, with members of the talitroidean fossorial family Dogielinotidae. The dogiel- AMPHIPACIFICA VOL. 11 NO, 1, AUG. 31, 1995 60 TABLE I. CHARACTERS AND CHARACTER STATES OF SPECIES OF EOffAl/SrO/f/l/S CHARACTER STATE VALUE CHARACTER Plesiomorphic 0 Intermediate 1 Apomorphic 2 ■ 1. Antenna 2, peduncle 4, number of <20 25 >30 posterior marginal setae 2. Antenna 2, flagellar segment 1, 1 2 3+ number postero-distal long setae 3. Mandibular palp segment 3, number of 10+ 7 5 posterior marginal comb spines Small 4. Maxilliped palp, segment 3, size Large 5. Peraeopod 3, coxal shape Squarish Semilunate 6. Peraeopod 4, hind lobe of segment 5 Short W>L Long L»W 7. Peraeopod 4, segment 5, hind lobe, Absent Present distal marginal spines 8. Peraeopod 5, length of segment 4 Long Short 9. Peraeopod 5, shape of segment 5 Narrow Wide 10. Peraeopod 5, segment 6, number 2-3 1 of posterior marginal spines 11. Peraeopod 6, length of segment 4 Long L»W Short W=L 12. Peraeopod 6, segment 5, number 2 1 of anterior marginal spine clusters 13. Peraeopod 6, segment 4, hind 1+ 0 marginal spines 14. Peraeopod 7, basis, proximal hind lacking present marginal cusp 15. Peraeopod 7, segment 5, number 2-3 1 of anterior marginal spine clusters 16. Peraeopod 7 segment 6, number 3-4 2 1 of posterior marginal spine clusters 17. Pleon plate 3, type of hind process short medium straight long, hooked 18. Uropod 1, inner ramus, number of 5+ 2 0 posterior marginal setae 19. Uropod 3, size of terminal seg- Long short ment of outer ramus 20. Telson lobes, form. elongate short AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 61 TABLE II.. DISTRIBUTION OF NORTH PACIFIC SPECIES OF EOHAUSTORIUS SPECIES BIOGEOGRAPH I CAL ZONES 1 2 3 4 5 6 7 8 9 E. subulicolus'^ X E, longicarpus^ X E, gurjanovae^ X X E, cheliferus^ X X E, robustus^ X E. eous^ X X E, estuarius* 9 X X X 9 E. washingtonianus* X X X X X E. brevicuspis* X X X E. sawyeri* X X X X E. sencillus^ X X X E. barnardi^ X X ZONES: 1. Japan Sea and southward 2. Sea of Okhotsk region 3. Bering Sea -W.Alaska 4. Southeastern Alaska 5. Northern British Columbia 6. Southern British Columbia 7. Washington-Oregon 8. North & Central California 9. Southern & Baja California Ecology:* Intertidal; ^ Subtidal inotid species, of similar or slightly larger size, tend to occur mainly intertidally, during summer months at least, along sandy beaches and in estuaries, often in very high densities (Kamihira, 198 1 ; Bousfield & Tzvetkova, 1982). The north- ernmost beaches are subject to freezing and ice scour, esp- ecially during the winter and early spring, during which time the dogielinotids shift from the littoral to the infralittoral zone. The regional haustoriid species occur subtidally, at least during summer months, and probably year-round. Perhaps intense competition with the filter-feeding and “sand- licking” dogielinotids in summer, and rigorous physical con- ditions in winter, are factors that have apparently prevented evolution of Asiatic regional intertidal haustoriid species. Along North American Pacific sandy shores however, the situation is strongly contrasting. Of the six species recorded from southeastern Alaska to southern California, the four northernmost species, E. estuarius, E. washingtonianus, E. brevicuspis and E. sawyeri occur essentially intertidally and shallow sublittorally. As noted on page 59, and in figure 16, these northern species show mostly plesiomorphic character states and probably evolved early during the penetration of the genus into the North Pacific region. The two southermost species, E. sencillus and E. bamardi, are strictly subtidal and their character states are significantly more advanced. However, the northern intertidal species and one southern subtidal species (£. sencillus) all co-occur in biogeographical zone 6 (Washington-Oregon), the very region in which the single North American dogielinotid species, Probosdnotus loquax (Barnard, 1967) occurs intertidally in great abundance (Hughes, 1982). '^\^%ptc\^^,dS[d.Eohaustonusbrevicuspis, co-occur intertidally on open surf sand beaches and are AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 62 presumed to be heavily preyed upon by shore birds, especially during late summer. However, despite these negative factors of competition and predation, intertidal haustoriids are able to occur commonly throughout zone 6, and indeed zones 4-9, almost certainly because of year-round near uniformity of coastal marine conditions; water temperature seldom fall below 5®C, and winter ice scour is non-existent (Thomson, 1981). These near-uniform physical conditions probably account for the relatively wide geographical range of the North American species, each of which occurs in 3-5 biogeographical zones vs. the 1-2 zones of the Asiatic species. With respect to its overall biogeographical affinities, Eohaustorius is essentially a cold temperate genus and, in this respect, closer to the presumed para-ancestral ponto- poreiid and perhaps distantly ancestral gammaroidean groups that are restricted to holarctic regions (Bousfield, 1970; Bousfield & Shih, 1994). In the North Pacific, members of the genus Eohaustorius occur well north of 60^^ north lati- tude, and into the Bering Sea region, but apparently not into arctic waters where the Pontoporeiidae dominate (Bousfield, 1987). In the western North Atlantic region, however, the 7 haustoriid genera are essentially temperate, and warm- temp- erate in thermal requirements. Species of the most eurytopic genus, Haustorius, range along North American shores north only to latitude 47® (southern Gulf of St. Lawrence) where they appear to be limited intertidally by the severity and duration of winter conditions (Bousfield, 1965). In western Europe, however, where winter conditions are relatively mild and reminiscent of those of the western north Pacific, the species H. arenarius attains 60® north latitude (southern Norway) (Lincoln, 1979). In conclusion, we have noted on p. 59 that Eohaustorius is grossly similar morphologically to the North Atlantic complex of haustoriid genera, but is here found biogeo- graphically unrelated to them. In absence of firm evidence to the contrary, the genus Eohaustorius is here surmised to have been isolated in the North Pacific for a considerable period of time. An hypothetical subtidal common ancestor may have connected it directly to the relatively primitive North Atlantic genus, Pseudohaustorius, possibly during the early Miocene epoch. At that time, the Panama isthmus had not yet formed and suitably cool marine connections existed between Atlantic and Pacific coastal marine regions (Adams, 1981). Although such an explanation is not entirely satisfactory, it does accord reasonably with rationale proposed for similar Pacific-Atlantic disjunct distributions in other amphipod groups. Thus, in some members of the fossorial phoxocephalid genus Eobrolgus (Jarrett and Bousfield, 1994b) and in two species of the non-substrate modifiying parapleustin genus Incisocalliope (Bousfield and Hendrycks, 1995), the distributional hiatus and its explanation may be similar, but the evidence for it appears to be more compelling. REFERENCES Adams, C.G., 1981. An Outline of Tertiary palaeogeography. Ch. 14, pp. 221-235. The Evolving Earth. P. H. Greenwood & R. L.M. Cocks (eds.). Brtish Museum Natural History. Cambridge University Press. Austin, W. C., 1985. An annotated checklist of marine in- vertebrates in the cold temperate Northeast Pacific. Khoyatan Marine Laboratory, Vol. HI., 1985. Barnard, J. L., 1957. A new genus of haustoriid amphipod from the northeastern Pacific Ocean and the southern distribution of \Jrothoe varvarini Gurjanova. Bull. So. Cal. Acad. Sci. 56, Part 2; 81-84, pi. 16. , 1962. A new species of sand-burrowing amphipod crustacean from Southern California. Bull. S. Calif Acad. Sci. 61; 249-252. 2 figs. , 1967. New and old dogielinotid marine Amphipoda. Crustaceana 13: 283-291, 6 figs. , 1975. Amphipoda: Gammaridea. pp. 313- 366. in Light's Manual (Intertidal invertebrates of the central California coast), 3rd edition. R. I. Smith & J. T. Carleton (eds.). 716 pp. , & M. M. Drummond, 1982. Gammaridean Amphipoda of Australia, Part V: Superfamily Haustori- oidea. Smiths. Contr. Zool. 360: 1-148, 58 figs. , and G. S. Karaman, 199 1 . The Families and Genera of Marine Gammaridean Amphipoda (Except Marine Gammaroids). Rec. Austral. Mus., Pts. 1 & 2: 866 pp., 133 figs. Bosworth, Jr., W. S . , 1973. Three new species of Eohaustorius (Amphipoda: Haustoriidae) from the Oregon Coast. Crustaceana, 25: 253-260, 2 figs. Bousfield, E. L., 1958. Ecological Investigations on shore Invertebrates of the Pacific Coast of Canda. Natl. Mus. Can. Bull. 147: 105-115. , 1963. Investigations on seashore inver- tebrates of the Pacific coast of Canada, 1957 and 1959. I. Station List. Natl. Mus. Can. Bull. 223: 49-57. , 1965. Haustoriidae of New England (Crustacea: Amphipoda). Proc. U. S. Natl. Mus. No. 3512, Vol. 117: 159-240, 31 figs. , 1968. Studies on littoral marine inverte- brates of the Pacific coast of Canada. I. Station List. Natl. Mus. Can. Bull. 223: 49-57. , 1970. Adaptive Radiation in sandburrow- ing amphipodcrustaceans. Chesapeake Sciencel 1 (3): 143- 154. , 1973. Shallow-water Gammaridean Am- phipoda of New England. Cornell Univ. Press. Ithaca, N. Y. 312 pp., 69 pi.. — , 1982a. Amphipoda (Palaeohistory). McGraw-Hill Yearbook Science & Technology. 1982- 83: 96-100. AMPHIPACIFICA VOL. 11 NO. 1, AUG. 31, 1995 63 , 1982b. Amphipoda. Gammaridea. in S. P. Parker [ed.]. Synopsis and classification of living org- anisms. McGraw-Hill, New York, vol. 2: 254-285, and 293-294. , 1987. Revised morphological relationships within the amphipod genera Pontoporeia and Gammar- acanthus and the "glacial relict" significance of their postglacial distribution. Jour. Fish. Aqu. Sci. 46(10)- 1714-1725. , 1990. Morphological Convergence in Free-burrowing amphipods and its significance in phyl- etic classification. Proc. 5th Amphipod Colloquium, Darling Marine Centre, Walpole, Me., September, 1989. Oral presentation. Abstr. ^ , & E. A. Hendrycks, 1995. The amphipod family Pleustidae on the Pacific coast of North America: Part III. Subfamilies Parapleustinae, Dactylopleustinae and Pleusirinae. Sy stematics and Distributional Ecology. Amphipacifica II (1): 65 - 134. — ^ -, & N. E. Jarrett, 1981. Station Lists of Mar- ine Biological Expeditions of the National Museum of Natural Sciences in the North American Pacific Coastal Region, 1966 to 1980. Syllogeus. Natl Mus. Nat. Sci. No. 34: 1-66. ^ , & D. E. McAllister, 1962. Station list of the National Museum marine biological expedition to south- eastern Alaska and Prince William Sound. Natl. Mus. Nat. Sci. Bull. 183:76-103. , and C.-t. Shih, 1994. The phyletic classif- ication of amphipod crustaceans: problems in resolut- ion. Amphipacifica 1(3): 76-134. — — , & N. L. Tzvetkova, 1982. Studies on Dog- ielinotidae (Amphipoda, Talitroidea) from the shallow waters of the North Pacific region. Expl. Fauna Seas 1982, 29 (37): 76-94. (In Russian). Bulycheva, A. N., 1952. Novye vidy bokoplavov (Amphi- poda-Gammaridaea)iz JaponskovoMorei. ILAkad. Nauk SSSR. Trud. Zool Inst. 12: 195-250, 39 figs. Conlan, K. E., 1983. The amphipod superfamily Corophioidea in the northeastern Pacific region. 3. Family isaeidae: systematics and distributional ecology. Natl Mus. Nat.Sci (Ottawa) Publ. Nat. Sci.: 1-75. Coyle, K. O, & G. J. Mueller, 1981. New records of Alask- an marine Crustacea. Sarsia 66: 7-18, 5 figs. Dang, N. T., 1968. Amphipods of North Vietnam. Zool. Zhum. 47: 212-222, 4 figs. Gurjanova, E. F., 1951. Bokoplay Moreii SSSR i sopred- 'elylnik vod (Amphipoda-Gammaridea) Akad. Nauk SSSR Opred. po Faune SSSR 41: 1029 pp., 705 figs. ^ , 1953. Novye dopolnenija k dal' nevost- ochnoi faune morskik bvokoplavov. Akad. Naul SSSR. Trud. Zool. Inst. 13:21 6-24 1 , 1 9 figs. - , 1962. Bokoplavy severnoi chasti Tixogo Okeana (Amphipoda-Gammaridea) chasf 1 .Akad. Nauk SSSR. Opred. po Faune SSSR 74: 440 pp, 143 figs. Hirayama, A., 1985. Taxonomic Studies on the shallow- water gammaridean Amphipoda of West Kyushu, Japan rv. Publ. Seto Mar. Biol. Lab. 30: 1-53., figs. 124- 161 Hughes, J.E., 1982. Life history ofthesandy-beach amphipod Dogielinotus loquax (Crustacea: Dogielinotidae) from the outer coast of Washington, USA. Mar. Biol. 72(2)- 167-175. Ishimaru, S., 1994, A Catalogue of Gammaroidean and In- golfiellidean Amphipoda recorded from the vicinity of Japan. Rept. Sado Mar. Biol. Sta., Niigata Univ., No. 24: 29-86. Jarrett, N. E., & E. L. Bousfield, 1994a. The amphipod sup- erfamily Phoxocephaloidea on the Pacific coast of North America. Family Phoxocephahdae. Part I. Metharpiniinae, new subfamily. Amphipacifica I (1): 58-140. , & E. L. Bousfield, 1994b. The amphipod sup- erfamily Phoxocephaloidea on the Pacific coast of North America. Family Phoxocephahdae. Part II. Subfamilies Pontharpiniinae, Parharpiniinae, Brolginae, Phoxoceph- alinae, and Harpiniinae. Systematics and Distributional Ecology. Amphipacifica I (2): 71-150. Kamihira, Y., 1981. Life history of sand-burrowing amphi- podHaustorioidesjaponicus (Crustacea: Dogielinotidae). Bull.Fac.Fish.HokkaidoUniv.32(4):338-348. Lincoln, R. J., 1979. British Marine Amphipoda. London: British Museum (Natural History). 658 pp., 280 figs. McLeay, et al. 1992. Acute Test for Sediment Toxicity Us- ing Marine or Estuarine amphipods. Environmental Pro- tection Series Biological Test Method. Report to Envir- onment Canada, MS Report, 1 16 pp., May, 1992. Schram, F. R., 1986. Crustacea. Oxford Univ Press, New York. 602 pp. Sneath, P. H. A., & R. R. Sokal, 1973. Numerical Taxon- omy. W. H., Freeman, San Francisco. 573 pp. Staude, C. P., 1987. Amphipoda: Suborder Gammaridea. pp. 346-391. ip E. Kozloff (ed.) Intertidal Invertebrates of the Pacifc Northwest. University Washington Press, Seattle. 511 pp. Stebbing, T. R. R., 1906. Amphipoda: Gamaridea. Das Tierreich. I. Berlin. 806 pp. Thomson, R. E., 1981. Oceanography of the British Col- umbia coast, Canada, Fish. & Aqu. Sci., Special Publ No 56: 1-291. Thorsteinson, E. D, 1941. New or Noteworthy Amphipods from the North Pacific coast. Univ. Washington, Publ. Oceanogr. 4: 50-96, 8 pis. Yee, S., M. Van Rikxoort, & D. McLeay, 1992. The effect of holding time on Eohaustorius washingtonianus dur- ing ten-day sediment bioassays and reference toxicant tests. Report to Environment Canada & Intergovern- mental Aquatic Toxicity Group. 40 pp.. Appendix. AMPHIPACMCA VOL. 11 NO. 1, AUG. 31, 1995 64 The Canadian Field-Naturalist A continuation of 115 years of publication on northern North American biodiversity 1880-1995. The Canadian Fie/d-Naturalist is the official publication of The Ottawa Field- Naturalists’ Club and features both articles and notes on original research, and observations on the natural history of northern North America (including distribution, faunal analyses, taxonomy, ecology, and behaviour). Issues include news and comment (Club annual meetings and awards, tributes and review papers) and book review and new title sections. Since 1984, it has presented edited Status Reports for individual species designated by the Convention on Species of Endangered Wildlife in Canada (COSEWIC). It is entirely supported through club membership and subscriptions, page and reprint charges. The Ottawa Field-Natulalists’ Club has 1041 members and The Canadian Field-Naturalist an additional 248 individual and 573 institutional subscribers, for a distribution of 1 862 copies. The Ottawa Field-Naturalists’ Club was formed in 1 879 by scientists from embryonic federal departments including the Geological Survey and the Dominion Experimental Farm, and leading amateurs; this type of mix remains its strength to this day. The Club quickly emphasized publication, and for seven years beginning in 1880, it annually issued the Transactions of the Ottawa Field Naturalists’ Club. With volume 3 in 1887, the Transactions became a subtitle of Volume I of The Ottawa Naturalist, a monthly publication. With Volume 3 of The Ottawa Naturalist in 1889, the emphasis changed from local members’ reports to national ones, and in 1919 the journal was renamed The Canadian Field-Naturalist (starting with Volume 33 which was Volume 35 of the Transactions but this subtitle was subsequently dropped). The issues per year were gradually reduced from 12 to 9 to 6 and eventually to 4, the latter beginning with Volume 67 in 1953. However, the annual number of pages increased, in 1988 (volume 102) reaching a record of 798 with a the largest single issue of 216 pages in 102(2). Since 1967, the Club has separately published a local (Ottawa area) natural history journal. Trail & Landscape, now also issued quarterly. Submissions to The Canadian Field-Naturalist and predecessors have long been peer reviewed, first through a “Publishing Committee”, later “Sub-editors”, and then “Assistant Editors” until the designation “Associate Editors” was adopted in 1 885 and maintained ever since. Currently, most submissions also go to at least one (and often more) additional reviewer(s). Associate Editors are listed in every issue and, since 1982, additional reviewers have been acknowledged annually in the Editor’s Report. A formal publication policy was published in The Canadian Field-Naturalist 97(2); 231-234. Advice to Contributors” is published in one or more issues annually. The current subscription rate is $23 for individuals and $38 for institutions. Postage outside Canada is $5.00 additional. Subscriptions should be sent to The Canadian Field-Naturalist, Box 35069, Westgate P.O., Ottawa, Ontario, Canada KIZ 1 A2. Manuscripts for consideration should be addressed to Dr. Francis R. Cook, Editor, Canadian Field-Naturalist, RR 3, North Augusta, Ontario, Canada KOG IRO. Francis R. Cook AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 65 THE AMPHIPOD FAMILY PLEUSTIDAE ON THE PACIFIC COAST OF NORTH AMERICA: PART IH. SUBFAMILIES PARAPLEUSTINAE, DACTYLOPLEUSTINAE, AND PLEUSIRINAE. SYSTEMATICS AND DISTRIBUTIONAL ECOLOGY. by E, L. Bouslield^ & E. A. Hendrycks^ ABSTRACT The gammaridean amphipod subfamily Parapleustinae Bousfield & Hendrycks, 1994, contains 28 described species of which 26 have been recorded from coastal marine regions of the North Pacific Ocean. From shallow coastal shelf waters of the both continental coasts are here described and figured the following tax a: Parapleustes americanus, new species; P . ishimarui, new species; Chromopleustes lineatus, new genus, new species; Gnathopleustes serratus new genus, new species, G. simplex, new species; G. trichodus, new species; G. pachychaetus, new species; Trachypleustes vancouverensis, new genus, new species; T. trevori, new species; Micropleustesnautiloides, new genus, new species and M, behningiodes, new species. Also proposed for inclusion within the subfamily ar^ Commensipleustes, new genus (type species; C. commensalis (Shoemaker, 1952); Incisocalliope J. L. Barnard, 1959 (revived status) (type species; /. newportensis Barnard, 1959). This genus contains eight species of which is newly described from the Sea of Japan. Also variously redescribed, or treated, are; Gnathopleustes den (J. L. Barnard, 1969b); G. pugettensis (Dana, \%5^)\ Incisocalliope newportensis J. L. Barnard, 1959; /. bairdi (Boeck, 1871); Chromopleustes oculatus (Holmes, 1908); C. johanseni (Guijanova, 1951); Micropleustes nautilus (J. L. Barnard, 1969b) and M. behningi (Guijanova, 1938). Dactylopleustes echinoides, new species (subfamily Dactylopleustinae Bousfield & Hendrycks, 1994) is newly described and figured, andPleusirus secorrus J. L. Barnard, 1969b (subfamily Pleusirinae Bousfield & Hendrycks, 1994) is redescribed and figured. Taxonomically, the seven parapleustin genera were found to be morphologically distinctive, and not very closely similar. A modified phenetic cluster analysis indicated that the most southerly, temperate and subtropical genus Incisocalliope is phyletically most advanced, and that the mainly N. American cold temperate genus Chromopleustes is the most primitive, despite the relatively advanced nature of its mouthparts, and weakly sexually dimorphic gnathopods. Biogeographically, of the 26 species of Parapleustinae recorded from the North Pacific region, 16 species (in seven genera; occur along the North American coast, nine species (in four genera) along Asiatic shores, and one species in the Hawaiian Islands, south central North Pacific. The genera Parapleustes, Chromopleustes, Micropleustes, Dactylopleustes andPleusirus are Pan-Pacific, with approximately equal numbers of species on North American and Asiatic coasts. However, the generaTrachypleustes, Gnathopleustes and Commensipleustes, containing about a dozen species in total, are apparently endemic to the North American Pacific region. The isolated occurrence of Parapleustes gracilis (Buchholz, 1874), and Incisocalliope aestuarius (Watling & Maurer, 1973) in different temperature regimes of the North Atlantic region, appear anomalous. Although explanations proposed for such disjunct distributions are not entirely satisfactory, they underscore the high regional endemicity of subfamily Parpleustinae within the North Pacific Basin. INTRODUCTION Pleustid amphipods form an important assemblage of microcarnivorous amphipod crustaceans in the North Pacific marine region. Of the 12 recognized subfamilies (Bousfield & Hendrycks, 1994), the Parapleustinae, with nearly 30 described species, is one of the largest and numerically dominant groups in shallow-water habitats of both Asiatic and North America coasts. The monotypic subfamily Pleusirinae is common along the North American coast. Species of Dactylopleustinae are commensals on echinoid echinoderms, rarely encountered, and the subfamily prob- ably more diverse than the three known species would indicate. Prior to the present investigation, only eight species of subfamily Parapleustinae had been recorded from North Amer-ican Pacific localites, all of which had been relegated to the genus Parapleustes by Barnard & Karman (1991). 1 Research Associate, Royal Ontario Museum, Toronto, Canada : 2 Research Assistant, Canadian Museum of Nature, Ottawa, Canac Early 19th century records of Dana, Stimpson, Boeck and others had been capably summarized by Stebbing (1906). In the first half of this century. Holmes (1908) described Ple- ustes oculatus from off California. Few other records accrued until J. L. Barnard commenced his monumental series of studies (1952, 1954, 1956 et sequ.) on amphipod commun- ities of the California coast. His paper with Given (1960) summarized information on five parapleustins known to that date, including Parapleustes newportensis Barnard, 1959, that had been described initially as the type species of a new genus, Incisocalliope. Shoemaker (1952) had earlier des- cribed P. commensalis from the pleopods of a spiny lobster off southern California, and later (1964, posthumously) added to records of Dana's "Parapleustes pugettensis" from Dillon Beach, California. Dana's species name was here found to embody several distinct taxa, mostly new to science. Barnard (1969b) described Parapleustes den, P. nautilus and Pleusirus secorrus from the Central California coast, KIP 6P4. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 66 and the following year (1970) added P. derzhavini makiki from the Hawaiian Islands. Very recently, Barnard & Karaman (1991) submerged P.johanseni Gurjanova, within P. oculatus Holmes, and synonymizedP. bairdi (Boeck) and P. newportensis (Barnard) with P. pugettensis (Dana). The pragmatic illustrated keys of Barnard ( 1975), Staude (1987), and the regional annotated listing of Austin (1985), provide useful summaries of existing knowledge and bases on which to conduct further studies. On the Asiatic Pacific coast, work on parapleustins commenced with Gurjanova’s description of Neopleustes derzhavini and Pleustes behningi (1938) and Parapleustes johanseni (1951). Kudryaschov (1972) provided records of P. nautilus (later proven to be a new species). Tzvetkova (1975) described the echinoid commensal species Para- pleustes echinoicus, later given separate generic status (as Dactylopleustes) by Karaman & Barnard (1979). Kudry- aschov & Tzvetkova (1975) concluded the Russian contrib- ution with a description of Pleusirus secorrus asiaticus. Workers from Japan entered the western Pacific para- pleustin scene with Irie & Nagata's preliminary regional listing (1962) of "Parapleustes oculatus" and "P. pugettensis". Ishimaru (1984) contributed most significantly with Para- pleustes dilatatus n. sp., P. longimanus, n. sp., and records of Parapleustes gracilis Buchholz, P. behningi Gurjanova, and P. derzhavini Gurjanova. Soon after, Ishimaru (1985) added Pleusirus secorrus to the regional list. Hirayama (1988) described Parapleustes filialis, n. sp. and Dactylo- pleustes obsolescens, n. sp. Finally, Ishimaru (1994) treated the entire pleustid fauna of Japan in his useful regional catalogue of gammaridean and ingolfiellidean species. The previous studies had revealed a significant new fauna of parapleustinids, pleusirins and dactylopleustins in the western Pacific and Californian regions. However, corresponding faunas of the enormous intervening costal areas were virtually unknown. Based on extensive new material from the coasts of British Columbia, southeastern Alaska, and Washington and Oregon states, the present study attempts to fill this large hiatus in systematic knowledge. It also attempts to relate these faunas phyletically and bio- geographically to faunas of adjacent regions and elsewhere. ACKNOWLEDGEMENTS The authors are greatly indebted to colleagues and their research institutions who provided field assistance, facilities and materials that made this study possible. Most of the field work was conducted by the senior author (ELB) during the period 1955 -1980, station lists for which have previously been made available (Bousfield 1958, 1963, 1968;Bousfield &Jarrett, 1981; Bousfield & McAllister, 1962). Ship-assisted parts of the work were based at the Pacific Biological Station, Nanaimo, with the help of the late D. B . (Dan) Quayle; at the Pacific Environmental Institute, West Vancouver, with the help of C. D. Levings; at the Bamfield Marine Station, with the help of A. D. Spencer and colleagues, and at the Friday Harbor Laboratories, with the help of C. P. Staude. The bulk of the study material is currently maintained by the Invertebrate Collections Unit, Canadian Museum of Nature (CMN), Ottawa. For the loan of study specimens, the authors thank Dr P. Slattery, Moss Landing, CA (Bering Sea material); the Los Angeles County Museum, Los Angeles, CA (J. L. Barnard material from Southern California), Dr Akira Hirayama, Kumamoto, Japan (Japanese material and from Russia (formerly USSR), Nina Tzvetkova, and the late Eupraxie F. Gurjanova whose extensive publications on the far-eastern pleustid fauna have been invaluable reference bases for the present study. Helpful commentary on various phases of manuscript preparation was provided by Pierre Brunei, University of Montreal, Roger Lincoln, British Mus- eum, C. P. Staude, Friday Harbor Laboratories, K. E. Con- lan, CMN, Ottawa, and Patrick Shaw, Vancouver, B. C. The line illustrations were prepared with the most capable assistance of Susan Laurie-Bourque, Hull, Quebec (see legend for figures, p. 133). Maijorie Bousfield, Montreal, provided translations of pertinent Russian literature. SYSTEMATICS Family PLEUSTID AE PARAPLEUSTINAE, Bousfield & Hendrycks, emended Parapleustinae Bousfield & Hendrycks, 1994; 41. Type genus. Parapleustes Buchholz, 1874 (p. 67). Genera. Chromopleustes, new genus (p. 73); Com- mensipleustes, new genus (p. 82); Gnathopleustes, new genus (p. 82); Incisocalliope J. L. Barnard (p. 95); Trachy- pleustes, new genus (p. 105); Micropleustes, nev^ genus (p. 111 );. Removals. Parapleustes assimilis (Sars,1883); P. bicuspis (Kroyer, 1838); P. monocuspis Sars, 1895; P. gag- arae Gurjanova, 1972; P. major Bulycheva, 1952, P. bi- cuspoides NugatSi, 1965; P. sinuipalmaDunbar, 1947, P. tri- anguloculatusBulycheva, 1952; P. tricuspislshimaru, 1984, to genera within subfamily Neopleustinae (Bousfield & Hendrycks, 1994, and in prep.). Diagnosis. Body generally small to medium, smooth above, not mucronate on pleon; external surface pattern often colourful or disruptive. Head, rostrum short, little or not exceeding rounded lateral head lobe. Eyes variable in size and form, usually medium large, subrotund. Antennae usually elongate; antenna 1 the longer, occasionally short, peduncular segments often shortened. Accessory flagellum minute. Mouthparts generally strongly modified. Upper lip distinctly notched, lobes variously asymmetrical. Lower lip broad, squat, outer lobes oblique. Mandible, molar small, weak, thumblike, apex pilose, triturating surface lacking or AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 67 vestigial; blades generally numerous, often strongly modified: chisel-shaped, cusplike, or molarized in form; left lacinia wide, multidentate, cutting edge straight; right lacinia lack- ing; incisor multidentate, third (distal) tooth largest; palp segment 3 not shorter than 2, with basal “A” seta (of Cole, 1980). Maxilla 1, inner plate with single apical seta; outer plate with 9 (rarely 15-18) apical spine teeth; palp occasionally broadened, with distal facial setae, apices spinose; segment 1 often with lateral ("shoulder") seta(e). Maxilla 2 ordinary, inner palate with stout inner marginal plumose seta(e). Maxilliped; palp strong, segment 2 usually longest, 3 lacking distinct distal process; outer plate narrow (vertical margins subparallel), sparsely setose and/or spinose; inner plate short, apex with “button” spines, inner margin with few setae and/or spines. Coxal plates large, deep, broad; coxa 1 generally broad- ening distally and rounded below; hind comers cuspate. Gnathopods various; weak to medium strongly developed; gnathopod 2 slightly larger, differing slightly in form, and occasionally sexually dimorphic. Gnathopod 1, basis, margins variously setose; meral cusp weak; propod, palm usually oblique, convex, with median tooth. Peraeopods 3 & 4 ordinary, normally spinose, dactyls short to medium. Peraeopods 5-7 homopodous; coxae medium deep, hind margins rounded, laterally smooth; segment 4 longer than 5 which it variously overhangs behind. Pleon plates 2-3, hind comers acuminate, not produced. Pleopods medium strong, ordinary. Uropods 1 & 2 ordinary; peduncle of uropod 1 with prominent distolateral spine; rami elongate, outer shorter, margins and apex strongly spin-ose. Uropod 3, inner ramus markedly the longer, margins spinose. Telson elongate, narrowing distally, keeled proximally; apex rounded; penicillate setae medio-distal. Coxal gills variable, smaller and saclike anteriorly, larger, platelike posteriorly. Brood plates large, broad. Distributional ecology. The subfamily is essentially endemic to eulittoral shelf habitats of the North Pacific region. However, three species occur in isolation elsewhere, viz., the northeastern North Atlantic, the western North Atlantic, and the Hawaiian Islands of the central North Pacific (seep. 131). Taxonomic commentary. The Parapleustinae is closely allied to subfamily Neopleustinae (Bousfield & Hendrycks, 1994). The latter differs, however, in having a well-developed keeled rostmm, dorsal body processes, a short, nearly centrally keeled telson, large mandibular palp, and a distally oblique and processiferous maxillipedal palp segment 3. Also, component members of the Neopleustinae occur in deep cold waters of the Arctic, North Atlantic and North Pacific regions; none is intertidal. Numerical taxonomic analysis of the Parapleustinae reveals a complex of 7 generic-level subgroups (Fig. 43, p. 127), the species of which are treated systematically below. Parapleustes Buchholz Parapleustes Buchholz, 1874: 337.— Stebbing 1906: 320.— Gurjanova, 1951: 648 (partim).— Barnard 1969a: 425 (partim). — Barnard & Karaman, 1991: 649 (part). Type species, Parapleustes gracilis Buchholz, 1874. Species composition (North Pacific). Parapleustes ishimarui (= P. gracilis Ishimaru, 1984) (p. 70); and P. americanus, new species (p. 71). Diagnosis. Body small, smooth above. Head, rostrum very short; anterior head lobe subacute; inferior antennal sinus broadly incised. Eye medium, elliptical to roundish. Antennae slender, medium long, weakly setose. Antenna 1 typically the longer; peduncle 3 short; peduncle 1, distal process weak; accessory flagellum minute. Mouthparts modified. Upper lip shallowly notched, lobes asymmetrical. Lower lip medium wide, squat; outer lobes thick, rounded, oblique. Mandible: molar reduced to a blunt setulose knob; incisor irregularly toothed, distal teeth smaller; left lacinia 8-10 dentate; blades 5-12 in row, stout, weakly molarized; palp slender, segment 3 with few (3-5), posterior marginal “D” spines; maxilla 1, outer plate with 9 mainly tall apical spines; palp not broadened, with -4 apical spines and several oblique subapical (facial) setae. Maxilla 2, inner plate little broadened, with marginal plumose seta. Maxilliped, palp strong, dactyl strong, segment 3 lacking distal process; segment 2 largest; outer plate short, little or not longer than inner, 1(2) apical spines; inner plate with few apical button spines and few marginal setae. Coxal plates wide, deeper than respective body plates; lower margins straight, hind notch(es) distinct; coxa 1 little smaller than 2, slightly expanded distally. Gnathopods medium large, closely subequal, little or not sexually dimorphic; propods broadening distally, palms smoothly convex, usually with central median tooth, postero- distal angle with 1-2 clusters of spines not extending onto palm; hind margin smooth, about equal in length to palm; carpus usually short, hind lobe deep; postero-distal process of merus acutely produced; bases slender, antero-marginal setae distally restricted. Peraeopods 3-7 slender, weakly spinose; segment 5 and dactyls slender, relatively long. Peraeopods 3-4, margins of segments 4-6 weakly spinose, lacking special setae. Peraeopods 5-7 regularly homopodous, bases broad, convex behind. Pleon plates broad, deep, smooth behind, hind comers weakly acuminate. Pleopods strong, not sexually dimorphic. Urosome short; urosome 2 not occluded dorsally. Uropods 1 & 2 rami slender, tips spinose, usually extending beyond uropod 3. Uropod 1, peduncle with distinct latero-distal spine; rarm subequal in length. Uropod 2, inner ramus the longer. Uropod 3, inner ramus markedly the longer. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 68 KEY TO KNOWN GENERA OF SUBFAMILY PARAPLEUSTINAE 1. Gnathopods 1 & 2, palm of propod with median tooth present, variously developed; gnathopod propod, length of palm about equal to (or longer than) posterior margin; gnathopod propods, hind margin lack- ing setae (except some Incisocalliope)’, gnathopod 2, carpus always relatively short, anterior margin <1/2 length of propod 3. — Gnathopods 1 & 2, propodal palm, median tooth lacking or very reduced; gnathopod propod, length of palm short, usually much less than posterior margin (except in some Micropleustes)\ propod, hind mar- gin with 1 - 4 setae or setal groups; gnathopod 2, carpus usually elongate, anterior margin about equal in length to propod (except some Micropleustes) 2. 2. Antennae slender, flagella elongate, antenna 1 usually markedly the longer; peraeopods 5-7, segment 4 postero-distally overhanging segment 5 by less than 1/4 length of segment 5; coxal plates 2 - 4 not ex- ceptionally large and/or deep, distal portions of respective bases exposed below, hind cusps of coxae 2 & 3 single Chromopleustes (p. 73) — Antennae short, stout, subequal, flagella little (or not) longer than respective peduncles; peraeopods 5 - 7, segment 4 overhanging segment 5 postero-distally by nearly half length of segment 5; coxae 2 - 4 large and deep, totally masking respective bases, hind comers with 2-5 small cusps (rarely single) .... Micropleustes (p. Ill) 3. Antennae short, flagellum; of A1 little longer than peduncle, of A2 shorter than peduncle; gnathopods 1 & 2, carpus very short, length less than 1/4 that of propod, hind lobe small, narrow; pleon plate 3, hind comer with small hook Parapleustes (p. 67) — Antennae normally elongate, flagellum distinctly longer than respective peduncle; gnathopds, dorsal margin of carpus more than one-fourth length of propod, hind lobe about half as wide as its dorsal mar- gin; pleon plate 3, hind comer acuminate, not mucronate 4. 4. Peraeopods 5-7, segment 6 broadened distally, anterior margin with stout spines, forming (with dactyl) a grasping organ; maxilliped, outer plate shorter than inner plate; coxa 1 not noticeably broadening distally, hind margin lacking proximal short spine(s) Commensipleustes (p. 82) — Peraeopods 5-7, segment 6 normally slender and spinose; maxilliped, outer plate slightly longer than inner plate; coxa 1 broadening distally, hind margin with proximal spine(s) 5. 5. Gnathopods large, strongly subchelate, variously sexually dimorphic; basis, anterior marginal setae confined to distal angle; antenna 2, peduncular segments not shortened, surfaces armed variously with clusters of short setae Gnathopleustes (p. 82) — Gnathopods medium subchelate, propod and carpus combined shorter than depth of coxa, not sexually dimorphic; basis, anterior margin often setose throughout; antenna 2, peduncular segments 4 & 5 shortened and/or bare of surface setal groups 6. 6. Antenna 1, peduncular segment 2 short, less than half length of segment 1; mandible, palp segment 2 weakly setose (6-7 setae); left lacinia 10-12 dentate; maxilliped, palp segment 3 lined medio-distally with short spines Incisocalliope (p. 95) — Antenna 1, peduncular segment 2 not shortened, length greater than half that of segment 1; mandible, palp segment 2 with numerous (10-15) medial setae; left lacinia 7-9 dentate; maxilliped, palp segment 3 lacking distal short spines Trachypleustes (p. 105) AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 69 FIG. 1. Parapleustes gracilis Buchholz. Female (2.5 mm). Norwegian Sea. (after Sars, 1895). Telson medium long, narrowing, subacute; dorsal penicillate setae slightly distad (of middle). Coxal gills sac- like, medium, unequal, smallest anteriorly. Taxonomic commentary. The following species are TQmoytdfromParapleustes, sens. str.\ P. assimilis Sars and P. tricarinatus lsYmR^nx-{\.oNeopleustesy,andP. commens- alis Shoemaker (to Commensipleustes), for the following combination of reasons: lack of a disto-lateral spine on the peduncle of uropod 1 ; the peraeopods are too long, or stout, dactyls too short; gnathopod propods are too slender, and/or the posterior margin is too strongly setose; the palmar tooth is lacking; the carpus is too long, shallow; the mouthparts are significantly different, especially in the mandibular blades; and the pleon is dorsally carinate. Within Parapleustes proper, the markedly smooth propods and narrow carpal lobes of the gnathopods might suggest a closer relationship with the genera Pleustes and Pleusymtes. Distributional commentary. The genus Parapleustes (sens, str.) is essentially arctic-subarctic in present distribut- ion, dipping southward variably, and mainly subtidally in the North Pacific and northern North Atlantic regions. Para- pleustes gracilis is not typical of the subfamily but became the type species because it is the only member occurring in the North Atlantic region where amphipod taxonomy began. Parapleustes gracilis Buchholz (Fig. 1) Parapleustes gracilis Buchholz, 1874; 337, fig. 1.— Steb- bing, 1906: 320.— Gurjanova, 1951: 648, fig. 444.— Bar- nard & Karaman, 1991: 650. non Parapleustes gracilis Ishimaru, 1984. — Hirayama, 1988? Paramphithoe brevicomis G. O. Sars, 1895: 353, pi 124. 2. Diagnosis. Female (2.5 mm); Head, eye medium roundish, black. Antenna 1, peduncular segment 2 short, length -1/2 segment 1; flagellum 13-segmented. Antenna 2, peduncular segments 4 & 5 slender, subequal; flagellum 8-segmented. Mouthparts not described (notin Sars 1895, norStebbing, 1906) but probably similar to those ofP. americanus (p.71). Coxae 1-3 deep, medium broad, lower margins weakly convex, hind comers each with single cusp. Gnathopod 1, basis with weak antero-distal setal cluster; mems with acute postero-distal process; carpus short, hind lobe narrow, deep; propod distinctly expanding distally, inner face smooth; palmar margin oblique, convex, postero-distal angle with spine groups on either side of distinct dactyl-tip depression. Gnathopod 2 closely similar in size and form; basis, antero- distal margin with several setae. AMPHIPACMCA VOL II NO. 1. AUG. 31, 1995 70 Peraeopods 3 & 4, bases with several antero-distal setae; segments 4-6 slender, elongate (especially segment 6); segments 4 & 5 subequal in length; marginal setae sparse; dactyl curved, elongate, length >1/2 segment 6. Peraeopods 5-7 slender, bases medium broad, postero-distal lobes shallow; segments 4 & 5 subequal; segmentb elongate; dactyl elongate, length > 1/2 segment 6. Pleon plate 3 , hind comer weakly acuminate, not hooked . Urosome 2 with free dorsal margin. Uropods 1-2 slender, peduncle and rami weakly spinose. Uropod 3, outer ramus 2/3 length of slender inner ramus . Telson medium, length ~1.5X basal width, apex subacute. fauna. Of the 21 species of Parapleustes listed by Barnard & Karaman, most are members of subfamily Parapleustinae, but only P. gracilis (= P. brevicomis Buchholz?) is retained in the genus Parapleustes. All others are removed to other genera, and in some cases, other subfamilies. It has been found advisable to restore to the original position a number of transfers, and a number of synonymies, by others. Thus, Micropleustes nautilus is removed from the synonomy of M. behningi, and restored to full species recognition, and the genus Incisocalliope J. L. Barnard, 1959, is removed from the synonomy of Parapleustes Buchholz and restored to its original full generic position. Distributional commentary. This species is endemic to arctic and arctic-boreal, North Atlantic waters. It has not been recorded authentically from the North Pacific region. As the type species of the genus, this North Atlantic form is included here for comparative purposes with North Pacific material previously ascribed to the name Parapleustes gracilis (above). Taxonomic commentary. Parapleustes gracilis is the type of a small group of species here restricted to a few members of the North Atlantic and North Pacific pleustid Parapleustes ishimarui, new species (Fig. 2) Parapleustes gracilis Ishimaru, 1984; 432, figs. 21-24. — Ishimaru, 1994: 54. Diagnosis. Female (2.4 mm): Head, eyes small, round, black. Antennae short. Antenna 1, peduncular segment 2 medium, length > 2/3 peduncular segment; accessory flagellum, apex rounded, with 1 plumose and 2 simple setae; flagellum 9-10 segmented. Antenna 2, peduncular segment AMPHIPACMCA VOL II NO. 1. AUG. 31, 1995 71 KEY TO KNOWN SPECIES OF PARAPLEUSTES (SENS. STR.) . 1 , peduncle 2 short; peraeopod 7, basis, posterior margin nearly straight; uropods 1 & 2, rami shorter -A~T ^ f P- (Buchholz)(p. 69) enna 1, peduncle 2 normal; peraeopod 7, basts, posterior margin strongly convex; uropods 1 & 2 inner ramus about equal m length to peduncle; peraeopods 1 & 2, dactyls shorter (15), right incisor with 9-12, dentations or serrations; left lacinia multicuspate (>20); blades tall, slender, numerous (10-15), some with basal “satellite” setae; palp segments relatively short, segment 2 medially sparsely setose. Maxilla 1, apical spines of outer plates numerous (13-17), slender tall; inner plate with single minute apical seta; palp distally widened, with 6-8 apical spines and several closely subapical setae. Maxilla 2, inner plate not broadened, inner marginal plumose setae slender. Maxilliped, segment 3 (outer plate segment) strikingly enlarged, much longer and larger than palp segment 1; segments 2 & 3 short, dactyl strong; inner plate with 2-3 stout inner marginal setae. Coxal plates medium, little (or not) deeper than corre- sponding body plates; coxa 1 not broadened or bent distally; postero-distal notch single, minute. Gnathopods small to medium strong, distinctly sexually dimorphic; propod and carpus elongate (especially in female), shorter, broader and stouter in male; palm of propod much shorter than posterior margin, straight, oblique, lined with short setae, lacking median tooth; carpal lobe shallow, medium to broad. Gnathopod 1, basis with proximo-posterior “hump”. Peraeopods 3-7 stout, medium long, weakly spinose, segment 5 strong; dactyls short, strong. Peraeopods 3 & 4, margins weakly spinose, lacking special setae. Peraeopods 5-7 regularly homopodous, bases somewhat narrowed be- hind. Pleon side plates very broad, medium deep, hind corners acuminate but not produced. Pleopods normal, strong, not sexually dimorphic. Urosome short, segment 2 not occluded dorsally. Uropods regularly spinose; rami of uropods 1 & 2 distinctly longer than respective peduncles; outer ramus slightly the shorter. Uropod 3, rami much longer (3X) than peduncle, outer ramus distinctly the shorter. Telson med- ium-long, rounding apically. Coxal gills large, platelike. Taxonomic commentary. Within the subfamily Parapleustinae, the genus Chromopleustes appears to be closest morphologically to the genus Incisocalliope, on the apomorphic side, and to Gnathopleustes on theplesiomorphic side. It is distinguished from the latter, however, rather superficially by the more slender antennae; longer, less spinose legs with shorter dactyls; more elongate uropods, and more striking, disruptive body colouration. In detailed characterization, itis most distinct (unique) in the form of the mouthparts, with specialized proliferation of pectinate spines, blade spines, and multi-dentate incisors and lacinia mobilis. To date, members of the genus have not been recorded outside the North Pacific coastal marine region, on both Asiatic and N. American coasts. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 74 KEY TO KNOWN SPECIES OF CHROMOPLEUSTES 1 . Eye small, remote from anterior head margin; antenna 2, flagellum <30-segmented; uropod 3, inner ramus with few (4-5) pairs of marginal spines; maxilliped, palp segment 1 longer than 2; Asiatic Pac- ific C. johanseni (p. 77) — Eyes large, near anterior head margin; antenna 2, flagellum >30-segmented; uropod 3, inner ramus with 8-10 pairs of marginal spines; maxilliped, palp segment 1 shorter than 2; North American Pacific . . 2. 2. Gnathopod 2, propod slender (both sexes), length >2X depth; telson elongate, length >2X width; mand- ible, left lacinia with about ~40 marginal teeth; maxilliped, inner plate with 3 inner marginal setae; telson elongate, length >2X width C. oculatus (p. 74) — Gnathopod 2, propod stout (both sexes), length <2X depth; telson short, length -1.5 X width; mandible left lacinia with about 20 marginal teeth; maxilliped, inner margin with stout single blade adjacent to facial seta; telson short, length -1.5 X width C. lineatus (p. 78) Chromopleustes oculatus (Holmes) (Fig. 4, 5, 6, 7) Neopleuste^ oculatus Holmes, 1908: 531, figs. 36, 37. Parapleustes oculatus Barnard & Given, 1960:1. — Barnard, 1969b: 198 (key).— Bousfield, 1985: 31, fig. 1.— Staude, 1987: 379.— Barnard & Karaman, 1991: 650. Material examined: Nearly 60 specimens in 15 lots ALASKA, (numbers of specimens in parentheses): Bering Sea: Amchitka I., Aleutians Ids., C. E. O’ Clair Sta. IA-2, Oct. 23, 1972 - I im. Southeastern Alaska, ELB Stns, 1961 : A3(70); A6(2); A1 8(2); A57(l); A168 (8); A174 (13); A175 (31); Stn. A8 (Tongass Narrows, opposite Ketchikan), rock and sand at LW, June 3, 1961 - 1 male (slide mount), (fig. ’d); female ov. (slide mount),(fig’d specimen), + 15 male, female specimens. ELB Stn. S19B1 (Kameno Pt., near Sitka), July, 1980 -1 male, 2 im. K. E. Conlan Stns., 1989: Torch Bay, 4.6-13.7 m, June 18 - male, female; Baranof I., Whale Bay, 4.5 - 6 m, June 21 - 1 male; Bocade Quadra, 30.5 m dredge, June 27 - 3 females; Frederick Sound, Brothers I., 5-6 m., P. Slattery coll.. Mar. 24, 1988 - 8 males, females. BRITISH COLUMBIA. Queen Charlotte Island, ELB Stns, 1957 : N2a (Parry Passage) 22 males, females; W8 (2); W15b(2). Naden Harbour, 9 m dredge. Sept 16, 1955 -1 female. North-central coast: ELB Stns, 1964: H3 (40); H5 (50); H7(6); H12(14); H29 (15); H33(30); H50 (60); H53 (16); H57 (2); H65 (7). South-central coast: Sutton I., Sechelt Narrows, 15 m dive, Neil McDaniel coll., July , 1978 - 1 male, 1 female, 7 im. Vancouver I., north end: ELB Stns., 1959: 03 (15); 05 (9)07b (15); V20 (Brown Bay) (9); V5 (Nigei I.) (2). Vancouver I., south end: ELB Stns. 1955: FI (1);F2 (1); F4 (3); P4 (9); P7 (2); ELB Stns., 1976: B4 (1); B5 (2); B8 (5); B21b(l). CALIFORNIA: Off Del Mar, 20 m, R. Rosenthal coll., June, 1969 - 6 im. Diagnosis. Male (8. 2 mm): Head, eye large, broadly ovate, black. Antenna 1, flagellum with -60 small segments; accessory flagellum minute. Antenna 2. peduncle 5 distinctly longer than segment 4; flagellum with -45 small segments. Upper lip, median notch V-shaped, half depth of labrum. Lower lip, inner lobes very broad. Mandible, spine row with 14-15 slender blades; incisor cutting edge nearly straight, with 25-1- teeth, strongest proximally; left lacinia, cutting edge slightly concave, with -50 fine teeth; palp segment 3 with 12 pectinate inner marginal and 3 long terminal setae. Maxilla 1, inner plate with single short apical setae; outer plate with 12-13 slender apical spines; palp segment 2 slightly widening distally, with 8-9 apical short spines. Maxilla 2, outer plate not wider than inner. Maxilliped , inner plate medium, with 3 ordinary inner marginal setae and 5 small apical denticles; outer plate medium, apex obliquely truncated; palp segment 1 shorter than 2. Coxae 1-3 relatively narrow, lower hind comer of each with minute cusp. Gnathopod 1, hind margin of basis with distinct proximal “hump”; carpus short, slightly longer than deep; propod slender, longer than deep; palm margin oblique, convex, merging imperceptibly with hind margin, postero- distal angle with 3+1 groups of short spines. Gnathopod 2, carpus short, little longer than deep; propod slender, length > 2X depth; palmar margin very oblique, merging with hind margin, postero-distal angle with 4 groups of spines and 2 singly inserted spines. Peraeopods 3 & 4 slender; segment 6 with 8- 1 0 posterior margin spine groups; dactyls very short, little curved. Peraeopods 5-7 closely homopodous in form and size; bases not strongly broadened, lower hind lobes shallow; dactyls very short. Pleon plate 3, hind comer weakly acuminate. Uropods 1 -3 relatively long, inner ramus > peduncle, margins strongly spinose. Uropod 3, inner ramus > 2.5 X peduncle, margins with 10-12 serial spines. Telson linguiform, length ~2X width, apex rounded. Distribution. The species ranges from the Bering Sea and southeastern Alaska, south through British Columbia, to California, commonly from LW level to depths of 20 m, in a variety of habitats, associated with Ulva and bryozoans. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 75 MXPD FIG. 4.Chromopleustesoculatus (Holmes, 1908). Female (11.0 mm). Monterey Bay, California. (modified from Holmes, 1908) FIG. 5, Chromopleustes sp. 1. (Barnard & Given, (after Barnard 1960). Female (6. 5 mm). Santa Monica Bay, 70 m. & Given, 1960) Taxonomic commentary. The present female speci- mens compare closely with the 11.0 mm female illustrated by Holmes (1908) from Monterey Bay (Fig. 4). However, they differ from the small mature female illustrated by Barnard and Given (loc. cit.) from Santa Monica Bay, south of Point Conception, California (Fig. 5). The latter has relatively short antennal flagella, larger and broader coxal plates 1 -4, broader bases of peraeopods 5-7, relatively weakly spinose uropodrami, relatively short telson, and much longer inner plate of the maxilliped. In order to clarify its taxonomic status, re-examination of the Santa Monica Bay material would seem desirable. Chrompleustes oculatus displays a disruptive “saddle back” colour pattern, with dark vertical stripe and bright yel- AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 76 FIG. 6. Chromopkustes oculatus (Holmes) Male (8.2 mm); female ov (11.0 mm). Tongass Chan., Alaska AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 77 FIG. 7. Chromopleustes oculatus (Holmes). Male ov (8.2 mm). Tongass Channel, Alaska. low spot on coxa 4 (see Bousfield, 1985, fig. 1), that is one of the most striking of all subhttoral North Pacific amphipods . The "saddle back" spot is wide, extending fully over the dor- sum of peraeon segments 5 & 6, but only over segment 5 and half of segment 6 in C lineatus. In C. oculatus, moreover, there are 3 dorso-lateral body stripes on each side, vs. 4-5 in C. lineatus, and coxal plates 1-3 are white, vs. brownish and vertically striped in C. lineatus (p. 81). As noted elsewhere (Bousfield & Hendrycks, 1994), such may be a form of warning colouration, indicating the presence of terpenes or similar body chemicals that are distatefiil to fishes and other potential predators. Chromopleustes johanseni (Guijanova) (Fig. 8) Parapleustes johanseni Guijanova, 1951: 550, fig. 446. Parapleustes oculatus Barnard & Karaman, 1991: 650. Ishimaru, 1994: 54 Diagnosis, (after Gurjanova, 1951): Female (7.0 mm). Head, eyes relatively small, rounded, brownish, remote from the anterior margin by an eye width. Antenna 1 slightly Shorter than antenna 2; flagellum 21-segmented. Antenna 2, flagellum 26-segmented. AMPHIPACIFICA VOL 11 NO. 1. AUG. 31, 1995 78 FIG. 8. Chromopleustes johanseni (Gurjanova). Female (7.0 mm). Bering Sea. (after Gurjanova, 1951). Mandible, spine row with about 20 slender blades; right incisor, cutting edge with 12 teeth, largest proximally; palp segment 3 with 6-8 pectinate “D” spines. Maxilla 1, inner plate narrowly lobate, lacking apical seta; outer plate with 9 apical spines; palp segment 2 inner margin bulging inward, apex with 4 stout spines. Maxilliped, inner plate very short, apex setose; outer plate short, apex obliquely truncate; palp segments 1 and 3 longer than 2 . Gnathopods slender. Gnathopod 1, basis stout, heavy, posterior margin with strong proximal “hump”, anterior margin richly setose; carpus large, longer than deep; propod more slender and a little longer than carpus, length ~2X depth, palm short, convex, oblique, postero-distal angle with few spines. Gnathopod 2, carpus elongate, length > 2X depth, posterior lobe shallow; propod more slender , slightly shorter than carpus, palm convex and more oblique than in gnathopod 1. Peraeopods 5-7 homopodous, bases broad. Uropod 3, inner ramus narrowly lanceolate, length ~2X peduncle , with 5-6 marginal spines; outer ramus short -60% of outer ramus, with a few marginal spines distally. Telson relatively short, length -1.5 X width, apex broadly acute. Distribution. Bering Sea and coast of Kamchatka, subtidally on Alariafistulosa. Strictly Asiatic Pacific. Taxonomic commentary. The species is plesiomorphic in most character states but is distinct in the weakly spinose rami of uropod 3, and very broadened palp of maxilla 1. Chromopleustes lineatuSf new species (Figs. 9, 10) Parapleustes oculatus Bousfield, 1985, part. Material Examined. About 25 specimens in 10 lots: ALASKA. Southeastern Alaska: ELB Stn. A171 (Puffin Bay, Baranof I.), rock and algae at LW level, July 25, 1961 - 22 im.; ELB Stns., July, 1980: S7B1 (Dry Pass, Chichagof L), under boulders, algae, LW - 1 female; SllBl (Column Pt., Lisianski Strait), bedrock and kelp atLW, July 30, 1980 - -50 specimens including males and females. BRITISH COLUMBIA. North-central coast: ELB Stn. N1 (Rivers Inlet), bedrock. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 79 FIG. 9. Chromopleustes lineatus, new species. Male (7.5 mm); Female ov (9.0 mm) Ahous Bay, B. C. I.), bedrock, Phyllo-spadix, sand, at LW, Aug. 18, 1959 - male (7.5 mm), Holotype (slide mount), CMN Cat. no. NMCC1995-(X)71; female ov (9.0 mm). Allotype (slide Phyllospadix, and coarse sand at LW, Aug. 3, 1959 - 25 specimens, including males, females, im. Vancouver I., north end: ELB Stn. 05 (Ferrer Pt. beach), under bedrock and kelp at LW, July 20, 1959 - 6 males 2 females, 3 im. Vancouver I., south end: ELB Stn. 012 (Ahous Bay, Vargas mount), CMN Cat. no. NMCC1995-(X)72; 7 males, 3 females, Paratypes, CMN Cat. No. NMCC1995-0073. ELB Stns., 1975: P5c (Taylor I, Trevor channel), from ascidians and AMPHEPACIFICA VOL II NO. 1. AUG. 31, 1995 80 sponges under large boulders at LW level, - 1 male. ELB Stns., 1976: B7 (Broken Is., Trevor Channel), from sponges under rock, LW level - 9 males 6 females, 6 im. ELB Stns., 1977: Bllb (Wickaninnish Bay, south end), from sponges and algae under steep bedrock walls at LW - 1 male, 2 females; B13 (Trevor channel, off Brady’s beach), 6-14 m dredge, sand, stone, algae - 1 female ov (14 mm); B14 (Trevor channel, off Execution rock), 44-54 m dredge, sandy mud, algae - 1 female ov. CALIFORNIA. Albion Cove, Mendocino Co., from Tealia species, 20 m depth, T. Chess coll., Sept. 26, 1978 - 1 10 females, 20 males. Diagnosis. Male (7.5 mm): Head, eye broadly ovate, black in alcohol. Antenna 1, flagellum ~60-segmented; accessory flagellum minutely subconical, with 3 apical setae. Antenna 2, peduncular segment 5 little longer than 4; flagellum ~35-segmented. 81 AMPHIPACIFICA VOL II NO. 1 . AUG. 31, 1995 ^O.n.CommensipUus,escommensalU (Shoemaker). Female ov (5.5 mm). Point Barrow, Alaska. (after Shoemaker, 1952). t U v-cleft separating asymmetrical lobes. Lower lip, inner lobes broad, flat. Mandible, spine row with 11-13 slender blades plus supernumerary setae; right incisor with 9, left incisor with 1 7 stout teeth; left lacinia with ~20 teeth, distally smallest; palp segment 3 with 10 pectinate “D” spines (of Cole, 1980) and 3 longer apical setae. Maxilla 1 , inner plate with single short apical setae; outer plate with ~18 slender apical spines; palp segment 2 apically rounding, with 8-9 short spines. Maxilla 2, outer plate broader than inner. Maxilliped, inner plate with large inner marginal blade-like spine and 4 small apical denticles; outer plate rounded apically; palp segment 1 shorter than 2 Coxae l-3relativelybroad,deep. Gnathopods distinctly sexually dimorphic. Gnathopod 1 , posterior margin of basis acking distinct proximal “hump”; carpus short, as deep as long; propod relatively deep, length ~ 1.5 X depth, palm oblique, nearly straight, postero distal angle with 4 groups of spines extending onto posterior margin. Gnathopod 2 , propod very short, length distinctly less than depth; propod larger than in gnathopod 1 , slightly broadening distally, palm oblique nearly straight, posterior angle with 4 spine clusters and adjacent single small spine on posterior margin; dactyls with minute posterior marginal setules. Peraeopods 3 & 4, segment 6 relatively short, hind margin with 6-7 spine clusters. Peraeopods 5-7 homopodous peraeopods 5 slightly the shortest; basis of peraeopod 5 less broadly expanded than in 6 & 7; dactyls medium, gentlv curved distally. Pleon side plate 3 , hind comer acuminate ; uropods 1 &2 slightly shorter and less strong than in C oculatus\ inner ramus of uropod 1 with 6-8 serial paired spines. Uuropod 2 Uropod 3, inner ramus, length ~-2X peduncle, margins with 8-9 serially paired spines Telson medium, length 1.5 X width, apex subtruncate. Female (9.0 mm): Slightly larger and heavier- bodied than male. Gnathopod 1 . carpus slightly longer, length slightly greater than depth; propod shorter, length ~ 1.3X depth. Gnathopod 2 , carpus not shortened, length -1.5 X depth- propod subrectangular, not broadening distally. Distribution. From southeastern Alaska, through the Queen Charlotte islands and north central mainland coast of Bntish Columbia to Mendocino Co., northern California oftenin association withsponges,coelenterates and tunicates’ on hard bottoms, from LW level in the north, subtidally to depths of over 50 m in the south. Etymology, from the Latin meaning lined, al- luding to the fine, orange, dorso-lateral body stripes, and vencal yellow stripes on brownish coxal plates 1 - 4 . Taxonomiccommentary, Thespecies differs markedly from C oculatus in colour, and from C. johanseni in char- acters of the key (p. 74), and additonally in the highly modified mouthparts, especially the mandible and maxilla 1 . AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 82 Commensipleustes, new genus Parapleustes Shoemaker, 1952: 231. — J. L. Barnard, 1969a: (partim). — Barnard & Karaman, 1991: 650. Type specis. Parapleustes commensalis Shoemaker, 1952: 231, fig. 83. (see Fig. 11). Diagnosis. Head, rostrum about equal to rounded anterior lobe. Eyes medium large, black. Antennae slender, peduncles short, flagella short (<15 segmented). Upper lip, medium notch shallow, lobes slightly asymmetrical. Lower lip inner lobes deep medium wide, rounded; outer lobes small, ovate, oblique. Mandible, molar process relatively strong, apex slightly triturative(?); spine row with numerous (10+) blades; left lacinia 10-dentate; palp segment 3 slender, with 2 inner marginal pectinate “D” spines. Maxilla 1, inner plate small, with single apical seta; palp segment 1 lacking shoulder seta(e) segment 2 stout, apex obliquely rounded, with 8 short spines, and a facial row of 3 setae. Maxilla 2 , inner plate regular, with single inner marginal plumose setae. Maxilliped, inner plate with 3 apical “button” spines and 2 slender spines; outer plate, apex with 2 slender spines, segment 3 lacking distal pectinations; palp relatively short, curved. Coxae 1-3 relatively narrow, 1 not expanded distally. Lower margins gently convex, hind cusp minute. Coxa 4 not broader than deep. Gnathopods medium strong, closely subequal, not sexually dimorphic (?). Gnathopod 1, basis, anterior margin strongly short-setose; hind margin weakly so merus lacking distal process; carpus, hind lobe relatively broad, rounded below; propod relatively short, not expanding distally; palm oblique, convex, median tooth apparently lacking. Peraeopod 3 & 4, basis, antero-distal margin with short setae; segment 5 short, length < segment 4; segment 6 stout, hind margin distally with groups of stout spines against which the dactyl closes, forming a grasping organ. Peraeopods 5-7 homopodous, short, stout; bases medium; segment 5 short; segment 6, anterior marginal spines and dactyl forming a grasping organ, as in peraeopods 3 & 4. Pleon plates 2 & 3, hind comers mucronate, slightly produced. Uropods 1 & 2, relatively short, little or not exceeding uropod 3. Uropod 3, inner ramus relatively long. Telson linguiform, medium, distally narrowing to rounded apex. Distributional ecology. Commensipleustes commens- alis, the only known species, occurs on pleopods of the spiny lobster, Panulirus interruptus, off Santa Barbara, CA. Also recorded by Wicksten (1982) off southern California. Taxonomic commentary. The prehensile peraeopods, in combination with the short peraeopodal segment 5, unexpanded coxa 1, and specialized mouthparts are here deemed sufficient for separate generic recognition. Gnathopleustes, new genus Parapleustes Guijanova, 1972: 131 (part).— Barnard, 1969b: 203 (part).— Barnard & Karaman, 1991: 649 (part). Neopleustes Stebbing, 1906: 311 & 728 (part). Parapleustinae, group 1 (part) Bousfield & Hendrycks, 1994: 42. Type species. Iphimedia pugettensis Dana, 1853, original description. Species. Gnathopleustes serratus, new species (= Parapleustes pugettensis Shocmdker, 1964); G. den (Barnard, 1969b); G. pachychaetus, new species; G. trichodus. new species; G. simplex, new species. Diagnosis. Body smooth above. Head, rostmm shorter than bluntly rounded anterior lobe; inferior antennal sinus broadly incised. Eyes medium large, subrotund. Antennae well-developed; posterior margins often setose. Antenna 1 the longer, peduncular segment 2 short; accessory flagellum minute, apex 2-3 setose. Antenna 2, peduncle strong, flagellum often with special thickened setae. Mouthparts strongly modified. UL shallowly notched, lobes asymmetrical. Lower lip broad, outer lobes rounded, oblique. Mandible: incisor regularly toothed; left lacinia 7- 10 dentate; blades 4-12 in number, stout, distally chisel- shaped; molar body reduced, slender, apex fuzzy; palp normal, segment 1 short, segment 2 medially setose. Maxilla 1, outer plate with 9 tall slender apical spines; palp with subapical facial setae. Maxilla 2, inner plate little expanded; maxilliped, palp strongly dactylate, segment 2 largest; outer plate segment longer than palp segment 1, not enormously developed; inner plate short, inner marginal setae numerous (4-9). Coxal plates wide, deeper than corresponding body plates; coxa 1 broadened distally, hind margin spinose near basis, postero-distal notch single, small. Gnathopods 1 & 2 large, subequal (Gnathopod 2 larger), variously sexually dimor- phic; basis stout, with antero-distal setal group; merus with slight distal process; carpus, posterior lobe short, deep (esp- ecially in male); propods subovate, palms strongly oblique, elongate, convex, palmar tooth distinct, near hinge; palmar margin tending to be lined with special thickened or blade- like setae; postero-distal angle with 2-4 groups of spines, hind margin short, bare, or longer, setose. Peraeopods 3-7 stout, spinose, normal; segment 5 strong, moderately overhung proximally by segment 4; dactyls medium strong, curved. Peraeopods 3 & 4, margins of segments 4, 5 & 6 may bear special thickened setae. Peraeopods 5-7 regularly homopodous, bases broad, convex behind. Pleon side plates broad, deep, hind comers acuminate but not strongly produced. Pleopods strong, normal, not sexu- ally dimorphic. Urosome short, segment 2 nearly occluded dorsally. Uropods 1 & 2 regularly spinose; uropod 1, rami AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 83 KEY TO KNOWN SPECIES OF GNATHOPLEUSTES moderately to strongly setose posteriorly; gnatho- pods tending to strong sexual dimorphism, palmar margins heavily lined with blade-setae or split-tipped °n^ f -50% length of antenna 1, flagellum ne^iy bare (short seMe'only);' gnathopods pods slightly sexually dimorphic, palmar margins lined with relatively few normal setae 5. margins heavily lined with split-tipped setae; mandible, blade row of 10-12 unmodified blades; antenna 1 (male), flagellum brushy G. simplex, (p 87) -Gnathopods (male), m^gms lined with “balloon" setae (pachychaete); mandible, blades (especially dist a y) modified, antennal setation weak, with no distinct “brush” (setose on hind margin only) 3. ^'stronglyletotr'*' 5-7 all lacking marginal setae; gnathopod palms -Antenna peduncles spinose and setose (flagella of A2 variously setose); peraeopods 3-4 oi ^7 sJonglv setose behind; gnathopod palms strongly setose (with “balloon” setae) 4 4 . Gnathopod 2, palmar margin distinctly concave, postero-distal angle with 2 spine groups; peraeopods ■ti Q of segments 4-6 with clusters of long brushlike setae (male); uropod 3, outer ramus with 6-9 nwgmal spines; antenna 1, peduncular segment 1 not elongate G. trichodus (p 91) -Gnathopod 2. palmar margin nearly straight, postero-distal angle with 3-4 spine clusters; peraeopods 5- 7, hind m^gins of segments 4 - 6 with spine clusters only (lacking setae); uropod 3, margins of outer ramus with 5-7 spines only; antenna 1, peduncular segment 1 long G. pachychaetus (p. 87) 5 Gnathopods, dactyls smooth behind; telson less than twice as long as wide; peraeopods 5-7, segment 5 ^stinctly shorter than 4, strongly overhung posteriorly by segment 4 G, pugettensis (p. 83) Gnathopods, dactyls postenorly finely serrate; telson elongate, at least twice as long as wide; peraeo- pods 5-7, segments 4 & 5 subequal in length, 5 normally overhung by 4 G serratus (p 91) subequal; uropod 2, outer ramus the shorter. Uropod 3, outer ramus distinctly the shorter. Telson elongate, narrow- ingdistally; dorsal penicillate setae about mid-point from base. Coxal gills large, broad. Taxonomic commentary. Members of Gnathopleustes overlap to considerable degree with members of Inciso- calliope . However, the two genera are maintained as distinct units for the present because they can be keyed, and the distributions are discreet. Within Gnathopleustes, two main subgroups Can be distinguished, as outlined in the key below. In the more advanced members (G. pugettensis, G. den, G. simplex) the gnathopods appear very slightly sexually dimor- phic, and the mouthparts, peraeopods and uropods are apo- morphic. Parapleustes pugettensis Barnard, 1969b: 203.— Austin, 1985:592. — Staude, 1987:379. — Barnard &Karaman, 1991- 650. TmJncisocalliope newportensis Barnard, 1959: 22. 1^ Parapleustes pugettensis Barnard & Given, 1960:43. — Ishimaru, 1984: 19. Material examined. 258 specimens in 38 lots- ALASKA. Southeastern Alaska. ELB Stns, June- July, 1961: A40 (4 + slide mount); A80 (1); A164 (1); A171 (1). BRITISH COLUMBIA. Queen Charlotte Islands. ELB Stns., July-August 1957- Wll (6) W15b(l). Distributional commentary. Members of the genus are restricted almost entirely to the Pacific coast of North America, from southeastern Alaska to southern California! Gnathopleustes pugettensis has been reported, but not confirmed, from Japanese waters by Irie & Nagata (1962). Gnathopleustes pugettensis (Dana) (Fig. 12, 13) Iphimedia pugettensis Dana, 1853: 932, pi. 63, fig. 6. Neopleustes pugettensis Stebbing, 1906:728. North-central coast, ELB Stns., July, 1964- H43 (!)• H53 (1);W64(2). Northern and central Vancouver I.: ELB Stns., 1959: HIO (40 specimens including males and females); N16 (1); V4b (Hope I., Roller Bay), under boulders, kelp, Phyllo-spadix, at LW level - male (slide mount) (fig'd specimen); female (slide mount) (fig'd specimen) + 8 other specimens; VIO(IO)- V17(1);V19(1). Southern Vancouver I.: ELB Stns., 1955: P9(l) ELB Stns 1970: P702 (20); P707 (5); P710b (1); P714 (1); P719 (5,' including females ov.). ELB Stns, 1975: P2 (25); P3a (1); P5a (1); P5b (1). ELB Stn. B4 , off Brady’s Beach, 60-70 m AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 84 FIG. 12. Gnathopleustes pugettensis (Dana). Male (4.0 mm). Southern California, (modified from Barnard & Given (1960). naturalist’ s dredge, sand and algae, June 25, 1976 - 2 females. ELB Stns., 1977: B8 (5); B 14(1). WASHINGTON-OREGON: Strait of Juan de Fuca to Newport. ELB Stns., July-Aug., 1966: W22 (30, including slide mount); W30 (1); W34 (1 1); W35 (9); W36(8); W40 (19); W50 (30, + slide mount); W53 (1); W57(l); W63 (6);W66 (2). Diagnosis. Male (6.0mm); Body relatively short, coxal and pleon plates deep. Head, eye large, subrectangular. Antenna 1 , peduncular segment 3 relatively long (1/2 segment 2); flagellum of 35-40 medium long segments; accessory flagellum conical, apex with single long seta. Antenna 2, peduncular segment 5 shorter than 4; flagellum with ~35 nearly marginally smooth segments. Upper lip strong, asymmetrical. Lower lip, inner lobes deep; outer lobes normally oval, oblique. Mandible, molar short, blunt; spine row with 8-10 stout, abruptly acute blades; incisor, cutting edge with 6 uneven teeth; palp seg- ment 3 with 8 inner marginal pectinate spines; left lacinia with 8 unequal teeth. Maxilla 1, palp segment 2 with 4 unequal apical spines. Maxilla 2, outer plate not narrowing distally, apex strongly setose. Maxilliped, inner plate rel- atively large, distally broad, with 7 distal facial setae, and 4 small apical marginal denticles; outer plate regular, apex subtruncate; palp, dactyl slender, curved. Coxae 1-3 relatively large, deep; coxa 5 deep. Gnathopod 1 , carpus medium, about as deep as long, carpal lobe medium; propod smoothly ovate, palmar margin convex, very oblique, postero-distal angle with groups of 4 and 3 spines and a single spine distally on posterior margin; dactyl, hind margin not serrated, with a few setules only. Gnathopod 2, carpus and dactyl slightly larger, but proportions and armature similar to that of gnathopod 1. Peraeopods 3 & 4 relatively short, distal segments (4/6) weakly marginally spinose; dactyls medium, > 1/3 length of segment 6. Peraeopods 5-7 closely homopodous, 5 slightly smallest; bases broadly expanded, hind margins convex; distal segments (4-6) weakly marginal spinose, not setose; dactyl medium. Pleon plates 1-3 deep, broad, hind comer of 3 squared. Urosome 2 occluded dorsally by 1 & 3. Uropods ordinary. Uropod Lpeduncularpostero-distal spine strong. Uropod2, outer ramus short, length ~2/3 inner ramus. Uropod 3 strong, inner ramus >2 X peduncle, margins with 5 spines. Telson subrectangular, length about 1.5X width, apex truncate. Female (5.5 mm): Gnathopods not described, presumably slightly smaller and less setose than in male. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 FIG. U.Gnathopleustespugettemis (Dana). Male (6. 0 mm). RoMerBay. B. C Distribution. From southeastern Alaska and northern British Columbia south through Washington & Oregon to Point Conception and Santa Barbara regions, subtidally to 70 m; replaced by /. newportensis south of Pt. Conception. Taxonomic commentary. Gnathopleustes pugettensis is the generic type and, in balance of character states, is most advanced. Overall, it is closely similar to G. den and G. simpleA. Gnathopleustes den (Barnard) (Fig. 14) Parapleustes den J. L. Barnard, 1969b: 199, fig. 54 — Staude, 1987: 319. — Barnard & Karaman, 1991: 650. Material examined. Male (8.0 mm), Holotype, J. L. Barnard Stn. 6, Allan Hancock Foundation Cat No. #559. Material of this species was not found in the study range, AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 86 FIG. 14. Gnathopleustes den (J. L. Barnard). Male (8. 0 mm). Corona del Mar, California. (after Barnard, 1969b). despite its close similarity to G. pachychaetus. Diagnosis (partly after Barnard 1969b). Male (8.0 m): Body and coxal plates medium, ordinary. Head, eyes medium, broadly short-reniform. Antenna 1, peduncular segment 3 medium, length 1/2 segment 2; accessory flagellum very short, with 2 slender apical spines; flagellum elongate (59 segments). Antenna 2, peduncular segment 5 not shorter than 4; flagellum with 50+ segments, proximally stoutest, nearly bare. Upper lip, apical cleft relatively deep, lobes nearly symmetrical. Lower lip, inner lobes deep, outer lobes steeply oblique. Mandible, molarprominent, apex subacute?; spine row with 13-15 medium stout blades; left lacinia 9- dentate; cutting edge of incisor with 6 irregular teeth; palp segment 3 with 11-12 inner marginal pectinate “D” spines. Maxilla I, palp, apex with 6-7 spines. Maxilliped, inner plate with 1 marginal spines and 2 facial setae; outer plate tall, columnar. Coxal plates 1-3 large, deep, relatively narrow; coxae 1 distally expanding, 1-3 with 3-4 hind marginal spines; coxa 5, lobes medium deep. Gnathopod 1 , c£upus medium, length and depth subequal; propod ovate, palmar margin shallowly oblique, very slightly convex, densely finely setose, continuous with hind margin, median tooth very weakly developed; postero-distal angle with 3 groups of spines (?); dactyl stout, hind margin smooth, not serrated. Gnathopod 2, propod distinctly larger and deeper than in gnathopod 2 ; palm nearly horizontal, nearly straight, densely finely setose, with weak median tooth, postero-distal angle with 3 groups of spines, a single distal spine on the posterior margin; dactyl stout, smooth behind. Peraeopods 3 & 4 strong; segment 6, hind margin with 6 spine groups; dactyl short. Peraeopods 5-7 relatively stout; bases slightly broadest distally, hind margins nearly straight, weakly crenulate; segment 4 broad, width -2/3 length; segment 6, margins spinose (not setose); dactyls medium, - 1/3 length of segment 6. Pleon plate 3, hind comer acuminate. Urosome2 with free dorsal margin. Uropods 1 & 2 stout, rami relatively short, not extending beyond uropod 3; uropod 2, rami subequal. Uropod 3, inner ramus with 6-7 pairs of marginal setae. Telson subrectangular, length ~ 2X width, apex subtruncate. Female (10.0 mm); Undescribed. Distribution. Known only from the type locality at Corona del Mar, south of Pt. Conception, California, in washes of tubes of the polychaete Phragmatopoma sp., at LW level. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 87 Taxonomic commentary. The type male specimen, figured by Barnard (1969b), differs from G. pachychetus in lacking posterior marginal setae on the peduncle of antenna 1, and in lacking brush setae on the flagellum of antenna 2. Gnathopleustes simplex, new species (Fig. 16) Material examined. BRITISH COLUMBIA: Southern Vancouver Island: Off Wouwer I., Barkley Sound, P. Lambert coll., June 29, 1973 - male Holotype (6.8 mm) RBCM loan No. 973-156. ELB Stn P17d, Kirby Pt. Bay, Diana I., under-rock habitat among sponges, tunicates, at LW, Aug. 6, 1975- 1 female ov. (5.0 mm). Diagnosis. Male (6.8 mm). Body slender coxal and pleonal plates relatively small, shallow. Head, eye medium small, broadly reniform. Antenna relatively short, 1 slightly longer than 2. Antenna 1 , peduncular segment 3 short, length 1/2 segment 2; accessory flagellum minute, conical; flagellum with 35 segments, nearly devoid of marginal setae. Antenna 2, peduncular segments 4 &5 short, 5 slightly longer, both with facial clusters of setae; flagellum of 30 weakly brush- like segments, basally stoutest, each with distal cluster of short setae. Mandible, molar small apically conical; spine row with 10-11 slender blades and a few supernumerary setae; cutting edge of incisor with 6 variably sized teeth; palp segment 3 short, inner margin with 1 1 pectinate “D” spines; leftlacinia with 12(?) teeth. Maxilla 1, palp slender with 4 apical slender spines? Maxilla 2? Maxilliped, inner plate short, broadest medially, with distal facial setae, and 4? apical marginal spinules; outer plate relatively short, distally narrowing, apex rounded; palp, dactyl curved. Coxae 1-4 medium, 1 & 2 each with 2-3 posterior marginal spines. Gnathopod 1, basis with antero-distal marginal setae; carpus short, deeper than long, hind lobe distally broad; propod short ovate, relatively deep, palmar margin shallowly oblique, nearly straight, moderately marginally simple-setose, with distinct median tooth, postero- distal angle with cluster of 3 spines, posterior margin with single distal cluster of 2 spines; dactyl smooth behind. Gnathopod 2 similar, but large; basis with fewer antero- distal setae; carpus, hind lobe slightly broader; propod more elongate, palmar margin slightly concave; postero-distal angle with cluster of 3 spines; hind margin strongly setose, with distal cluster of 3 spines; dactyl smooth behind. Peraeopods 3 & 4 ordinary, not setose; dactyls medium. Peraeopods 5-7 bases not strongly broadened, hind margins nearly straight; segment 4 short; segments 4-6 anterior and posterior strongly spinose and setose; segment 6, anterior margin with 6-7 clusters of spines and setae; dactyls medium. Pleon plate 3 weakly spinose below, hind corner acuminate. Urosome 2 occluded dorsally by segments 1 & 3. Uropod 1 , rami not elongate, weakly spinose marginally. Uropod 2, outer ramus distinctly the shorter. Uropod 3 regular(?). Telson medium, narrowing distally 7 to sharply rounded apex. Distribution. Known only from Barkley Sound, Vancouver I., British Columbia, LW and shallow subtidally, associated with sponges and tunicate, under rocks. Etymology. From the Latin “simplex”, meaning simple, not ornate, with reference to the unshortened, unbroadened blades of the mandibular spine row. Taxonomic commentary. Gnathopleustes simplex encompasses some plesiomorphic character states (e.g., slen- der mandibular blades) but, in balance of character states, is apomorphic. It appears not unlike G. pugettensis and the more southerly G. den, in the form of the antenna and other features of the mouthparts, especially the maxilliped. Gnathopleustes pachychaetus, new species (Figs. 17,18) Material examined. ALASKA. Southeastern Alaska. ELB Stns., June-July, 1961: A6 (1); A8(4 + slide mount); ABO (4); A171 28 + slide mount). ELB Stns, July, 1980: S4B4 (2); SllBl (2); S18B1 (!)• S22F1 (1). BRITISH COLUMBIA. Queen Charlotte Islands. ELB Stns., July- August, 1957: E21 (3); W9 (4). Flamingo Harbour, Stn. 3539, July 17, 1935 - 4 females ov; J FRB Stn. Ml-65-55, DBQ, JWS coll., Aug. 6, 1965 - 1 female ov. North-central coast, ELB Stns., July, 1964: H35 (-lOO)- H39 (15); H40 ~70); H41 (-25). Northern and central Vancouver I.: ELB Stns, July, 1959: 05 (-15); 017 (7); N18 (17, incl. males and females). R. M. O’Clair Stns, 1976: #760007, Kelsey Bay (1 male; # 760023, Squirrel Cove, Cortez I. - 30 males and female (+ slide mount); #760046, Port Hardy - 1 female ov. Southern Vancouver I.: ELB Stns, July-August, 1955: P4 (~15); P6a(-40)P6c(-15);F5 (-15); Ml 1 (-30). ELB Stns, 1970; P704 (1); P702 (1); P707 (-25); P708 (1). ELB Stns, 1 975 : P 1 7d ( 1 female + slide mount); P5c (5); P20a ( 1 ); P20c (2). ELB Stns., 1976: B 1 (10); B2 (6); B4 (9); B5 (44); B7 (2); B8(l);B12b(-160+ slide mounts); B 1 3 (-30)B28 ( 1 ). ELB Stns, 1977: B6a (3); B8 (1): B1 la (1); Bllb (2); B13 (1); B 19b(2). R. M. O’Clair Stns., 1976: #760028, Sturdies Bay, Galiano I. - 9 males Sc females. # 760031 Miner’s Bayi Mayne I. (-30 males, females). #760034, Horton Bay, Mayne I., June 22, 1976 - Male (6.8 mm), Holotype (slide mount), CMN Cat. no. NMCC 1995-0076; female (5.8 mm). Allotype (sUde mount), CMN Cat. no. NMCC 1995-0077, -i- 8 males, 12 females, Paratypes, CMN Cat. no. NMCC 1995-0078. ’ Ogden Pt. breakwater, Victoria, R. J. Long coll., 1976 - 2 females, 1 male. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 88 FIG. 16. Gnathopleustes simplex, n.sp. Male (6.8 mm); female ov (5.0 mm). Barkley Sound, B. C. WASHINGTON-OREGON. Coastal Stations, ELB, July-August, 1966: W2 (4 + slide mount); W5 (2); W22 (9 + slide mounts); W24 (-300); + slide mounts); W34 (15) W45 (9); W50(~50); W53 (10); W57 (-25); W58 (-28); W61 (23); W63 (-70). Eagle Cove, San Juan I., R. M. O’Clair Stn. 74001, June 21, 1974 - 2 females (slide mount). Charleston, Ore., mouth of Coos Bay, floating dock below LW, among Enteromorpha and Polysiphonia sp., K. E. Conlan coll., July 8, 1986: Stn 07- 1 - -70 males, females, im; Stn. 08-23 - 3 females, 4 im. Diagnosis. Male (6.8 mm): Body slender, coxal and pleonal plates medium deep. Head, eye relatively small, short- reniform. Antenna 1 , peduncular segments each with posterior marginal clusters of long setae; segment 3 long, length -2/ 3 segment 2; accessory flagellum cone-like, with strong apical seta; flagellum with 48 segments. Antenna 2 shorter than 1; peduncular segment 5 not shorter than 4, both with posterior and facial clusters of setae; flagellum relatively short, with -40 short segments, brush-like posteriorly. Upper lip tall, apical cleft shallow, lobes asymmetrical. Lower lip, inner lobes deep; outer lobes large, ovate, strongly oblique. Mandible, molar small apex subacute; spine row with 8-9 short thick blades, cutting edge of incisor with 7 regular teeth; palp segment 3 narrowing distally , inner margin with 1 8 pectinate “D” setae; left lacinia with 8-9-dentate. Maxilla 1, palp slightly narrowing distally, with 5 apical spines. Maxilla 2, outer plate narrowing distally apex relatively sparsely setose; inner plate with stout median marginal setae. Maxilliped, inner plate broad, with 7 distal facial setae and 5 apical marginal spinules; outer plate tall, columnar, apex rounded; palp segment 3 large stout, palp slender curved. Coxal plates 1-3 each with single posterior marginal spine. Gnathopod 1, carpus shorter, deeper than long; propod ovate, narrowing distally, palm nearly horizontal with distinct median tooth, and dense clusters of long thick AMPHIPACMCA VOL II NO. 1. AUG. 31, 1995 89 90 AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 Fig. 18. Gnathopleustes pachychaetus, new species. Male (6.8 mm). Mayne I., B. C. marginal "balloon" setae, margin merging smoothly with posterior margin, spine group at postero-distal angle with 4 spines, outermost largest, posterior margin with single distal cluster of 3 spines; dactyl, hind margin with a few small setules. Gnathopod 2 very similar but slightly larger, carpal lobe slightly deeper; palmar margin relatively short , distally slightly concave, postero-distal angle, spine cluster with 4 spines, posterior margin distally with a single spine and single cluster of spines. Peraeopods 3 & 4, segment 4-6 with dense clusters of spines and setae especially posteriorly; dactyls medium. Peraeopods 5-7 similar, bases slightly broadening distally, hind margins gently convex; segment 5 short, segment 6 long, margins spinose, not setose; dactyls medium. Pleon plates 2 and 3, lower margins weakly spinose, hind comers acuminate, slightly produced. Urosome 2 occluded dorsally by segments 1 &3. uropods 1 & 2 slender, slightly exceeding uropod 3 . Uropod 2 , outer ramus distinctly shorter than inner ramus. Uropod 3 , inner ramus with 6 pairs of marginal spines, outer ramus relatively large, = 3/4 inner ramus, margins 5 -spinose Telson broadly linguiform, apex broadly rounded. Distribution. From southeastern Alaska, commonly throughout B. C. coastal waters, to southern Oregon, under rocks and among algae at LW level to shallow subtidal. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 Etymology. From the Greek root words "pachy", meaning thick, and '"chaite" meaning hair, in reference to the thick, broad, laminate setae comprising the setose armature of the gnathopods. Taxonomic commentary. Gnathopleustes pachy- chaetus is somewhat similar to the more southerly species, G. den, in the strongly setose, weakly sexually dimorphic gnathopods, and in some mouthparts (e.g., mandibular blades). However, the gnathopod setae are more strongly thickened, and thick setae occur also on the distal se gm ents of the peraeopods, especially in the male. The posterior margins of peduncular segments of antenna 1 have 6-8 clust- ers of strong setae, and the flagellum of antenna 2 is brush- like, whereas corresponding parts of G. den are bare. Gnathopleustes trichodus, new species (Fig. 19) Material Examined. BRITISH COLUMBIA. Southern Vancouver I.; West of Amphitrite Point, N. A. Powell Stn 67-83, 22 m, Aug. 22, 1967 - male Holotype (slide mount) CMN Cat. no. NMCC 1995-0083. Diagnosis. Male (8. 5 mm): Body slender, coxal and pleonal plates medium deep. Head, eye broadly reniform, black. Antenna 1 shorter than antenna 2; peduncular segment 3 short, length< 1/3 segment 3; accessory flagellum conical, with 1 large apical setae; flagellum with 55 segments basally slightly short-setose. Antenna 2, peduncular segment 5 longer than 4, both with distal and facial clusters of setae; flagellum elongate, with -50 segments, each with prominent distal whorl of short setae. Upper lip, median notch shallow, lobes nearly symmetrical. Lower lip, inner lobes relatively shallow, outer lobes regularly ovate, oblique. Mandible, molar process prominent, apex subacute; spine row with 9 medium stout blades, tips obliquely acute; cutting edge of incisor with 6 irregular teeth; palp segment 3 slender, elongate, with 13 inner marginal pectinate “D” spines; left lacinia9- 1 0 dentate. Maxilla 1 , palp slender, with 4 apical spines. Maxilla 2, outer plate distally narrowing, apex strongly setose. Maxilhped, inner plate short,, with 7 distal facial setae and 5 apical marginal short spines; outer plate short narrowing to subtruncate apex; palp segment 3, inner margin with pectinate setae, dactyl slender, nearly straight. Coxal plates 1-3 relatively broad, each with 1-3 hind marginal short spines, coxa 4 very broad, width and depth subequal. Coxa 5 shallow. Gnathopod 1, carpus short, deep>er than long, lobe narrow; propod, palmar margin straight or slightly concave, median tooth strong, postero-distal angle with 2 groups of spines; median face with numerous clusters of slender thickened setae, giving densely setose appearance to propod; dactyl strong, not serrated behind. Gnathopod 2, similar, larger, very heavily setose; palm of propod distinctly concave; dactyl stout, nearly smooth behind. Peraeopods 3 & 4, stout, margins of segment 4-6 setose and spinose; dactyls strong, >1/3 length of segment 6. Peraeopods 5-7 subsimilar, bases regularly broadly ovate, smooth behind; segment 4-6 hind margins strongly setose and spinose; segment 4 relatively short; dactyls medium. Pleon plate 3, lower margin weakly spinose, hind comer acuminate, slightly produced. Urosome 2 nearly occluded dorsally by segments 1 & 3. Uropods slender, elongate. Uropod 1, distal peduncular spine short. Uropod 2, outer ramus slightly shorter than inner ramus. Uropod 3 inner ramus slender, margins with 8 pairs of spines; inner ramus relatively long, with 5-6 pairs of marginal spines. Telson linguiform, medium long, apex broadly rounded. Distribution. Known only from the type locality near Amphitrite Pt., outer coast of southern Vancouver Island. Etymology. From the Greek “trichos” mean hair, alluding to the dense setation of the gnathopods and peraeopods. Taxonomic commentary. Gnathopleustes trichodus is a primtive species, phyletically isolate from others of the group, especially in the form of the mouthparts, relative lengths of the antennae, broad coxal plates, concave gnatho- pod palms and densely setose peraeopods. Gnathopleustes serratus, new species (Figs. 20,21) Parapleustes pugettensis Shoemaker, 1964: 410, fig. 10. Material Examined. About 40 specimens in 15 lots: ALASKA. Southeastern Alaska. ELB Stns, 1961: A75 (Kayak, Wingham I.), LW, under boulders, June 27 - 5 males 3 females. BRITISH COLUMBIA. Queen Charlotte Island. ELB Stns, 1957: W12a(3);Hll(l); Stn HI 4a, Yakan Pt., Graham I., under boulders atLW, Aug. 25 - male (8.7 mm), Holotype (slide mount) CMN Cat. no NMCC 1995-0068; female ov. (10.0 mm) Allotype (slide mount), CMN Cat. no. NMCC 1995-0069; plus 10 males, 9 females, 1 im.,Paratypes,CMNCat.no.NMCC1995-0070. Northern Vancouver L: ELB Stns N1 (Open Bight, Rivers Inlet)(5);V5(NigeiL,)(2). Southern Vancouver I.: ELB Stn. 015 (Box I, north end Wickaninnish Bay) (20); ELB Stn P719 (Cape Beale), 1970 - 1 male, 1 im. ELB Stn. B3 (Diana L, Trevor Channel), 1976 - 1 female. ELB Stn B6a (Trial I. Point, Victoria), 1977 - 4 specimens WASHINGTON-OREGON. ELB Stns, 1966: W 40 (4); W57 (2); W58 (4); W61 (1); W63 (Cape Kiwanda) (>100). AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 92 FIG. 19. Gnathopleustes trichodus, new species. Male (8.5 mm). West of Amphitrite Pt., V. I., B. C. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 93 FIG. 20. Gnathopleustes serratus n. sp. Female (9.0 mm). Dillon Beach, CA. (after Shoemaker, 1964). CALIFORNIA. Albion Cove, at Cone Rock, Mendocino Co., Tony Chess coll., June 29, 1978 - 1 male. Diagnosis. Male (8.7 mm): Body relative slender, coxal plates shallow. Head, eye large, subrhomboidal. Antenna 1 , peduncular segment 3 medium; flagellum with ~45 short segments; accessory flagellum, truncate apex with 2 longish setae. Antenna 2, peduncular segment 5 not shorter than 4.; flagellum with ~25 segments, thickest proximally, each with distal ring of short “bottle-brush” setae. Upper lip lobes distinctly asymmetrical. Lower lip, inner lobes deep, outer lobes short-ovate. Mandible, molar prominent, apex blunt; spine row with 8-10 thick, apically acute blades; incisor, cutting edge with 6 uneven teeth; left lacinia 8-dentate; palp segment 3 with 11-12 pectinate inner marginal “D” spines. Maxilla 1, palp stout, with 6 apical spines. Maxilla 2, outer plate not narrowing distally, apex strongly setose. Maxilliped, inner plate with 10 apical facial setae and 3 short apical spines; outer plate tall, distally narrowing; palp, dactyl slender, nearly straight. Coxae 1 & 2, hind margin with 1-2 median short spines; coxa 4 shallow, broad. Gnathopod 1, carpus shorter than deep, hind lobe narrow; propod ovate, palm very oblique, gently convex, postero-distal angle with groups of 3 & 4 spines; dactyl strongly denticulate or serrated along proximal 2/3 of inner margin. Gnathopod 2, carpus short, hind lobe smaller than in gnathopod 1 ; propod long-ovate, very oblique palm merging smoothly with hind margin, not heavily marginally setose; postero-distal angle with 2 groups of 4 spines; dactyl serrated behind. Peraeopods 3 & 4, segments regularly spinose; segments 5 , hind margin with 5 clusters of short spines; dactyls short. Peraeopods 5-7 closely homopodous, 5 slightly shortest; bases broadly expanded, hind margin strongly convex, minutely serrulate; segment 5 distinctly shorter than 4; dactyls short. Pleon plate 3, hind comer acuminate. Urosome 2 nearly totally occluded dorsally by segment 1 & 3. Uropod 2, outer ramus 2/3 length of inner ramus. Uropod 3, inner ramus with 5 serially paired marginal spines. Telson linguiform, relat- ively narrow, length nearly twice width, apex sharply rounded. Distribution. From southeastern Alaska to central California (Dillon Beach), mostly under boulders, associated with sessile invertebrates, Egregia, Corallina and other algae, at LW level. Etymology. From the Latin ^'serratus", with reference to the serrated hind margins of the gnathopod dactyls. Taxonomic commentary* Gnathopleustes serratus is relatively primitive species in characters of the mouthparts (maxilliped) and gnathopods (serrated dactyls), and near the base of the genus phyletically. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 94 FIG. 21. Gnathopleustes serratusy new species. Male (8. 5 mm); female (10.0 mm). Graham I., B. C. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 Incisocalliope J. L. Barnard 95 Incisocalliope }. L. Barnard, 1959: 22. Parapleustes Gurjanova,1951: 645 (part.).— Barnard & Given, 1960: 42 (part.).— Guijanova, 1972; 131 (part.).— Watling & Maurer, 1973: 1 (part).— Barnard & Karaman, 1991: 649 (part).— Ishimaru, 1994: 46 (part). Parapleustes (derzhavini group) Ishimaru, 1984:407,450. Type species. Incisocalliope newportensis Barnard, 1959, original designation. Species composition. Incisocalliope dilatatus (Ishi- maru, 1984); /. bairdi (Boeck, 1871); /. derzhavini (Gurjanova, 1938); I. nipponensis, new species; /. makiki (J. L. Barnard, 1970); /. aestuarius (Watling & Maurer, 1973); I. filiaris (Hirayama, 1988). Diagnosis. Body small to medium, slender, smooth above. Head, rostrum short, little exceeding rounded ante- rior head lobe. Eye small, medium rounded to ovate. Antennal flagella slender, nearly bare; antenna 1 longer than antenna 2. Antenna 1, peduncular segments 2 & 3 short, peduncle 1 lacking postero-distal cusp; accessory flagellum minute, triangular. Mouthparts modified. Upper lip, median notch deep, lobes asymmetrical. Lower lip broad, squat, outer lobes steeply oblique. Mandible, molar reduced to a small setulose knob; left lacinia 9-12 dentate; blades numerous (9-14), unmodified; incisors 8-dentate; palp segment 2 medially sparsely setose, segment 3 longest, apically truncate, segment 1 medium. Maxilla 1, inner plate with 1 apical seta; outer plate with 9 medium strong pectinate spine-teeth; palp not broadened, surface setulose, apex rounded, with few spines, segment 1 with lateral seta(e). Maxilla 2, inner plate little broadened, inner margin with single large plumose seta. Maxilliped, inner plate with few (2-4) “button” spines; seg- ment 3 longer than palp segment 2; outer plate columnar, palp segment 3 largest, segment 3 often with short inner distal spine-teeth; dactyl slender. Coxal plates 1 -4 medium deep; coxa 4 largest & strongly excavate behind; coxa 1 shortest, slightly expanding distally ; hind cusps small, single or double. Gnathopods 1 & 2, variously (mainly strongly) subchelate, subequal, not sexually dimorphic. Gnathopod 1, basis normal, anterior margin often strongly setose; meral process weak; carpus short, deep; propod, palm convex, with median tooth, not continuous with weakly setose posterior margin; postero-distal angle with 2-3 spine groups not extending onto palm. Peraeopods of medium length and stoutness, segments spinose but not setose; segment 4 slightly longer than and distally overhanging segment 5; dactyls medium, curved. Peraeopods 5-7 homopodous, increasing slightly posteriorly; coxae medium deep, rounded behind; bases broad, hind margin nearly flat. Pleon segments normal, hind comers acuminate (but not hooked), lower margins lightly spinose. Pleopods normal, not sexually dimorphic, rami medium strong. Uropods 1 & 2 extending to or beyond uropod 3, rami spinose. Uropod 1 , inner ramus slightly the longer. Uropod 2, outer ramus distinctly the shorter. Uropod 3, rami relatively short, inner ramus distinctly the longer. Telson medium long, keeled proximally below, apex rounded, with small paired notch and seta. Coxal gills undescribed. Brood plates large, broad. Taxonomic remarks. Incisocalliope is phyletically the most advanced genus, with closest relationships to Gnatho- pleustes and, to some extent, to Trachypleustes. These groups may be distinguished by a combination of character trends, as outline in the key and Table I. (p. 128). Distributional ecology. Species of Incisocalliope occur mainly in temperate or subtropical regions of pan-Pacific and North Atlantic regions, in shallow occasionally estuarine habitats. By contrast, the slightly less phyletically advanced members of Gnathopleustes are confined to open coast habitats of the North American Pacific region, but some (e.g., G. pachychaetus) exhibit brackish- water tolerance. Incisocalliope newportensis Barnard (Fig. 22) Incisocalliope newportensis Barnard, 1959: 22, pi. 2. Parapleustes pugettensis Barnard & Given, 1960: 43, fig. 4.— Barnard, 1969b: 178.— Barnard & Karaman, 1991: 650. Material examined. J. L. Barnard's type specimen (Stn. #9, AHF- # 522) has been made available for this study, courtesy of the Los Angeles County Museum. Diagnosis. Female (5.0 mm): Head, eyes medium, oval, black. Antennae especially peduncles, stout. Antenna 1 the longer; peduncular segment 1 large, 2 & 3 short; flagellum long. Antenna 2, peduncular segment 5 > segment 4. Mandible, spine row with 8-9 blades; left lacinia 8-9 dentate; palp segment 3 with 6-7 posterior marginal pectinate D spines. Maxilla 1, palp segment 2, surface setulose, segment 1 with single “shoulder” seta. Maxillas 2, inner plate broad, short. Maxilliped, inner plate with button spines. Coxal plate 1 large, expanding distally, little shorter than 2, with single postero-distal cusp. Coxa broad, width = depth. Gnathopods strongly subchelate, propods medium large; basis, anterior margin with a few scattered short setae; hind margin with a few setae proximally. Gnathopod 2, basis, anterior margin nearly bare. Peraeopods 3 & 4, segment 5 short, length < segment 5; Peraeopods 5-7, bases broad, convex behind; segment 5 short dactyls strong. Pleon plate 3, hind comer acuminate, hind margin nearly straight. Uropod l,peduncle,outermargin strongly spinose. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 96 KEY TO SPECIES OF INCISOCALUOPE 1. Coxa 1 distinctly shorter than coxa 2; gnathopod 1, basis, anterior margin strongly setose (20+ setae); peraeopods 3 & 4, basis, anterior margin lined with short setae throughout 2 —Coxa 1 about as deep as coxa 2; gnathopod 1, basis, anterior margin nearly bare or with fewer than 15 setae; peraeopods 3 & 4 basis, anterior margin weakly setose 2. Uropod 2, rami subequal; peraeopod 7, basis medium broad, postero-distal lobe ordinary, not reaching to segment 4; dactyls short, < 1/3 segment 6 L aestuarius (p. 104) — Uropod 2, outer ramus distinctly (1/3) the shorter; peraeopod 7, basis narrow, hind lobe deep, reaching segment 4 behind; dactyls heavy, strong, >1/3 segment 6 Lfilialis (p. 102) 3. Gnathopods 1 & 2, propods relatively weak, depth not greater than carpus; gnathopod 1, basis with antero-distal cluster of 3 long setae —Gnathopods 1 & 2, propods relatively stout, strong, depth greater than carpus; gnathopod 1, bas- is antero-distally with 0-2, or 4, long setae 5. 4. Gnathopod 2, basis with 2 strong antero-distal setae; antenna 1, peduncular segment 1 large, distinctly longer than segments 2 & 3 combined /• derzhavini (p. 102) Gnathopod 2, basis lacking strong antero-distal setae; antenna 1, peduncle 1 ordinary, length about equal to segments 2 & 3 combined nipponensis (p. 1(X)) 5. Gnathopod 1, basis, anterior marginal setae long, length > width of basis; antenna 2, peduncular segment 5 not longer than 4 makiki (p. 98) Gnathopod 1, basis, anterior marginal setae short, length < width of basis; antenna 2, pedunc- ular segment 5, length distinctly > segment 4 6. 6. Peraeopods 3 & 4, segment 5 regular, length ~ segment 4; antenna 2, peduncular segments 4 & 5 slender, length 3-4 X width (p. 96) —Peraeopods 3 & 4, segment 5 short, thick, length < segment 4; antenna 2, peduncular segments 4 & 5 relatively short, thick, length "'2X width 7. 7. Peraeopod 4, coxa broad, width -depth; uropod 1, peduncular outer margin lined with 10-12 strong spines; uropod 3, inner ramus with 5-6 pairs of marginal spines . . I. newportensis (p. 95) —Peraeopod 4, basis narrow, width < depth; uropod 1, peduncular margin proximally with cluster of 3-4 Stout spines; uropod 3, inner ramus, margins with 3-4 pairs of spines. /. dilatatus (p. 97) Uropod 2, outer ramus -3/4 inner ramus. Uropod 3, inner ramus with 6 pairs of marginal spines. Telson long, apex truncated. Taxonomic and distributional commentary. The type locality of Incisocalliope newportensis is Newport Bay , California. The species has been recorded authentically on the eastern Pacific coast only south of Pt. Conception. 1 1 has been confused with Gnathopleustes pugettensis. How- ever, morphological differences are major, and the latter is also larger at maturity and more northerly in distribution. Incisocalliope newportensis and/, bairdi (J. L. Barnard) form a primitive species pair within the genus. Further species of the genus may yet be discovered, especially in the Baja and Gulf of California regions, and in the southern Sea of Japan and China Sea regions. Differences noted here between this pair and the remaining six species may eventually form a basis for recognition of the two phyletic groups at the subgeneric level (Fig. 43, p. 127). Incisocalliope bairdi (Boeck) (Fig. 23) Paramphitoe bairdi Boeck, 1871: 45-46, 50, pi. 1, fig. 3. — Barnard, 1956: 36, Plate 12. — Barnard & Karaman, 1991: 650. Neopleustes bairdi Stebbing, 1906: 314-315. non Parapleustes pugettensis Barnard & Given, 1960. Diagnosis. Male (5.5 mm): Head, eyes medium large, oval-round, black. Antenna 1 the longer, flagellum 36- segmented. Antenna 2, peduncular segment 4 & 5 slender, segment 5> 4. Mandible, spine row with 1 5 blades; lacinia with 9 teeth; palp segment 3 with 9-10 posterior marginal “D” spines. Maxilla 1 , palp segment 2, apex with 7 spines and facial setal row, segment 1 with 2 short “shoulder “ setae. Maxilla 2, plates small, inner plate not broadened. Maxilliped, inner plate with 4-5 apicEil marginal “button” spines outer plate columnar; palp segment 3 large, heavy. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 97 FIG. 22. Incisocalliope newportensis (Barnard 1959). Female (5.0 mm). New port Bay, California. Coxal 1 large, broadening distally, lower margin gently convex, with single postero-distal cusp. Coxa 4 narrow, width < depth. Gnathopods large, strongly subchelate. Gnathopod 1, basis, anterior and posterior margins nearly smooth; merus with short distal process ; propod, hind margin straight, with single distal setal group. Gnathopod 2, hind margin of coxa with 2-3 short spines; basis nearly bare of setae. Peraeopods 3 & 4, segment 5 not shortened, length ~= segment 4. Peraeopods 5-7, bases medium broad, hind margins nearly straight; segment 5 not shortened. Dactyls medium. Pleon 3, hind comer acuminate, Uropod 1, peduncular outer margin with 7-8 spines, outer ramus very slightly the shorter. Uropod 2, outer ramus about 3/4 length of inner r am - us. Uropod 3, inner ramus with 5 pairs of marginal spines. Telson medium, narrowing to smoothly rounded apex. Taxonomic commentary. The species was first described by Boeck (1872) from southern California, and rediscovered in fresh material from the same region by J. L. Barnard (1956). Barnard's description and figures, more detailed than the accounts of Boeck (loc. cit.) and Stebbing “(1906) form the basis of the present analysis. Incisocalliope dilatatus (Ishimam) (Fig. 24) Parapleustes dilatatus Ishimam, 1984: 425, figs. 17-20.— Barnard & Karaman, 1991: 650.-Ishimam, 1994: 54. Diagnosis. Male (4.7 mm): Head, eye medium large almond-shaped, black. Antennae relatively short, first slightly the longer. Antenna 1, peduncular segment 1 short, thick; flagellum 27-segmented. Antenna 2, peduncular segments 4 & 5 relatively long, slender, 5 > 4; flagellum 1 8-segmented. Mandible, spine row with 10 blades; left lacinia 9- dentate; palp segment 3 with 6 posterior marginal “D” spines. Maxilla l,palp segment 1 with 2 "shoulder” setae; segment 2, apex oblique, with 4 spines and numerous facial AMPHIPACmCA VOL II NO. 1. AUG. 31, 1995 98 FIG. 23. Incisocalliope bairdi (Boeck, 1971). Male (5.5 mm). S. California, (after Barnard, 1956). setae. Maxilla 2, inner plate very slightly broadened. Maxilliped, inner plate with 3 apical “button” spines; outer pate, with 2 slender apical spines; palp segment 3 with distal inner facial scales . Coxal plate 1 large, distal margin convex, hind comer with 2 small cusps, posterior margin with 2 short spines. Coxa 4 medium, depth > width. Gnathopods strongly subchelate, propods relatively large. Gnathopod 1, basis with 1-2 stout anterior marginal setae, hind margin nearly bare; mems lacking postero-distal process; propod with superior medial facial cluster of setae; hind margin with single distal setal group. Gnathopod 2, anterior and posterior margins with weak, short setae; merus with strong postero- distal process. Peraeopod 3 & 4, segment 4 short, length > segment 5, dactyl medium. Peraeopods 5-7, bases broad, rounded behind; segment 5 short, length < segment 4. Pleon plate 3, hind corner acuminate. Uropod 1, peduncular outer margin relatively weakly spinose, with cluster of 3 strongest spines proximally; rami weakly marginally spinose; outer ramus distinctly the shorter. Uropod 2, peduncle with 2 strong outer marginal spines. Uropod 3, rami short, inner ramus with 3-4 marginal spines. Telson relatively short narrowly slightly to broadly rounded apex. Female (6.0 mm). No discernible difference from the male Taxonomic commentary. Incisocalliope dilatatus is morphologically closest to /. makiki Barnard from the Hawaiian Islands (Fig. 44, p. 129). Both are members of the advanced subgroup that includes, /. derzhavini and I. filialis of the western Pacific region. Distribution. Japan Sea, southern shores of Hokkaido, under marine algae, LW level. Females ov. , May to August. Incisocalliope makiki (J. L. Barnard) (Fig. 25) Parapleustes derzhavini makiki Barnard, 1970: 227. Diagnosis. Female (4.2 mm): Head, eye medium large, reddish or dark brownish, irregularly roundish. Antenna 1 , peduncular segment 1 large > 2 & 3 combined, flagellum 24+ segmented. Antenna 2, peduncular segment 4 & 5 medium stout, subequal, flagellum 18+ segmented. Mandible, spine row with 8 blades, left lacinia 10-11- AMPHIPACIFICA VOLH NO. 1. AUG. 31, 1995 99 VIG.HX. IndsocamopedUatatus (Ishimaru, 1984). Male (4. 7 mm). Hokkaido, (after Ishimaru, 1984). dentate; palp segment 3, inner margin with 7 pectinate “D” setae. Maxilla 1, inner plate small, with 1 apical seta, Maxilliped, inner plate with 2 apical “button spines; outer plate with 2 slender apical spines; palp segment 3, with pectinations or scales at base of dactyl. Coxa 1 medium large, lower margin convex, hind comer with 1-2 cusps, hind margin with single spine. Coxa 2 with 1 postero-distal cusp. Coxa 4 broad, as wide as deep. Gnathopods strongly subchelate; propod of gnathopod 2 l3rger than 1. Gnathopod 1, basis, anterior margin with numerous (~10) strong setae, each longer than width of basis, hind margin weakly setose proximally ?; mems lacking distal process 1; propod with superior facial group of 2 setae; posterior margin bare. Gnathopod 2, basis virtually lacking marginal setae; merus with postero-distal process; propods, hind margin with distal group of spines and setae. Peraeopods 3 & 4, basis, margins weakly short-setose; segment 5 slightly shorter than 4; segment 6, hind margin spinose. Peraeopods 5-7, basis moderately broad, hind margins convex, lower hind lobe shallow, not reaching AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 100 FIG. 25. Incisocalliope makiki (J. L. Barnard). Female (4.2 mm). Hawaii (after Barnard, 1970). segment 4; segment 5 shorter than segment 4. Pleon 3, hind comer minutely acuminate. Uropods 1 & 2 strong. Uropod 1 , peduncle, outer margin strongly spinose; outer ramus distincdy the shorter. Uropod 3, inner ramus slender, margins with 6 spines. Telson short, broad, little longer than wide, normally rounding apically. Distribution. Oahu, Hawaiian Islands; 3-4 m in depth. Taxonomic commentary. Incisocalliope makiki merits full species status here. Its presumed common ancestor with I. dilatatus may have penetrated the Hawaiian archipelgo in the early Tertiary Period (p. 130). Incisocalliope nipponensisy new species (Fig. 26) Parapleustes denhavini Ishimaru, 1984: 417.-Ishimaru, 1994: 54 (part.) Diagnosis. Female (5.0mm); Head, eye small, rounded, black. Antenna 1, peduncular segments 1-3 short, segment 1 = 2 and 3 combined; flagellum, slender 25-segmented. Antenna 2, peduncular segment 4 shorter than 5, medium thick; flagellum slender, 24-segmented. Mandible, spine row with 8 blades; left lacinia 11- dentate; palp segment 3 with 7 posterior marginal “D” setae. AMPHIPACIFICA VOLH no. 1. AUG. 31, 1995 101 FIG. 26. Incisocattiope nipponensis , new speci es. Female (4.6 mm). Japan Sea. (after Ishimaru, 1984). Maxilla 1, palp segment 1 with single “shoulder” seta; segment 2 apically with 4 spines and facial row of 3 setae. Maxilla 2, inner plate short, not broadened. Maxilliped, inner plate with 3 “button” spines; outer plate with 2 apical slender spines; palp segment 3 with distal inner marginal pectinations. Coxa 1 small, 1/3 shorter than 2, with single postero- dts^ cusp and 1 -2 posterior marginal short spines. Coxa 4 Type material Female “a” /5 n mmt c. Pleon plate 3, hind comer strongly acuminate. Uropod 1, peduncle, outer margin strongly spinose, Uropod 2, inner ramus longer than peduncles, 1/3 longer than outer ramus. Uropod 3, inner ramus 1/3 longer than outer ramus, with 4- 5 pairs of marginal spines. Telson medium long, narrowing to sharply rounded apex. weakly subchelate, propods only slightly broadened. Gnathopod 1, basis with 15+ long anterior marginal setae and ~ 10 short postero proximal marginal setae, merus with distal cusp; propod, hind margin with single distal spine. Gnathopod 2, basis, margins nearly bare merus with acute postero-distal cusp. Peraeopods 3 & 4, regular, segment 5 not noticeably shortened, dactyls medium. Peraeopods 5-7, base broadly expanded, hind margins convex, dactyls stout. 2 females. Paratypes, at stations 2-4 along south coast of Hokkaido, 0.5 m depth, among algae. Collections of the Zoological Museum, Faculty of Science, Hokkaido University. Distribution. Shores of Hokkaido, LW to 5 m depth Sargassum belt, Laminaria belt; among Leathesia and other algae scraped from surface of boulders. AMPHIPACIFICA VOLH NO. 1. AUG. 31, 1995 102 FIG. 27. Incisocalliope derzhavini (Gurj., 1938). Female (4.0 mm). Japan Sea. (after Gurjanova, 1951). Taxonomic commentary. This description is based on the careful work of Ishimaru (1984). He had previously found it very similar to the female (4.0 mm) of Neopleustes derzhavini from the sea of Japan, described by Guijanova (1951), that is treated below (see also Fig. 27). Incisocalliope derzhavini Gurjanova (Fig. 27) Neopleustes derzhavini Gurjanova, 1938: 317, fig. 31. Gurjanova, 1951: 645, fig. 442. Parapleustes derzhavini Barnard & Karaman, 1991: 650 (part) Diagnosis. Female (4.0 mm): Head, eyes medium, round, black. Antenna 1, peduncle 1 large, length > seg- ments 2 & 3 combined; flagellum medium long, slender, 25- 27 segmented. Antenna 2, peduncular segment 4 & 5 short, thick, 5 > 4; flagellum 18- segmented. Mandible, spine row with 6-8 blades; palp segment 3 with 5-6 pectinate “D” spines. Maxilla 1, palp segment 1 with 1 shoulder seta; segment 2, rounded apex with 4 spines. Maxilla 2, inner plate not broadened. Maxilliped, inner plate with 3 (?) button spines, palp segment 3 with pectinations at base of dactyl? Coxa 1 relatively short, little broadening distally, lower margin convex, with 1 hind cusp. Gnathopods relatively weakly subchelate; propods not deeper than respective carpus. Gnathopod 1, basis, anterior margin with 9-10 stout setae, concentrated distally, mostly longer than width of basis; merus lacking distal process; propod hind margin bare. Gnathopod 2, basis, antero-distal margin with 2 very large stout setae, hind margin nearly bare; merus with short distal process?, propod, hind margin with single distal seta. Peraeopods 3 & 4 ordinary. Peraeopods 5-7 ordinary; bases moderately expanded, ovate. Pleon plate 3, hind corner acuminate, lower margin gently convex, with 4-5 small spines. Uropod 3, inner ramus slender, margins each with 4 spines. Telson medium long, narrow, sharply rounding at apex. Distributional ecology. Japan Sea; tidal zone. Taxonomic commentary. Gurjanova's original figures and description are limited but sufficiently detailed to separate /. derzhavini from the material of Ishimaru (loc. cit.) des- cribed above as /. nipponensis, new species. Incisocalliope fHiaUs (Hirayama) (Fig. 28) Parapleustes filialis Hirayama, 1988; 40, figs. 265-268. — Barnard & Karaman, 1991: 650. — Ishimaru, 1994: 54. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 103 FIG. 28. Incisocalliope filialiss (Hirayama). Male (3, Diagnosis. Male (3.5 mm): Body small, pleonites slightly raised postero-dorsally. Head, eyes medium large, nearly round, black. Antennae slender, medium long. Antenna 1, peduncular segment 2 short, - 1/2 segment 1 ; flagellum - 1 5- segmented. Antenna 2, peduncular segments 4 & 5 stout, 5 slightly the longer; flagellum 16-segmented. Upper lip with relatively deep V-notch, lobes asymmetrical. Lower lip inner lobes broad, outer lobes oblique. Mandible, molar process small, vestigial; spine row with 6 short blades; incisor (left) with 4 proximal large teeth and 4-5 distal denticles; palp segment 3, basal “A” seta small, inner margin with 5-6 pectinate “D” spines; left lacinia 10- dentate. Maxilla 1, inner plate with single apical seta; palp segment 1 with single “shoulder” seta; distal segment, apex with 4-5 slender spines. Maxilla 2, inner plate short, not broadened, inner margin with single proximal plumose seta. Maxilliped, innerplate medium, inner margin notched distally, apex with 5 slender spines; outer plate slender, truncate apex with 2 slender spines; palp stout, segment 3 with distal 5 mm). Ariake Sea, Japan, (after H irayama, 1988). pectinate denticles at base of dactyl; dactyl slender, straight, length about equal to segment 3. Coxal plates 1-3 lower margins broadly rounded, hind margins with 1 -2 median short spines, hind comers each with single cusp. Coxa 1 distinctly shorter than 2. Gnathopod 1, anterior margin of basis strongly setose, (20+ setae), some setae longer than width of basis; hind margin of basis proximally with 6-8 shorter setae.; carpus short, as deep as long, hind lobe stout; propod short, expanding distally, inner face with scattered setae; palmar margin convex, oblique slightly longer than hind margin, postero-distal angle with spine groups on either side of short dactyl-tip depression, distal spines larger; dactyl slender, with small distal unguis. Gnathopod 2, anterior margin of basis weakly setose, with single distal seta; hind margin proximally with row of setae; carpus short, hind lobe narrow propod subovate, longer and more slender than in gnathopod 1 ; two groups of longer and stronger spines at palmar angle. Peraeopods 3 & 4 relatively short and stout; bases. AMPHIPACIFICA VOL II NO. I. AUG. 31, 1995 104 FIG. 29. Incisocalliope aestuarius (Watting & Maurer, 1973). Female (4. 0 mm). Delaware Bay. anterior and posterior margins moderately strongly setose; segment 5 shorter than 4; segment 6, hind margin with 3 groups of stout spines; dactyl heavy, medium. Peraeopods 5-7, bases only moderately broadened, least in peraeopod 7, postero-distal lobes large, deep, reaching segment 4; segment 5 shorter than 4; dactyls stout. Pleon plate 3, lower margin weakly spinose, hind corner squared, not acuminate. Pleopod peduncles, outer margin strongly setose. Uropods 1 & 2 large, extending well beyond uropod 3. Uropod 1, peduncle large, outer margin finely spinose. Uropod 2, outer ramus distinctly the shorter. Uro- pod 3, outer ramus long, length -2/3 long inner ramus, with 6 pairs marginal spines. Telson oblong, apex subacute. Distribution. Ariake Sea, Japan; sublittoral. Taxonomic commentary. Hirayama likened Inch- calliope filialis to Incisocalliope derzJtavini but found sev- eral species differences. The species is an atypical Para- pleustes, with several features more reminiscent of Gnatho- pleustes. These include the unlike gnathopod propods, narrow peraeopod bases; and in mouthparts, the broad lower lips, "shoulder" seta on palp of maxilla 1, etc. The species is close to /. dilatatus in the armature of the maxilliped palp. Incisocalliope aestuarius (Watling & Mauer) (Fig. 29) Parapleustes aestuarius Watling & Mauer, 1973: 252, figs. 1-4. — Fox & Bynum, 1975: 230. — Ishimaru, 1984: 431. — Barnard & Karaman, 1991: 650. Diagnosis. Female (4.0 mm): Head, eye small round, black. Antenna 1, peduncular segment 1 large, stout, length about equal to segments 2 & 3 combined. Flagellum long, -40 segments. Antenna 2, peduncular segments 4 & 5 short, medium, segment 5> 4; flagellum ! 25-segmented. Mandible, spine row with ~14 slender blades, distally largest; left lacinia 10-dentate; palp segment 3 with 8-9 slender pectinate “D” spines. Maxilla 1, segment 1 with AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 105 single shoulder seta; segment 2 , with numerous short facial seme, rounded apex with 4 spines; outer plate, inner apical spine elongate. Maxilla 2, inner plate not broadened. Maxilliped, inner plate with 2-3 apical marginal “button” spines; outer plate with 4 apical slender spines; palp segment 3 distally with pectinations at base of dactyl. Coxal plate 1 short, lower margin convex, hind comer with 2-3 cusps posterior margin with 2-3 stout spines. Coxa 4 little broadened deeper than wide. Coxa 5 deep. Gnathopods relatively weakly subchelate; basis, anterior margin lined with numerous (20+) setae some longer the width of basis, hind margin strongly lined with shorter setae; mems lacking distal cusp; propod relatively short, not deeper than carpus; with superior and inferior facial clusters of small setae; hind margin shorter than palm, with single distal setal group. Gnathopod 2, basis distal with short setae, hind margin distally with several setal groups; merus with short posterior tooth; propod, hind margin with 2 distal setal groups. Peraeopods 3 & 4 basis, anterior margin strongly short- setose; segment 5 shorter than 4; dactyls relatively short. Peraeopods 5-7, bases moderately broadened, hind margins convex; segment 5 slightly shorter than 4. Pleon plate 3, hind comer acuminate, slightly produced. Uropods 1 & 2 strong, rami longer than peduncle. Uropod 1, peduncle, outer margin strongly spinose; rami subequal. Uropod 2 outer ramus little shorter than inner, margins strongly spinose. Uropod 3 rami long, slender, inner ramus with 7 pairs of margins spines. Telson medium long, apex rounded. Distributional ecology: From Delaware Bay, Chesapeake Bay to Albemarle Sound and estuaries of the southeastern states, on wharf pilings, among bryozoans, hydroids, and other sessile invertebrates. Taxonomic & distributional commentary. The original description (as Parapleustes aestuarius) is limited in a number of features, some of which were pointed out by Fox & Bynum (loc. cit.). The species is remarkably close morphologically to Incisocalliope filialis from the Sea of Japan. The relationship appears closely phyletic, but the disjunct distribution of the two forms defies explanation that is entirely satisfactory (see p. 130). Trachypleustes, new genus Type species. Trachypleustes vancouverensisy new species. Species composition. Trachypleustes trevori, new species (and varieties: Pribilof Islands, San Juan Batista I). Diagnosis. A group of small, smooth-bodied pleustids having short antenna 1 peduncular segments, unequal gnathopods, slender legs, slender unequal rami of uropods, and heavily chitinized, “molanzed”, or otherwise strongly modified mandibular blades. Body smooth above, slender. Head small; rostrum slightly produced beyond subacute head lobe. Eyes large. Antennae slender, elongate. Antenna 1, peduncle 1 large, without postero-distal process; segment 2 medium short; accessoiy flagellum minute, triangular, with a few apical setae. Antenna 2, peduncular segments 4 & 5 subequal, setose; flagellum elongate. Mouthparts strongly modified. Upper lip moderately incised and asymmetrical. Lower lip broad, squat, outer lobes oblique. Mandible, molar minute; spine row with few (4-6), strongly thicked and/or flattened blades; left lacinia irregularly 10-11 dentate; incisor multidentate; palp, segment 3 longest, medial pectinate setae numerous ( 12+); segment 2 sparsely setose medially. Maxilla 1, outer plate short, spines tall; palp long, apex with slender spines and setae, segment 1 lacking lateral setae; inner plate 1-setose. Maxilla 2, inner plate medium broad, with 1 large inner plumose seta; maxilliped, palp and dactyl strong; inner plate short, apex sloping, with 3-5 button-teeth and 4-6 inner marginal setae; outer plate narrow, apex and inner margin slender-spinose. Coxal plates 1-4 increasing in size posteriorly; coxa 1 small, not expanded distally; coxa 2-4 deeper than body plates; lower margins nearly straight, with hind cusp. Gnathopods 1 & 2 weakly subchelate, similar in form but unequal in size, not sexually dimorphic; gnathopod 2 distinctly the larger. Gnathopod 1, basis weakly setose anteriorly; carpus shallow, more than half length of propod; length of palm oblique, with small median tooth; length about equal to smooth hind margin; postero-distal angle with 2 groups of spines; dactyl slender. Gnathopod 2, carpus shorter, hind lobe deeper, anterior margin about half length of propod; 2- 3 spine groups at posterior angle. Peraeopods 3-7 slender, dactyls normally developed. Peraeopods 5-7 normally homopodous; bases regularly broad and rounded behind; segment 4 (merus) postero-distal process strongly overhanging segment 5. Pleon plates 1-3 regular; lower margins spinose, hind comers variously acuminate. Pleopods strong, not sexually dimorphic. Urosome 2 not occluded dorsally. Uropods 1 & 2 slender, marginally strongly spinose; rami unequal, inner ramus longer than peduncle. Uropod 3, rami markedly unequal, strongly spinose. Telson medium, apex rounded; penicillate setae slightly proximal to mid point. Coxal gills small to medium, saclike, largest on peraeopods 4 & 5. Distributional commentary. Members of the genus are known only from northern parts of the North American Pacific coastal marine region, in association with sponges and large sessile invertebrates. Etymology. A combining form of the Greek root ''trachytes'^ roughness, and the generic name Pleustes, that alludes to the rough, molarlike appearance of the mandibular blades AMPHIPACMCA VOL II NO. 1. AUG. 31, 1995 106 Taxonomic Commentary. This generic group is distinguished by the heavily molarized and pavementlike mandibular blades, the unequal, non sexually dimorphic gnathopods, slender peraeopods, and the elongate, spinose uropod rami. Phyletically the genus Trachypleustes appears closest to Gnathopleustes, but more distant from Inciso- calliope. Trachypleustes vancouverensis, new species (Fig. 30) Material examined. eBRITISH COLUMBIA. Northern Vancouver 1. : ELB Stn 0 1 , Cape Scott, Experiment Bight, under boulders, among algae, LW level, July 18, 1959. - female ov. (4.5 mm), Holotype (slide mount), CMN Cat. no. NMCC 1995-0086. Diagnosis. Female ov. (4.5 mm): Head, rostrum pro- longed beyond lateral head lobe; eye subquadrate. Antenna 1, peduncular segment 1 long, extending to midpoint of peduncular segment 4 of antenna 2; flagellum ~'28-segmented. Antenna 2, length about equal to antenna 1 ; flagellum -28- segmented. Lower lip, inner lobes very broad, shallow. Mandible, molar process prominent, apex blunt; spine row distally with 4 thick short blades having rough, conical apices, and proximally with several short vestigial blades; cutting edge of incisor with 7-8 unequal teeth; palp segment 3 apex blunt, inner distal margin with 1 2 slender pectinate “D” spines; left lacinia large, broad, cutting edge with 10 small uneven teeth. Maxilla 1, palp slightly narrowing distally, rounded apex with 6 slender spines. Maxilla 2 outer plate narrow. Max- illiped, inner plate short, with 3 inner marginal plumose setae, and 4 apical button spines; outer plate slender, nar- rowly subtruncate, with 2 very slender spines; palp ordinary. Coxae relatively deep, broad, hind comers with single small cusp. Gnathopod 1, propod about half size of propod of gnathopod 2; palmar margin smoothly continuous with posterior margin; proximal spine group at postero-distal angle with single spine and split-tipped seta; posterior margin distally with single spine and setae. Gnathopod 2, carpal lobe, some distal setae pectinate; propod stout, subovate; proximal spine group at postero-distal angle with 5 spines and split-tipped seta; posterior margin distally with small cluster of split-tipped setae. Peraeopods 3 & 4 ordinary, slender; segment 4, anterior margin with 3-5 tufts of slender spines; dactyls strong. Peraeopods 5-7 closely homopodous; bases broad, hind margins smoothly convex; margins of segments 4-6 with cluster of short spines; segment 5 slightly shorter than 4; dactyls strong, curved. Pleon plates 1-3, hind comers acuminate. Urosome 2 with free dorsal margin. Uropod 3, outer ramus relatively long, -60% of inner ramus. Telson distally with several dorsal setules; apex unevenly rounded. Coxal gills on peraeopods 4-6 relatively large, broadly saclike. Etymology. The name alludes to the type locality on Vancouver Island, British Columbia. Distributional ecology. The species has been confirmed only for the type locality. Northern Vancouver Island, from under rock and algal habitats at LW level Taxonomic commentary. The species name vancouv- erensis alludes to its known distribution on Vancouver Is- land, British Columbia. Trachypleustes trevori, new species (Figs. 31, 32, 33) Material examined. About 130 specimens taken at 23 loc- alities, as follows: ALASKA. Pribilof Islands: D. B. Quayle coll., Nov. 23, 1965 - 1 female ov (slide mount). Southeastern Alaska. ELB Stns,. 1961: A168, Klokachef I - 1 female; A175 , San Juan Batista L, under rock, among algae, LW level, July 26, 1961 - 1 female ov. (slide mount). BRITISH COLUMBIA. Queen Charlotte Islands; ELB Stn. E14a, Onward Pt. Moresby I. July 13, 1957 - 1 ov. female (slide mount), 2 other specimens. Northcentral coast. ELB Stns., July, 1964: H7, McCauley I. - 1 female ov; H65, Christie Pass - 2 females ov (slide mounts), 1 im. ELB , 1959, Stn. N22, off Banks 1. - 1 male (slide mount), 1 female, 28 other specimens. Northern Vancouver L: ELB Stns., July, 1959: V5, Lemon Pt., Nigei I. - 1 female ov (Slide mount); 03, Grant Bay - 5 females ov (2 slide mounts). Southern Vancouver I.: ELB Stns., July 1970: P702 , Long Beach, south end, from algae and sessile invertebrates, under boulders, at LW level July 6-1 female; P719, Botanical Beach, from kelp and sponges, under boulders at LW level, Aug. 1-1 female ov. ELB Stns., 1975: P2, Bamfield Marine Laboratory, from floating log fouling community at surface, July 23-1 male, 1 female, 2 im.; P5c, Taylor I., Trevor channel, from ascidians and sponges, under large boulder, July 25-2 males, 2 females. ELB Stns., 1976 : B4, Off Brady’s Beach, naturalist's dredge, 60-70 m, sand & algae June 25-1 female; B7, Wouwer I., Broken L, from algae and sponges on bedrock walls at LW, June 27 - 1 male, 1 female; B1 lb, Wickininnish Bay, south end, LW sandy mud, June 29-2 females; B28, Edward King L, among algae, under boulders, LW, July 10-1 female. ELB Stns., 1977: B13, Trevor Channel, off Brady’s Beach, 6- 14m naturalist’s dredge, sand, stone, algae. May 25, 1977 AMPHIPACMCA VOL II NO. 1. AUG. 31, 1995 107 FIG. 30. Trachypleustes vancouverensis, n. sp. Female ov (4.5 mm). Cape Scott, Vancouver Island. ^ Vancouver I.. LW level,Anita Voss coll., April NMCC1995-0084; 2 females, Paratypes, CMN Cat. No. 25, 1986 - 1 male (slide mount) + -40 other specimens NMCC1995-0085. B21b, Off Brady’s beach, 10-20 m O + 4U omer specimens. naturalist’s dredge, algae, debris over sand, June 1 - 3 fe- WASHINGTON-OREGON ofFnl'n ■ w ^ ^ ^August, 1966: W40, OffEdw^d King I., from sponge, W.C. Austin Stn. 101/76 Mukkaw Bay at Sooes Pt. - 2 females, 12 male (slide - 1 male (slide mount), 2 females. mounts); W58, Seal Rock - 1 male (slide mount). AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 108 FIG. 31. Trachypleustes trevori, new species, Diagnosis. Female ov. (5.0 mm): Head, rostrum short, little exceeding lateral process; eye nearly round. Antenna 1 much longer than antenna 2; peduncular segment 1 not exceptionally large, length slightly longer than segments 2 & 3 combined; flagellum with ~42 segments, alternately with aesthetascs. Antenna 2, peduncular segments 4 & 5 relatively short, slender; flagellum with ~38 short segments, each with whorl of short setae. Female ov (5.0 mm). Trevor Channel, B. C. Lower lip, inner lobes relative narrow and deep. Mandible, molar minute much smaller than blades; spine row with 4-5 very short, thick, flat, pavementlike blades; cutting edge of incisor with 9-10 uneven teeth, smallest distally; palp segment 3 narrowing gradually, inner margin with 12 slender pectinate “D” spines; left lacinia broad, deep, cutting edge with 10 uneven teeth. Maxilla 1 palp cylindrical, obliquely rounded apex with 7 slender spines. Maxilla 2, AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 109 FIG. 32. Trachypleustes trevori, new species, A.-D locations; variations in mandibular blades & palp. outer plate regular. Maxilliped, inner plate with 6 inner marginal setae and 4 apical marginal “button” spines; outer plate, apex narrowly rounding, with singly slender spine; palp ordinary. Coxae 1-3 medium, relatively shallow, hind comers each with single small cusp. Gnathopod 1, propod much smaller than propod of gnathopod 2; proximal spine group at postero-distal angle with 2 spines; hind margin smooth, lacking spines or setae. Gnathopod 2, carpal lobe lacking pectinate setae; propod with proximal group of four spines at postero-distal angle; hind margin with distal cluster of short simple setae. Peraeopods 3 & 4 ordinary, slender; segment 4, anterior margin weakly setose; dactyls medium. Peraeopods 5-7, bases not exceptionally broad, increasing posteriorly; segments 4-6, margins with clusters of short spines; segment 5 not shorter than 4; dactyls medium, curved. Pleon plates 1 & 2, hind comers acuminate; pleon plate 3, hind comer squarish. Urosome 2, dorsal margin nearly occluded by segments 1 & 3. Uropods 1 & 2 long, slender, margins of rami strongly serially spinose. Uropod 3, outer ramus short, length -1/2 slender inner ramus having 7-8 pairs of marginal spines. AMPHIPACIFICA VOLE NO. 1. AUG. 31, 1995 110 A Pribilof i. Female (4,0 mm) B Experiment Cove Female (4.5 mm) off Brady's beach Female (5.0 mm) off Brady's Beach Female (5.0 mm) FIG. 33. Trachypleustes trevori, new species. A-E locations. Variations in mandibular blades & palp. Telson ordinary, apex smoothly rounded. Coxal gills on peraeopods 4-5 short, saclike Etymology. The species name alludes to the type locality in Trevor Channel, Vancouver Island, British Columbia. Distributional ecology. The species ranges from southeastern Alaska, commonly throughout British Columbia to central Oregon, along exposed rocky coasts, associated with sponges and tunicate in under-rock habitats at LW level . Taxonomic commentary. Material from the following stations are presently considered variants ofT. trevori . This treatment is not entirely satisfactory, since "variants" may prove to be specifically distinct when more extensive material can be studied: Trachypleustes (small-eyed variety, Fig. 32D) having only 3-4 “pavement blades”, at Stns. A175; H14a: W40; W58. Trachypleustes (northern variety, Fig. 33 A) having 5-6 thick, acute blades, palp with 6-7 pectinate spines, from the Pribilof Islands, Bering Sea. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 Micropleustes, new genus 111 Parapleustes Barnard, 1969a: 425 (partim). — Ishimam, 1984: 432 (partim). — Barnard & Karaman, 1991: 649 (part). Type species. Parapleustes nautilus J. L. Barnard 1969b: 199. Species composition. Micropleustes behningi (Ishi- maru, 1984); M. behningioides, new species; M. longimanus (Ishimam, 1984); M nautiloides, new species. Diagnosis. Body small, smooth to slightly mgose above. Head, rostmm very short; head lobe subacute; inferior antennal sinus elongate, shallow. Eyes small, roundish. Antennae short, subequal, flagellaUttlelonger than respective peduncles, weakly setose; accessory flagellum minute. Antenna 1 shghtly the longer in male. Mouthparts somewhat modified. Upper lip shallowly and submedially notched, lobes slightly asymmetrical. Lower lip wide, inner lobes deep, outer lobes oblique, rounded. Mandible: incisor with few (6-8) teeth; left lacinia 6-9 cuspate; blades medium heavy, distally pectinate, 7-9 in number; molar small, apex blunt, weakly setulose; palp seg- ments relatively short, stout; segment 2 with few (3-8) inner marginal setae; segment 3 subequal with few (5-10) inner marginal pectinate setae. Maxilla 1, outer plate with 9 tall apical spine-teeth; inner plate with single apical setae, occasionally lacking; palp segment 2 normal, apex with 4 short spines, segment 1 with 1+ outer marginal setae. Maxilla 2, inner lobe slightly broadened, inner margin often with 2 plumose setae. Maxilliped, segment 3 not conspicuously en- larged, longer than palp segment 1; dactyl strong, palp segment 3 lacking distal process; inner plate with 1-2 stout, apically pectinate inner marginal setae. Coxal plates large, broad, deep; coxa 1 not broadened or bent forward distally; postero-distal notch minute, often multiple (2-4). Gnathopods small to medium strong, not sexually dimorphic; propod tending to elongation; carpus variable, hind lobe short or lacking; palm of propod shorter than posterior margin, smoothly convex, lacking median tooth, postero-distal angle with 1-2 groups of spines. Peraeopods 3-7 short, medium stout, normally spinose; segment 5 distinctly shorter than 4; dactyls normal, strong. Peraeopods 5-7 regularly homopodous, bases very broad. Pleon side plates deep, medium broad, hind comers little produced. Pleopods normal, not sexually dimorphic, rami subequal, slightly longer than peduncles. Urosome short, segment 2 nearly occluded dorsally. Uropods short; rami of uropod 1 and uropod 2 subequal, outer slightly the shorter, sparsely spinose, about equal in length to peduncle. Uropod 3 short, extending less than twice length of telson; outer ramus distinctly the shorter. Telson elongate, dorso-lateral penicillate setae mark- edly distal. Coxal gills of two types: anterior two pairs slender, sublinear; posterior three pairs larger, platelike, smallest on peraeopod 6. Etymology. A combining form of the Greek “mikros “ (small) and the root generic name “pleustes”, referring to the small body size of component members of the genus. Distributional ecology. All five species of the genus are endemic to the North Pacific region, three on the Asiatic, and two on the North American coast. Taxonomic commentary. Within subfamily Parapleust- inae, the genus Micropleustes occupies a somewhat isolated position. It combines a number of relatively plesio-morphic character states, especially in the mouthparts, with arelati vely advanced condition of the antennae, coxal plates, gills, uropods, and telson. In balance, however, the genus is least distant from the type genus Parapleustes (p. 127). Micropleustes nautilus (J. L. Barnard) (Fig. 34) Parapleustes nautilus J. L. Barnard, 1969b: 199, fig. 55. — Austin, 1985: 592.— Staude, 1987: 379, fig. 18.77.— Barnard & Karaman, 1991: 650. Material examined. About 185 specimens in 44 lots: ALASKA. Bering Sea: Attu I., Massacre Bay, C. E. O’Clair coll, June 23, 1972 - 2 females. Amchitka I., Banjo Pt., Sta. BlGl, C. E. O’Clair coll. Aug. 14, 1971 - 32 specimens incl. males, females, im. (male, female slide mounts); Ibid.. Stn. IA-2, plot 28, bedrock reefs uplifted by underground nuclear tests. May 22, 1974 - 2 females. Southeastern Alaska. ELB Stn. S5B7, 1980 - 1 female. BRITISH COLUMBIA. Queen Charlotte Islands. ELB Stns., June- July, 1957: W4a (1);W12(1); W9a(l);H14(l). Northcentralcoast. ELB Stns., July, 1964, 1959: H1(4);H33 (8); H39 (2); H44 (-20); H47 (1); N1 (1). Vancouver I., north end. ELB Stns, July, 1959: 01 (4); 05 (1) ;07b (4); 015 (1). Vancouver I., southern end. ELB Stns., July-August, 1955: FI (2);P4(l);P6c(3). ELB Stns., 1970: P702 (2); P712 (7). ELB Stns., 1975: P3a (2) ; P5a (2); P5b (2); P5d (3); P20 (2). ELB Stns., 1976: B3 (l);B13(5);B28(2).ELBStns.,1977:B6a(l);B8(2);Bllb (l);B19b(2). Wizard Inlet, D. Kittle Stn. 712, July 28, 1972 - 1 male, 1 female (fig'd specimen) (slide mounts) -i- 1 female, 3 im. Barkley Sound, Broken I. group, C. Lobban coll., July 7, 1971 - 1 female; Ibid.. July 9-10 specimens. Bordelais I., from sponge at LW level, R. J. Anderson coll, June 26, 1976 - 1 male (slide mount). WASHINGTON-OREGON. Coastal localities. ELB Stns., July-August, 1966: W22 (1); W40 (8); W58 (-15 ); W60 (6). AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 112 FIG. 34. Micropleustes nautilus (J. L. Barnard). Female ov (3.1 mm). Wizard Inlet, B. C. AMPfflPACIFICA VOL II NO. 1. AUG. 31, 1995 113 KEY TO SPECIES OF MICROPLEVSTES OF THE NORTH PACIFIC REGION 1. Gnathopods, propod elongate, length of lower margin -2Xpropod depth; palm of propod short, length less than half that of posterior margin; maxilla 1 , inner plate bare; inner ramus of uropods 1 shorter than peduncle 2 —Gnathopods, propod not elongate, length less than twice depth; propod palm normal, length more than half postenor margin, maxilla 1 inner plate with single apical seta; uropods 1, inner ramus not shorter than peduncle ,, 2. Gnathopod 1, carpus distinctly longer than carpus of gnathopod 2; coxal plates 1-4 only slightly deeper than corresponding body plates; peraeopods 5-7, segment 4 wide, width = length; telson length about twice width, hnguiform in shape m. longimanus (p. 1 17) —Gnathopod 1, carpus about equal to that of gnathopod 2; coxal plates 1-4 very deep, much deeper than corresponding body plates; peraeopods 5-7, segment 4 normal, length distinctly greater than width; tel- son length about 3 X width, apex narrowly rounding m. nautiloides, n. sp. (p. 1 13) 3. Peraeopod 7, segment 4 postero-distally nearly totally overhanging segment 5 ... M, behningi (p. 1 15) Peraeopod 7, segment 4 less broad, postero-distally overhanging segment 5 by 1/2 to 2/3 4. 4. Gnathopods, palm of propod distinctly shorter than posterior margin; postero-distal palmar angles with two distinct groups of spines; telson regularly narrowing distally M. nautilus (p.l 1 1) —Gnathopods, palm of propod about equal in length to posterior margin, postero-distal angle with two tight clusters of spines appearing almost as one group; telson, margins constricted medially behningioides (p. 116) Coos Bay, Oregon, K. E. Conlan Stn. 08-23 - 2 females, 8 other specimens. Diagnosis. Female ov (3.2 mm): Body and coxal plates medium deep. Head, eye round, black. Antenna 1 medium, peduncle 1 large, length> segments 2 & 3 combined; flagellum 14-segmented. Antenna 2, slightly longer than 1, peduncular segment 4 & 5 subequal; flagellum 14-segmented. Upper lip with broad apical V-cleft; lobes asymmetrical. Lower lip, inner lobes shallow, outer lobes smoothly ovate, oblique. Mandible, molar very small apex rounded; spine row with 7-9 medium, distally pectinate blades; cutting edge of incisor with 7-8 unequal teeth; palp segment 3 with 9 inner marginal pectinate spines and 1 long terminal seta; left lacinia 8-dentate. Maxilla 1, inner plate with single apical seta, palp segment 1 with single “shoulder” seta; segment 2 slightly broadest medially, apex with 4 spines. Maxilla 2, inner plate slightly broadened distally, inner margin with 2 plumose setae. Maxilliped, inner plate with 2 inner marginal spines and 2 apical teeth; outer plate medium, narrowing to rounded apex, with 2 slender curved spines; palp, dactyl slender minutely pectinate, not longer than segment 3. Coxa 1 broadest distally. Coxa 5, lobes shallow. Gnathopod 1, carpus short, deeper than long; propod short- rectangular, length -1 .5 X depth, with proximal cluster of 2 stout median facial setae; palmar margin short, convex, postero-distal angle with cluster of 5 spines; hind margin nearly straight, with distal cluster of 2 spines; dactyl weakly setulose behind. Gnathopod 2 subsimilar, propod slightly heavier and deeper than in gnathopod 1. Peraeopods 3 & 4 relatively short and stout, segment 4 slightly broadened; dactyls short. Peraeopods 5-7 closely homopodous in size and form; bases broad, rounded behind, postero-distal lobe medium deep; segment 4 slender, postero- distal lobe overhanging segment 5 by half its length; dactyls medium, length about 1/2 segment 6. Pleon plate 3, hind comer not acuminate. Uropodl slen- der, rami subequal, with 1 -2 marginal spines. Uropod 2, rami subequal, slightly shorter than peduncle. Uropod 3, outer ramus short, with 3-4 marginal spines, length - 1 .5 X each of peduncle and outer ramus. Telson medium, slightly narrowing distally to rounded apex, penicillate setae distal. Distribution. From SE Alaska to middle and southern California, intertidal to shallow depths (5 m), associated with under-rock algal and sponge communities. Taxonomic commentary. Morphological variations were noted in O’Clair material from Alaska, and in ELB material at Stns. F*7 1 2 and W40, but were not considered sig- nificant at the species level. Micropleustes nautiloides, new species (Fig. 35) Parapleustes species "A" J. L. Barnard, 1969b: 203? Material examined: BRITISH COLUMBIA. Southern Vancouver!.: ELB Stn. P712, Off Hanes L, Trevor Channel, under boulders and algal mats, LW level, July 2 1 , 1970 - 4 males, 2 females, 2 im. AMPHIPACMCA VOL II NO. 1. AUG. 31, 1995 114 FIG. 35. Micropleustes nautiloides, new species. Female ov (2.9 mm). Sunset Bay, Oregon. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 115 WASHINGTON-OREGON. Coastal Localities. ELB Stn. W40, Mukkaw Bay, at Sooes Pt., from bedrock walls and under boulders, LW level, July 31, 1966 - 9 specimens. Sunset Bay, south of Charleston, Coos Co., K. E. Conlan Stn. 06-06, in Rhodomela larix^ July 8, 1986 - female (2.9 mm) Holotype (slide mount), CMN Cat. no. NMCC 1995-0074; Ibid.. Stn. 06-03 - 3 females (to 3.1 mm) (1 slide mount), Paratypes, CMN cat. No. NMCC 1995-0075; Ibid.. Stn. 06-12 - 9 females ov, 3 imm; Ibid. . Stn 08-6 - 2 im. Diagnosis. Female ov (2.9 mm): Body and coxal plates deep. Head small, flat-rounded, black. Antennae short. Antenna 1, peduncular segment 1, length = segments 2 & 3 combined; flagellum 11 -segmented. Antenna 2, slender, slightly the longer, flagellum 1 1 -segmented. Upper lip deep, with narrow apical V-notch; lobes nearly symmetrical. Lower lip inner lobes deep, outer lobes large, oblique. Mandible, molar medium, apex sharply rounded; spine row with 7-9 stout distally pectinate blades; cutting edge of incisor with 7 unequal teeth; palp segment 3 with elongate basal “A” seta, inner margin with 9 pectinate spines; left lacinia 8-dentate. Maxilla 1, inner plate small, lacking apical set; palp segment 1 with single “shoulder seta; palp segment , narrowing, with 4 apical spines. Maxilla 2, inner plate broad, with 2 inner marginal plumose setae, maxilliped inner plate large, narrowing distal with 2 inner marginal spines, and 3 apical marginal short spines; outer plate relatively tall, with single curved spine at subconical apex; dactyl nearly straight, minutely pectinate, not longer than segment 3. Coxal 1 little expanded distally, hindcorner with 3 small cusps. Coxae 2-3, depth ~2X width, hind comers each with 3 small cusps. Coxa 4, width = depth. Coxa 5 , lobes deep. Gnathopod 1, carpus longer than deep, hind lobe shallow, short; propod slender, elongate, length ~2X depth, palmar margin short, oblique convex, postero-distal angle with group of 4-5 spines, one distinctly largest; hind margin straight, with distal cluster of 2 short spine and a few cleft- tipped setae; dactyl short, weakly setulose behind. Gnathopod 2 closely subsimilar, propod slightly stouter. Peraeopods 3 & 4, slender; dactyls medium. Peraeopods 5-7 homopodous; segment 4 relatively short, broad, postero- distal process overhanging 2/3 of short segment 5; dactyls large, length > 1/2 segment 6. Peraeopod 5 slightly shortest; basis broadest, rounded behind; bases of peraeopods 6 & 7 less expanded, hind margin nearly straight. Pleon plate 3, lower margin convex, hind comer acute, produced. Uropods 1 & 2 rami shorter than peduncle, distally narrowing. Uropod 2, outer ramus distinctly the shorter. Uropod 3 ordinary, inner ramus with 3 marginal spines. Telson elongate linguiform, narrowing to sharply rounded apex; penicillate setae distal. Distributional ecology. From central British Columbia to southern Oregon, possibly central California, intertidally and inimediately subtidal, in algal mats (Rhodomela) and Phyllospadix clumps, of lotic high salinity waters. Etymology. A combining form of “nautilus” + “oides” in reference to the overall similarity of this species to Micropleustes nautilus. Taxonomic commentary. Micropleustes nautiloides is taxonomically closer to M. longimanus than to M. nautilus (see Fig. 38, p. 118). Parapleustes sp. "A*' of Barnard (1969b) may be this species. Micropleustes behningi (Guijanova) (Fig. 36) Neopleustes behningi Gurjanova, 1938; 315, fig. 30. Pleustes behningi Guijanova, 1951: 641, fig. 438. Parapleustes behningi Barnard & Karaman, 1991: 650 (part). — Ishimaru, 1994: 54 (part?). Parapleustes behningi Ishimam, 1984: 407, figs. 3-9. Diagnosis, (mainly after Gurjanova, 1951). Female (1.5 mm): Body and coxal plates short, deep. Head, eye subquadrate, black. Antennae very short. Antenna 1 , ped- uncular segment 1 stout, length ~ 2X segments 2 & 3 com- bined; flagellum 8-segmented. Antenna 2 stout, slightly the longer; peduncular segment 4 & 5 very short; flagellum 8- segmented. Upper lip with narrow epistome; labrum, lobes nearly symmetrical. Lower lip broad, shallow, outer lobes ovate, nearly vertical. Mandible, molar short, apex bluntly rounded; spine row with 7-8 uneven blades, distally thick, proximally short, slender; cutting edge of incisor with 6(?) irregular teeth; left lacinia 7-8 dentate. Maxilla 1, inner plate small, with short apical seta; palp slender, segment 1 lacking shoulder seta; segment 2 slender, with 3? apical spines. Maxilla 2, inner plate small, little broadened distally, with single short inner margin plumose seta Maxilliped, inner plate regular; outer plate short, with 2 curved spines at round- ed apex; palp, dactyl stout, slightly longer than segment 3. Coxae 1-4 relatively deep, narrow. Coxa 1 not expanded distally, hind Comer with single stout cusp. Coxa 2, distal margin straight, hind comer with 4-5 distinct cusps. Coxa 4 deeper than broad. Gnathopod 1, carpus short, depth > length; propod medium long, length -1.5 X depth, palmar margin short, oblique, nearly straight; postero-distal angle with cluster of 3 stout spines; hind margin straight, with distal spine; dactyl strong, minutely setulose behind. Gnathopod 2, somewhat similar, but carpus slightly shorter, hind lobe deeper and narrower than in gnathopod 1; propod more elongate and more slender; length - 2X depth. Peraeopods 3 & 4 slender, margins of segments 4-6 weakly spinose; dactyl strong, > 1/2 segment 6. Peraeopods 5-7 relatively short; bases medium broad, hind margin convex, with 6-8 broad crenulations; segment 4 short, postero-distal process elongate, nearly totally overhanging short segment 5 by 80%; dactyls large. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 116 FIG. 36. Micropleustes behningi (Gurjanova). Female (4.0 mm). Japan Sea. (after Gurjanova, 1951). Micropleustes behningioides, new species (Fig. 37) Parapleustes behningi Ishimaru, 1984: 407, fig. 4. — Barnard & Karaman, 1991; 650 (part). — Ishimaru, 1994: 54. Diagnosis. Female (5.9 mm). Body short, compact, coxal plates deep. Head, eye round, medium large. Antenna 1, peduncular segment 1 short < 2 & 3 combined; flagellum long, relatively stout, 19-segmented. Antenna 2 shorter, peduncular segments 4 & 5 short, subequal; flagellum 16- segmented. Upper lip regular, lobes slightly asymmetrical. Lower lip inner lobes, deep, outer lobes large, oblique. Mandible, molar prominent, slender, apex subacute; spine row with 9 short stout blades; cutting edge of incisor with 8 unequal teeth; palp segment 3 with short, proximal "A" seta, and 10? inner marginal pectinate “D” spines; left lacinia with 7(?) teeth. Maxilla 1, inner plate with single apical plumose seta; palp segment 1 with 2 "shoulder" setae; segment 2, surface finely setulose, apically with 4-5 short spines. Maxilla 2, inner plate short, broadly expanded, inner margin with 2 unequal plumose setae. Maxilliped, inner plate medium, with few distal facial setae, and 4 apical marginal spines; outer plate short, apex narrowly rounded, with 2 slender spines; palp, dactyl stout, nearly straight, not longer than segment 3. Coxa 1-3 medium broad, deep. Coxa 1 slightly broadened distally, hind comer with 1-2 minute cusps. Coxae 2 & 3, hind comer with 3 minute cusps. Coxa 4 deeper than broad. Coxa 5 lobes deep. Gnathopod 1, carpus short, deep, hind lobe narrow; propod short, length ~1.5X width; palmar margin relatively long, about equal to posterior margin, convex, oblique, postero-distal angle with 3 spines; dactyl minutely setulose behind. Gnathopod 2 subsimilar; carpus slightly shorter and deeper; propod slightly expanding distally . Peraeopods 3 & 4 stout, 3 distinctly the larger; segment 4 broadened abmptly, with subparallel margins; dactyls medium strong. Peraeopods 5-7 short, subsimilar; bases moderately expanded, hind margins gently convex, minutely crenulate; hind lobes deep; segment 4 broadened, nearly as wide as deep, postero-distal lobe 2/3 overhanging short segment 5; dactyls stout. Pleon plate 2 , hind comer rounded; pleon plate 3 hind comer acuminate. Uropods 1 & 2 short, little or not exceeding uropod 3. Uropod 1, rami and peduncle subequal in length. Uropod2, outerramus distinctly the shorter. Uropod 3, outer ramus shorter, length barely 1/ inner ramus. Telson slender, “pinched” medially, narrowing to rounded apex; penicillate setae distal. Etymology. A combining form of the species name “behningi “ and the suffix "oides ", like the regionally co- occurring species M. behningi (Gurjanova, 1938). AMPHIPACIFICA VOL 11 NO. 1. AUG. 31, 1995 117 Type material. Ishimam, 1984, figs. 3-7: Female "a" (5.9 mm), Holotype, Samani, Hokkaido; Ibid-, fig. 8: Male "e" (4.0 mm), AUotype, Oshoro, Hokkaido. Collections of the Faculty of Science, Hokkaido University. Distribution. Eastern Sea of Japan and southern Hok- kaido, among andSargos^w/n, LW-0.5 m depth. Taxonomiccommentaiy. Micropleustes behningioides is readily separable from M. behningi (Guijanova, 1938), and appears morphologically closer to M. nautilus (see key,’ p. 113; also fig. 34, p. 112 ). Parapleustes longimanus Ishimam, 1984: 438, figs. 25-28. —Barnard & Karaman, 1991: 650.— Ishimam, 1994: 54. Diagnosis. Female (2. 9 mm); Body short, compact, coxal plates medium deep. Antennae short, slender, subequal. Antenna 1, peduncular segment 1 short, length < segments 2 & 3 combined; accessory flagellum broadly conical, with 4 apical setae; flageUum 8-segmented. Antenna 2, peduncular segments 4 & 5 slender, subequal; flagellum 8-segmented. Upper lip shallowly V-cleft apically, lobes nearly symmetrical. Lower lip, inner lobes deep, outer lobes small ovate, oblique. Mandible, molar process, short, conical; AMPHIPACMCA VOL II NO. 1. AUG. 31, 1995 118 FIG. 38. Micropleustes longimanus (Ishimaru). Female (2.9 mm). Japan, (after Ishimaru, 1984). spine row with 6-7 short blades; cutting edge of incisor with 6-7 unequal teeth; palp segment 3 with 5 inner marginal pectinate “D" spines; left lacinia 6-7-dentate. Maxilla 1, inner plate small, lacking apical seta; palp segment 1 lacking “shoulder” seta; segment 2 narrowing distally, apex with 3- 4 slender spines. Maxilla 2, inner plate slightly shorter than outer plate, little broadened, with 1 short inner marginal plumose seta. Maxilliped, inner plate very short, with 1 inner marginal stout seta, apex with 2 stout and 2 slender spines; outer plate very short, subtruncate apex with 2 slender spines; palp, dactyl curved shorter than segment 3. Coxae 1-4, lower margins rounded. Coxa 1 slender, hind comer with single small cusp. Coxae 2-3, lower border minutely crenulate, hind comer with single cusp. Coxa 4 deeper than wide. Coxa 5, lobes deep. Gnathopodl, carpus slender, hind lobe very small, length ~2X depth; propods AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 119 slender, length ~3X depth, margins subparallel, palmar margin very oblique, very short, postero-distal angle with single cluster of 3 spines (one large); dactyl short, inner margin with 5 short curved setules. Gnathopod 2 subsimilar, except carpus and propod slightly shorter and deeper. Peraeopods 3 & 4, segments 4-6 relatively stout, 4 not broadened; dactyl medium. Peraeopods 5-7 very short, closely subsimilar; bases broad, lower hind lobes very deep, hind margins gently convex; segment 4 expanded, broader than deep, postero-distal lobe nearly totally overhanging short segment 5; segment 6 stout, with 2 anterior marginal spines; dactyl medium. Pleon plate 3, hind comer squared. Pleopods, peduncles stout, outer margins short-spinose; rami short, 12-segmented. Uropods 1 & 2 slightly exceeding uropod 3. Uropod 1 , rami subequal weakly marginally spinose. Uropod 2, outerramus slightly the shorter. Uropod 3, outer ramus short, length -60% inner ramus. Telson short, slightly narrowing distally to broadly rounded apex; penicillate setae marginally subapical. Distribution. The species is known from inshore shallows of the mainland and Japanese coast of the Sea of Japan. Taxonomic commentary. Micropleustes longimanus is distinctive in nearly every character state, but in balance appears closest to Af. nautiloides ofthe North American Pac- ific region. Dactylopleustinae, Bousfield & Hendrycks Dactylopleustinae Bousfield & Hendrycks, 1994: 38. Type Genus. Dactylopleustes Karaman & Barnard, 1979, monotypy. Diagnosis. A monotypic group of primitive but second- arily specialized commensal and/or parasitic pleustids. Rostmm short. Eyes large, reniform. Antennae short, pediform. Accessory flagellum minute. Upper lip, notch shallow, lobes only slightly asymmetri- cal. Lower lip with deep, distinct inner lobes. Mandible, molar rounded, non-triurating; palp segment 2 short, seg- ment 3 swollen, lacking baso-facial CA") setae ; right lacinia lacking; Maxilla 1, outer plate short, wide, with 9-16 pectinate spine-teeth; inner plate with 1 apical seta; palp large, terminal segment broad. Maxilla 2, plates short, subequal. Maxilliped, plates small, weakly armed; palp segments short; dactyl pectinate. Coxae 1-4 deep, 1 shortest. Gnathopods with elongate carpus and propod, longer in gnathopod 2; palmar margins short, lacking median tooth, hind margin setose. Peraeopods 3-7 short; dactyls short, inner margins finely crenulate or pectinate. Peraeopods 5-7 basically homopodous; coxae regularly and strongly postero-lobate; bases broad. Pleon plates regular, unmodified. Urosome 2 not oc- cluded dorsally. Uropods 1 & 2 broad-lanceolate, rami sub- equal, broad-lanceolate. Uropod 3 medium, rami unequal. Telson keel proximally. Coxal gills saclike on peraeopods 2-4, plate-like on 5 & 6 . Taxonomic commentary. This monotypic group (con- sisting to date of three species in one genus) was formerly assigned to the genus Parapleustes based on the non-triturat- ing molar and ordinary form of the maxillipedal palp. How- ever, the unusual mixture of plesiomorphic and apomorphic character states justified elevation of the genus Dactylople- ustes to subfamily ranking (Bousfield & Hendrycks, 1994). Dactylopleustes Karaman & Barnard Parapleustes Tzvetkova 1975: 121 (part). Dactylopleustes Karaman & Barnard, 1979: 112.— Barnard & Karaman, 1991: 647. Type species. Parapleustes echinoicus Tzvetkova, 1975, original designation Species,Dactylopl€ustesechinoides, new species (p. 121); D. (Apodactylopleustes) obsolescens Hirayama, 1988. Diagnosis. Body small, smooth above, lysianassiform; coxae deep, legs short. Head, rostrum short, about equal to broadly rounded anterior head lobe; inferior antennal sinus shallow. Antenna 1 not longer than antenna 2, segment 2 short, segment 3 very short, flagellum shorter than peduncle; Antenna 2, flagellum shorter than peduncle. Mouthparts highly modified. Lower lip, inner lobes tall, outer lobes large, oblique to nearly horizontal. Mandible, molar forming a smoothly rounded protuberance beneath 6- 8 slender blades; left lacinia with 6-7 rounded teeth; palp slender; segment 1 short, segment 2 weakly setose; segment 3 with few pectinate inner marginal setae. Maxilla 1, outer plate short, broad, apical spines slender, innermost strongest. Maxilla 2, outer plate with heavy spinelike apical setae. Maxilliped, plates weakly armed; inner plate lacking distal “button” spines, outer plate, inner margin concave, apex weakly spined; palp short, segment 2 shortest, segment 3 longest, with medio-distal row of spines; dactyl slender. Coxal plates 1-4 very deep, broad, much deeper than body plates; coxa 1 distinctly smallest, but not expanded distally; hind cusps 2-5 per plate, small. Gnathopods small, short, subequal, subsimilar, non sexually dimorphic; bases slender, anterior margin setose (more strongly in Gnathopod 1); merus rounded distally; carpus shallow- setose behind, length about equal to propod; palm very short, convex, with few short spines at postero-distal angle, long hind margin with groups of pectinate setae; dactyl short, smooth. Peraeopods 3-7 short, segmental margins short-spinose; dactyls very short, body heavy, inner margin nearly straight, micro-crenulated. Peraeopods 5-7 regularly homopodous, coxae very deep, hind lobes rounded below; bases broad, AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 120 KEY TO SPECIES OF DACTYLOPLEUSTES 1. Eyes large, deep, reniform; mandibular palp, segment 2 distinctly longer than segment 1; coxa 1 dist- inctly shorter than coxa 2; telson elongate; uropods 1 & 2 not modified 2. — Eyes medium, ovate, few large facets; mandibular palp slender, segment 2 little longer than 1; coxa 1 slightly shorter than coxa 2; uropods 1 & 2 (male), inner ramus short, broad, weakly armed D. (Apodactylopleustes) obsolescens (p. 123) 2. Maxilla 1, outer plate with 9 apical spine teeth; peraeopod 5, basis with angular postero-distal lobe; mandibular palp, segment 3 broad, with 7 inner marginal pectinate setae; maxilliped palp, segment 2 subequal to 1, dactyl thick, tip pectinate; gnathopod bases nearly bare of setae . D, echinoicus (p. 120) — Maxilla 1, outer plate with 15 slender apical spine-teeth; peraeopod 5, basis smoothly rounded behind; mandibular palp, segment 3 slender, with 5 inner marginal setae; maxilliped palp, segment 3 shorter than either 1 or 3, dactyl slender, acute, not conspicuously pectinate; gnathopods 1 & 2, basis strongly setose anteriorly D. (Neodactylopleustes) echinoides (p. 121) evenly rounded behind. Pleon side plates medium deep, broad, smooth below, hind comers acuminate. Pleopod peduncles short, raim with reduced numbers of segments, not sexually dimorphic. Uropods 1 & 2 short, stout; rami suramceolate, margins serially spinose , tips not spinose . Uropod 3 , peduncle short, stout, rami broad-lanceolate, inner ramus distinctly the larger. Coxal gills largest on peraeopods 4 & 5, smallest on peraeopod 6. Taxonomic commentary. The three component species of the genus are sufficiently distinct to justify separate generic status. Although Hirayama (1988) recognizes D. obscolescens as a distinct subgenus, Apodactylopleustes (see key above), further subdivision must await analysis of more extensive material in which new taxa are anticipated. Gnathopod 1 weakly subchelate; basis slender, bare; carpus and propod slender, subequal; hind margin of propod with 3 groups of setae. Gnathopod 2 , segment 5 lacking hind lobe, segment 6, hind margin strongly setose, palm very short, oblique, dactyl short. Pereopods 3 & 4, segment 5 < 4, hind margins with short spines; dactyl short, body with 5-6 prominent posterior pectinations, unguis slender, curved. Peraopods 5-7, coxae relatively deep ; bases expanded to different degrees , 5 sharply angled behind, 7 very broad, rounded, smooth behind; segment 5 shorter than 4; dactyls with small marginal pectinations. Pleon plates 1-3, hindcomer slightly acuminate. Uropod 3 stout, rami broad; inner ramus almost equal to peduncle slightly longer than half outer ramus; outer margin of the outer ramus bare, inner margin with 4 spines. Telson short almost parallel-sided; apex rounded, unarmed. Dactylopleustes echinoicus (Tzvetkova) (Fig. 39) Parapleustes echinoicus Tzvetkova, 1975:122, fig, 1. Dactylopleustes echinoicus Karaman & Barnard, 1979: 1 12. — Barnard & Karaman, 1991 : 647. . Diagnosis. Female (5.0 mm): Head, rostrum small, shorter than lateral lobes. Eyes moderate, reniform, black. Antennae short, 1<2; segments of the peduncle and flagellum shortened and broad. Flagellum of antenna 1 of 8 segments, of antenna 2 of 5 segments. Upper Up, lobes slightly asymmetrical. Mandible, spine row with 12 slender short blades; incisor 7-dentate; palp strong; segment 3 longest, with 7 inner marginal pectinate "D" spines. Maxilla 1, palp segment 2 with 5 apical spines, segment 1 lacking shoulder seta. Maxilla 2, plates subequal Maxilliped, inner plate with 3 apical button spines; outer plate short, with stout apical spine snd slender seta; palp segment 3 slender, dactyl short, broad, with apical inner marginal pectinations. Coxal plates 1 and 2 rectangular, lower margin convex, hind comer with 2 cusps. Coxal plate 4 deeper than broad. Distributional ecology. Known only from Bering Is- land (Commander Islands, off the east coast of Kamchatka), reef south of Nikol’skoye village. D. echinoicus is an obligate symbiont of the sea urchin Strongylocentrotus polyacanthus. The peraeopod dactyls are modified for holding the cmstacean onto the body of the sea urchin, as if “wedged in”, and to move around the movable spines on the surface of the test. Taxonomic commentskry, Dactylopleustes echinoicus is phyletically more primitive than the other two species of the genus subsequently described from Asiatic and North American coast (pp. below). The dactyls of this genus are adaptive to a lifestyle of clinging to the spines and surfaces of sea urchin tests. A less sophisticated form of grasping dactyl was noted in Commensipleustes commensalis (Shoe- maker) (p. 82). In that species, the dactyl and expanded spinose propod of peraeopods 3-7 form a subchelate claw- like mechanism that enables the amphipod to cling to the pleopods of the spiny lobster Panulirus interruptus. Such morphological specializations underscore the high degree of adaptive radiation within subfamily Parapleustinae that is associated with a commensal lifestyle. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 121 / MX 2 / ^__v^;D CTYLX) ' MXPD Fro. 39. Dactylopleustes echinoicus (Tzvetkova). Female (5.0 mm). Bering Sea. (after Tzvetkova. 1975) DactylopUmte.echino^es , new species 14 long slender distally curved apical spines; palp ^ broad, With 6 Stout apical spines. Maxilla 2, plates short, dactylopleustes echinoicus Au%tm 1985- 592? Rpm»rH A *2 heavy apical spines. Maxilliped KaramaC 1991: 647X^1? 1985.592?-Ban,ard& mner plate short, apex sloping inward, with 3 minute button spines; outerplate slender, inner margin excavate, apex with Material 2 setae; palp segment 2 short, 3 with BRITISH COLUMBIA pectinations near base of thin pectinate dactyl. Northern Vancouver I • ELB Stn Nlfi Port 1 distinctly shorter than 2, hind comer with 4 1 Qo< rtnon ^ Setae, palm very short, oblique, overhung by stout dactyl. 1995-0080. Diagnosis. Femaleov (3. 3mm); Head, rostrum as long as lateral head lobe. Eye deep reniform, black. Antenna very short. Antenna 1 peduncle 3 not larger than basal flagellar segment, flagellum 5-segmented. Antenna 2, flagellum 5- segmented. Upper lip, median notch sharp, shallow, lobes nearly - ' ' 1 — > “ ■ -'“““a ovwui uaci^i. Onathopod 2, basis less strongly setae; carpus longer, propod subrectangular, palm distinct, strongly convex,’ nearly vertical, hind margin with 3 setal clusters. Peraeopods 3 & 4, margins of bases lined with short setae; dactyls short, stout, inner margins with 10+ minute pectinations. Peraeopods 5-7 closely homopodous, bases broadly rounded behind; segment 4 widening distally; equal. Lowerlip,innerlobedeep,n;rrow broadly rounded behind, segment 4 widening distally; nearly horizontal. Mandible molar large, broadly rounded; beL”d ‘^^'*®'’°'^''“®'>'P«‘=*“a'« Coxa6deep spinerow with? slender blades; incisor 8-dentate;leftlacinia Plenn h' zt a j 8-9 dentate; palp segment 2 relatively long; segment 3 with l * ' ^’^"‘*‘=°™®>'P’'od“ced, acuminate. Uropod 4 inner marginal pectinate "D” spines. Maxilla fouter plate mar.' * "I’ “ peduncle, P nes.MdXllia i, outerplate margins strongly spinose. Uropod 3, inner ramus heavy. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 122 Taxonomic & distributional commentary. The host echinoid has not been determined precisely. However, the sea urchin Strongyocentrotus purpuratus occurred com- monly at the type locality . The echinoid fauna of the region is diverse (Ricketts & Calvin, 1968) and would indicate that several other host-specific species of Dactylopleustes may yet be discovered in the North American Pacific region. thick, margins with 4-5 spines; outer ramus with 3 spines on each margin. Telson relatively long, length 2X width, apex smoothly rounding. Etymology, Combining the suffix "oides" - like, or sim- ilar to, the type species D. echinoicus. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 123 Dactylopleustes (Apodactylopleustes) obsolescens, Hira- yama, 1988: 44, figs. 269-271. — Ishimaru, 1994; 54. Diagnosis. Male? (2.0 mm): head, rostrum equal to lateral head lobes. Eye oval, large, orange. Antennae relat- ively long. Antenna 1, peduncular segment 3 larger than adjacent flagellar segment; flagellum 6-segmented. Antenna 2, peduncular segments 4 & 5 slender, subequal ; flagellum 5- segmented. Lower lip, outer lobes nearly vertical. Mandible, molar process evanescent spine row with 5 short blades; incisor 7- 8 dentate; left lacinia 8-9 dentate; palp segment 2 very short; segment 3 long and slender with 1 -2 inner marginal pectinate “D” spines. Maxilla 1, outer plate with 11 apical spines; palp, terminal segment apically truncate, with 5 spines! Maxilla 2, outer plate much the stouter, with 3-5 apical spines. Maxilliped, inner plate apically truncate, lacking button spines; outer plate slender, inner margin excavate; palp segment 2 short, distally pectinate, dactyl pectinate. * Coxa 1 not noticeably shorter than 2, hind comer with 2 cusps. Coxae 2-3 with 2-3 hind cusps. Coxa 4 relatively broad, hind process curved upwards. Gnathopod 1, basis weakly setose; carpus stronger than propod, dactyl stout. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 124 overhanging short, vertical palm. Gnathopod 2, basis nearly bare; propod rectangular, slightly longer than carpus, dactyl overhanging short vertical palm, hind margin with 2 groups of setae. Peraeopods 3 & 4, hind margins of segment 4-6 with regular spines, dactyl finely pectinate behind. Peraeopods 5- 7 irregularly homopodous, bases unevenly expanded, hind margins nearly straight, 6 relatively narrow, 7 broadest, hind lobes deep; segment 4 broad; segment 5 short, 6 relatively long; dactyls thick, anterior margins very finely pectinate. Pleon plate 3 hind comer strongly produced acuminate. Uropods relatively stout, rami short, broad, especially outer ramus, much shorter than peduncle, margins weakly spinose. Uropod 3, inner ramus, margins each with 3 spines; outer ramus, our margin with 2 pines, inner margin bar. Telson medium short, length 1.7 X width, apex evenly rounded. Distribution. Ariake Sea (1 specimen only). Taxonomic commentary. Dactylopleustes obsolescens is clearly distinct from echinoicus, but more closely similar to echinoides. It is distinctive in the unlike form of peraeopods 5-7, the short, weakly armed uropods, and the very elongate mandibular palp segment 3. Pleusirinae Bousfield & Hendrycks, 1994 Pleustidae Gurjanova 1972: 135, 138 (key) (part).— Barn- ard & Karaman, 1991; 649. Pleusirinae Bousfield & Hendrycks, 1994; 40. Type genus. Pleusirus Barnard, 1969b, original des- cription. Diagnosis. Body small, slender, dorsally smooth; urosome 2 occluded dorsally. Head, rostrum short, deflexed, anterior head lobe broadly rounded. Eye rounded. Antennae slender, medium, antenna 1 the longer. Antenna 1 , peduncles 2 & 3 short; accessory flagellum minute, apex setose; an- tenna 2, peduncle medium strong. Mouthparts strongly modified. Upper lip broad, lobes asymmetrical. Lower lip, inner lobes deep, narrow. Mandi- ble, molar reduced to a large smooth lobe; spine row short, blades short; left lacinia multi-dentate (9-10); right lacinia lacking; palp slender, segment 2 longest; segment 3 shorter, lacking baso-facial seta; segment 1 elongate. Maxilla 1, inner plate small, bare; outer plate with 9 apical spines; palp slender, facially pilose, apex weakly armed. Maxilla 2, plates small, weakly setose-spinose. Maxilliped, inner plate short, with few apical and inner marginal spines; outer plate narrow, colunmar; palp large, subcheliform; segment 3 wid- est medially, not produced beyond base of slender dactyl. Coxal plates 1-4 increasing in size posteriorly, rounded below, lacking hind cusps. Gnathopods 1 & 2 slender, subequal, “eusiroidean” in form, not sexually dimorphic; carpus elongate, hind lobe shallow; propod subovate, palm long, lacking median tooth; posterior angle with 2 spine clusters. Peraeopods 3-7 slender; dactyls short. Peraeopods 5-7 closely homopodous in size and form; bases broad, rounded behind; segment 4 little overhanging segment 5 behind. Pleon plates 1-3, hind comers acuminate. Pleopods strong, not sexually dimorphic. Uropods 1-3 slender, rami elongate, spinose. Telson elongate, keeled proximally,pem- icillate setae median. Coxal gills narrow, saclike on peraeopods 2 & 3, plate- like on peraeopods 4-6, increasing posteriorly. Taxonomic commentary. The subfamily appears allied with the subfamily Parapleustinae in most character states, especially of the mouthparts. It is unique in the eusiroidean form of the gnathopods, the generally reduced form of maxillae 1 & 2, the inflated, distally smooth mandibular molar; elongate mandibular palp segment 1 ; and the semi-subchelate form of the maxilliped palp. Pleusirus J. L. Barnard Pleusirus J. L. Barnard, 1969b: 204.— Gurjanova, 1972: 135. — Barnard & Karaman, 1991: 649. Type species. Pleusirus secorrus Barnard, 1969b: 204. Subspecies. Pleusirus secorrus asiaticus Kudrjaschov & Tzvetkova, 1975, original designation. Diagnosis. With the characters of the subfamily , and in addition: Antenna 1, peduncular segment 1 with postero- distal process; flagellar segments, posterior marginal aesth- etascs paired, prominent. Mandibular blades thick, distally pectinate; incisor 7-8- dentate, third tooth largest. Maxilla 1, palp segment 1 with "shoulder" seta. Maxilla 2, inner plate not broadened, lack- ing inner marginal plumose seta. Maxilliped, inner plate with stout inner marginal and apical spines. Gnathopods 1 & 2, bases slender, margins not strongly setose; propod, hind margin smooth; dactyl slender. Peraeopods 5-7, coxae deep, postero-lobate, hind lobes rounded, segment 5 not longer than 4. Uropods 1 & 2, inner ramus longer than peduncle. Uro- pods 2 & 3, outer ramus short. Telson rounded, penicillate setae median. Male; Antennal segments with prominent aesthetascs; per- aeopods 5-7 relatively slender; dactyls relatively long, slender, nearly straight. Taxonomic and distributional commentary. The genus encompasses two forms, one a subspecies of the other, one on the Asiatic and the other on the North American Pacific coast. AMPHIPACIFICA VOLII no. 1. AUG. 31, 1995 125 Pleusirus secorrus J. L. Barnard, 1969b: 204, fig. 56.— Guijanova, 1972: 135, 138 (key). — ^Austin, 1985: 592. Staude, 1987: 379. — Barnard & Karaman, 1991; 650. Material examined. ALASKA. 46 specimens (all females, afew subadults) from 18 localities, as follows: Southeastern Alaska: ELB Stns., June-July, 1961: A3 (8); A6 (12); A8 (1); A48 (1); A75 (3); A80(7); A8 1 (1); A92 (6); BRITISH COLUMBIA. 252 specimens (including 1 male?) at 59 localities, as follows; Queen Charlotte Islands. ELB Stns., July- Aug 1957- H14 (2);W4a(2);W4b(3); E5(1);E25(1);W8(7); W9(1V W 1 1 (7);W12a(3). Northcentral coast. ELB Stns., July, 1964: HI (15)- H3 (2)- H5 (30); H7 (12); H8 (2); HIO (2); H12 (8); H26 (5)- H 23 (1)H29 ( 1); H30 (10); H47 (1); H48 (2); H50 (3); H53 (20+)- H57 (1); H65 (6). ELB Stn., 1959: N22 (2). AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 126 Vancouver Island, north end: ELB Stns., July, 1959: 01 (1); 05 (3); 01 1 (3); 013 (7); 015 (7); V5 (2); V7 (3); VI 1 (1); V17 (2); V18 (1); N 1 1 (1); N16 (1). Vancouver Island, south end: ELB Stns., July-Aug., 1955: FI (6); F4 (1); P2 (1); P7 (1). ELB Stns., 1970: P715 (1); P716(2); P718(13);P719(1). ELB Stns., 1975:P5b(2);P5c (1); (20(4). ELB Stns., 1976:B3(2);B4(2);B5(1); B7(10). ELB Stns., 1977: B7a ( (8); Bllb (1); B14 (1); B19b (2); B21b (3). ELB Stn. 015, Box I., Wickaninnish Bay, in Phyllospadix clumps, algal mats, over bedrock, LW level, Aug. 16, 1959 - female ov (3.7 mm) (slide mount) (fig’d specimen) + 7 other females. Duncan Bay, Middle Pt., barge, 3-4 m dive, tZ/va &bryozo- ans,P.Shawcoll.,Seot5, 1987- 1 male (fig’d) + 6 specimens. WASHINGTON-OREGON. 22 specimens at 3 localities, as follows: Coastal localities: ELB Stns, July-Aug., 1966: W40 (18); W42 (2); W58 (2). Diagnosis. With the characters of the genus and sub- family. The subspecies Khudrjaschov& Tzvetkova, 1975, may prove to be morphologically, if not ecologically, distinct, but western Pacific material was not re-examined in this study. Distributional ecology. On the North American Pacific coast this species occurs from southeastern Alaska, through British Columbia, Washington and Oregon, to southern Cal- ifornia. It occurs commonly from the extreme LW level to to depths of 25 m, in clumps of Phyllospadix, algae, and in organic debris, often on shelly sand bottoms, mainly at cold, high salinity, outer coast locations. Pleusirus secorrus asiaticus Kudrjashov & Tzvetkova PleusirussecorrusasiaticusK.udTi3shov&TzyQlko\3i, 1975: 1314, fig. 2A. — Tzvetkova Kudryashov, 1985: 1. Pleusirus secorrus Ishimaru, 1985d: 103. — Ishimaru, 1994: 54. Taxonomic and distributional commentary. This form was collected from clumps of algae and Phyllospadix at stations on South Sakhalin I., in the southern part of the Sea of Okhotsk, and south to Pos'yet Bay in the Sea of Japan. It is also recorded from amongst fronds of Tichocarpus carin- atus, Cytoseira sp., and Laminaria japonica. Females with eggs and early juveniles occur in July and August. The Asiatic form of P. secorrus has been synonymized by Ishimaru (loc. cit.) and Barnard & Karaman (loc. cit.). However, taxonomic differences noted in the original description (Kudrjashov & Tzvetkova, loc. cit.) suggest that a different species may be involved. In order to justify recognition of asiaticus as a full species, it is recommended that the original material be re-examined, redescribed and fully figured. Systematic and Biogeographical Analyses This study treats the systematics and distributional ecology of 29 species of the gammaridean subfamily Parapleustinae that occur along both Asiatic and North American coasts of the North Pacific region. A modified phenetic cluster analysis, and corresponding cladistic analysis, indicated the Parapleustinae to be the most advanced phyletically of the 12 recognized subfamilies within family Pleustidae (Bousfield & Hendrycks, 1994). We conclude here by commenting in greater detail on aspects of the morphology and lifestyle and on biogeographical rel- ationships of its component genera and species. The seven genera of Parapleustinae appear similar in the overall plesiomorphic form of the body and appendages. Greatest morphological diversity occurs in the numbers and kinds of mandibular blades, in the cutting edges of the incisors and left lacinia, and to lesser extent in the form and armature of the gnathopods. Sexually dimorphic gnathopods occur, uniquely in this subfamily, among the Pleustidae.The taxonomic and phyletic relationships of the seven genera are not readily apparent through general inspection, but may be clarified through numerical analysis of characters and character states of those body features (Fig. 43,' page 127). For this purpose, a modification of the UPGMA cluster ana- lysis system of Sneath and Sokal (1973) is utilized. The 20 selected taxonomic characters and corresponding character states are outlined in Table I. The overall degree of evolutionary advancement of the genus is provided by a plesio-apomorphic (P.-A.) index, derived by summing the values for each character state for each species, as explained in previous analyses (e.g. Bousfield and Hendrycks, 1994; Jarrett & Bousfield, 1994). The phenogram of morphological relationships (Fig. 43) suggests that the seven genera are not very closely similar, at least in the characters considered. Only two generic pairs, the North American endemic Gnathopleustes- Trachypleustes, and the broadly temperate-subtropical Incisocalliope-Commensipleustes cluster at similarities of 70% or better. The pan-Pacific genera Micropleustes and Parapleustes cluster at 60-65% with the latter complex. However, the mainly North American genus Chromopleustes stands in isolation, with less than 50% similarity to the other generic groupings. The P.-A. index is slightly less than 20 (less than 50% of maximum apomorphy) for all genera except the relatively advanced genus Incisocalliope where the value is 30 (75% of maximum). These values may indicate that the members of the Parapleustinae are evolutionary “stable”, i. e., they remain “locked in” to exploitation of specialized shoal-water niches (e.g., within Phyllospadix communities) of the North Pacific region that either do not exist elsewhere (e.g., in the cold-temperate North Atlantic or antiboreal regions), or else are inaccessible because of past and present physical and physiological barriers to dispersal. A phenogram of morphological relationships within species of the genus Incisocalliope is provided in Figure 44, AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 127 B t 40 1 38 >- H 36 CC < 34 i 32 (/) Id 30 1- < 28 (/) 26 n Id 1- 24 O < cc 22 < X 20 o Q 18 Ld cc. 16 < a. 1 14 1 12 18 17 19 17 10 19 30 P.-A. INDEX GENERA A - Ch ro m o p / eu s t es B -Gnathop/eustes C - Trachyp/eustes D - Mi cro p / eu s tes E - Parap/eu stes F - Co m m en sip / eu s tes G - in ci s o cai i i o p e 75 “ f£ 50 0) FIG. 43. PHENOGRAM OF GENERA OF SUBFAMILY PARAPLEUSTINAE p. 129. The analysis is based on 16 characters and cor- responding character states orvided in Table II, p. 1 30. The 8 species cluster into three main assemblages at similarities of 65-75%, viz., a relatively primitive newportensis-bairdi group, a very advanced dilatatus-makiki group, and a slightly less advanced derzhavini-aestuarius group of two closely similar species pairs. These three major assemblages cluster at about the 50% similarity level and appear therefore not closely related. The newportensis-bairdi subgroup, known only from inshore waters of southern California, is especially plesiomorphic in character states of themouthparts and peraeopods, but the gnathopods are powerfully subchelate, and relatively advanced. Possible biogeographical relationships of the dilatatus- makiki group are discussed below (pp. 129-30). The close similarity of the regionally co-occurring sibling species pair of derzhavini and is not unexpected. However, the 90% morphological similarity between the widely separated Asiatic Pacific and the North American Atlantic aestuarius is unexpected and defies ready explan- ation. Similar analysis of the North American endemic genus Gnathopleustes suggests th^t G. pugettensis,a simplex, G. pachychaetus and G. den form a relatively advanced and closely related species complex that collectively have a continuous distribution from southeastern Alaska to southern California (Table II, p. 129). Gnathopleustes trichodus ond G. JerratMj are relatively primitive morphologically, isolated phyletically and more restricted distributionally. The Trachypleustes species complex, with highly modified mandibular blades, and possibly more speciose than here considered, is more northerly in distribution. At least one species attains the Bering Sea region but has not yet been taken on the Asiatic coast. The Micropleustes complex is more speciose on the Asiatic coast. However, the most common North American species of this genus, M nautilus, has die widest range of any parapleustin in the North American Pacific region, from the Bering Sea to southern California. With respect to subfamily Pleusirinae, Pleusirus secorrus, including its Asiatic subspecies, is the only known member of family Pleustidae to occur in all nine biogeographic zones of the North Pacific region. Subfamily Dactylopleustinae is AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 128 TABLE I. CHARACTERS AND CHARACTER STATES: GENERA OF PARAPLEUSTINAE CHARACTER STATES CHARACTERS Plesiomorphic 0 Intermediate 1 Apomorphic 2 1. Antennal, peduncular long short segment 2: segment 1 short 2. Antenna 2, peduncular long segments 4 & 5 3. Upper lip, lobes shallow subequal deep, markedly asymmetrical 4. Lower lip, inner lobes deep narrow shallow broad 5. Mandibular blades numerous (>10) (7-8) few (~5) long, slender short, acute short, flat 6. Mandible, palp segment 3, 12-15 8-10 -5 number of “D” spines 10 + 7. Mandibular left lacinia, 5-6 7-9 number of teeth 11 15+ 8. Maxilla 1, outer plate. 9 number of apical spines 1 9. Maxilla 1, palp segment 1, 0 2 number of setae 10. Maxilla 2, width of narrow broad, inner plate L>W L-W 11. Maxilliped, inner plate, 7-10 0-2 number facial setae large 12. Maxilliped, segment 3 short 13. Gnathopods 1 & 2, weak strong size of propod shallow deep 14. Gnathopods 1 & 2, elongate short size of carpus shallow deep 15. Gnathopods 1 & 2, degree none marked of sexual dimorphism 16. Gnathopods 1 & 2, strong vestigial lacking palmar tooth 3-4 17. Coxae 1-3, number of posterior marginal spines none 18. Peraeopods 3-7, size of subequal 5 distinctly shorter segment 5: segment 4 19. Uropods 1 & 2, ramal spines numerous strong few weak 20. Telson shape short broad elongate narrow AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 129 I > H (L 32 30 28 < 26 (/) LU I- < I- (0 CE LU I- o < a: < X o o lU cc < Q. 24 22 20 18 16 14 12 10 INCiSOCALLtOPE A - n e wp orten si 8 B - bairdi C - diiatatu s D - makiki E - nipponensis F - derzh a vini G - aestuarius H - fi tiai is 75 QC < 50 (/) FIG. 44. PHENOGRAM OF SPECIES OF INCISOCALUOPE represented on Asiatic and North American coasts by the species pair of Dactylopleustes obsolescens and D. echin- oides, respectively. Although these echinoid-commensal species probably have geographical ranges similar to their host species of Strongylocentrotus, locality records are yet insufficient for meaningful biogeographical analysis. Biogeographical considerations The subfamily Parapleustinae is essentially endemic to continental coasts of the North Pacific region (Table III, p. 131). The distribution of five of the seven genera (i.e. Chromopleustes, Micropleustes, Gnathopleustes, Trachypleustes and Commensipleustes) is essentaially cold- temperate, whereas Parapleustes is subarctic-boreal, and Incisocalliope is temperate-subtropical. Of its 28 described species here included, only three species have been recorded elsewhere, Viz., Parapleustes gracilis from arctic-subarctic, marine parts of the N orth Atlantic and western Arctic Oceans ; Incisocalliope aestuarius from temperate estuaries of the western North Atlantic, and 1. makiki from the Hawaiian Islands in the south-central subtropical North Pacific. In the northern North Pacific region, 16 species of parapleustins, representative of all seven genera, occur along the coasts of continental North America, whereas only nine species, in four genera, have been recorded to date from the Asiatic continental coast (Table III). In the eastern North Pacific, species numbers are largest along the coast of British Columbia ( 1 0 species in each of zones 5, 6) but decrease both northwards and southwards. In the western North Pacific, the fauna of the Asiatic coast is less well known, but most (7) parapleustin species occur in the northern part of the sea of Japan, and fewer (3) in the cold waters of the Sea of Okhotsk to the north. Although no single species has yet been recorded from both continental coasts, the Bering Sea contains five species in four genera, and presumably provides the major pathway of gene flow between the two continental populations. However, North American species of Incisocalliope (i.e. newportensis and bairdi) are widely separated from their Asiatic counterparts (e.g.filialis, derzhavini, nipponensis and dilatatus) and are relatively primitive morphologically (Fig. 44, above). These facts would suggest that these populations have been separated geographically for a considerable time, perhaps since the early Palaeogene (50- 60 m.y.b.p.) when northern Pacific sea levels were lower, and marine climates were warmer and more equable (Adams, AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 130 TABLE n. CHARACTERS AND CHARACTER STATES: INCISOCALUOPE SPECIES CHARACTER CHARACTER STATE Plesiomorphic Intermediate Apomorphic 0 1 2 1. Antenna 1, number 30+ ~25 <15 flagellar segments 2. Antenna 2, number 20+ 10-15 -5 flagellar segments 3. Mandible, palp seg. 3, ~10 -5 number “D” setae 4. Mandible, number 10 5 of blades in row 5. Maxilla 1, palp 2, 4 0 number facial setae 6. Maxilliped, inner pi.. 4+ 3 2 apical “button” spines 7. Gnathopodl, basis. nearly bare strong ant. marginal setation throughout 8. Gnathopod 1, carpal broad narrow lobe shallow deep 9. Gnathopod 1, posterior 3 0 margin, no. setal gps. 10. Peraeopods 3 & 4, subequal markedly segments: segment 4 shorter 11. Peraeopods 5-7, broad narrow width of basis width-depth width« depth 12. Peraeopods 5-7 deep, reaching shallow hind lobe depth segment 4 13. Uropod 1, peduncle numerous few (4) outer marginal spines (10+) basal position 14. Uropod 2, length long markedly of outer ramus: inner subequal shorter 15. Uropod 3, length long short outer ramus: inner (75%+) (-60%) 16. Telson, rel. form long, slender short, broad 1981). During that period, and perhaps later, early members of the genus may have penetrated via a southern waterway (now blocked by the Panamanian isthmus) to the western Atlantic region where Incisocalliope aestuarius remains a sole survivor. The widely disjunct distributions of the filialis-aestuarius species pair is also reminiscent of somewhat similar disjunct distributions of the coastal aquatic arachnid order Xiphosurida (Savory, 1964), and the coastal aquatic reptilian genus Alligator (Carr, 1963). Both these groups may have been biogeographically continuous between southern Asia and North America during early to middle Cretaceous times, via a Tethyan marine pathway outlined by Howarth (1991). Such a hypothesis is unlikely for para- pieustins and related subfamily members of which no relict modern representatives now exist along that route and/or are physiologically unsuited to those marine thermal regimes. The presence in the remote Hawiaiian islands of Incisocalliope makiki, closely related to /. dilatatus of the Asiatic group. is anomalous. However, /. makiki may prove to be a relict species, representative of an ancestral group from Japan that penetrated the Hawaiian Archipelago, perhaps during the early Tertiary. They may have survived by “island hopping” as the volcanic islands of the chain successively emerged in the east and eroded away in the west (Howarth & Mull, 1992). In summary, subfamily Parapleustinae encompasses diverse, relatively advanced morphotypes and specialized lifestyles of pleustid micropredators. These occupy various niches within the Phyllospadix and sessile invertebrate communities of intertidal and shallow water habitats, almost exclusively within the North Pacific region. Although this fauna is believed relatively ancient, and probably originated during Mesozoic times (Bousfield, 1982b), the long-term stability of regional shallow-water ecosystems and their marine climates may have been major factors in dampening evolutionary thrust in other directions. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 131 TABLE III . DISTRIBUTION OF GENERA AND SPECIES OF PARAPLEUSTINAE IN THE NORTH PACIFIC REGION. TAXON BIOGEOGRAPHIC ZONE 1 2 3 4 5 6 7 8 9 1 . Chromopleustes C.johanseni X JC C. oculatus X X X JC C. lineatus X X X JC 2. Micropleustes longimanus X X behningioides X behningi nautilus X X X X X X X X nautiloides X X X? 3. Parapleustes ishimarui americanus gracilis * JC X X X X 4. Gnathopleustes serratus X X X X X pachychaetus X X X X trichodus X simplex X pugettensis X X X X X 7 den X X 5. Trachypleustes trevori (+ varieties) X X X X 9 vancouverensis X 6. Commensipleustes commensalis 7 X 7. Incisocalliope filialis X derzhavini X nipponensis X dilatatis makikU newportensis X X bairdi aestuarius+ X * N. Atlantic-subarctic; ! Hawaiian Islands; + N. American Atlantic temperate BIOGEOGRAPHIC ZONES; 1. Sea of Japan; 2. Sea of Okhotsk; 3. Bering sea and Aleutians; 4. Southeastern Alaska; 5. Northern B. C.; 6. Southern B. C.; 7. Wash.-Oregon; 8. Northern California; 9. Southern & Baja California. AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 132 REFERENCES Adams, C.G., 1981. An outline of Tertiary palaeogeography. Chapter 14; 221-235. ijL P.H. Greenwood (ed.). The Ev- olving Earth. British Museum. Cambridge Univ. Press. Anderson, R., 1988. Occurrence of toxic biochemical com- pounds in marine invertebrate animals. Trans. Roy. Soc. Canada, 5 (6): Austin, W. C., 1985. Annotated checklist of marine invert- ebrates in the cold temperate northeast Pacific. Khoyo- tan Marine Laboratory, Vols. I-III; 1-682. Barnard, J. L., 1952. Some Amphipoda from central Cali- fornia. Wasmann Jour. Biol. 10: 9-36, 9 pis. , 1954. Marine Amphipoda of Oregon. Oregon State Monographs. Studies in Zoology 8: 1-103, 33 pis. , 1956. Two rare amphipods from California with notes on the genus Bull. S. Calif. Acad. Sci., 55: 35-43, pis. 12-14. , 1959. Estuarine Amphipoda ini Ecology of Amphipoda and Polychaeta of Newport Bay, California. Occ. Pap. 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Karaman, G. S., & J. L. Barnard, 1979. Classification re- visions in gammaridean Amphipoda (Crustacea) Part 1 Proc. Biol. Soc. Wash. 92 (1): 106-165. Kroyer, H., 1838. Gronlands amfipoder beskrevne af Hen- rik Kroyer. Danske Vidensk. Selsk. Naturvid. Math. Afhandl. 7: 229-326, 4 pis. Kudrjaschov, V. A., 1972. K faune i ekologii bokoplavov (Amphipoda- Gammaridea) privilo-otlivnoi zony Kuril' skikh ostrovov (Litoral’o-vov Iturup, Urup, Simuschir, Paramuschir). Uchenye Zapiski Dvgu 60: 79-116. , & N. A. Tzvetkova, 1975. New and rare species of Amphipoda Gammaridea from coastal waters of the South Sakhalin. Zool. Zhum. 54: 1306- 1313, 3 figs. Lincoln, R. J., 1979. British marine Amphipoda: Gammar- idea. Brit. Mus. (Nat. Hist.), London. 1-658, 280 figs. Nagata, K., 1965. Studies on marine gammaridean Amph- ipoda of the Seto Inland Sea. II. Publ. Seto. Mar. Biol. Lab. 13: 171-186, figs. 16-26. Ricketts, E. F., & J. Calvin, 1968. Between Pacific Tides. 4th edition. Stanford Univ. Press, California. 614 pp. Sars, G . O., 1895. Amphipoda. An account of the Crusta- cea of Norway. Christiana and Copenhagen. Vol 1. Amphipoda. pp. i-viii, 1-711, pis. 1-240, 8 suppl. pis. Savory, T., 1964. Arachnida. Academic Press, New York. 291 pp., 109 figs. Shoemaker, C. R, 1952. A new species of commensal am- phipod from a spiny lobster. Proc.U. S. Natl. Mus. 102 (3299): 231-233, 1 fig. , 1964. Seven new amphipods from the west coast of North America with notes on some unus- ual species. Proc. U.S. Natl. Mus. 115 (3489): 391-429. Sneath, P. H. A., & R. R. Sokal, 1973. Numerical Taxon- onomy. W. H. Freeman and Company, San Francisco. 573 pp. Staude, C. P., 1987. Amphipoda: Suborder Gammaridea. pp. 346-391. in E. Kozloff (ed.). Marine Intertidal In- vertebrates of the Pacific Northwest. Univ. Washing- ton Press, Seattle. 51 1 pp. Stebbing, T. R. R., 1906. Amphipoda 1: Gammaridea. Das Tierreich, 21: 1-806. figs. 1-127. Tzvetkova, N. L., 1975. A new species of Pleustidae (Am- phipoda), a commensal of sea urchins, from the Kom- mander Islands. Zool. Zhum. 54:121-124, 1 fig. (in Russian). , & V. A. Kudrjaschov, 1985. On the fauna and ecology of gammarids (Amphipoda: Gammaridea) in the biocenosis of the upper parts of the shelf of South Sakhalin. Issled. Fauna Morei 20(38): 292-345, (in Russian). Watling, L., & D. Maurer, 1973. A new euryhaline species of Parapleustes (Amphipoda) from the east coast of North America. Proc. Biol. Soc. Wash. 86: 1-8, 4 figs. Wicksten, M. K., 1982. Cmstaceans from baited traps and gill nets off southern California. California Fish & Game 68: 244-248, 1 fig. LEGEND FOR FIGURES A1 antenna 1 MX 1 - maxilla 1 A2 antenna 2 MX2 - maxilla 2 AC FL - accessory flagellum BR. coxal gill MXPD - maxilliped BR PL - brood plate O.P. - outer plate CX coxal plate(s) P3-P7 - peraeopods 3-7 DACT - dactyl PLEOS - pleosome DORS - dorsal view PLP - palp EPl-3 - pleon plates 1-3 RT right GNl gnathopod 1 SET - seta(e) GN2 gnathopod 2 SP spine HD head T telson I.P. inner plate U1-U3 - uropods 1-3 I.R. inner ramus UROS - urosome LFT left X magnified LL lower lip (f male MD mandible 9 female AMPHIPACIFICA VOL II NO. 1. AUG. 31, 1995 134 Additions to Amphipacifica, Voi. 1(4), 1995. The following catalogue numbers have been provided through the courtesy of the Invertebrate Curatorial Unit, Canadian Museum of Nature, Ottawa, pertinent to the following paper: Bousfield, E. L., & E. A. Hendrycks, 1995. The amphipod superfamily Eusiroidea in the North American Pacific Region. 1. Family Eusiridae: systematics and distributional ecology. Amphipacifica I (4): 3-59. l .Eusiruscolumbianus Bousfield & Hendrycks, 1995, pp. 10-11, fig. 5. Female (5.2 mm), Holotype (slide mount). CMN Cat. no. NMCC1995-0001. 2. Rhachotropis calceolata Bousfield & Hendrycks, 1995, pp. 26-27, fig. 16. Female ov (8.7 mm), Holotype (slide mount). CMN Cat. no. NMCC1995-0005. 3. Rhachotropis boreopacifica Bousfield & Hendrycks, 1995, p. 29, fig. 17. Female br. I (10.5 mm), Holotype (slide mount). CMN Cat. no. NMCC 1995-0006. Female (unspecified), Paratype. CMN Cat. no. NMCC1995-0007. 4. Rhachotropis minuta Bousfield & Hendrycks, 1995, p. 35, fig. 22. Female ov (3.8 mm), Holotype (slide mount). CMN Cat. no. NMCC1995-0008. 2 other females, ELB Stn. P3, West Bay, B. C., Nov. 2, 1977, Paratypes. CMN Cat. no. NMCC 1995-0009. 5. Rhachotropis conlanae Bousfield & Hendrycks, 1995, p. 37, fig. 23. Female (4.5 mm), Holotype (slide mount). CMN Cat. no. NMCC1995-0010. Female (4. 1 mm), Bocade Quadra, southeastern Alaska, June 27, 1989, Paratype. CMN Cat. no. NMCC1995-001 1 . Catalogue numbers remain pending for the following species: 1, Eusirus hirayamae Bousfield & Hendrycks, 1995, p. 10, fig. 3. Male (6.5 mm), Holotype. Ariake Sea, Japan. Original material described and figured (as E. longipes Boeck) in: Hirayama, A., 1985. Publ. Seto Mar. Biol. Lab. 30; 29, figs. 142-147. Collections of the Amakusa Marine Biological Laboratory (AMBL), Amakusa, Japan. l.Cleonardomoirae Bousfield & Hendrycks, 1995, pp. 15- 17, fig. 7. Female ov. (7.0 mm), Holotype. Institute of Ocean Sciences (lOS), Sidney, B. C. 3. Rhachotropis barnardi Bousfield & Hendrycks, 1995, pp. 29-31, fig. 18. Male (3.3 mm), Holotype. Unspecified Paratypes. Original material briefly described and figured (as R. clemens Barnard) in; Barnard, J. L., 1971; Smiths. Contr. Zool. 61: 10, figs. 6, 7. Off Oregon, 200 m. Collections of the United States National Museum, Washington, D. C. 4. Rhachotropis americana Bousfield & Hendrycks, 1995, p. 40, fig. 26. Female (11.3 mm), Holotype (slide mount); male (9.5 mm), AUotype); 5 females, 1 male, Paratypes. RBCM/ CMN Stn. 91-1-119. Collections of the CMN, Ottawa. INSTRUCTIONS TO AUTHORS Manuscript submission. Manuscripts submitted for publi- cation should represent original contributions that have not been published elsewhere. The text should be written in English or French, with Abstract in either language. The Abstract should be suitable for separate publication in an abstract journal. Manuscripts must be submitted primarily on 3 1/2 inch high density diskettes, utilizing either IBM- or MAC-compatible computerized publishing systems (e.g. Aldus Pagemaker, Quark Xpress), preferably in 2-column form. Diskettes must be accompanied by one 8.5 X 1 1 -inch (22 X 29 cm) hard copy (printed manuscript), with 1-in. text margins. Papersmust have previously been refereed and text-ed- ited. The name of the referee must in- clude his/her address (and/or telephone number). 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