UNiVtkSiTY OF ILLINOIS LIBRARY AT URBANA CHAMPAIGW BIOLOGY jir JY 31 199 oology NEW SERIES, NO. 25 A Review of the South American Catfish Tribe Hoplomyzontini (Pisces, Aspredinidae), with Descriptions of New Species from Ecuador Donald J. Stewart OCT 0 July 31, 1985 Publication 1360 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY Information for Contributors to Fieldiana General: Fieldiana is primarily a journal for Field Museum staff members and research associates, although manuscripts from nonaffiliated authors may be considered as space permits. The Journal carries a page charge of $65 per printed page or fraction thereof. Contributions from staff, research associates, and invited authors will be con- sidered for publication regardless of ability to pay page charges, but the full charge is mandatory for nonaffiliated authors of unsolicited manuscripts. Payment of at least 50% of page charges qualifies a paper for expedited process- ing, which reduces the publication time. 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Each author will normally receive a copy of the edited manuscript on which deletions, additions, and changes can be made and queries answered. Only one set of page proofs will be sent. All desired corrections of type must be made on the single set of page proofs. Changes in page proofs (as opposed to corrections) are very expensive. Author-generated changes in page proofs can only be made it the author agrees in advance to pay for them. FIELDIANA Zoology NEW SERIES, NO. 25 A Review of the South American Catfish Tribe Hoplomyzontini (Pisces, Aspredinidae), with Descriptions of New Species from Ecuador Donald J. Stewart Assistant Curator, Fishes Department of Zoology Field Museum of Natural History Chicago, Illinois 60605-2496 Accepted for publication August 7, 1984 July 31, 1985 Publication 1360 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY © 1985 Field Museum of Natural History Library of Congress Catalog Card Number: 84-63121 ISSN 0015-0754 PRINTED IN THE UNITED STATES OF AMERICA Table of Contents List of Illustrations Abstract 1 Resumen 1 Introduction 1 Methods 2 HOPLOMYZONTINI FeRNAnDEZ-YePEZ 2 Key to Genera and Species of Hoplomy- zontini Fernandez- Yepez 4 Hoplomyzon Myers 5 Hoplomyzon atrizona Myers 7 Hoplomyzon papillatus, new species .... 8 Dupouyichthys Schultz 10 Dupouyichthys sapito Schultz 10 Ernstichthys Fernandez- Yepez 12 Ernstichthys anduzei Femandez-Yepez .. 12 Ernstichthys megistus (Orces) 15 Ernstichthys intonsus, new species 16 Acknowledgments 18 Literature Cited 19 1 . Pre-anal-fin plates for Hoplomyzon atri- zona, H. papillatus, Dupouyichthys sapi- to, Ernstichthys anduzei, E. megistus, and E. intonsus 3 2. Ventral view of head, showing mouth and barbels for Hoplomyzon atrizona, H. papillatus, Ernstichthys anduzei, and E. megistus 6 3. Ventral view of head, breast, and belly, showing mouth and barbels for Ernst- ichthys intonsus 7 4. Dorsal views of Hoplomyzon atrizona and H. papillatus 8 5. LaXisTal view of Hoplomyzon papillatus .. 9 6. Dorsal views of Dupouyichthys sapito and Ernstichthys anduzei 11 7. Localities for Ernstichthys anduzei, E. megistus, and E. intonsus 12 8. Dorsal views of Ernstichthys megistus ..13 9. Dorsal and lateral views of Ernstichthys intonsus 14, 15 10. Ventral view of posterior coracoid pro- cess and anterolateral extension of pel- vic bone in Ernstichthys anduzei and E. intonsus 17 List of Tables 1 . Mensural characteristics of the six species of Hoplomyzontini 5 lU A Review of the South American Catfish Tribe Hoplomyzontini (Pisces, Aspredinidae), with Descriptions of New Species from Ecuador Abstract Two new species of aspredinid catfishes be- longing to the tribe Hoplomyzontini were collect- ed on expeditions to the Rio Napo basin, eastern Ecuador, in 1981 and 1983. Hoplomyzon papil- latus, new species, is distinguished from all known aspredinids by having ( 1 ) five stout papillae along the upper lip and (2) mentum with two pairs of longer barbels and about 36 short, papillae-like barbels; it differs further from all other species of Hoplomyzontini by having the snout deeply emar- ginate at midline. Ernstichthys intonsus, a new species collected by trawling in the Rio Napo mainstream, is distinguished from all known as- predinids by having (1) a branched maxillary bar- bel with about 15 threadlike secondary barbels; (2) more than 100 slender barbels on mentum, breast, and belly; (3) anterolateral branch of pelvic bone expanded to form a superficial plate extend- ing anteriorly to meet a relatively short coracoid process; and (4) dorsal fin i,7 (vs. dorsal fin i,l-6 in all other aspredinids). The tribe Hoplomyzon- tini is revised, and a key to genera and species is provided. Dupouyichthys Schultz is removed from the synonymy of Hoplomyzon Myers, and Hoplo- myzon megistus Orces is reassigned to the genus Ernstichthys Femandez-Yepez. Resumen Dos especies nuevas de los bagres aspredinidos de la tribu Hoplomyzontini fueron colectados en expediciones a la cuenca del no Napo, Ecuador oriental, en 1981 y 1983. Hoplomyzon papillatus, especie nueva, se distingue de todos los otros as- predinidos por tener ( 1 ) cinco papilas cortas y ro- bustas a lo largo del labio superior, y (2) menton con dos pares de barbillas relativamente largas rodeadas por mas o menos 36 barbillas cortas como papilas; ademas difiere de las todas las otras es- pecies de Hoplomyzontini por tener el hocico pro- fundamente emarginado en la linea media. Ern- stichthys intonsus, una nueva especie colectada mediante una rastra en medio del curso mayor del no Napo, se distingue de todos los aspredinidos conocidos por tener (1) barbillas maxilares rami- ficadas con mas o menos 1 5 filamentos secunda- rios, (2) mas que 1 00 barbillas en el menton, pecho y vientre, (3) rama anterolateral del hueso pelvico expandida formando una placa superficial que se extiende anteriormente hasta encontrar el relati- vamente corto proceso coracoide, y (4) aleta dorsal i,7 (versus aleta dorsal i,l-6 en todos los otros aspredinidos). La tribu Hoplomyzontini es revi- sada y una clave de generos y especies es provista. Dupouyichthys Schultz es removido de la sinoni- mia de Hoplomyzon Myers y Hoplomyzon me- gistus Orces es reasignado al genero Ernstichthys Femandez-Yepez. Introduction An expedition to the Rio Napo basin of eastern Ecuador in late 1981 provided an opportunity to sample the deeper channels of an Amazonian headwater tributary using a bottom trawl. Strong currents and abundant snags made trawling ex- tremely difficult, but eventually, several rare and undescribed fishes were collected from the never- STEWART: SOUTH AMERICAN CATFISH before-sampled depths of the Rio Napo main- stream. The most spectacular of these new deep- river fishes represents an undescribed species of Ernstichthys Fernandez- Yepez (1953). On a sec- ond expedition to the Rio Napo in 1983, a new species of Hoplomyzon Myers (1942) was collect- ed. These two new species are described herein, and the aspredinid tribe to which they belong, Hoplomyzontini Femandez-Yepez, is revised. Ernstichthys anduzei, type species of the genus, was described by Femandez-Yepez (1953) based on a single specimen from the Rio Pao Viejo drain- age in Estado Cojedes, Venezuela. Orces (1961) described a superficially very similar species, Hop- lomyzon megistus, from the Rio Bobonaza, an Amazonian headwater tributary in eastern Ecua- dor and, at the time, apparently was not aware of the genus and species described by Femandez-Ye- pez. A comparison of these two species reveals that they are distinct and apparently congeneric. Methods Anal-fin-base length includes the membrane connecting the posterior ray to midline of caudal peduncle posteriorly, and caudal-peduncle length is measured from posterior end of anal-fin base to middle of caudal-fin base. Lengths of posterior cleithral (humeral) process, posterior coracoid process, pectoral spine, and first branched p)ectoral ray are all taken from where the anterior margin of the erect pectoral spine meets the pectoral gir- dle. Pectoral-spine length does not include the flex- ible distal extension. Dorsomedian-head length is measured to the posterior tip of the supraoccipital. Interorbital width is measured between the fleshy margins of the orbits. Maxillary-barbel length is measured from its junction with the membrane that forms the lateral margin of the mouth (e.g., just lateral to the base of the rictal barbel in Ern- stichthys anduzei). Fin-ray counts include all ele- ments. Terminology used herein for various su- perficial bony plates or scutes in Hoplomyzontini is as follows: Dorsal plates— counted along dorsum between dorsal-fin origin and caudal-fin base, not including plate(s) just anterior to dorsal-fin origin. Ventral plates— counted along venter between anal-fin origin and caudal-fin base. Pre-anal-fin plates— those between anus and anal-fin origin; best seen by cutting and parting the skin along the midline and drying the plates slightly with a stream of air, but often at least partially visible extemally. Lateral-line scutes— counted along lateral line from back of head to caudal-fin base, including 2- 4 relatively elongate ossicles between back of head and start of more conspicuous midlateral series of scutes. Abbreviations for institutions are: California Academy of Sciences, San Francisco, CAS-SU; Field Museum of Natural History, Chicago, FMNH; Natural History Museum of Los Angeles County, Los Angeles, LACM; Museo de Biologia de la Escuela Politecnica Nacional, Quito, Ecua- dor, MEPN; and Florida State Museum, Univer- sity of Florida, GainesvUle, UF. Hoplomyzontini Femandez-Yepez Myers (1960) divided Aspredinidae into subfamilies Aspredininae and Bunocephalinae, with the latter divided into tribes Bunocephalini and Hoplomyzontini. This arrangement is iden- tical to that proposed earlier by Femandez-Yepez (1953), but with the hierarchical level of each tax- on one step lower in Myers's version. Femandez- Yepez (1953) should be credited with the family- group name based on Hoplomyzon Myers, which he introduced as subfamily "Hoplomizoninae." Myers (1960) apparently did not see the 1953 pa- per by Femandez-Yepez, as he did not include Ernstichthys in his review of the family. The tribe Hoplomyzontini is distinguished from other aspredinids by presence of double rows of sup>erficial bony plates on the dorsum from dorsal- fin origin to caudal-fin base, and on the venter from anal-fin origin to caudal-fin base (Femandez- Yepez, 1953; Myers, 1960). Another series of plates, which may be variously fused along the ventral midline, is also present between anus and anal-fin origin. Given that these rows of plates are absent in other aspredinids and all of the relatively generalized or primitive catfishes of the world (in- cluding Diplomystidae, Pimelodidae, Ictaluridae, and Bagridae), I assume that they are a derived feature providing evidence for the monophyletic status of Hoplomyzontini. Hoplomyzontini includes Hoplomyzon with two species and two subspecies, Ernstichthys with three species, and the monotypic genus Dupouyichthys Schultz ( 1 944). I know of three more new species being studied by colleagues, and it seems possible that further explorations, especially in the large rivers, will yield even more new species belonging FIELDIANA: ZOOLOGY 2 mm 2 mm 2mm Fig. 1 . Pre-anal-fin plates for a, Hoplomyzon atrizona, 24.0 mm standard length, paratype, CAS-SU 36495; b, H. papillatus, 16.9 mm standard length, holotype, FMNH 94908; c, Dupouyichthys sapito, 21.1 mm standard length, FMNH 85938; d, Ernstichthys anduzei, 35.3 mm standard length, FMNH 94441; e, E. megistus. 36.5 mm standard length, LACM 41741-5; and f, E. intonsus, 49.6 mm standard length, holotype, FMNH 94603. The dark oval indicates approximate position of the anus for each species. STEWART: SOUTH AMERICAN CATFISH to this group. Thus, with the pubhcation of this paper, at least one-third of the tribe will still be undescribed. Most or all members of this tribe are small, fast-water fishes that are extremely difficult to collect (or extremely rare?). The three species of Ernstichthys, for example, are known from a total of nine specimens. This paucity of material precludes osteological studies at this time. The following classification is an attempt to de- fine monophyletic taxa, but given the foregoing limitations, it should be viewed as a beginning framework or a set of hypotheses to be tested when sufficient materials become available. The pri- mary assumptions on which it was based were as follows. Form of the upper-lip papillae in Hoplo- myzon was assumed to be a derived feature uniquely shared by the two included species. The corresponding primitive condition in aspredinids and all other catfishes is the absence of strictly comparable papillae. Form of the pre-anal-fin plates in Hoplomyzon (with four sets of paired elements; fig. la,b) was assumed to represent the relatively primitive condition for Hoplomyzontini because similar paired elements are present farther posterior on the venter and on the dorsum of all species of Hoplomyzontini. Whether pre-anal-fin plates of other armored catfishes (e.g., callichthy- ids, loricariids) are homologous to those in Hop- lomyzontini is unknown. Fusion of the pre-anal- fin plates along the midline was assumed to be a derived feature joining Dupouyichthys and Ernst- ichthys as the sister-group of Hoplomyzon. Configuration of the pre-anal-fin plates in Du- pouyichthys was considered to be an autapo- morphic feature defining that monotypic taxon (fig. Ic). Finally, two features were considered to be synapomorphies linking the three species of Ern- stichthys as the sister-group of Dupouyichthys— form of the pre-anal-fin plates (fig. 1 d-0 and the relatively long, recurved pectoral spines which are much longer than the first branched pectoral-fin ray. The relatively primitive condition for the pec- toral spines of aspredinids and most other catfishes was assumed to be with the spines relatively straighter and not extending noticeably beyond the tip of the first branched pectoral-fin ray. Key to Genera and Species of Hoplomyzontini Fernandez- Yepez 1 . Upper lip with four or five stout, fleshy papillae; pre-anal-fin plates 1 1 , with four sets of paired elements (fig. la,b); pectoral-spine length (excluding the flexible tip) less than 25% standard length. Hoplomyzon Myers 2. Dorsal-fin rays i,6; four stout, fleshy papillae along upper lip and a relatively long, slender rictal barbel on each side of the mouth (fig. 2a); two pairs of mental barbels; maxillary barbel extending posteriorly beyond pectoral-fin origin and attaching broadly to side of head by membrane (fig. 2a); snout broadly rounded and only slightly emarginate at midline .... Hoplomyzon atrizona Myers (with two subspecies differing in pigmentation; Schultz, 1 944) 2. Dorsal-fin rays i,3,i; five fleshy papillae along the upper lip and no rictal barbel (fig. 2b); two pairs of moderately long barbels and about 36 short, papillae-like barbels on mentum; maxillary barbel not extending posteriorly as far as pectoral-fin origin and only proximal part attached to side of head by membrane (fig. 2b); snout appearing bilobed, deeply emarginate at midline Hoplomyzon papillatus, new species 1. Upper lip without stout, fleshy papillae; pre-anal-fin plates 5-9, with 1-3 sets of paired elements (fig. Ic-f); pectoral-spine length greater than 25% standard length. 3. Pectoral-fin spine with 5-6 serrations on posterior margin, not strongly recurved and only slightly longer than first branched pectoral-fin ray; lateral-line scutes 33-39; pre-anal-fin plates five, with one set of paired elements (fig. Ic) Dupouyichthys sapito Schultz 3. Pectoral-fin spine with 10-18 serrations on posterior margin, strongly recurved and noticeably longer than first branched pectoral-fin ray; lateral-line scutes 42-64; pre-anal-fin plates 7-9, with 2-3 sets of paired elements (fig. Id-f) Ernstichthys Fernandez- Yepez 4. Dorsal fin i,7; anal fin vii,4; maxillary barbel with about 15 threadlike secondary barbels; more than 100 short, slender mental and postmental barbels (fig. 3); pectoral spine with 16 sharp, antrorse serrations on anterior margin and 1 8 retrorse serrations on posterior margin Ernstichthys intonsus, new species 4. Dorsal fin i,4-5; anal fin ii,5; maxillary barbel simple, unbranched; only two pairs of relatively FIELDIANA: ZOOLOGY stout mental barbels and no postmental barbels; pectoral spine with anterior margin entire and about 10-14 retrorse serrations on posterior margin. 5. Short, stout rictal barbel present near anterolateral comer of mouth (fig. 2c); snout distinctly convex in lateral profile; width between pectoral-fin insertions 28.0%-28.6% standard length Ernstichthys anduzei Fernandez- Yepez 5. Rictal barbel absent (or, at most, represented by a low bump; fig. 2d); snout relatively straight in lateral profile; width between pectoral-fin insertions 24.7%-26.3% standard length Ernstichthys megistus (Orces) Hoplomyzon Myers Hoplomyzon Myers, 1942: 94-95; Hoplomyzon atri- zona Myers, 1942, type species by original desig- nation. Diagnosis— Distinguished fi-om all known as- predinids by having four or five stout, fleshy pa- pillae on upper lip. Differs further from other gen- era of Hoplomyzontini in having pre-anal-fin plates 1 1 , with four sets of paired elements (fig. la,b), pectoral-spine length (excluding flexible tip) less than 25% standard length, and relatively short posterior cleithral and coracoid processes; resem- bles Dupouyichthys, but differs from Ernstichthys in having relatively deeper caudal peduncle, great- er width between anterior nostrils, and wider in- terorbital (table 1). Table 1. length. Mensural characteristics of the six species of Hoplomyzontini expressed in thousandths of standard Character Hoplomyzon Dupouy- Ernstichthys papil- latus megistus intonsus atrizona Holo- ichthys , Holo- Holo- Paratype type sapito Ottuf'^^' »4.» - type type CAS-SU FMNH FMNH FMNH UF MEPN LACM FMNH 36495 94908 85938 94441 35393 4305 41741-5 94603 24.0 16.9 21.1 35.3 32.8 66.8 36.5 49.6 142 136 166 141 143 130 132 101 400 408 455 439 439 463 433 401 179 147 183 140 137 144 175 200 250 254 242 249 259 232 241 210 42 47 46 32 30 25 30 27 207 218 201 195 180 200 213 529 527 536 541 549 545 548 490 225 224 220 204 195 199 200 306 200 154 194 195 207 172 208 164 300 325 374 367 348 361 340 337 221 183 204 235 213 259 216 196 83 83 99 92 93 115 85 87 212 189 282 363 366 332 411 387 246 195 249 252 259 226 255 250 125 101 156 163 159 144 164 149 108 89 156 178 168 154 162 131 263 272 299 314 302 307 293 264 296 237 322 286 280 247 263 272 138 136 171 143 137 156 132 93 108 107 123 127 128 138 126 101 25 12 33 23 21 18 18 10 75 95 76 57 58 45 55 63 67 83 66 51 46 49 47 52 79 83 103 83 76 97 82 73 195 130 152 184 171 186 151 377 92 71 81 115 104 183 85 [44-65] 50 41 47 48 40 75 38 Standard length, mm Body depth Predorsal length Dorsal-fin height Caudal-peduncle length Caudal-peduncle depth Caudal-fin length Preanal length Anal-fin-base length Anal-fin height Prepelvic length Pelvic-fin length Pelvic-fin interspace Pectoral-spine length Anterior branched pectoral ray Posterior-cleithral-process length Posterior-coracoid-process length Dorsomedian-head length Width between pectoral insertions Head depth at occiput Snout length Eye diameter Interorbital width Width between anterior nostrils Mouth width Barbel lengths: Maxillary Lateral mental Medial mental STEWART: SOUTH AMERICAN CATFISH 0\ ^ .< 3 ^ -2 5 ^ so g- « ^^ <^ c TT E ^ P m ^ >. 5 2k; s: vL o eg ^ VI o c 5 CO O . - ^ T3 C ■B « 3 .- O <» C OS O o "3 00 d ^ 15 FIELDIANA: ZOOLOGY Fig. 3. Ventral view of head, breast, and belly showing mouth and barbels for Ernstichthys intonsus, 49.6 mm standard length, holotype, FMNH 94603. Scale bar is 5 mm. (Drawn by Qara Richardson.) Hoplomyzon atrizona Myers. Figures la, 2a, 4a Hoplomyzon atrizona Myers, 1942: 95-96, fig. 3. Paratopotype— CAS-SU 36495, 24.0 mm standard length, Venezuela, Estado Tachira, small tributary to Rio Zulia, at Estacion Tachira, 60 km north of San Cristobal, altitude about 1 50 m, Lago de Maracaibo basin, F. F. Bond, 14 Jvme 1938. Diagnosis— Distinguished from all known as- predinids by having four stout papillae along up- STEWART: SOUTH AMERICAN CATFISH Fig. 4. Dorsal views of a, Hoplomyzon atrizona, 24.0 mm standard length, paratype, CAS-SU 36495; and b, H. papillatus, 16.9 mm standard length, holotype, FMNH 94908. Scale bars are 5 mm. per lip, and from all species of Bunocephalinae by its relatively long, slender rictal barbel (fig. 2a) and dorsal-fin rays i,6. Differs further from its only congener in having (1) only two pairs of mental barbels; (2) maxillary barbel extending posteriorly beyond pectoral-fin origin and attaching broadly to side of head by membrane; (3) snout broadly rounded, not strongly emarginate at midline; (4) lateral-line scutes in relatively straight line; (5) pel- vic fin relatively rounded posteriorly, third ray longest and not extended posteriorly as filament; and (6) dorsal and anal fins not attached poste- riorly to body midline by membranes. Description — Mensural characters are pre- sented in Table 1 . Meristic data follow: dorsal fin i,6; anal fin ii,4; pectoral fin I,4-5,i with posterior ray simple; pectoral spine with anterior margin entire and six serrations on posterior margin, ser- rations absent on proximal fourth of spine; pelvic fin i,5 or i,4,i with last ray branched on one fin and simple on other, and posterior margin of fin rounded with third ray longest; caudal fin i,7,i; dorsal plates 20; ventral plates 14; pre-anal-fin plates as in Figure la; lateral-line scutes 47, in- cluding three elongate ossicles anteriorly. Distribution— Known only from the Lago de Maracaibo basin in western Venezuela. Comments -Schultz (1944, pp. 248-249, plate 4C, fig. 4a) described a new subspecies, H. atri- zona petroleus, from the Rio Motatan, another tributary of Lago de Maracaibo. Schultz distin- guished his new subspecies on the basis of what seem to be minor differences in pigmentation. I have not examined the holotypes of these two nominal subspecies, so will defer judgment on the validity of petroleus. Schultz, however, had only two specimens from a single locality. It seems pos- sible that larger samples will reveal variation in pigmentation encompassing that of these two nominal subspecies. Hoplomyzon papillatus, new species. Figures lb, 2b, 4b, 5 HoLOTYPE-FMNH 94908, 16.9 mm standard length, Ecuador, Napo Province, Rio Aguarico, about 1 km upstream from confluence with Rio Shushufindi, lat. 0°17'S, long. 76°25.4'W, bottom sandy, strong current just offshore with large ed- dies along beach, water level rose 1-2 m in pre- FIELDIANA: ZOOLOGY ceding few hours and still rising rapidly at time of collection, seining at night to depth of 1.5 m, field no. DJS83-91, D. Stewart, M. Ibarra, and R. Bar- riga, 24 November 1983. Diagnosis— Distinguished from all known as- predinids by having five stout papillae along upper lip and mentum with two pairs of longer barbels and about 36 short, papillae-like barbels (fig. 2b). Distinguished from all other species of Hoplo- myzontini by having snout deeply emarginate at midline, appearing bilobed. Differs further from its only congener in having (1) no slender rictal barbel; (2) dorsal-fin rays i,3,i (vs. i,6); (3) maxillary barbel relatively short, not extending posterior to pectoral-fin origin ( 1 3% vs. 1 9.5% standard length, extending posteriorly beyond pectoral-fin origin); (4) lateral-line scutes in zig-zag pattern (vs. rela- tively straight line); (5) second pelvic-fin ray long- est, extending posteriorly as short filament (vs. third ray longest and not extended); and (6) dorsal and anal fins attached posteriorly to body midline by membranes (vs. not attached). Description — Mensural characters are pre- sented in Table 1 for comparison with other species of Hoplomyzontini. Anterior nostril on short tube situated just behind anterior margin of snout and directed anteriorly. Posterior nostril closer to eye than to anterior nostril, with lunate opening about equal in size to eye diameter. Delicate, conical teeth present in narrow row near distal end of mandible and on premaxilla in small patch asso- ciated with lateral groove of upper lip (i.e., dorsal to the two lateralmost upper-lip papillae). Meristic Data for Holotype— Dorsal fin i,3,i with posterior margin relatively straight; dorsal-fin base (including membrane attaching posterior ray to body midline) extends posteriorly to anterior mar- gin of ninth dorsal plate, and depressed first dorsal ray to anterior margin of seventh plate; anal fin ii,4 with first or second branched ray longest and posterior margin relatively straight; anal-fin base extends posteriorly to anterior margin of ninth ventral plate; pectoral fin I,2,iv on one side and I,3,iii on other side; pectoral spine with anterior margin entire and posterior margin with seven re- trorse serrations; flexible extension of pectoral-fin spine equals 40% length of spine and reaches pos- teriorly to point ventral to third branched dorsal- fin ray; pelvic-fin origin ventral to posterior tip of supraoccipital; pelvic fin v or vi, no branched rays and second ray longest, extending posteriorly as flexible filament about 30% longer than next long- est pelvic ray, extending to second plate anterior to anal-fin origin; first pelvic-fin ray ventral to / o i I I I -* o •— (A 5.1 oi u. STEWART: SOUTH AMERICAN CATFISH second ray at base and joined to second only along proximal fourth of length; caudal fin i,7,i, oblique- ly truncate but rounded ventrally, with two ven- tralmost branched rays about equal in length and longer than other caudal-fin rays; dorsal plates 23; ventral plates 17; pre-anal-fin plates as in Figure lb; lateral-line scutes 51, including four ossicles anteriorly; lateral body armature formed by alter- nating dorsal and ventral plates; rounded lateral- line scutes associated with each plate form a zig- zag pattern (fig. 5) which contrasts noticeably with relatively straight series of lateral-line scutes in H. atrizona. Pigmentation— General color of most of head, body, and fins dark olive brown to dark gray; fol- lowing parts contrast with this darker background color in being beige or sandy-colored: anterior margin of snout, maxillary and mental barbels, interorbital/frontal region of head, posteriorly convex band extending across nape and anterior back from one posterior cleithral process to other, spot on dorsum and upper flank covering dorsal plates 9-12, spot on four posteriormost dorsal plates and extending posteroventrally to form band covering caudal-fin base, pelvic fins, most of anal fin, and distal margins of pectoral and caudal fins; lips and associated papillae relatively unpigment- ed. Comments— Among species of Hoplomyzon- tini, only Ernstichthys intonsus described below has more than two pairs of mental barbels. Hop- lomyzon papillatus differs noticeably from E. in- tonsus, however, in having what appear to be two classes of mental barbels— two pairs of longer bar- bels apparently homologous with those in all other Bunocephalinae and numerous shorter barbels. In E. intonsus, all mental barbels are slender, and none can be clearly identified as homologous to the two pairs seen in other bunocephalins. All mental barbels of H. papillatus are covered with small tubercles like those on mental barbels of all other bunocephalins, except E. intonsus (see com- ments under that species account below) which differs in having naked mental barbels. Hoplomyzon papillatus appears to differ further from its only congener in various morphometric and meristic characters, but without enough spec- imens to evaluate variation, I hesitate to include them in the diagnosis. For example, papillatus seems to have relatively shorter anterior branched pectoral-fin ray, narrower width between pectoral- fin insertions, wider interorbital and distance be- tween anterior nostrils, and shorter mental barbels (table 1). This is also the only species of Hoplo- myzontini for which jaw teeth could be observed with a dissecting microscope. Teeth are either ab- sent in the other species or too delicate to be seen, even when the jaws were dried slightly with an airstream. Etymology— From the Latin papillatus, with buds, in reference to the numerous short, papillae- like mental barbels. Dupouyichthys Schultz Dupouyichthys Schultz, 1944: 244-245; Dupouy- ichthys sapito Schultz, 1 944, type species by original designation. Diagnosis— Distinguished from all known as- predinids by its unique configuration of five pre- anal-fin plates with only one set of paired elements (fig. Ic). Differs further from other Hoplomyzon- tini by its relatively deeper body and low number of lateral-line scutes (33-39). Differs further from Hoplomyzon by (1) absence of upper-lip papillae, (2) relatively longer posterior coracoid and cleith- ral processes, and (3) longer pectoral spine. Differs further from Ernstichthys in its ( 1 ) relatively short- er pectoral spine, only slightly longer than first branched pectoral-fin ray and with 5-6 serrations on posterior margin; (2) relatively larger eye; and (3) wider interorbital (table 1). Comments— Myers (1960) considered Du- pouyichthys to be a synonym o^ Hoplomyzon. Based on configuration of the pre-anal-fin plates (fused along midline) and absence of stout upper-lip pa- pillae, Dupouyichthys appears to be more closely related to Ernstichthys than to Hoplomyzon. I have therefore chosen to remove Dupouyichthys from the synonymy of Hoplomyzon and recognize it as a distinct genus until the interrelationships of these fishes are better known. Dupouyichthys sapito Schultz. Figures Ic, 6a Dupouyichthys sapito Schultz, 1944: 245-246, plate 4D, fig. 4b. Nontype-FMNH 85938, 21.1 mm standard length, Venezuela, Estado Zulia, Rio Guasare at El Paso, flat gravel bar, field no. VE75-29, D. Hicks and party, 26 August 1975. Diagnosis— Distinctive features of the only known species of Dupouyichthys are given in the generic diagnosis above. Description — Mensural characters are pre- 10 FIELDIANA: ZOOLOGY Fig. 6. Dorsal views of a, Dupouyichthys sapito, 21.1 mm standard length, FMNH 85938; and b, Ernstichthys anduzei, 32.8 mm standard length, UF 35393. Scale bars are 5 mm. sented in Table 1 . Meristic data follow (with range of values reported by Schultz, 1 944, for the ho- lotype and seven paratypes given in parentheses): dorsal fin i,4 (i,4-5); anal fin ii,4 (ii,5-6); pectoral fin I,5,i (1,6) with posterior ray simple; pectoral spine with anterior margin entire and 5 (5-6) ser- rations on posterior margin, serrations absent on proximal 40% of spine; pelvic fin i,4,i (i,5) with first branched ray longest and outer branch of that ray extending posteriorly as short filament, sixth pelvic-fin ray simple; caudal fin i,7,i (i,7-8,i) with ventralmost branched ray longest; dorsal plates 21 (20-23); ventral plates 16 (17-18); pre-anal-fin plates as in Figure Ic; lateral-line scutes 34 (33- 39), including three elongate ossicles anteriorly; two pairs of mental barbels and no rictal barbel (similar to E. megistus, fig. 2d). Distribution— The type locality is in the Rio STEWART: SOUTH AMERICAN CATFISH 11 Fig. 7. Localities for the three species of Ernstichthys, with type locahties marked with letters as follows: A, (anduzei); M, • {megistus); and I, ▲ (intonsus). Motatan, a tributary entering the east side of Lago de Maracaibo, Venezuela (Schultz, 1944). The specimen reported herein and four of Schultz's paratypes come from tributaries to the west side of Lago de Maracaibo, and elsewhere, D. sapito is known from the Rio Librija in the Rio Magdalena basin, Colombia (Miles, 1945). Ernstichthys Fernandez- Yepez Ernstichthys Fernandez- Yepez, 1953: 4-5; Ernstich- thys anduzei Fernandez- Yepez, 1953, type species by original designation. Diagnosis— Distinguished from all other known aspredinids by pre-anal-fin plates 7-9, with 2-3 sets of paired elements (fig. Id-f), and pectoral-fin spine with 10-18 serrations on posterior margin, strongly recurved and noticeably longer than first branched pectoral-fin ray. Differs further from other genera of Hoplomyzontini in having rela- tively shallower caudal peduncle, narrower width between anterior nostrils, and narrower interor- bital (table 1). Differs further from Hoplomyzon in having no stout papillae along upper lip and relatively longer posterior cleithral and coracoid processes. Differs from Dupouyichthys in having more than 40 lateral-line scutes. Ernstichthys anduzei Femandez-Yepez. Figures Id, 2c, 6b Ernstichthys anduzei Femandez-Yepez, 1953: 5-6, fig. 1. 12 FIELDIANA: ZOOLOGY Fig. 8. Dorsal views of Ernstichthys megistus: a, 66.8 mm standard length, holotype, MEPN 4305; and b, 36.5 mm standard length, LACM 41741-5. Scale bars are 5 mm. NoNTYPES— FMNH 94441, 35.3 mm standard length, Venezuela, Estado Barinas, Rio Bocono at La Veguita, lat. 8°49'N, long. 70°0'W, beach seine, water 22.5° C, turbid, depth to 1 m, bottom sand and mud, current very strong (over 1.5 m/s), field no. DCT80-82, D. Taphom, C. Lilystrom, and S. Reid, 21 July 1980; UF 35393, 32.8 mm standard length, same locality. Diagnosis— Distinguished from its two conge- ners by having short, stout rictal barbel (fig. 2c). Differs further from E. megistus in having snout distinctly convex in lateral profile and relatively greater width between pectoral-fin insertions (ta- ble 1). Distinguished from E. intonsus by its lower dorsal- and anal-fin-ray counts, unbranched max- illary barbels, and pectoral spine with only 10-14 serrations on posterior margin (also, see diagnosis of E. intonsus for other contrasting characters). Description— Mensural characters are pre- sented in Table I . Meristic data follow (range given only where the two specimens differ): dorsal fin i,4 (i,5 in holotype; Fernandez- Yepez, 1953); anal fin ii,5; pectoral fin I,5,i with posterior ray simple; pectoral spine with anterior margin entire and 1 0- STEWART: SOUTH AMERICAN CATFISH 13 :^? 14 FIELDIANA: ZOOLOGY u 14 serrations on posterior margin, serrations ab- sent or rudimentary on proxmal third of spine; pelvic fin i,4,i with first branched ray longest and outer branch of that ray extending posteriorly as short filament, sixth pelvic-fin ray simple; caudal fin i,7,i with ventralmost branched ray longest; dorsal plates 2 1-22; ventral plates 1 5-1 6; pre-anal- fin plates as in Figure Id; lateral-line scutes about 43-44, including two elongate ossicles anteriorly. Distribution— This species is known only from the Rio Orinoco basin in western Venezuela (fig. 7). Comments— The holotype of this species, orig- inally in the Museo de Historia Natural La Salle, Caracas, Venezuela (Cat. No. 7779), is now in the fish collection at the Museo de Biologia, Univer- sidad Central de Venezuela, Caracas (F. Mago- Leccia, personal communication). The rounded second median pre-anal-fin plate of E. anduzei (fig. Id) differs markedly from its more slender homologue in the other two species of Ernstichthys (fig. le,f). This feature was omitted from the diagnosis, however, because two speci- mens of E. anduzei examined by D. Taphom (Guanare, Venezuela, letter of 27 March 1984) apparently showed variation in shape of this plate, with one individual having a slender element more like those in Figure le,f The second specimen from the Rio Bocono (UF 35393) also has a slen- der second plate, while Femandez-Yepez's (1953) illustration of the holotype shows a rounded ele- ment. This variation could be due to sexual di- morphism. Examination of the gonads in one specimen of each form did not reveal obvious dif- ferences, but perhaps inactive females have gonads superficially similar to those of males. Other species of Hoplomyzontini could have similar dimor- phisms and should be checked when adequate samples become available. Ernstichthys megistus (Orces). 8a,b Figures le, 2d, Hoplomyzon megistus Orc6s, 1961: 3-6, figs. 1 and 2. Holotype— MEPN 4305, 66.8 mm standard length, Ecuador, lower Rio Bobonaza at Chich- erota, about 25 km upstream from mouth in Rio Pastaza, approx. lat 2°23'S, long. 76°39'W, P. Mena, November 1959. NoNTYPE— LACM 41741-5, 36.5 mm standard length, Peru, Departamento Amazonas, Rio Ma- ranon across from Santa Maria de Nieva and con- fluence with Rio Nieva, lat. 4°35'S, long. 77°52'W, STEWART: SOUTH AMERICAN CATFISH 15 beach seine, water turbid and rising rapidly due to heavy rains, depth to 1.5 m, bottom sandy with some rock cobble and logs, current strong, field no. DJS80-44, D. Stewart and D. Stamm, 1 6 April 1980. Diagnosis— Distinguished from E. anduzei by absence of rictal barbel (or, at most, low bump present; fig. 2d), snout relatively straight in lateral profile, and relatively narrower width between pectoral-fin insertions (table 1). Distinguished from E. intonsus by its lower dorsal- and anal-fin-ray counts, unbranched maxillary barbel, only two pairs of stout mental barbels, and pectoral spine with only 13-14 serrations on posterior margin (also, see diagnosis of E. intonsus for other con- trasting characters). Description — Mensural characters are pre- sented in Table 1 . Meristic data follow (range given only when the two specimens differ): dorsal fin i,4; anal fin ii,5; pectoral fin I,5,i with posterior ray simple; pectoral spine with anterior margin entire and 13-14 serrations on posterior margin, serra- tions absent or rudimentary on proximal fourth of spine; pelvic fin i,4,i with first branched ray longest and outer branch of that ray extending posteriorly as short filament, sixth pelvic-fin ray simple; caudal fin i,7,i with ventralmost branched ray slightly longer than ray just dorsal to it; dorsal plates 19-20; ventral plates 13-15; pre-anal-fin plates as in Figure le; lateral-line scutes about 42- 44, including three elongate ossicles anteriorly. Distribution— The types for this species both come from the lower Rio Bobonaza in eastern Ecuador (fig. 7). The recently collected specimen from the Rio Maraiion, Peru, extends the range southward. Comments— The paratype and only other known specimen of this species was originally deposited in a small collection at Universidad Central del Ecuador, Quito (Cat. No. 270); it could not be located and is presumably lost. The specimen from Peru differs noticeably from the holotype in having relatively shorter barbels and higher median fins (table 1). The holotype is almost twice as large as the Peruvian specimen, so observed differences could be due to allometric changes or, perhaps, sexual dimorphism. Ernstichthys intonsus, new species. Figures If, 3, 9 Holotype— FMNH 94603, 49.6 mm standard length, Ecuador, Napo Province, Rio Napo at An- angu (fig. 7), lat. 0°30.8'S, long. 76°24.0'W, trawl sample in mid-river, altitude just under 200 m, water about 28° C (measured five days earlier and farther upstream), turbid, depth 3-4 m, bottom sandy with some leaf litter and logs, strong current, field no. DJS81-51, D. Stewart, M. Ibarra, and R. Barriga, 12 October 1981. Diagnosis— Distinguished from all known as- predinids by (1) extremely elaborate development of short, slender barbels as follows (fig. 3): max- illary barbel branched with about 15 threadlike, secondary barbels; more than 1 00 such barbels on mentum, breast, and belly, with posteriormost barbel near pelvic-fin origin (but absent on skin covering pectoral girdle ventrally); similar short barbels surrounding mouth and on roof and floor of buccal cavity; each premaxilla with small ro- sette of papillae on fleshy pedicel; (2) anterolateral branch of pelvic bone expanded to form superficial plate (having rugose texture like posterior coracoid process and covered with thin, loose skin), ex- tending forward to meet relatively short coracoid process about halfway between pelvic-fin origin and posterior end of pectoral-fin base (fig. 1 Ob); and (3) dorsal fin with unbranched, flexible first ray and seven branched rays (vs. dorsal fin i,l-6 in all other aspredinids). Distinguished from all aspredinids, except species of Aspredinichthys Bleeker, in having integumentary tubercles vir- tually absent from mentum, belly, and associated barbels, giving smooth texture to skin. Further distinguished from other species of tribe Hoplomyzontini by its high number of anal-fin rays (vii,4 vs. anal fin iii,4 or ii,5-6), serrations on posterior margin of pectoral spine (about 1 8 vs. 14 or less), serrations on anterior margin of pectoral spine (about 1 6 vs. none), and midlateral scutes (about 64 vs. 5 1 or less). Numerous men- sural characters appear to distinguish this taxon from its two congeners (table 1); for example, E. intonsus has very long maxillary barbel, greatly depressed head and body, and relatively small eye (some of these apparent mensural differences may show overlap when more specimens are exam- ined). Description— Mensural characters are pre- sented in Table 1 for comparison with other species of Hoplomyzontini. Relative lengths and positions of fins and barbels of holotype are depicted in Figures 3 and 9. Coloration of preserved speci- mens varies from dark gray on dorsal fin and mid- body to dirty white on mentum and belly; pig- mentation pattern is illustrated in Figures 3 and 9. Teeth apparently absent on premaxilla and mandible. 16 FIELDIANA: ZOOLOGY • ^,^,M.IA..M.IJI.....J..i a 2mm 0 2mm Fig. 10. Ventral view of posterior coracoid process and anterolateral extension of pelvic bone in a, Ernstichthys anduzei, 35.3 mm standard length, FMNH 94441; and b, E. intonsus. 49.6 mm standard length, holotype, FMNH 94603. Meristic I>ata for Holotype— Dorsal fin i,7; anal fin vii,4; pectoral fin 1,6, posterior ray branched on left side offish and simple on right side; pectoral spine with about 1 6 antrorse serrations on anterior margin and 18 retrorse serrations on posterior margin, proximal posterior serration close to base of spine; short, fleshy filament extending poste- riorly from tip of pectoral spine; pelvic fin i,5 with first branched ray longest and outer branch of that ray extending posteriorly as short filament; differ- ing fi*om its two congeners in having sixth pelvic- fin ray branched; caudal fin i,7,i with second branched ray of ventral lobe longest; dorsal plates 24; ventral plates 18; pre-anal-fin plates as in Fig- STEWART: SOUTH AMERICAN CATFISH 17 ure If; lateral-line scutes about 64 with 3-4 elon- gate ossicles anteriorly. Ecology— Ernstichthys intonsus was collected in the Rio Napo mainstream just upstream from its confluence with Rio Anangu Cocha (fig. 7). The Rio Napo is wide and relatively shallow there, with broad, sandy beaches exposed at low water. The deepest water which we encountered in the area was about 10 m (measured with a portable echo-sounder), but depth was less than 4 m at the type locality. The strong current, turbid water, and loose-sand substrate probably mean that benthic productivity is relatively low. The extremely nu- merous barbels of E. intonsus seem most likely to be an adaptation for locating food. The ventral mouth and tiny, dorsally situated eyes of intonsus, like those of other species of Hoplomyzontini, es- sentially preclude the use of vision for finding food. Other fishes collected by trawling in the Rio Napo mainstream near Aiiangu were: Xiliphius leptus Orces and X. melanopterus Orces, aspre- dinid catfishes with tiny, dorsal eyes and numer- ous, short barbels along the lower lip; an as-yet- unidentified species of Loricariinae with profusely branched maxillary barbels; a parasitic tricho- myterid catfish of the genus Paracanthopoma which has relatively degenerate eyes and no pig- mentation; two undescribed species of pimelodid catfishes, both of which may represent new genera; and finally, one specimen of Pimelodella. Results from these and trawl samples taken elsewhere in the Rio Napo suggest the presence of a specialized deep-river assemblage of fishes of which E. inton- sus is a part. Most of the fishes taken by trawling in the mainstream were not collected by any other method or in any other habitat. Comments— All previously described species of Bunocephalinae have two pairs of relatively stocky mental barbels, contrasting noticeably with the abundant, threadlike barbels of £■. intonsus. None of the mental barbels of £". intonsus can be clearly identified by position or external morphology as homologous to the mental barbels of other species of Bunocephalinae. Numerous, threadlike mental and postmental barbels also occur (evolved in- dependently?) in species of Aspredinichthys, subfamily Aspredininae; the two species in that genus have 7-10 pairs of barbels arranged in a relatively symmetrical pattern (Taylor, 1978). The superficial, platelike anterior branch of the pelvic bone in E. intonsus is unique among as- predinids (fig. 10). The anterior projection of the pelvic bone in other aspredinids is typically hidden below skin and muscle, at least distally. In the other two species of Ernstichthys and other aspre- dinids with a relatively long posterior coracoid process, the anterior projection of the pelvic bone always lies mesial to the coracoid. The number of dorsal-fin rays in aspredinids appears to be relatively conservative, with most species having i,4. The exceptionally high number of dorsal-fin rays in E. intonsus (i,7) is approached only by that in Hoplomyzon atrizona (i,6). The mentum and mental barbels of nearly all species of aspredinids are covered with tiny tu- bercles apparently similar to those on most of the rest of the head, body, and at least the leading edges of various fins. Roberts (1982) identified such tubercles from the flank of Agmus lyriformis Eigenmann as "partially unculiferous tubercles" or unicellular homy projections. Ernstichthys in- tonsus is distinctive among species of Bunocepha- linae, at least, in lacking such tubercles on mentum and most of the mental barbels (or they are so reduced that they cannot be seen with a light mi- croscope). Tubercles are abundant, however, on the body, dorsal surface of the head, and leading edges of the maxillary barbels, and pectoral and pelvic fins (fig. 9). Etymology— From the Latin intonsus, un- shaved or bearded, in reference to the extreme proliferation of barbels. Acknowledgments The 1981 expedition to the Rio Napo, Ecuador, was funded in part by the American Philosophical Society (Grant No. 8877, Penrose Fund); the 1983 Napo expedition was supported in part by a grant from the National Science Foundation (INT 8303194); and the Field Museum of Natural His- tory provided supplementary support for both ex- peditions. I especially want to thank Myriam Ibarra (now at Field Museum) and Ramiro Barriga, Escuela Politecnica Nacional, Quito, for their as- sistance with all aspects of the fieldwork. Various other Ecuadorians and their institutions provided logistic and material support, including Gustavo Orces and Luis Albuja of the Departamento de Ciencias Biologicas of the Escuela Politecnica Na- cional, Carlos Aguirre and numerous field repre- sentatives of the Ministerio de Agricultura y Gana- deria, Corporacion Estatal Petrolera Ecuatoriana who provided the boat used for trawling near Aii- angu and for trips to the lower Rio Aguarico, and Comandancia Militar de la Brigada de la Selva 18 FIELDL\NA: ZOOLOGY No. 19 "Napo." Qara Richardson, FMNH, de- serves special thanks for the long hours sp)ent pre- paring Figures 3, 5, and 9; Zbigniew Jastrzebski and Ron Testa, FMNH, assisted with some of the other illustrations. Jonathan Baskin, Camm Swift (LACM), William Eschmeyer (CAS-SU), and Car- ter Gilbert (UF) provided loans of specimens in their care; Donald Taphom (Guanare, Venezuela) donated a specimen of E. anduzei to FMNH. Fi- nally, I thank reviewers for constructive criticism of the manuscript. Literature Cited Fernandez- Yepez, A. 1953. Algunas notas sobre los peces Asprediformes con descripcion de Ernstichthys anduzei, nuevo e interesante bunocephalido. Nove- dades Cientificas del Museo de Historia Natural La Salle, Serie Zool6gica, no. 11,7 pp. Miles, C. 1945. Some newly recorded fishes from the Magdalena River system. Caldasia, 3(15): 453-464. Myers, G. S. 1942. Studies on South American fresh- water fishes. I. Stanford Ichthyological Bulletin, 2(4): 89-114. . 1960. The genera and ecological geography of the South American banjo catfishes, family Aspredi- nidae. Stanford Ichthyological Bulletin, 7(4): 1 32-1 39. Orces, G. 1961. Hallazgo de peces de los generos A'/- liphius y Hoplomyzon en el sistema del Amazonas. Descripci6n de una nueva especie. Ciencia y Natura- leza, 4(1): 3-6. Roberts, T. R. 1982. Unculi (homy projections arising from single cells), an adaptive feature of the epidermis of Ostariophysan fishes. Zoologica Scripta, 11(1): 55- 76. ScHULTZ, L. P. 1944. The catfishes of Venezuela, with description of thirty-eight new forms. Proceedings of the United States National Museum, 94: 173-338. Taylor, W. R. 1978. Aspredinidae, pp. aspred 1-4. In Fischer, W. ed., FAO Species Identification Sheets for Fishery Purposes: Western Central Atlantic (Fish- ing Area 31), vol. 1. Food and Agricultural Organi- zation of the United Nations, Rome. STEWART: SOUTH AMERICAN CATFISH 19 Field Museum of Natural History Roosevelt Road at Lake Shore Drive Chicago, Illinois 60605-2496 Telephone: (312) 922-9410