Cetopsis othonops (Eigenmann, 1912)

Vari, Richard P., Ferraris Jr, Carl J. & de Pinna, Mário C. C., 2005, The Neotropical whale catfishes (Siluriformes: Cetopsidae: Cetopsinae), a revisionary study, Neotropical Ichthyology 3 (2), pp. 127-238 : 184-189

Cetopsis othonops (Eigenmann, 1912)

Figs. 33 , 34 , Tables 9 -15

Hemicetopsis othonops Eigenmann, 1912b: 17 [type locality: Colombia, Girardot].–1920a: 13 [ Colombia, río Magdalena basin].–1920c: 29 [ Colombia, upper río Magdalena, río Cauca].–1923: 56, pl. 3, fig. 1 [ Colombia, río Magdalena basin; redescription based on Eigenmann, 1912b].– Fowler, 1942: 131 [ Colombia, río Magdalena basin]; 1943: 245 [ Colombia, río Magdalena].– Miles, 1943: 34 [ Colombia, río Cauca; common name].– Dahl et al., 1963 [ Colombia, río San Jorge; relative rarity].– Dahl, 1964: 41 [ Colombia, río Sinú, Naín, and Tucurá; relative rarity]; 1971: 65, unnumbered Fig. [ Colombia; lower portions of río Magdalena, upper río Cauca, río Sinú; common name].– Miles, 1973: 31, fig. 8a [ Colombia, río Magdalena; shifted from Pseudocetopsis to Hemicetopsis without comment].– Burgess, 1989: 292 [basins of río Magdalena and río Cauca].– Ibarra & Stewart, 1987: 44 [holotype and paratype despository].–Ferraris & Vari, 1992: 16 [paratype depository].–Mojica-C., 1999: 565 [ Colombia, río Magdalena, río Cauca, río San Jorge, río Sinú].

Pseudocetopsis othonops – Schultz, 1944: 253 [in key, assignment to Pseudocetopsis ].– Miles, 1947: 86 [ Colombia, río Magdalena, upper and lower río Cauca; common name].– Evers & Seidel, 2002: 741 [listing].–Vari & Ferraris, 2003: 259 [in check list; distribution, common name].

Pseudocetopsis sp. – Cala, 1995: 49 [ Colombia, río Magdalena basin, Betania Reservoir].

Diagnosis. Cetopsis othonops can be distinguished from all of its congeners by the combination of the presence of an eye, the conical teeth on the vomer and the dentary, the rounded posterior nares that is distinctly separated from the contralateral nares by a distance greater than the width of the posterior nares, the moderately wide mouth approximately equal to the distance from the tip of the snout to the posterior margin of the orbit and much less that one-half of HL, the unpigmented anterior and lateral margins of the snout, the absence of a dark humeral spot, the absence of a posteriorlyrounded, variably-developed, bilobed patch of dark pigmentation at the base of the caudal fin, the absence of a pattern of dark pigmentation on the distal portions of the pectoral and anal fins, the limitation of dark pigmentation to the basal portions of the middle rays of the dorsal fin and the absence of dark pigmentation on the remainder the fin or along the length of the first dorsal-fin ray, the absence of dark pigmentation across all of the caudal fin other than for a thin stripe along the margin, and the possession of 45 to 48 total vertebrae, 23 to 28 total anal-fin rays, and 13 to 15 precaudal vertebrae.

Description. Body relatively elongate, laterally-compressed anteriorly and becoming progressively distinctly-compressed posteriorly. Body depth at dorsal-fin origin approximately 0.21- 0.22 of SL, and slightly shorter than HL. Lateral line on body complete, unbranched, and midlateral; extending from vertical through pectoral-fin base onto hypural plate with slight dorsal bend on hypural plate and with short, ventrally-directed branches on caudal peduncle extending off of main canal. Dorsal profile of body straight from nape to dorsal-fin origin and nearly straight from dorsal-fin origin to caudal-fin base. Ventral profile of body convex along abdomen, approximately straight, but posterodorsally-slanted, along base of anal fin. Caudal-peduncle depth greater than caudal-peduncle length.

Head in profile acutely triangular overall with bluntlyrounded snout. Dorsal profile of head gently convex from tip of snout to nape. Ventral profile of head slightly convex. Margin of snout in dorsal view rounded anteriorly and obtusely triangular overall. Postorbital margins of head running nearly in parallel from dorsal view. Enlarged jaw musculature not evident externally on dorsal surface of postorbital portion of head.

Opercular membrane attaching to isthmus only to region anterior to vertical through pectoral-fin insertion. Opercular opening moderate; extending ventral of pectoral-fin insertion by distance equal to width of orbit and extending dorsal of pectoral-fin insertion by distance equal to width of orbit.

Eye situated on lateral surface of head; located entirely dorsal to horizontal extending through pectoral-fin insertion; eye visible in dorsal view, but not in ventral view, of head. Middle of orbit at approximately anterior one-third of HL. Eye diameter slightly larger than one-half of snout length. Interorbital width approximately equal to distance from tip of snout to middle of eye. Anterior narial opening circular, surrounded by short, anteriorly-directed, tubular rim of skin. Opening of anterior nares located along horizontal extending through both tip of snout and maxillary-barbel origin. Distance between anterior nares approximately equal to snout length. Posterior narial opening located on dorsal surface of head, situated along vertical through anterior margin of orbit. Posterior narial opening nearly round with anterior two-thirds of aperture bordered by flap of skin, with anterior portion of flap highest.

Mouth inferior; its width approximately equal to distance from tip of snout to posterior margin of orbit and much less than one-half of HL. Margin of lower jaw gently rounded, its posterior limit reaching to vertical through middle of eye. Premaxillary tooth patch in form of gently-arched band, continuous across midline and with anterior margin convex and posterior margin concave and running in parallel to anterior margin. Teeth on premaxilla small, conical, sharply-pointed, and arranged in three, relatively regularly-arranged rows. Vomerine teeth arranged in single, irregular row continuous across midline.Vomerine teeth conical and stout, distinctly larger than those on premaxilla. Dentary teeth comparable in shape to, but longer than, premaxillary teeth. Dentary dentition consisting of two tooth rows at symphysis that taper to one row laterally.

Maxillary barbel slender, its length approximately equal to one-half of HL; barbel origin located ventral to middle of orbit. Mental barbels approximately equal in length to maxillary barbel and to each other. Medial mental-barbel origin located along vertical through rictus. Lateral mental-barbel origin situated slightly posterior of vertical through posterior margin of orbit. Tips of adpressed mental barbels falling just short of posterior margin of opercle.

Dorsal fin moderately large overall with length of dorsalfin base approximately 0.33 of HL. Length of longest branched dorsal-fin ray equal to two-thirds of HL. Dorsal-fin spinelet absent. First dorsal-fin ray not spinous, with moderately long filament in females and immature males and prolonged distal filament in mature males. Distal margin of dorsal fin straight other than for filament in presumed mature males, with first ray longest. Dorsal-fin origin located at approximately anterior 0.30-0.31 of SL and along vertical extending through distal one-fourth of adpressed pectoral fin. Tip of adpressed dorsal fin, excluding distal filament on first ray in presumed mature males, reaching nearly to vertical through tip of adpressed pelvic fin. Posterior most dorsal-fin ray without posterior, membranous attachment to body.

Caudal fin deeply-forked, symmetrical; tips of lobes pointed. Length of longest caudal-fin ray approximately two times length of middle fin rays.

Base of anal fin moderately long. Anal-fin origin located well posterior of middle of SL, and slightly anterior to vertical through middle of TL. Anal-fin margin straight in females and immature males, with posterior most unbranched anal-fin ray longest and subsequent rays becoming gradually shorter. Anal-fin margin slightly convex in mature males. Posterior most anal-fin ray with posterior, membranous attachment to body along basal one-third of fin.

Pelvic fin moderately long; distal margin nearly straight, with first ray longest. Pelvic-fin insertion located far anterior of middle of SL and along vertical through posterior portion of base of dorsal fin. Tip of adpressed pelvic fin extending slightly beyond middle of SL but falling short of anterior limit of vent. Medial most pelvic-fin ray with membranous attachment to body along basal two-thirds of its length.

Pectoral-fin length approximately two-thirds of HL. Pectoral-fin margin very gently convex, with first ray longest. First pectoral-fin ray not spinous, without distal filament in females and immature males and with moderately-developed filament in mature males.

Coloration in alcohol. Head and body with scattered, dark pigmentation dorsal of lateral line, pigmentation somewhat more concentrated dorsally; dark pigmentation particularly apparent in smaller specimens collected in río Sinú basin, in which dark pigmentation extends further ventrally on head. Scattered, dark, pigmentation present on caudal peduncle and base of caudal fin. Dark pigmentation on head extending ventrally to level of horizontal running through eye, with additional dark pigmentation encircling orbit. Tip of snout unpigmented. Ventral surface of head and abdomen lacking dark pigmentation.

Dorsal fin with scattered, dark pigmentation basally and with dark pigmentation extending over approximately basal one-half of first interradial membrane. Caudal fin with scattered, dark pigmentation throughout, but overall fin not distinctly dusky. Pectoral, pelvic, and anal fins without dark pigmentation.

Maxillary barbel with dark pigmentation along lateral margin. Mental barbels pale, or with at most few dark chromatophores.

Coloration in life. Fowler (1943: 245) reported that Cetopsis othonops has a golden-yellow coloration in life.

Sexual dimorphism. Presumed mature males of Cetopsis othonops have longer filaments on the first ray of the dorsal and pectoral fins than are present in examined females and immature males of the species (filaments obvious in male holotype of the species illustrated by Eigenmann, 1923, pl. 3, fig. 1). The smallest examined male of the specimens in which an elongate filaments was present was 89 mm SL. The presumed mature males of C. othonops also have a convex margin to the anal fin contrary to the straight margin on that fin that characterizes females and immature males of the species.

Distribution. Cetopsis othonops is known from the Caribbean Sea versant río Magdalena and río Sinú basins of northwestern Colombia ( Fig. 33 ).

Common Name. Colombia: “Baboso,” “Bobo,” “Ciego” ( Miles, 1947: 86; Dahl, 1971: 65).

Material examined. 44 specimens (40 specimens, 40-110 mm SL). Colombia. Antióquia: río Cauca basin, Caucasia, El Jardim (8°00’N, 75°12’W), MZUSP 42207, 1 (79). Chocó: río Sinú tributary, at Tierralta, quebrada emptying 300 m below Urrá Hydroelectric Station (9 o 31’N, 77 o 33’W), NRM 36777, 2 (47-58). Tierralta, outlet of dam of Urrá Hydroelectric Station into río Sinú (9 o 31’N, 77 o 33’W), NRM 39624, 1 (40). Cundinamarca: río Magdalena at Girardot (4°18’N, 74°49’W), CAS 64606, 6 (53-97, paratypes of Hemicetopsis othonops ). Girardot (4°18’N, 74°49’W), USNM 79213, 2 (55-78, paratypes of Hemicetopsis othonops ); USNM 167853, 4 (65-94, paratypes of Hemicetopsis othonops ); FMNH 56040, 1 (93, holotype of Hemicetopsis othonops , adult male).Apulo (now Rafael Reyes, 4°31’N, 74°36’W), CAS 64607, 18 (50-110, paratypes of Hemicetopsis othonops ); USNM 76972, 6 (53-93, paratypes of Hemicetopsis othonops , 89 mm specimen mature male; 1 specimen, 82 mm, cleared and stained); FMNH 77885, 1 (91, adult male). Valle: río Cauca, near Cali (3°27’N, 76°31’W), CAS 64608, 1 (75, paratype of Hemicetopsis othonops ).

Problematic Colombian localities: No specific locality, ANSP 83511, 1 (not measured as consequence of condition). El Quamo, upper río Magdalena basin (departamento unknown), USNM 100758, 1 (97).

Cetopsis parma Oliveira, Vari, & Ferraris, 2001 Figs. 33 , 35 , Tables 9 -15

Cetopsis parma Oliveira et al., 2001: 575 [type locality: Peru, Departamento de Ucayali, Provincia Coronel Portillo, río Tambo, río Ucayali basin, Pucallpa , Atalaya (8°23’S, 74°32’W)].– Vari & Ferraris, 2003: 257 [in check list, distribution].

Diagnosis. Cetopsis parma can be distinguished from all of its congeners by the combination of the presence of an eye, the conical teeth on the vomer and the dentary, the rounded posterior nares that is distinctly separated from the contralateral nares by a distance greater than the width of the posterior nares, the dark humeral spot, the pattern of a darkly pigmented pectoral and pelvic fins other than for thin, clear margins, and the possession of 23 to 25 total anal-fin rays.

Description. Body stout, slightly laterally compressed anteriorly, increasingly more so posteriorly. Body depth at dorsalfin origin approximately 0.24-0.27 of SL, and slightly less than HL. Lateral line on body complete, unbranched, and midlateral; extending from vertical through pectoral-fin base to hypural plate. Dorsal profile of body straight and slightly obliquelyslanted from nape to dorsal-fin origin, straight from dorsal-fin origin to caudal-fin base. Ventral profile of body convex along abdomen, approximately straight, but posterodorsally-slanted, along base of anal fin. Caudal-peduncle depth slightly greater than caudal-peduncle length in holotype and single non-type specimen, slightly less than caudal-peduncle length in both much larger paratype (MEPN 1034) and non-type specimen that originated in rio Negro Basin (MZUSP 79993). Caudal peduncle distinctly-compressed transversely.

Head in lateral view triangular with bluntly-rounded snout. Dorsal profile of head gently convex from tip of snout to nape. Ventral profile of head convex. Profile of snout broadly rounded from dorsal view. Profiles of postorbital portion of each side of head running in parallel. Dorsal surface of postorbital part of head with enlarged jaw musculature obvious externally.

Opercular membrane attaching to isthmus as far posteriorly as vertical through pectoral-fin insertion. Opercular opening moderate; extending ventral of horizontal extending through pectoral-fin insertion for distance equal to snout length and extending dorsal of pectoral-fin insertion for distance slightly less than snout length.

Eye situated on dorsolateral surface of head; located one to two orbital diameters dorsal of horizontal extending through pectoral-fin insertion; eye visible in dorsal view, but not ventral view, of head. Middle of orbit located slightly anterior to limit of anterior one-fourth of HL. Eye diameter approximately one-third of snout length in holotype (73 mm SL), slightly less than one-third of snout length in smaller non-type specimen (ANSP 178105, 119 mm SL), approximately one-fourth of snout length in large non-type specimen collected in rio Negro basin (MZUSP 79993, 180 mm SL), and apparently proportionally of that size in paratype (MEPN 1034, 170 mm SL), albeit impossible to measure accurately as consequence of thicker integumentary layer overlying eye in that individual. Interorbital width distinctly larger than distance from tip of snout to posterior margin of orbit and approximately 0.4-0.5 of HL. Anterior narial opening circular, surrounded by short, anteriorly- to anteromedially-directed, tubular rim of skin and located along horizontal extending through both tip of snout and maxillary-barbel origin. Distance between anterior nares ranging from nearly equal to length of snout to nearly equal to distance from tip of snout to posterior margin of orbit. Posterior narial opening nearly round or slightly ovoid but without obvious long axis; located on dorsal surface of head and along vertical through anterior margin of orbit. Anterior two-thirds of posterior narial opening bordered by flap of skin; flap only slightly higher anteriorly. Distance between posterior nares less than distance between anterior nares.

Mouth inferior, its width approximately one-half of HL. Margin of lower jaw nearly transverse, its posterior limit reaching to vertical through posterior margin of orbit. Premaxillary tooth patch elongate and crescentic, continuous across midline; anterior margin convex and posterior margin transverselyaligned and nearly straight. Premaxillary teeth relatively small, conical, and sharply-pointed, with teeth arranged in four or five, irregular rows (five rows present in paratype, largest examined specimen). Vomerine teeth arranged in one gentlycurved row continuous across midline. Vomerine teeth large and bluntly conical. Dentary dentition consisting of one row of teeth similar in size and shape to dentition present on vomer.

Maxillary barbel slender, length of barbel ranges from approximately equal to snout length to equal to distance from tip of snout to posterior margin of orbit; barbel origin located along vertical through anterior margin of orbit. Undamaged mental barbels approximately equal in size and length to maxillary barbel and to each other. Medial mental-barbel origin located along vertical through posterior margin of orbit. Origin of lateral mental barbel located slightly posterior to vertical through posterior margin of orbit. Tips of adpressed mental barbels falling short of margin of branchial membranes.

Dorsal fin relatively small overall with length of base approximately 0.33-0.35 of HL. Distal margin of dorsal fin straight, with first ray longest and equal in length to one-half of HL. Dorsal-fin spinelet absent. First dorsal-fin ray not spinous and with short, distal filament. Dorsal-fin origin located slightly posterior of one-third of SL and along vertical extending through distal one-fourth to one-half of adpressed pectoral fin. Tip of adpressed dorsal fin reaching to vertical through pelvic-fin insertion or slightly beyond that point. Posterior most dorsal-fin ray with variably-present, short, posterior, membranous attachment to body.

Caudal fin shallowly-forked and symmetrical; tips of lobes bluntly pointed. Length of longest caudal-fin rays approximately 1.5 times length of middle fin rays.

Base of anal fin relatively short, approximately 0.24-0.27 of SL. Anal-fin origin located well posterior to middle of SL and slightly posterior to middle of TL. Anal-fin margin straight. First branched anal-fin ray longest, with following rays becoming gradually shorter. Posterior most anal-fin ray without posterior, membranous attachment to body.

Pelvic fin short, with distal margin slightly convex and first branched ray longest. Pelvic-fin insertion located anterior to middle of SL and just posterior to vertical through posterior terminus of base of dorsal fin. Tip of adpressed pelvic fin extending beyond middle of SL, but falling short of anterior limit of vent. Medial most pelvic-fin ray with membranous attachment to body along its basal one-half.

Pectoral-fin length approximately one-half of HL. Pectoral-fin margin slightly sigmoid with first and middle fin rays longest. First pectoral-fin ray not spinous and with very short, distal filament.

Coloration in alcohol. Body slightly darker dorsally in holotype and paratype; distinctly darker overall in more recently preserved, non-type specimens. Sides of body darker as far ventrally as level of horizontal extending through pectoralfin base in holotype and paratype. Non-type specimens with irregular, mottled, dark pigmentation extending ventrally nearly to midventral line; dark pigmentation less concentrated ventral of horizontal extending through ventral limit of base of pectoral-fin insertion and in form of variablycoalesced spots slightly larger that orbital diameter. Abdomen in darkly pigmented specimens with only few scattered, dark spots. Postpelvic region of ventral portion of body in dark specimens heavily pigmented. Irregular, vertically-elongate, dark blotch present on lateral surface of body dorsal to basal one-half of pectoral fin in holotype and paratype; blotch not readily apparent in more recently-preserved, nontype specimens. Height of blotch approximately equal to length of pectoral fin in holotype, proportionally slightly higher in paratype.

Head somewhat darker dorsally in holotype and paratype, much more so in non-type specimens with dark pigmentation forming dense field extending ventrally to level of horizontal running through base of maxillary barbel. Non-type specimens with few ( ANSP 178105 ) to many ( MZUSP 79993 ) dark spots located ventral of horizontal extending through base of maxillary barbel, with dark pigmentation extending nearly to ventral midline, particularly along lower jaw. Snout margin dark in all specimens, more so in more recently-collected, nontype specimens. Ventral surface of head pale or with few scattered, dark spots .

Dorsal fin in holotype pale but irregularly covered with dark pigmentation in paratype. Non-type specimens with dark, parallel lines slanting across interradial membranes and with scattered, dark pigmentation at base of fin. Caudal fin pale in holotype but covered with scattered, eye-size, dark spots in other larger specimens. Non-type specimens with caudal fin as dark basally as caudal peduncle and with irregular fields of dark pigmentation extending onto each caudal-fin lobe; dark pigmentation becoming progressively less intense towards distal margin of fin. Anal fin dusky basally and pale distally in holotype and paratype, with irregular, dark, basal pigmentation in non-type specimens (particularly ANSP 178105 ) and with scattered, dark spots on distal portions of fin. Pectoral fin with interradial membranes darkly pigmented on dorsal surface except along fin margin; dark pigmentation more intense in non-type specimens. Pelvic fin of holotype and paratypes with scattered, dark pigmentation on dorsal surface of interradial membranes, except along fin margin. Non-type specimens with dark pigmentation on dorsal surface of interradial membranes except along fin margin .

Maxillary barbels dusky basally and pale distally. Mental barbels pale.

Sexual dimorphism. No evidence of sexual dimorphism comparable to that present in many species of the Cetopsinae was apparent among the four available specimens of Cetopsis parma .

Distribution. Cetopsis parma is only known from three definite localities in the western portions of the Amazon basin in Brazil, Ecuador, and Peru ( Fig. 33 ) and one lot from an indefinite locality (ANSP 178165). It is likely that the last of these lots was collected in the vicinity of Iquitos, Peru (M. Sabaj, ANSP; pers. commun., 2002), a locality somewhat down river from the holotype locality.

Remarks. In their original description of Cetopsis parma, Oliveira et al. (2001: 575) noted that they assigned that species to Cetopsis on the basis of the traditional definition of that genus, but cautioned that ongoing phylogenetic studies might reveal that its relationships lay elsewhere within the Cetopsinae . The potential intrageneric phylogenetic relationships of the species could not be critically evaluated as a consequence of a lack of osteological information resulting from the absence of material of C. parma that could be cleared and stained, nonetheless it falls within the expanded concept of the genus Cetopsis utilized herein (see “Systematic Overview” above).

Oliveira et al. (2001: 577, 578) inconsistently reported that the holotype of Cetopsis parma had alternatively 25 and 18 branched anal-fin rays. Examination of the type series reveals that the holotype has 20 branched anal-fin rays and the paratype 18 branched anal-fin rays. In the original description of Cetopsis parma, Oliveira et al. (2001: 578) noted the distinct difference in the number of branched anal-fin rays (18 and the erroneous count of 25) in the two then available specimens of the species. The additional, non-type specimens examined in this study ( ANSP 178105 ) has a count of 20 branched anal-fin rays that matches the value in the holotype .

Material examined. 4 specimens (3, 73-180 mm SL). Brazil. Amazonas: rio Tiquié, between settlements of Caruru and Boca de Sal, rio Uaupés basin (approximately 0°04’59"N, 68°24’59"W), MZUSP 79993, 1 (180). Ecuador. Pastaza: río Pastaza basin, near río Chicherota, in vicinity of Montalvo (2°04’S, 76°58’W), MEPN 1034, 1 (170, paratype of Cetopsis parma ). Peru. Ucayali: Provincia Coronel Portillo, río Tambo, Pucallpa, Atalaya (8°23’S, 74°32’W), MUSM 2266, 1 (73, holotype of Cetopsis parma ). Loreto: reportedly from region of Iquitos, ANSP 178105, 1 (119, purchased from fisherman for ornamental fishes in Iquitos (Belém)).

Figures

Fig. 33. Map of central and northern SouthAmerica showing geographic distribution of Cetopsis orinoco (1 = holotype locality of Pseudocetopsis plumbeus orinoco), Cetopsis othonops (2 = holotype locality of Hemicetopsis othonops), Cetopsis parma (3 = holotype locality), Cetopsis pearsoni (4 = holotype locality), and Cetopsis plumbea (5 = lectotype locality of Cetopsis plumbeus) (some symbols represent more that one locality and/or lot of specimens).

Fig. 34. Cetopsis othonops, paratype of Hemicetopsis othonops, USNM 167853, 85.7 mm SL; Colombia, Cundinamarca, Girardot (4°18’N, 74°49’W) (dark spots on side of body are postmortem damage).

Fig. 35. Cetopsis parma, holotype, MUSM 2266, 73 mm SL; Peru, Ucayali, Provincia Coronel Portillo, río Tambo, Pucallpa, Atalaya (8°23’S, 74°32’W).