Paracetopsis bleekeri Bleeker, 1862

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 : 224-228

Paracetopsis bleekeri Bleeker, 1862

Figs. 55-56 , Tables 23-29

Paracetopsis bleekeri Bleeker, 1862b: 16 [type locality unstated; herein interpreted as río Guayas or río Santa Rosa basins, southwestern Ecuador; herein restricted to Guayaquil by neotype designation].– Schultz, 1944: 251 [as valid].–Vari & Ferraris, 2003: 258 [in check list; synonymy, distribution, common names].–[not Chang & Ortega, 1995: 4].

Cetopsis ventralis Gill, 1870: 95 [type locality: Maranon or Upper Amazon, and Napo Rivers; herein interpreted as río Guayas or río Santa Rosa basins, southwestern Ecuador, see under “Remarks” concerning type locality].– Eigenmann & Eigenmann, 1888: 157 [listing]; 1890: 322 [listing]; 1891: 36 [listing].– Boulenger, 1898b: 9 [comparison with Cetopsis macroteronema ].– Fowler, 1941: 472 [ Peru, río Marañon].–1945: 70 [ Peru, río Marañon].– Ferraris and Vari, 1992: 16 [holotype repository].–Vari and Ferraris, 2003: 258 [as synonym of Paracetopsis bleekeri Bleeker ].

Cetopsis occidentalis Steindachner, 1880: 100 [48 of offprint], pl. 8, fig. 2 [type locality: ( Ecuador) Guayaquil].– Eigenmann and Eigenmann, 1888: 157 [listing].–1890: 322 [listing]; 1891: 36 [listing].–Eigenmann and Bean, 1907: 665 [as type species of Paracetopsis ].– Schultz, 1944: 251 [treated as synonym of Paracetopsis bleekeri ].–Vari and Ferraris, 2003: 258 [as synonym of Paracetopsis bleekeri Bleeker ].

Cetopsis (Pseudocetopsis) occidentalis .– Steindachner, 1902: 136 [ Ecuador, Guayaquil, río de Bodegas].

Paracetopsis occidentalis .–Eigenmann & Bean, 1907: 665 [designation of species as type species of Paracetopsis ].– Eigenmann, 1920a: 13 [Guayaquil basin].

Pseudocetopsis ventralis .– Eigenmann, 1910: 398 [erroneously cited as present in Maranon].–Eigenmann & Allen, 1942: 149 [“known only from Orton’s specimens”].– Schultz, 1944: 252 [in key to species of Pseudocetopsis ].– Gosline, 1945: 55 [listing].– Fowler, 1954: 5 [erroneously cited as present in Alto Amazonas, Peru].– Burgess, 1989: 292 [erroneously cited as present in (río) Maranon and upper (río) Napo].–Evers & Seidel, 2002: 741 [listing].–[Not Ortega & Vari, 1986: 15].

Cetopsogiton occidentalis .– Eigenmann, 1910: 398 [( Ecuador) Guayaquil].– Eigenmann, 1921: 514 [( Ecuador) Guayas]; 1923: 56 [Guayaquil market].– Gosline, 1945: 55 [listing].– Ovchynnyk, 1967: 35 [ Ecuador: río Daule, Province Guayas; río Vinces, near Vinces].–1968: 255 [ Ecuador: río Daule, Province Guayas; río Vinces, near Vinces].– Burgess, 1989: 292 [rivers near Guayaquil ( Ecuador)].

Cetopsigoton occidentalis .– Barriga, 1991: 56 [generic name misspelled; Ecuador, Piso Tropical y Subtropical Oriental].

Diagnosis. Paracetopsis bleekeri is distinguished from all other species in the Cetopsinae with the exception of P. atahualpa and P. esmeraldas by the combination of the possession of a vomerine tooth patch with more than one row of teeth and a medial separation of the contralateral components of the patch. Paracetopsis bleekeri differs from P. atahualpa in the relative length of the pelvic fin (tip of fin falling short of the vent versus completely overlapping the vent, respectively), in the pigmentation on the operculum (lacking an opercular pigmentation patch versus having a distinct patch of dark opercular pigmentation, respectively), the overall coloration of the head and body (light versus dark, respectively), the extent of the medial gap in the vomerine tooth patch (with a distinct medial gap between the contralateral components of the tooth patch equivalent to the width of three or four vomerine teeth versus with a limited medial gap equivalent to the width of one or two vomerine teeth, respectively), and to a degree in the number of total vertebrae (50 in all specimens versus 47 to 50 with 49 most common and 50 in only 1 of 21 radiographed specimens, respectively; Table 29). Paracetopsis bleekeri differs from P. esmeraldas in the pigmentation on the operculum (lacking an opercular pigmentation patch versus having a distinct patch of dark opercular pigmentation, respectively), in the extent of the medial gap in the vomerine tooth patch (separated by a distinct medial gap between the contralateral components of the tooth patch equivalent to the width of three or four vomerine teeth versus a limited gap equivalent to the width of one or two vomerine teeth, respectively), and in the mode and to a degree in the range of the caudal vertebrae (34 to 38 with 36 most common versus 37 to 40 with 38 most common, respectively; Table 28).

Description. Body relatively elongate, slightly-compressed laterally anteriorly and becoming progressively distinctlycompressed posteriorly. Body depth at dorsal-fin origin approximately 0.22-0.24 of SL, and approximately equal to distance from anterior margin of orbit to posterior margin of opercle. Lateral line on body complete, unbranched, and midlateral; extending from vertical through pectoral-fin base to hypural plate with short, dorsal bend on hypural plate. Portion of lateral line on caudal peduncle with few, short, ventrally-directed branches. Dorsal profile of body straight from nape to dorsal-fin origin and slightly convex from dorsal-fin origin to caudal-fin base. Distinct notch in dorsal profile of body obvious from lateral view between posterodorsal margin of externally apparent enlarged jaw musculature and anterodorsal margin of epaxial musculature. Ventral profile of body convex along abdomen, approximately straight, but posterodorsally-slanted, along base of anal fin. Caudal-peduncle depth approximately equal to caudal-peduncle length.

Head in profile acutely triangular overall with bluntlyrounded snout. Dorsal profile of head slightly convex from tip of snout to vertical through anterior margin of orbit and straight from that point to nape. Ventral profile of head slightly convex. Margin of snout from dorsal view obtusely triangular overall and rounded anteriorly. Postorbital margins of head running nearly in parallel from dorsal view. Enlarged jaw musculature slightly evident externally on dorsal surface of postorbital portion of head.

Opercular membrane attaching to isthmus only anterior of vertical through pectoral-fin insertion. Opercular opening large; extending ventral of pectoral-fin insertion by distance equal to distance from tip of snout to posterior margin of orbit and extending dorsal of pectoral-fin insertion by distance equal to snout length.

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-fourth of HL. Eye diameter approximately equal to one-half of snout length. Interorbital width approximately equal to distance from tip of snout to posterior margin of orbit; narial openings relatively small compared to that in other species of the Cetopsinae . 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 distance from tip of snout to middle of eye. Posterior narial opening located on dorsal surface of head, situated along vertical through anterior margin of orbit; narial opening approximately round and nearly completely surrounded by flap of skin, with anterior portion highest and narrow gap posteriorly between margins of flap.

Mouth inferior; its width approximately one-half of HL. Margin of lower jaw gently rounded, its posterior limit reaching to vertical situated slightly posterior of posterior margin of orbit. 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, and sharply-pointed, with teeth arranged in four rows; teeth arranged in distinct rows medially but irregularly-arranged laterally. Vomerine teeth arranged in distinct contralateral tooth patches to each side of midline. Tooth patches obliquelyaligned and separated medially by distance equivalent to width of three or four vomerine teeth. Vomerine teeth similar in form and size to those on premaxilla, with teeth in each patch arranged in one row medially and two rows laterally in smaller specimens and two complete rows with shorter third row laterally in larger individuals. Dentary teeth comparable in size and shape to premaxillary teeth. Dentary dentition consisting of four tooth rows medially that taper to two rows laterally.

Maxillary barbel slender, its length approximately equal to distance from tip of snout to posterior margin of orbit. Maxillary-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 posterior of vertical through middle of adpressed medial mental barbel. Tips of adpressed mental barbels falling short of base of branchiostegal rays.

Dorsal fin moderately large overall with length of dorsalfin base approximately 0.30-0.35 of HL. Longest dorsal-fin ray equal in length to two-thirds of HL. Dorsal-fin spinelet absent. First dorsal-fin ray not spinous and lacking short, distal filament in immature males and apparent females, but with short filament present in single, apparently mature, male. Distal margin of dorsal fin straight, with first ray longest. Dorsalfin origin located at approximately anterior 0.40 of SL and along vertical extending through distal one-fourth of adpressed pectoral fin. Tip of adpressed dorsal fin reaching nearly to vertical through tip of adpressed pelvic fin. Posterior most dorsal-fin ray without posterior, membranous attachment to body.

Caudal fin moderately-forked, symmetrical; tips of lobes slightly rounded. Length of longest caudal-fin ray approximately one and three-fourths times length of middle fin rays.

Base of anal fin comparatively long. Anal-fin origin located distinctly posterior of middle of SL, and approximately along 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 single apparently mature male. Posterior most anal-fin ray without posterior, membranous attachment to body.

Pelvic fin moderately long; distal margin nearly straight, with first ray longest. Pelvic-fin insertion located anterior to middle of SL and along vertical through posterior terminus of base of dorsal fin. Tip of adpressed pelvic fin extending beyond middle of SL and just reaching 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 one-half of HL. Pectoral-fin margin very gently convex, with first ray longest. First pectoral-fin ray not spinous and without distal filament in immature males and apparent females, but with short, distal filament present in single, apparently mature, male.

Coloration in alcohol. Available specimens all faded and without any dark pigmentation obvious. Following description based on original illustration of Cetopsis occidentalis (herein considered a synonym of Paracetopsis bleekeri ; see “Remarks”) by Steindachner (1880, pl. 8, fig. 2). Head and body with scattered, dark pigmentation dorsally and laterally with underside of snout, abdomen, and ventral portions of region above anal-fin base paler.

Dorsal fin with basal dusky pigmentation and irregular dark spots distally. Anal fin dusky with distal margin pale.

Barbels apparently pale.

Sexual dimorphism. The single examined apparently mature male of Paracetopsis bleekeri has distinct, but short, distal filaments on first rays of the dorsal and pectoral fins contrary to conspecific females and immature males that lack those structures. Mature males also have a slightly convex anal-fin margin contrary to the straight margin to the fin in conspecific females and immature males.

Distribution. Paracetopsis bleekeri is only known from the Pacific Ocean versant río Guayas and río Santa Rosa basins of southwestern Ecuador ( Fig. 55 ).

Remarks. Paracetopsis bleekeri was originally described by Bleeker (1862b: 16) based on an unstated number of specimens and without an indicated collecting locality. The type material of Paracetopsis bleeker i was examined by Bleeker in the “Mus. Paris” [=MNHN] and in his description of that species, Bleeker apparently utilized a manuscript name or jar label name originally proposed by Guichenot to whom he credited the species. Searches through the MNHN collections during this study failed to reveal the existence of any specimens that may have been the basis of the original description of P. bleekeri . The MNHN registers also do not document that any relevant specimens were ever catalogued into the holdings of that institution. The name Paracetopsis bleekeri was not used by subsequent authors for nearly eight decades until Schultz (1944: 251) recognized that this nominal species was the oldest available name for the species known until that time as Cetopsogiton occidentalis (Steindachner) .

Notwithstanding the lack of a type series of Paracetopsis bleekeri , the original description of the species by Bleeker (1862b: 16) noted that the vomer in that species had a tooth patch with more than one row of teeth and with the tooth patch interrupted medially. This combination of features is only known to occur in three species within the Cetopsinae : P. bleekeri , a species that is only known to occur in tributaries of the Gulf of Guayaquil in southwestern Ecuador; P. atahualpa , a species endemic to the río Tumbes basin of northwestern Peru and upper portions of the río Zarumilla in southwestern Ecuador; and P. esmeraldas a species that is apparently endemic to the Pacific Ocean versant rivers of northwestern Ecuador. The two latter species are described as new in this paper.

Examination of the three species of Paracetopsis demonstrated that although the gap between the contralateral components of the vomerine tooth patch that was cited by Bleeker (1862b) in the description of P. bleekeri is general for all species in the genus, such a discontinuity in the tooth patch is, however, only readily apparent in the material herein considered to be P. bleekeri . It seems unlikely that the much smaller gap between the contralateral components of the vomerine tooth patch that is characteristic of P. atahualpa and P. esmeraldas would have been obvious to Bleeker fourteen decades ago in light of the limitations of the microscopes of the period.

Above and beyond such a supposition involving the sophistication of the optical equipment available to Bleeker, there is also a significantly greater likelihood that the specimen available to Bleeker originated in the río Guayas basin, the home of the form herein considered to be P. bleekeri . The río Guayas is the largest river basin on the Pacific Ocean versant of South America and has long had an active major seaport (Guayaquil) at is mouth. As a consequence, the río Guayas basin has been the source of specimens for museum collections for two centuries. The río Tumbes and río Zarumilla systems that are inhabited by P. atahualpa are, in contrast, much smaller and less accessible river systems than is the río Guayas, and both remain poorly sampled ichthyologically until the present time. Similarly the Pacific Ocean versant rivers of northwestern Ecuador that are inhabited by P. esmeraldas remained effectively terra incognita ichthyologically until the latter part of the nineteenth century ( Orcés, 1967: 137), a considerable period after the original description of P. bleekeri . These considerations along with the details of vomerine dentition discussed above lead us to equate P. bleekeri with the populations of the Cetopsinae from the río Guayas basin that have been more typically identified as Cetopsogiton occidentalis .

Stabilization of the nomenclature of Paracetopsis bleekeri is necessary in light of the existence of two similar species in drainage systems located close to the range of P. bleekeri in the río Guayas and río Santa Rosa basins ( P. atahualpa , in the río Tumbes and río Zarumilla basins; and P. esmeraldas , in various river systems of northwestern Ecuador). We herein designate the holotype of Cetopsis occidentalis Steindachner (1880) , NMW 47377, a species herein considered a junior synonym of Paracetopsis bleekeri (see discussion in following paragraph) as the neotype for Paracetopsis bleekeri .

Cetopsis occidentalis was described by Steindachner (1880: 99, pl. 8. figs. 2, 2a) based on a single female that was collected near Guayaquil, Ecuador, apparently in 1880 (H. Wellendorf, NMW; pers. commun., 2003). Although we have been unable to examine the holotype of C. occidentalis (NMW 47377), the detailed original description of the species and the accompanying figures, in conjunction with the fact that only a single species of Paracetopsis , and indeed the Cetopsinae , was found to be present within the series of specimens examined in this study that originated in the río Guayas, make it clear that C. occidentalis is equivalent to the form that is identified as Paracetopsis bleekeri herein.

Cetopsis ventralis was originally described in a publication ( Gill, 1870: 95) that was based on a collection of fishes said, according to the title of that contribution, to have originated from the “Maranon or Upper Amazon, and Napo Rivers.” In light of the title of Gill’s publication, many subsequent authors assumed that all of the material cited in that report originated in the Amazon basin (see synonymy of Cetopsis ventralis at beginning of this species account). The introductory remarks to Gill’s publication (1870: 92) noted, however, that the material was collected by Prof. Orton in an “expedition to the Andes of Ecquador [= Ecuador] and Peru and thence across the continent of South America.” This geographically more encompassing description of the route of the collecting party raises the possibility that portions of the fish fauna of some Trans-Andean river systems may have been sampled during the early phases of the Orton expedition.

Our examination of the holotype of Cetopsis ventralis demonstrated that it cannot be differentiated from what is herein considered to be Paracetopsis bleekeri . Given that the known distribution of P. bleekeri is restricted to the Pacific Ocean slopes of southwestern Ecuador, the conspecificity of the two nominal species indicates that the holotype of Cetopsis ventralis must have originated from the western slopes of the Andean Cordillera rather than from within the Amazon basin as was assumed to be the case by prior authors. A comparable situation occurs with the indefinite type locality of “ Peru ” reported for Curimatus brevipes that was described by Eigenmann & Ogle (1907: 3) on the basis of a specimen also collected by Orton, the collector of the holotype of Cetopsis ventralis . This inexact locality was subsequently interpreted by various authors (e.g., Eigenmann & Allen, 1942: 299) to indicate that the holotype of Curimatus brevipes originated in the Amazon basin. Analysis demonstrated ( Vari, 1989b: 19) that C. brevipes is rather conspecific with Pseudocurimata troschelii (Günther) , a species endemic to the rivers of the Pacific versant of northwestern Peru and southeastern Ecuador, a distribution paralleling, in part, that of Paracetopsis bleekeri . On the basis of the evidence of the conspecificity of the holotype of Cetopsis ventralis with Paracetopsis bleekeri and in light of the non-specific locality information associated with the holotype, we herein restrict the type locality of Cetopsis ventralis to the río Guayas or río Santa Rosa basins of southwestern Ecuador.

Material examined. 45 specimens (94-246 mm SL). Ecuador. Guayas: Guayaquil market, CAS 77029, 7 (145-216); CAS 77030, 2 (172-183); CAS-SU 83331 , 1 (242); USNM 76971 , 5 (128-203, 1 specimen cleared and stained); MUSM 6680 , 1 (180). 3 km out of Santo Domingo on road to Esmeraldas, FMNH 96446, 1 (123). El Oro: Gualtaco , río Santa Rosa , near mouth (3°26’S, 80°11’W), USNM 163899 , 1 (205). Guayas: Guayaquil (2°10’S, 79°54’W), AMNH 5353 SW, 1; CAS-SU 22751 , 1 (204); CAS-SU 69689 , 1 (164); CAS-SU 9303 , 1 (168); MCZ 30965, 2 (183-183); USNM 53519 , 1 (128); ZMH 12207, 1 (177); ZMH 12208, 5 (151-193); ZMH 12209, 1 (226), ZMH 12210, 1 (230); ZMH 12211, 1 (158). río Guayas basin, tributary of río Baba , Puerto Ila (0°31"45’S, 79°21"03’W), MEPN 1719 , 1 (196). Unspecific locality, MNHN B-0279, 2 (183-246) .

Questionable locality: “Maranon or Upper Amazon, and Napo Rivers” (= río Marañon and río Napo; stated locality incorrect, specimen probably originated in the río Guayas basin of western Ecuador, see “ Remarks ” above), USNM 8307 , 1 (113; holotype of Cetopsis ventralis ) .

No locality information: USNM 304883, 5; MZUSP uncataloged, 1; AMNH 97234, 1 (94, specimen cleared and stained).

Figures

Fig. 55. Map of northwestern South America showing geographic distribution of Paracetopsis atahualpa (1 = holotype locality), Paracetopsis bleekeri (2 = neotype locality; also holotype locality for Cetopsis occidentalis), and Paracetopsis esmeraldas (3 = holotype locality) (some symbols represent more that one locality and/or lot of specimens).

Fig. 56. Paracetopsis bleekeri, ZMH 12211, 158 mm SL; Ecuador, Guayas, Guayaquil (2°10’S, 79°54’W).