Cetopsis gobioides Kner, 1857

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 : 168-171

Cetopsis gobioides Kner, 1857

Figs. 19 , 21 , 22 , Tables 9 -15

Cetopsis gobioides Kner, 1857: 407 , fig. 16 [(type locality: Brazil), Irisanga].– Günther, 1864: 199 [( Brazil), Irisanga, based on Kner, 1857].– Eigenmann & Eigenmann, 1888: 157 [in listing of Cetopsis species ]; 1890: 322 [in listing of Cetopsis species ]; 1891: 36 [in listing of Cetopsis species ].–[not Perugia, 1897: 23; Fowler, 1940b: 97].

Silurus pygmaeus .–Natterer, in Kner, 1857: 408 [nomen nudum].

Pseudocetopsis gobioides .– Bleeker, 1862a: 403 [assignment to, and designation as type species of, Pseudocetopsis ; brief redescription]; 1862b: 16 [brief redescription]; 1863: 111 [brief redescription].– Eigenmann, 1910: 398 [distribution; not (río) Marañon citation].– Miranda-Ribeiro, 1912: 378 [ Brazil, Irizanga; redescription]; 1918: 735 [ Brazil: Minas Gerais, rio Sapucahy, Pouso Alegre; Piracicaba].– Eigenmann & Allen, 1942: 149 [in listing of species, not citation of species in region from “both sides of Ecuadorean Andes to Central Brazil ”].– Bertoni, 1939: 51 [ Paraguay, Puerto Bertoni].– Gosline, 1945: 54 [distribution].– Fowler, 1954: 3, fig. 592 [literature compilation].– Ringuelet & Arámburu, 1961: 46 [ Argentina].– Alonso de Arámburu et al., 1962: 237 [ Argentina: Corrientes].– Ringuelet et al., 1967: 349, fig. 32a [ Argentina, Corrientes; not citation of species from Alto Amazonas].– Britski, 1972: 97 [ Brazil, state of São Paulo].– Ringuelet, 1975: 63 [ Argentina, río Paraná and río Paraguay].–Braga & Azpelicueta, 1986: 87 [ Argentina, Provincia de Misiones, río Paraná between Isla Sarandí and Pozo Heller].– Burgess, 1989: 291 [in listing of species].–Oliveros & Rossi, 1992: 77 [ Argentina, río Colastiné].– Bennemann et al., 1995: 11 [ Brazil, Paraná, rio Tibagi].–Gómez & Chebez, 1996: 61 [ Argentina, Misiones, río Paraná; common name].– Pavanelli & Caramaschi, 1997: 26 [ Brazil, Paraná, rio Paraná, Porto Rico].– Britski et al., 1999: 115 [ Brazil, Pantanal].– Agostinho & Júlio, 1999: 385 [ Brazil, upper rio Paraná].– Nakatani et al., 2001: 256, fig. [eggs, larvae, juveniles].–Evers & Seidel, 2002: 741 [listing].– López et al., 2003: 37 [ Argentina, río Paraná system; rare species].– Vari & Ferraris, 2003: 259 [in check list; synonymy, distribution, common name].–[Not Castello, 1969: 407; López et al., 1984: 85].

Cetopsis chalmersi Norman, 1926: 116 [type locality: ( Brazil) rio das Velhas, approximately 32 miles (=51.2 km) north of Belo Horizonte].– Fowler, 1954: 4 [ Brazil, rio São Francisco].– Gosline, 1945: 54 [rio das Velhas, probably E of state of São Paulo].– Burgess, 1989: 292 [rio das Velhas, probably E of state of São Paulo].–Evers & Seidel, 2002: 741 [listing].–Vari & Ferraris, 2003: 259 [as synonym of Pseudocetopsis gobioides Kner ].

Pseudocetopsis chalmersi .– Schultz, 1944: 252 [in key].– Fowler, 1954: 4 [ Brazil, rio São Francisco].– Travassos, 1960: 43 [ Brazil, rio São Francisco].– Britski et al., 1984: 31 [ Brazil, rio São Francisco].– Britski et al., 1986: 31 [ Brazil, rio São Francisco].–Sato & Godinho, 1999: 412 [ Brazil, rio São Francisco].

Pseudocetopsis sp. – Bertoletti et al., 1989: 10 [ Brazil, rio Grande do Sul, upper rio Uruguai].

Diagnosis. Cetopsis gobioides can be distinguished from all of its congeners by the combination of the presence of an eye, the conical teeth on the vomer and dentary, the rounded posterior nares that is distinctly separated from the contralateral nares by a distance greater than the width of the posterior nares, a mouth width that is approximately one-half of HL, the absence of a dark humeral spot, the absence of a posteriorly-rounded, variably-developed, bilobed patch of dark pigmentation at the base of the caudal fin, the absence of dark chromatophores on the anterior and lateral margins of the snout, the limitation of dark pigmentation on the dorsal fin to, at most, the basal regions of the middle portion of the fin in the form of spot with a semicircular margin, and the possession of 17 to 22 branched anal-fin rays, 22 to 27 total anal-fin rays, and 42 to 45 total vertebrae (see also under “Remarks” concerning the differences that discriminate C. gobioides from the very similar C. plumbea ).

Description. Body typically relatively stout, but shallower in some individuals, somewhat laterally compressed anteriorly and becoming increasingly compressed posteriorly. Body depth at dorsal-fin origin approximately 0.24-0.25 of SL, and approximately equal to HL. 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. Dorsal profile of body straight and obliquelyslanted from nape to dorsal-fin origin, straight from dorsal-fin origin to caudal-fin base. Ventral profile of body straight to slightly convex along abdomen, approximately straight, but posterodorsally slanted, along base of anal fin. Caudal-peduncle depth approximately equal to caudal-peduncle length.

Head in lateral view acutely triangular, with bluntlyrounded snout. Dorsal profile of head broadly rounded from tip of snout to vertical through anterior margin of eye, slightly convex from that point to nape. Ventral profile of head convex. Profile of snout in dorsal view broadly rounded. Width of postorbital portion of head gradually increasing posteriorly. Dorsal surface of postorbital part of head with enlarged jaw musculature externally obvious but not pronounced.

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

Eye situated on lateral surface of head; located slightly less than one orbital diameter dorsal of horizontal extending through pectoral-fin insertion; eye visible in dorsal view, but not in ventral view, of head. Middle of orbit at slightly less than anterior one-third of HL. Eye diameter approximately one-half of snout length. Interorbital width approximately equal to snout length. Anterior narial opening circular, surrounded by short, anteriorly-directed, tubular rim of skin. Opening of anterior nares located along horizontal extending through tip of snout and above horizontal extending through maxillarybarbel origin. Distance between anterior nares approximately equal to snout length. Posterior narial opening situated on dorsal surface of head, and along vertical through anterior margin of orbit; opening nearly rounded and without obvious long axis. Anterior two-thirds of narial opening bordered by approximately nearly uniformly-high flap of skin; flap only slightly higher anteriorly. Distance between contralateral posterior nares slightly less than distance between contralateral anterior nares.

Mouth inferior; its width approximately one-half of HL. Margin of lower jaw broadly rounded, its posterior limit reaching to vertical through middle of orbit. Premaxillary tooth patch elongate and crescentic, continuous across midline with anterior margin convex and posterior margin concave. Premaxillary teeth relatively small, conical, and sharply-pointed, with teeth in three or four, irregularly-arranged rows. Teeth near premaxillary symphysis larger than remaining teeth on premaxilla. Vomerine teeth large, bluntly conical, and in one to three irregularly-arranged, transversely-oriented, anteriorlyconvex rows; tooth rows continuous across midline. Number of tooth rows increasing ontogenetically. Posterior tooth row with irregularly-spaced teeth on each side of symphysis in smaller specimens. Dentary dentition consisting of three or four rows of teeth in region proximate to symphysis, with dentition progressively reduced to one tooth row along posterior one-half of jaw. Dentary teeth large and conical, with lateral teeth and largest medial teeth equivalent in size to largest teeth on premaxilla.

Maxillary barbel slender, its length approximately equal to distance from tip of snout to posterior margin of orbit; barbel origin located along vertical through anterior margin of orbit. 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 of vertical through posterior margin of orbit. Tips of adpressed mental barbels falling short of posterior margin of opercle.

Dorsal fin moderately large overall with length of base approximately 0.43-0.47 of HL. Longest dorsal-fin ray equal in length to distance from anterior margin of orbit to posterior margin of head. Dorsal-fin spinelet absent. First dorsal-fin ray not spinous; with short distal filament in females and moderate extension in single examined male with intact dorsal fin. Distal margin of dorsal fin straight, with first ray longest. Dorsal-fin origin located at approximately anterior one-third of SL and along vertical extending through middle of adpressed pectoral fin. Tip of adpressed dorsal fin, excluding distal filament, reaching to, or falling slightly short of, vertical through tip of adpressed pelvic fin. Posterior most dorsal-fin ray without posterior, membranous attachment to body.

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

Base of anal fin relatively long, slightly less than onethird of SL.Anal-fin origin located well posterior of middle of SL and slightly anterior of middle of TL.Anal-fin margin straight in females and immature males, with first branched anal-fin ray longest and length of subsequent rays becoming gradually shorter. Anal-fin margin convex in two examined mature males. Posterior most anal-fin ray without posterior, membranous attachment to body.

Pelvic fin short, with distal margin slightly to distinctly convex and first branched ray longest. Pelvic-fin insertion located anterior to middle of SL and along vertical through posterior portion of base of dorsal fin. Tip of adpressed pelvic fin extending beyond middle of SL, and falling short of vent in most examined samples, but reaching to vent in some smaller specimens from rio Tocantins basin. 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 convex with first ray longest. First pectoralfin ray not spinous and with short, distal filament in females and moderately long filament in single examined male with intact pectoral fin.

Coloration in alcohol. Body distinctly dark dorsally. Some specimens with marmoration along indistinct boundary between light and dark regions; boundary between those regions typically located dorsal to lateral line ( Fig. 22 ), but extending in some darkly pigmented specimens ventral of lateral line in region dorsal to posterior portion of base of anal fin and also along caudal peduncle. Some individuals with eye-size, dark blotches scattered across base pigment pattern on dorsolateral portion of body ( Fig. 21 ). Widely scattered, fine, dark pigmentation present to varying degrees on lateral surface of body. Ventral surface of abdomen pale. Postorbital portion of head distinctly dark dorsal to level of orbit. Snout distinctly lighter than postorbital region of head with at most few, dark chromatophores on dorsal surface of snout, but without such pigmentation on anterior and lateral surfaces of snout. Orbital region slightly darker than snout and lateral surface of head. Lateral and ventral surface of head pale, but not as dark as dorsal postorbital region of head.

Dorsal fin pale except for semicircular, dark spot present basally on middle rays of fin in some specimens. Pectoral and pelvic fins pale or with few, scattered spots of dark pigmentation. Anal fin pale with few, scattered spots of dark pigmentation basally in some specimens. Caudal fin with variably-developed, bilobed, dusky spot at base of fin and with scattered, dark pigmentation on dorsal lobe in some darkly pigmented specimens.

Barbels with scattered, dusky pigmentation basally and pale distally.

Coloration in life. Based on a transparency provided by F.A. Bockmann, LIRP, of a live male, now MNRJ 17008 , collected in Município de Perdtes , rio Grande basin, upper rio Paraná system, Minas Gerais, Brazil, and photographed in an aquarium. Overall dark coloration as described above, but with fins hyaline other than for dark pigmentation at base of dorsal fin. Silvery sheen overlying lateral surface of head and body, with silvery coloration more intense on anterior twothirds of body .

Sexual dimorphism. The presumed mature males of Cetopsis gobioides have the distal filaments on the first rays of the dorsal and pectoral fin more elongate than are those structures in females and immature males of that species. Mature males of C. gobioides also have a convex anal-fin margin contrary to the straight margin of the fin that is present in females and immature males of the species.

Distribution. Cetopsis gobioides is known from the upper portions of the rio São Francisco basin in Brazil, and the rio Paraná and río Uruguay basins in Argentina, Brazil, Paraguay, and Uruguay, the upper rio Paraguay in Brazil, and the coastal rio Juquiá of the state of São Paulo, Brazil ( Fig. 19 ).

Common Name. Brazil, rio São Francisco basin: “Candiruaçú” ( Britski et al., 1984: 31); Argentina, Misiones: “Bagrecito,” “Tiburoncito” (Gómez & Chebez, 1996: 61).

Remarks. Cetopsis gobioides is very similar to C. plumbea , a species endemic to the western portions of the Amazon basin, in its overall head and body form, overall coloration, and meristic values. The two species are distinguishable in the lack of the dark chromatophores on the anterior and lateral surfaces of the snout in C. gobioides , versus the presence of such dark pigmentation in that region of C. plumbea . The distribution of dark pigmentation on the dorsal fin differs between the two species with such pigmentation forming at most a dark semicircular spot at the base of the fin in C. gobioides , versus a more extensive distribution of dark pigmentation across the fin with the first fin ray and associated interradial membranes darkly pigmented in C. plumbeus . The two species also have much different, albeit slightly overlapping ranges in the numbers of total vertebrae (see Table 15), with a broader interspecific overlap but different modes for the two species in the number of branched anal-fin rays ( Table 10), total anal-fin rays ( Table 11), precaudal vertebrae ( Table 13), and caudal vertebrae ( Table 14).

The original description of Cetopsis gobioides by Kner (1857: 407) was based on two syntypes that we were unable to examine. Nonetheless, the data and illustration in the original description and more importantly the fact that there only one species of the Cetopsinae is known to occur in the upper rio Paraná basin, the type drainage of the species, makes it clear that the material identified herein as C. gobioides is conspecific with that species.

In the original description of Cetopsis chalmersi , based on specimens from the rio São Francisco basin of eastern Brazil, Norman (1926: 116) compared his new species to C. occidentalis (= Paracetopsis bleekeri in this study). Paracetopsis bleekeri , however, is limited to the Trans- Andean portion of Ecuador, a considerable distance to the west of the type locality of Cetopsis chalmersi . Norman did not elaborate on the restriction of the comparison of C. chalmersi to C. occidentalis (= Paracetopsis bleekeri ) to the exclusion of the geographically more proximate nominal species, C. gobioides , which was described by Kner (1857: 407) based on specimens collected at Irisanga, Brazil, a locality in the upper rio Paraná basin of Brazil. A comparison of numerous specimens of C. gobioides from the rio São Francisco and rio Paraná basins, including the type series of C. chalmersi , has failed to reveal any consistent differences between these two nominal forms (see also next paragraph). As a consequence Cetopsis chalmersi is herein considered to be a synonym of C. gobioides .

Although we were unable to identify any features useful in unequivocally separating populations of C. gobioides from the rio São Francisco and rio Paraná basin, there does occur a pronounced degree of intraspecific ontogenetic variation in the degree of development of the oral dentition among the population samples of what is herein considered C. gobioides . This variation does not, however, demonstrate any geographic pattern that supports the continued recognition of two species, but this question should be revisited once adequate population samples of the species from the rio São Francisco basin become available.

Norman (1926: 116) based his original description of Cetopsis chalmersi on three specimens collected by Chalmers. One of these ( BMNH 1925.10.1.4) was examined in the course of this study and the other two syntypes ( BMNH 1925.1.12.2-3) are still extant. We herein designate the examined syntype ( BMNH 1925.10.1.4) as the lectotype of the species. In addition we examined a fourth specimen of the species ( BMNH 1925.12.31.70) that appears to have collected at the same time and location as the type specimens but which apparently is not part of the type series .

Pseudocetopsis gobioides was cited from the río Bermejo in the Province of Salta, northwestern Argentina by Castello (1969: 407) and López et al. (1984: 85). Although Cetopsis gobioides is present in Argentina in the río Paraná basin of the northeastern portions of that country, we have not examined any specimens of that species from the northwestern region of Argentina. The only member of the Cetopsinae known to occur to the río Bermejo drainage is C. starnesi and the report of Pseudocetopsis gobioides from the río Bermejo is, thus, tentatively considered to be based on specimens of Cetopsis starnesi .

Material examined. 65 specimens (61, 28-110 mm SL). Argentina. Misiones: río Paraná, Puerto Iguazu (25°34’S, 54°34’W), MHNG 2389.14 , 1 (98) . Brazil. Mato Grosso: Município de Cuiabá, Chapada dos Guimarães, riacho tributary to rio Carlos Augusto , MZUSP 35217 , 3 (60-91) . Rio Araguari, Salto de Nova Ponte, Município de Nova Ponte , MZUSP 38564 , 3 (2, 65-84; 1 specimen, 71 mm, cleared and stained) . Rio Araguari, Salto Ponte, Nova Ponte (approximately 18°21’S, 48°40’W), MZUSP 38825 , 1 (96) . Rio Acorizal , at bridge between Acorizal and Baus (15°12’10"S, 56°22’5"W), MNRJ 11305 , 1 (47) . Rio Paraná, Ilha Solteira , MZUSP 24455 , 8 (7, 28-55, 1 specimen, 41 mm, cleared and stained) . Córrego Água Lima, tributary of rio Abaeté, along road from Quirinos to Major Porto , MZUSP 39599 , 1 (98; specimen cleared and stained) ; MZUSP 40217 , 2 (1 specimen, 108 mm, cleared and stained) . Riacho tributary to rio Carlos Augusto, on road of Fazenda da Cascata , Chapada dos Guimarães, MZUSP 35217 , 3 (59.5-91) . Mato Grosso do Sul: Alcinópolis, “riacho” near Córrego do Engano (18°12’5"S, 52°22’43"W), MZUSP 59355 , 1 (31) . Município de Jupiá, rio Paraná, in front of Jupiá (20°47’S, 51°39’W), MZUSP 22804 , 1 (109) . Pouso Alegre, rio Sapucai (approximately 20°08’S, 48°27’W), MZUSP 2313 , 1 (89) . Minas Gerais: rio das Velhas, approximately 20 miles (= 32 km) N of Bello Horizonte (=Belo Horizonte), BMNH 1925.10 . 1.4, 1 (108, lectotype of Cetopsis chalmersi , designated herein); BMNH 1925.12 . 31.70, 1 (105). Fortuna de Minas, rio Paraopeba , Fazenda Chaparral, MZUSP 51539 , 1 (50) . Rio Cabo Verde, Alfenas (approximately 21°15’S, 45°47’W), MZUSP 22762 , 3 (2, 97-106, 1 specimen, 106 mm, cleared and stained) . Gi-Mirim (=Poço Fundo), tributary of rio Machado (21°48’S, 45°58’W), MNRJ 944 , 2 (72-96) . Rio Grande do Sul: Município de Maximiliano de Almeida, rio Forquilha along road between Maximiliano de Almeida and Machadinho, rio Uruguai basin (27°31’S, 51°49’W), MCP 13403, 1 (93) . Santa Catarina: rio Uruguai, at Itá (27°16’S, 51°19’W), MCP 13386, 1 (92; specimen cleared and stained) . São Paulo: Município de Itú, Itú , rio Tietê , Fazenda Pau D’Olho (23°16’S, 47°19’W), MZUSP 23214 , 1 (74) ; MZUSP 22749 , 1 (88) ; MZUSP 22464 , 1 (74) . Piracicaba (22°03’S, 44°46’W), MZUSP 3095 , 2 (87.5-92.5) ; MZUSP 2312 , 2 (65-70) . Lagoas along margin of rio Corumbataí (22°14’S, 47°38’W), MZUSP 22760 , 1 (77) . Rio Mogi-Guaçu, Emas (21°56’S, 47°22’W), MZUSP 22945 , 6 (50-92; 1 specimen, 77 mm, cleared and stained) . Rio Paraná, Ilha Solteira , MZUSP 23091 , 8 (40- 79; 1 specimen, 61 mm, cleared and stained) . Rio Tietê, Barueri (23°31’S, 46°53’W), MZUSP 3209 , 1 (80) . Rio Turuo, km 27 along highway from São José do rio Preto to Olimpia, MZUSP 35420 , 1 (70) . Rio Paraná, Porto Castillo, 170 km below Porto Epitacio (22°15’S, 52°31’W), MZUSP 38760 , 1 (98) . Marginal lagoon of rio Juquiá , Registro, above fish farm of João Paca, MZUSP 36763 , 1 (110) . Rio Turro, tributary of rio Grande near São José do rio Preto , MZUSP 38808 , 2 (1 specimen, 85 mm, cleared and stained) . Paraguay, upper río Paraná basin, Foz de Iguazu (25°33’S, 54°35’W), ITAIPU 57 , 1 (103) . Uruguay. Near junction of río Quequay and río Uruguay (32°09’S, 58°09’W), BMNH 1947.11 .20.1, 1 (45).

Figures

Fig. 19. Map of central and northern SouthAmerica showing geographic distribution of Cetopsis coecutiens (type locality inexact = Brazil), Cetopsis fimbriata (1 = holotype locality), and Cetopsis gobioides (2 = lectotype locality of Cetopsis chalmersi) (some symbols represent more that one locality and/or lot of specimens).

Fig. 21. Cetopsis gobioides, MZUSP 51539, 50 mm SL; Brazil, Minas Gerais, Fortuna de Minas, rio Paraopeba, Fazenda Chaparral.

Fig. 22. Cetopsis gobioides, ITAIPU 57, 103 mm SL; Paraguay, upper río Paraná basin, Foz de Iguazu (25°33’S, 54°35’W).