Cetopsis fimbriata, Vari & Ferraris Jr & de Pinna, 2005

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 : 165-168

publication ID

https://doi.org/ 10.1590/S1679-62252005000200001

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scientific name

Cetopsis fimbriata

new species

Cetopsis fimbriata , new species

Figs. 19 View Fig , 20 View Fig , Tables 9 -15

Pseudocetopsis amphiloxa [not of Eigenmann, 1914].–de Pinna & Vari, 1995: 2, fig. 2 [illustrated].

Diagnosis. Cetopsis fimbriata can be distinguished from all of its congeners by the combination of the presence of an eye, a 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, the presence of a dark, distal, margin along the anal fin, the dark distal margin of the pectoral fin, 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, and the presence of 46 to 48 total vertebrae, 25 to 28 total anal-fin rays, and 20 to 22 branched anal-fin rays.

Description. Body somewhat deep, slightly-compressed laterally anteriorly, becoming increasingly compressed posteriorly. Body depth at dorsal-fin origin equal to HL and slightly less than 0.25 of SL. Lateral line on body complete, unbranched, and midlateral; extending from vertical through pectoral-fin base onto hypural plate and terminating prior to posterior margin of hypural plate. Dorsal profile of body slightly convex and distinctly inclined from nape to dorsalfin origin; nearly straight from dorsal-fin origin to caudal-fin base. Ventral profile of body slightly convex along abdomen, approximately straight, but posterodorsally slanted along base of anal fin. Caudal-peduncle depth slightly less than caudal-peduncle length.

Head triangular in lateral view and broadly rounded anteriorly. Dorsal profile of head convex from tip of snout to vertical through posterior nares and slightly convex from that point to posterior of nape. Ventral profile of head gently convex. Profile of snout in dorsal view obtusely triangular overall and rounded at tip. Portion of head posterior of nares with lateral profiles running nearly in parallel from dorsal view. Dorsal surface of posterior portion of head without externally apparent enlarged jaw musculature.

Opercular membrane attaching to isthmus until point slightly anterior of vertical through pectoral-fin insertion. Opercular opening relatively wide; extending ventral of pectoral-fin insertion by distance approximately equal to distance from tip of snout to middle of eye and extending dorsal of pectoral-fin insertion by distance approximately 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 slightly less than anterior one-fourth of HL. Eye diameter approximately two-thirds of snout length. Interorbital width approximately equal to distance from tip of snout to posterior margin of orbit. Anterior narial opening circular, surrounded by short, anteriorly-directed, tubular rim of skin. Opening of anterior nares located at horizontal extending through both tip of snout and through maxillary-barbel origin. Distance between anterior nares approximately equal to distance between anterior and posterior nares, and approximately equal to snout length. Posterior narial opening large and located near dorsal profile of head dorsal to anterior onehalf of orbit; opening ovoid, with long axis of aperture aligned perpendicular to long axis of body, and with anterior two-thirds of opening bordered by flap of skin. Distance between posterior nares slightly less than distance between anterior nares.

Mouth inferior; its width approximately one-half of HL. Margin of lower jaw broadly rounded, its posterior extent reaching slightly beyond vertical through middle of eye. Premaxillary tooth patch elongate, continuous across midline; anterior margin convex, posterior margin concave and running in parallel to anterior margin. Premaxillary teeth of moderate size, conical, and sharply-pointed, with teeth arranged in three rows along entire tooth patch. Teeth of anterior premaxillary tooth row slightly smaller than those of other two tooth rows. Vomerine teeth arranged in continuous, anteriorly-convex row. Vomerine teeth bluntly conical and distinctly larger than premaxillary teeth. Dentary dentition consisting of two series of teeth. Primary dentary tooth row consisting of uniformly-sized, conical teeth approximately of same size as those on vomer. Second row of dentary teeth less extensive than anterior row and consisting of 5 or 6 shorter teeth extending laterally from each side of symphysis.

Maxillary barbel slender, its length distinctly greater than distance from tip of snout to posterior margin of orbit and nearly equal to one-half of HL; barbel origin located near vertical through anterior margin of orbit. Mental barbels approximately equal in size and length and slightly shorter than maxillary barbel. Medial mental-barbel origin located along vertical through posterior margin of orbit. Lateral mental-barbel origin situated slightly posterior of vertical through posterior margin of orbit. Tips of adpressed mental barbels reaching to, or beyond, posterior margin of opercle.

Dorsal fin moderately large overall with length of dorsalfin base approximately 0.44-0.49 of HL and slightly longer than distance from tip of snout to posterior margin of orbit. Longest dorsal-fin ray, excluding distal filament, equal to threequarters of HL. Dorsal-fin spinelet absent. First dorsal-fin ray not spinous, with short distal filament in females and immature males and with long distal filament in mature males. Distal margin of dorsal fin distinctly concave, with first ray longest. Dorsal-fin origin located slightly short of one-third of SL and along vertical through middle of adpressed pectoral fin. Tip of adpressed dorsal fin, excluding distal filament, reaching to vertical through anterior one-quarter of base of anal 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 slightly more than 1.5 times length of middle fin rays.

Base of anal fin moderate, approximately one-third of SL. Anal-fin origin located distinctly posterior of middle of SL. Anal-fin margin straight in immature males and presumed females, with posterior most unbranched anal-fin ray longest and subsequent rays gradually becoming shorter. Anal-fin margin in mature males convex, with rays of central portion of anal fin slightly longer than rays situated more both anteriorly and posteriorly. Posterior most anal-fin ray with posterior, membranous attachment to body for basal one-fifth of its length.

Pelvic fin moderate, its distal margin slightly convex, with second branched ray longest. Tip of adpressed pelvic fin barely reaching middle of SL and falling slightly short of vent. Insertion of pelvic fin located along vertical through posterior terminus of base of dorsal fin. Medial most pelvic-fin ray with membranous attachment to body for basal two-thirds of its length.

Pectoral-fin length, excluding distal filament, approximately three-quarters of HL. Posterior margin of branched pectoralfin rays slightly concave, with first ray distinctly longest. First pectoral-fin ray not spinous; with only slight, fleshy, distal extension in females and immature males, but with distinct distal filament in adult males.

Coloration in alcohol. Very dusky over most of head and body, becoming progressively lighter ventrally with overall pigmentation pattern often somewhat marmorated. Underside of head and abdomen without dark pigmentation.

Dorsal fin dark both basally and along entire length of first unbranched and first branched rays. Variably-developed, dark pigmentation present on distal portions of other dorsalfin rays. Dark pigmentation of body continues onto base of anal fin, with remainder of anal fin hyaline other than for irregular but very dark pigmentation present along distal portions of fin. Distal chromatophores form distinct, dark, distal margin to anal fin of some specimens. Caudal fin dusky with some irregularity to pattern. Pelvic fin with scattered, dusky pigmentation along base and along first ray. Pectoral fin with dark pigmentation on dorsal surface of base and variable dark pigmentation on distal portions of fin. Darkly pigmented individuals with dark subterminal band on pectoral fin.

Maxillary barbels dusky for basal one-half, pale distally. Mental barbels with few scattered, dark pigmentation spots near base.

Sexual dimorphism. Mature males of Cetopsis fimbriata have very elongate filaments on the distal portions of the first rays of the dorsal and pectoral fins; with such extensions distinctly more well developed than are the filaments that are present in conspecific females. The anal-fin margin in mature males of C. fimbriata is convex, contrary to the straight margin of the fin that is present in all examined females and immature males of the species.

Distribution. Cetopsis fimbriata is apparently endemic to the río Nercua, a tributary of the río Truando that flows into the río Atrato basin of the Caribbean Sea versant of northwestern Colombia ( Fig. 19 View Fig ).

Etymology. The species name, fimbriata , from the Latin for fringed, refers to the dark pigmentation along the distal portion of the anal fin that characterizes this species.

Remarks. It is uncertain whether the citation of Hemicetopsis amphiloxa from the río Atrato system by Mojica-C. (1999: 565) referred to Cetopsis amphiloxa or to C. fimbriata , or a combination of those two species. Both of these species occur within the río Atrato basin, albeit in distinctly separate portions of that drainage system. In the absence of information as to the locations within the río Atrato basin from which the specimens examined by Mojica-C. (1999) originated, it is premature to associate that citation with a particular species.

Material examined. 57 specimens (49-103 mm SL). Holotype. Colombia. Choco : Creek of upper río Nercua (approximately 7°01’N, 77°30’W), large tributary of río Truando, H. G. Loftin et al., 28 August 1957, USNM 305348 View Materials , 1 View Materials (83, male) GoogleMaps . Paratypes. 8 specimens (70-87 mm SL). Colombia. Choco : Creek of upper río Nercua (approximately 7°01’N, 77°30’W), large tributary of río Truando, H. G. Loftin et al., 28 August 1957, USNM 372825 View Materials , 4 View Materials (70-84, all mature males) GoogleMaps ; USNM 372826 View Materials , 2 View Materials (73-87, cleared and stained) GoogleMaps ; ICN-MHN 7272, 2 (74-76, both mature males). Nontype specimens. 48 specimens (49-103 mm SL). Colombia. Choco : Quebrada near río Nercua (7°11’N, 77°33’W), USNM 257763 View Materials , 47 View Materials (49-103, 2 specimens, 84-99 mm, cleared and stained) GoogleMaps . Quebrada Barrial , tributary of río Nercua (7 o 06’N, 77 o 32’W), USNM 295647 View Materials , 1 View Materials GoogleMaps (50).