Cetopsis montana, 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 : 174-176

publication ID

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

persistent identifier

https://treatment.plazi.org/id/E56BC71F-0E18-FF91-3C99-FF74FA42E183

treatment provided by

Carolina

scientific name

Cetopsis montana
status

new species

Cetopsis montana , new species

Figs. 25 View Fig , 26 View Fig , Tables 9 -15

Diagnosis. Cetopsis montana 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, the absence of a dark humeral spot, the presence of a posteriorly-rounded, variably-developed, bilobed patch of dark pigmentation at the base of the caudal fin, the absence of a spot of dark pigmentation on the base of the dorsal fin and absence of prominent dark pigmentation along the membrane behind the first ray of the dorsal fin, the presence of approximately eye-size, dark spots on the lateral surface of the body, the absence of finely scattered, dark pigmentation across the lateral and anterior surfaces of the snout and the lateral surface of the body, and the possession of 19 to 21 branched anal-fin rays.

Dorsal and anal fins shown with scattered, dark pigmentation. Caudal fin with band of dark pigmentation on distal onehalf but with fin margin less intensely pigmented and with dark band wider on dorsal lobe.

Sexual dimorphism. It is impossible to determine whether this species demonstrates the sexually-dimorphic features of the anal, pectoral, and dorsal fins because the species is known only from the holotype. The holotype is a mature female as evidenced by the well-developed eggs that are apparent through the desiccated body wall.

Distribution. Cetopsis jurubidae is only known from the río Jurubidá of the Pacific Ocean versant of western Colombia ( Fig. 25 View Fig ).

Remarks. The holotype and only known specimen of Cetopsis jurubidae is in poor condition, apparently having been largely desiccated at some point. Although no other samples of the Cetopsinae from the río Jurubidá are available, the holotype is considered to represent a distinct species as evidenced by the features discussed in the “Diagnosis” above.

Material examined. 1 specimen (approximately 90 mm SL). Colombia. Choco : río Jurubidá, Nuquí (5°42’N, 77°17’W), ANSP 71430 View Materials , 1 View Materials (approximately 90 mm SL; exact length cannot be determined because of desiccation of specimen; holotype of Pseudocetopsis jurubidae ) GoogleMaps .

Description. Body moderately stout, slightly laterally compressed anteriorly and becoming progressively distinctlycompressed posteriorly. Body depth at dorsal-fin origin approximately 0.26-0.28 of SL and approximately equal to HL. Lateral line on body complete, unbranched, and midlateral; extending from vertical through pectoral-fin base posteriorly to, and slightly upturned on, hypural plate and terminating prior to posterior margin of hypural plate. Dorsal profile of body slightly convex from nape to dorsal-fin origin and 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.

Head in profile acutely triangular overall with bluntlyrounded snout. Dorsal profile of head slightly convex from tip of snout to nape. Ventral profile of head slightly convex. Margin of snout in dorsal view bluntly triangular. 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 moderate; extending ventral of pectoral-fin insertion by distance equal to snout length and extending dorsal of pectoral-fin insertion by distance slightly less than 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 located at approximately anterior one-fourth of HL. Eye diameter approximately 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; opening nearly round, with anterior two-thirds of aperture surrounded by flap of skin with anterior portion of flap highest.

Mouth inferior; its width approximately one-half of HL. Margin of lower jaw gently rounded, its posterior limit reaching to vertical through 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 and arranged in three or four, irregular rows. Teeth of inner most row of premaxillary dentition slightly larger than teeth in other rows. Vomerine teeth arranged in single, irregular row continuous across midline. Vomerine teeth stout, conical, and much larger than teeth on premaxilla or dentary. Dentary teeth comparable in shape to, but larger than, all but largest premaxillary teeth; with three, irregular tooth rows medially that taper to one row laterally.

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

Dorsal fin moderately large overall with length of dorsalfin base approximately 0.40-0.42 of HL. Longest branched dorsal-fin ray, excluding distal filament on first ray, equal in length to two-thirds of HL. Dorsal-fin spinelet absent. First dorsal-fin ray not spinous but with distal filament present in both sexes, filament proportionally longer in mature males. Distal margin of dorsal fin concave, with first ray longest. Dorsal-fin origin located at approximately anterior 0.34-0.35 of SL and along vertical extending through distal one-fourth of adpressed pectoral fin. Tip of adpressed dorsal fin reaching nearly to vertical through vent. 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 of vertical through middle of TL. Anal-fin margin straight in females and immature males, with posterior most unbranched anal-fin ray longest in fin and subsequent rays becoming gradually shorter.Anal-fin margin slightly convex in mature males. Posterior most anal-fin ray without posterior, membranous attachment to body.

Pelvic fin moderate; 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 falling far 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, excluding distal filament, equal to approximately two-thirds of HL. Pectoral-fin margin sinusoidal, concave laterally and convex medially, with first ray longest and prolonged into distal filament, filament proportionally longer in mature males. First pectoral-fin ray not spinous.

Coloration in alcohol. Dark pigmentation covering dorsal portion of head from interorbital region to posterior of head. Dorsal portion of body dark. Lateral surface of body pale with scattered, approximately eye-size, dark spots. Spots more concentrated on dorsal and dorsolateral portions of body and on lateral surface of caudal peduncle. Ventral surface of head and body pale. Snout margin pale from posterior nares to tip of snout. Entire upper lip pale.

Dorsal fin pale other than for semicircular, basally-situated, dusky region and for dusky interradial membrane between first and second fin rays. Caudal fin with dark, bilobed spot extending from base of branched fin-rays posteriorly approximately to vertical through middle of length of innermost fin rays. Interradial membrane between posterior most unbranched and first branched rays of each lobe dusky in some darkly pigmented specimens. Remainder of caudal fin pale. Anal, pectoral, and pelvic fins pale.

All barbels dusky on basal one-half of anterior surface and otherwise pale.

Sexual dimorphism. The presumed mature males of Cetopsis montana have the filaments on the first rays of the dorsal and pectoral fins proportionally more elongate than are the extensions on those fins that occur in females and immature males. Mature males also have a slightly convex anal-fin margin rather than the straight margin to the fin that occurs in conspecific females and immature males. Both of the mature males of the species examined in this study are among the smallest available specimens of C. montana .

Distribution. Cetopsis montana occurs in the western portions of the Amazon basin in northeastern Peru and southeastern Ecuador ( Fig. 25 View Fig ).

Etymology. The species name, montana , from the Latin for pertaining to mountains, refers to the piedmont regions of the eastern slopes of the Andean Cordilleras that are drained by the river systems inhabited by this species.

Remarks. We examined one lot of six small, very pale specimens (LACM 41741-2) that originated close to the location where the type series of Cetopsis montana was collected, but that lack the pigmentation pattern characteristic of C. montana . This population sample, nonetheless, agrees fully in meristic values and other features with the examined material of C. montana and is tentatively considered to be conspecific with that species.

One specimen from the rio Amazonas collected in the region above the mouth of the rio Madeira (INPA 8485) is apparently a member of the complex of species with the distinct, dark, bilobed patch at the base of the caudal fin that is characteristic of Cetopsis montana , C. pearsoni , and C. umbrosa . The overall dark pigmentation of the head and body of the specimen is, however, faded to such a degree as to render impossible a definitive identification of the specimen to species. Nonetheless, this record represents a major range extension eastward for the group of species that share this distinctive caudal-fin pigmentation pattern, and potentially represents yet another species of this complex. A resolution of that question must remain in abeyance until additional material with the characteristics of this assemblage of species from the central portions of the Amazon basin becomes available.

Material examined. 23 specimens (21-119 mm SL). Holotype. Peru. Amazonas : 100 m upriver from Caterpiza (approximately 3°55’S, 77°42’W), M. P. Achamposh, 16 February 1980; LACM 41989-1 View Materials , 1 View Materials (108) GoogleMaps . Paratypes. 11 specimens (45-119 mm SL). Peru. Amazonas : Caterpiza (approximately 3°55’S, 77°42’W), M. P GoogleMaps .

Achamposh, 31 December 1979; LACM 41895-1 View Materials , 1 View Materials (119) . Caterpiza, Quebrada Kayamasa (approximately 3°55’S, 77°42’W), M. P. Achamposh, 11 December 1979; USNM 372759 View Materials , 1 View Materials (88, formerly LACM 41873-1 View Materials ) GoogleMaps . Caterpiza (approximately 3°55’S, 77°42’W), M. P. Achamposh, 28 December 1979; LACM 41893- 1 View Materials , 1 View Materials (72) GoogleMaps . Río Santiago , La Poza (4°01’S, 77°45’W), C. Swift et al., 20 January 1980; LACM 39887-3 View Materials , 1 View Materials (45) GoogleMaps . 100 m upriver from Caterpiza (approximately 3°55’S, 77°42’W), C. Swift et al., 15 February 1980; LACM 39922-1 View Materials , 1 View Materials (57) GoogleMaps . 200 m upriver from Caterpiza (approximately 3°55’S, 77°42’W), M. P. Achamposh, 6 February 1980; LACM 41945-2 View Materials , 1 View Materials (107) GoogleMaps . Caterpiza (3°55’S, 77°42’W), M. P. Achamposh, MUSM 20298 , 2 (61-99, formerly LACM 42113-1 View Materials ) GoogleMaps . Loreto: río Napo, beach and backwater along right bank, just upstream from mouth of río Mazan , near town of Mazan (03°29’10"S, 73°06’24"W), M. H. Sabaj et al., 5 August 2001; ANSP 178173 View Materials , 1 View Materials (60.4) GoogleMaps Ecuador. Pastaza: Chunigrama in Chichirota (2°23’S, 76°39’W), MEPN GoogleMaps uncataloged, 1 (86.5), collected February1954. Napo: río Catapino, río Pucuno basin (0°40’S, 77°19’W), J. Olalla, November 1980; USNM 177224 View Materials , 1 View Materials (75) GoogleMaps . Nontype specimens. 11 specimens (6, 21-54 mm SL). Peru. Amazonas: río Marañon , vicinity of Santa Maria de Nieva (4°35’S, 77°54’W), LACM 41741-2 View Materials , 6 View Materials (25-52) GoogleMaps . Río Marañon , in El Pongo, LACM 41736-1 View Materials , 1 View Materials (47; specimen cleared and stained) . Río Santiago, Pinglo , LACM 41735-1 View Materials , 1 View Materials (21; specimen cleared and stained) . Ecuador. Napo: río Payamino , 23.3 km upstream from mouth in río Napo, sandy beach on right bank, FMNH 111690 View Materials , 1 View Materials (54) . Sucumbios: río Napo at Destacamento Tiputini, FMNH 111691 View Materials , 2 View Materials (38-40).