Helogenes uruyensis Fernández-Yépez 1967

fisheries: of no interest

Helogenes uruyensis Fernández-Yépez

Helogenes marmoratus uruyensis Fernández-Yépez, 1967:166, pl. 2, pl. 3: fig. 2, table 2 [type-locality: Venezuela: Guayana, Río Uruyén near Auyantepui].—Mago-Leccia, 1970:82 [citation].—Glodek and Carter, 1978:76 [in key].

DIAGNOSIS.—Helogenes uruyensis, the most distinctive species in the family, can be distinguished from all other helogenids in having 32 to 37 anal-fin rays in contrast to 39 to 49 in the remainder of the family. The possession of 15 principal caudal fin rays, with eight principal rays on the lower lobe of the caudal fin, further distinguishes the species from H. gouldingi and H. castaneus, which have nine principal rays on the lower lobe of the fin and a total of 16 principal rays. Helogenes uruyensis is also separable from H. castaneus and H. gouldingi by a series of morphometric characters (see Table 2).

DESCRIPTION.—Morphometrics of the paratypes are given in Table 2.

Dorsal profile of body smooth, slightly convex from snout to dorsal portion of caudal peduncle. Ventral profile of body slightly convex from lower jaw to anus. Base of anal fin straight. Pectoral fin with seven rays, reaching to or falling slightly short of vertical through insertion of pelvic fin. Pelvic fin with six rays, reaching to vertical through insertion of second or third anal-fin rays. Anal-fin margin slightly convex anteriorly, concave posteriorly. Anal-fin rays 32 to 37. Rayed dorsal fin small, with five rays. Adipose dorsal fin present in all specimens examined.

Premaxilla with two rows of teeth, inner smaller, largely covered by fleshy lining of mouth. Lower jaw with a cardiform band of teeth, outer row enlarged.

Anterior and posterior nares well separated, anterior tubular. Maxillary barbel extending posteriorly to slightly beyond vertical through insertion of pectoral fin. Medial and lateral mandibular barbels of same length or medial barbel slightly longer; medial barbel extending posteriorly to vertical through line approximately two-thirds along length of pectoral fin.

Five vertebrae in anterior vertebral complex; free vertebrae posterior to complex 38 (1), 39 (6).

COLORATION.—Overall coloration of head and body brown, somewhat mottled. Dorsal portions of head and nape somewhat darker. A series of unpigmented spots along lateral line; spots more numerous anteriorly, nearly contiguous in that region. Dark body pigmentation extending onto anterior one-third of caudal fin rays; posterior border of dark pigmentation on caudal fin discrete, with somewhat irregular margin.

Rayed dorsal fin mottled, somewhat darker basally. Adipose fin mottled, with hyaline border. Caudal fin dark on basal one-third, mottled on posterior two-thirds, borders hyaline. Anal fin dark brown on fleshy basal portion, mottled along medial one-third, distal one-third of fin hyaline. Pectoral and pelvic fins mottled basally, hyaline distally.

DISTRIBUTION.—Known only from the type-locality, the Río Uruyén, which flows from the southeast of Auyantepui in Guayana, Venezuela (Figure 4). The Río Uruyén is part of the Río Caroní system, a southern tributary of the Río Orinoco. The map in Glodek and Carter (1978, fig. 2) incorrectly indicates the locality as being in the Río Cuyuni system, a tributary of the Essequibo River.

MATERIAL EXAMINED.—9 specimens (7, 36.5–43.1 mm SL).

VENEZUELA. Bolivar: Río Uruyén, south side of Auyantepui, USNM 219598, 1 (43.1, paratype of Helogenes marmoratus uruyensis Fernández-Yépez; formerly MBUCV V-2615, in part); MBUCV V-2615, 3 (36.65–40.0, paratypes of H. m. uruyensis); MBUCV V-10852, 5 (3, 36.5–39.6, paratypes of H. m. uruyensis, formerly MAC 56028 and AFY 56614; anal-ray counts, but no other data taken from 2 other specimens.

Helogenes uruyensis is a species of the whale catfish that is endemic to Venezuela, where it is found in the Uruyén River basin. This species reaches a length of 4.3 cm (1.7 inches).