Imparfinis usmai

description

Description. Morphometric data given in Table 1. Small heptapterid catfish (largest specimen 100.8 mm SL), with elongated body, triangular in cross-section at dorsal-fin origin, progressively more laterally compressed to tail region. Dorsal profile slightly convex from snout tip to dorsal-fin origin, slightly concave just posterior to dorsal-fin base to adiposefin origin, straight and descending along adipose-fin base, then ascending along caudal peduncle. Ventral profile of head straight, slightly convex along abdomen, then straight to analfin origin and slightly descending along caudal peduncle. Head conical and depressed, dorsally covered by thin skin. Snout short and broadly rounded. Mouth subterminal. Premaxillary teeth conical and pointed arranged in rectangular band with 4 - 5 irregular rows. Dentary with 4 - 5 irregular rows of teeth. Barbels dorsoventrally flattened. Maxillary barbels surpassing pelvic-fin base. Anterior portion of maxillary barbel in shallow groove, extending below eye. Bases of outer and inner mental barbels aligned. Outer mental barbels surpass pectoral-fin base. Inner mental barbels reach pectoral-fin origin. Eye dorsolateral in position. Orbital margi

Two new trans-Andean species of Imparfinis Eigenmann & Norris, 1900 (Siluriformes: Heptapteridae) from Colombia

diagnosis

Diagnosis. This species is distinguished from congeneric trans-Andean species by having the first ray of dorsal fin longest and slightly projected or not beyond dorsal-fin margin, length of first dorsal-fin ray: 19.1 - 23.2 % in SL (vs. slightly shorter than second ray in I. lineatus, 14.0 - 17.6 %; I. spurrellii, 16.0 - 17.6 %; and I. timana, 16.3 - 21.0 %; or extended as a conspicuous and long filament beyond fin margin in I. nemacheir, 29.2 - 33.1 %); and by the intermediate long upper caudal-fin lobe (24.4 - 39.2 % in SL vs. 22.7 - 26.0 % in I. lineatus; 38.2 - 52.1 % in I. nemacheir; 22.8 - 26.5 % in I. spurrellii; 21.9 - 28.0 % in I. timana). Imparfinis usmai differs from all trans- Andean species, except I. nemacheir, by having a longer maxillary barbel (40.3 - 63.8 % in SL vs. 24.0 - 32.6 % in I. lineatus; 32.1 - 35.2 % in I spurrellii; 32.3 - 45.0 % in I. timana), and by the number of vertebrae (39 - 40 vs. 42 in I. lineatus; 45 in I. spurrellii; 42 - 43 in I. timana). Specimens of Imparfinis usmai exceeding 30 mm SL, are readily distinguished from all trans- Andean species, except I. timana, by having an upper caudalfin lobe pointed and longer than lower lobe, and a lower

Two new trans-Andean species of Imparfinis Eigenmann & Norris, 1900 (Siluriformes: Heptapteridae) from Colombia

discussion

Remarks. Proper taxonomic recognition of Imparfinis usmai has an especially confusing record in the ichthyological literature, even in strictly taxonomic works. Eigenmann (1922), while redescribed Imparfinis nemacheir, listed a series of specimens coming from the ríos Patía and Cauca, as reference material for this species. Some of these specimens (FMNH 58129, 58131 - 32), formerly catalogued at the Carnegie Museum, were reexamined, and we found that these population samples are assignable to I. usmai. This species has also been misidentified as I. nemacheir in Ortega-Lara et al. (2000) (photograph on p. 41, where the scarcely projected first dorsal-fin ray beyond fin membrane and shorter maxillary barbel are evident when compared to the actual I. nemacheir), and in Maldonado-Ocampo et al. (2005) (illustration of Fig. 154, p. 289, showing the characteristic configuration of the caudal fin of I. usmai, with upper lobe longer and pointed and lower lobe rounded; along with most of the reference material therein listed and reidentified in the present work: see CZUT-IC and IMCN lots of paratypes and non-type material of I. usmai). Even more surprising are the identifications of pictured

Two new trans-Andean species of Imparfinis Eigenmann & Norris, 1900 (Siluriformes: Heptapteridae) from Colombia

distribution

Distribution. This species is broadly distributed along the upper basin of río Cauca and río Magdalena, and in the lower río Patía basin on the Pacific slope of western cordillera of Colombia (Fig. 2). Imparfinis usmai is sympatric with I. nemacheir in the río Magdalena.

Two new trans-Andean species of Imparfinis Eigenmann & Norris, 1900 (Siluriformes: Heptapteridae) from Colombia