Ituglanis agreste

biology_ecology

Ecological notes. Ituglanis agreste was found along a stretch of about 200 m in a mid-small size river with width up to 8 m, in a moderate slope with clear and cold water, with transparency of about 2 m (Fig. 7). The water flow was mainly turbulent, with alternating areas of currents and pools, though a predominance of moderate to strong drifts. Substrate consists of rocks or sand. The most common depth observed was about 0.5 m, but some parts had about 1.7 m. Some sites had underwater aquatic macrophytes and riparian vegetation. The backwaters area had vegetation composed of Typha sp. The margins were deforested and the environment was mainly composed of pastures. A reservoir without a lake formed by the dam of the river was observed above the collection site. Other species collected with Ituglanis agreste were: Astyanax bimaculatus (Linnaeus), Callichthys callichthys (Linnaeus), Geophagus brasiliensis (Quoy & Gaimard), Rhamdia quelen (Quoy & Gaimard) and Poecilia reticulata Peters, this last an exotic species.

Ituglanis agreste, a new catfish from the rio de Contas basin, northeastern Brazil (Siluriformes: Trichomycteridae)

description

Description. Morphometric data for holotype and paratypes are given in Table 1. Body elongated, subcylindrical about to dorsal-fin origin, and gradually compressed in caudal peduncle. Dorsal and ventral side view straights, except in dorsal part of the head, which is slightly convex. Head depressed, longer than wide, rounded in dorsal view. Eyes rounded and small, without free orbital margin, covered by a thin translucid membrane, lightly located on anterior half of head. Barbels and head covered by minute papillae. Mouth subterminal. Tip of nasal barbel reaching posterior edge of opercular patch of odontodes; tip of maxillary barbel reaching pectoral-fin base and tip of rictal barbel reaching posterior edge of interopercular patch of odontodes or the anterior edge of pectoral-fin. Total vertebrae 36, 12 - 13 precaudal and 23 - 24 caudal. Ribs 5 (2) or 6 (1). Origin of dorsal-fin in a vertical through the 22 nd vertebra. Origin of anal-fin in a vertical through the 23 rd vertebra and through the base of the 7 th ray of dorsal fin. Origin of pelvic fin in a vertical through the 17 th- 18 th vertebra. Pectoral-fin rays i, 6, pectoral fin triangular, first ray simple and pectoral fila

Ituglanis agreste, a new catfish from the rio de Contas basin, northeastern Brazil (Siluriformes: Trichomycteridae)

diagnosis

Diagnosis. Ituglanis agreste is distinguished from all species of the genus, except I. paraguassuensis by the reduced number of vertebrae 36 (vs. 38 or more in all other Ituglanis, except in I. paraguassuensis, I. nebulosus, I. bambui, I. epikarsticus, I. ramiroi, and I. passensis; unknown for I. guayaberensis); number of ribs (5 - 6) (vs. 2 or 3 in I. amazonicus, I. eichorniarum, I. gracilior, I. ina, I. macunaima, I. nebulosus, and I. parkoi; 4 in I. laticeps and I. cahyensis; 7 in I. passensis); number of pectoral-fin rays i, 6 (vs. i, 4 in I. cahyensis, I. macunaima, and I. parahybae; i, 5 in I. amazonicus, I. eichorniarum, I. metae, and I. nebulosus; i, 7 in I. bambui, I. epikarsticus, I. mambai, I. passensis; iii, 5 in I. guayaberensis; i, 8 in I. ramiroi); and skin covered by irregular brown blotches (vs. distinct color pattern in all other Ituglanis; absence in I. ina and the subterranean species, I. bambui, I. passensis, I. epikarsticus, and I. ramiroi). Ituglanis agreste is also easily distinguished from the subterranean species by large eyes (vs. minute eyes) and intense pigmentation (vs. pigmentation absent or almost lack). Ituglanis agreste is distinguished from I. par

Ituglanis agreste, a new catfish from the rio de Contas basin, northeastern Brazil (Siluriformes: Trichomycteridae)

distribution

Distribution. Ituglanis agreste is only known from the type locality, in rio Tarugo, municipality of Boa Nova, Bahia, northeastern Brazil. This river is a tributary of the rio Uruba, that flows into rio Gongogi, principal drainage of right margin on the middle section of rio de Contas basin (Fig. 10). This is the transition zone of the Serra da Ouricana, where small remnants of a formerly extensive humid forest that delineates the limits of the Atlantic Forest domain in the region (Gonzaga et al., 1995). Just a few kilometers to the west, the landscape gives way to the semi-arid Caatinga region, typically known for regular droughts. Thus, it is possible that the rio Tarugo represents the western geographical limit of distribution for this species. During a two year sampling (2008 - 2009) along a 325 km transect of the rio de Contas (between the municipalities of Ibuaçussê and Uruçuca), Ituglanis agreste was found only at one site.

Ituglanis agreste, a new catfish from the rio de Contas basin, northeastern Brazil (Siluriformes: Trichomycteridae)