Trichomycterus steindachneri

description

Description. Morphometric data presented in Table 1. Body elongated, depressed in anterior region of trunk and becoming gradually compressed to caudal-fin base. Dorsal and ventral profiles straight and parallel, sloping dorsally and ventrally just posterior to dorsal and anal-fin bases, respectively (Figs. 4 - 5). Cross-section of body elliptical at pectoral-fin insertion with longest axis along horizontal plane. Head depressed, nearly as long as wide, parabolic in dorsal view in specimens shorter than 90 mm SL and square in larger specimens. Lateral portion of head of large specimens (90 mm SL or more) swollen by well-developed jaw muscles, resulting in square aspect of head in dorsal view. Eye small, located dorsolateral, approximately on middle of head length. Eye rim not free, skin covering eye continuous with head skin. Mouth subterminal. Lateral fleshy lobe of lower lip scarcely conspicuous as thickening of lateral portion of lip. Premaxilla with four irregular rows of conical teeth. Dentary with four irregular rows of teeth, similar to those of premaxilla. Anterior nostril small, surrounded by low fleshy thin flap, posterolaterally continuous with nasal barbel. Posterior nos

A new catfish species of the genus Trichomycterus (Siluriformes: Trichomycteridae) from the río Orinoco versant of Páramo de Cruz Verde, Eastern Cordillera of Colombia

diagnosis

Diagnosis. Trichomycterus steindachneri is distinguished from most Trichomycterus species (except T. cachiraensis Ardila Rodríguez, 2008) by having several broad foramina on cleithrum lamina (Fig. 1 a) (vs. cleithrum not pierced). The new species is also distinguishable from most congeners except T. cachiraensis and T. brachykechenos Ferrer & Malabarba, 2013 by having a small posterior cranial fontanel (Fig. 2 a), restricted to the parieto-supraoccipital (vs. a long somewhat rectangular fontanel extending anteriorly between frontal bones and posteriorly into anteromedian region of parietosupraoccipital). Trichomycterus steindachneri differs from T. cachiraensis by having 40 or 41 free vertebrae (vs. 37 - 39), 14 - 18 ribs (vs. 12), a single upper hypural plate: 3 + 4 + 5 (Fig. 3 a) (vs. two hypural plates: 3,4 + 5, Fig. 3 b), and by its coloration pattern (ground color dark brown with a thin mid-lateral dark stripe vs. ground color light brown with three lateral rows of small dark spots). Trichomycterus steindachneri can be distinguished from T. brachykechenos by having four rows of premaxillary and dentary teeth (vs. three), 13 - 14 opercular odontodes (vs. 8 - 11), 41 - 43 intero

A new catfish species of the genus Trichomycterus (Siluriformes: Trichomycteridae) from the río Orinoco versant of Páramo de Cruz Verde, Eastern Cordillera of Colombia

distribution

Distribution and habitat. Trichomycterus steindachneri is known from quebrada El Charco, a tributary of quebrada Santa Bárbara, which drains the east flank of the Eastern Cordillera of Colombian Andes, to empties into río El Palmar of the río Meta drainage, río Orinoco basin (Fig. 6). The collecting site is a typical lotic environment of high altitude (2700 m), about 50 cm wide, with small pools and falls (not higher than 40 cm). Stream banks had dense riparian vegetation, constituted by shrubs and grasses, and dominated by the chusque (Chusquea scandens). Other marginal sections were only covered with pasture.

A new catfish species of the genus Trichomycterus (Siluriformes: Trichomycteridae) from the río Orinoco versant of Páramo de Cruz Verde, Eastern Cordillera of Colombia

etymology

Etymology. The specific epithet steindachneri (adjective genitive masculine singular) is a patronym honoring the prominent Austrian zoologist Franz Steindachner (1834 - 1919), in recognition of his dedicated life and significant work in documenting the fish biodiversity, especially that from South America. His profuse morphological descriptions mainly contributed to settle the current standard in ichthyological taxonomic works.

A new catfish species of the genus Trichomycterus (Siluriformes: Trichomycteridae) from the río Orinoco versant of Páramo de Cruz Verde, Eastern Cordillera of Colombia