New species of trichomycterid catfish described


A second species of trichomycterid catfish in the genus Trichogenes from southeastern Brazil has been described by Brazilian ichthyologists in the most recent issue of the journal Neotropical Ichthyology.

Mário de Pinna, José Helmer, Heraldo Britski and Leandro Nunes name the new catfish Trichogenes claviger, the species name being Latin for "club-bearing" and referring to the presence of a large process on the opercle in the males of this species.

The new species differs from all other members of the Trichomycteridae in having a large posterior process of the opercle in males, a terminal mouth, deeply bifurcating anterior neural spines and the presence of a large anterodorsal claw-like process on the neural arches of the first four free vertebrae.

It is further distinguished from its only other congener, T. longipinnis, in the shapes of the body, head, interopercle, coronoid process on the lower jaw, tooth cusps, and posterior nostrils, having an entirely differentiated lateral fleshy lobe on the lower lip, the absence of branched anal-fin rays, a pelvic splint, and an antorbital (a bone in the head), a more slender caudal peduncle, deeper head, fewer vertebrae, pleural ribs and branchiostegal rays, and colour pattern.

The new species is known only from the headwaters of the Itapemirim River in southeastern Brazil, where it inhabits slow-flowing streams with dark, tea-stained water with a substrate of sand and leaf litter. This is considerably different from the rocky torrential habitats typically inhabited by T. longipinnis.

The feeding ecology of the new species is poorly known. An analysis of the gut contents revealed disarticulated arthropod fragments, and the authors hypothesise that the new species feeds mostly from the surface and midwater on the basis of its head morphology.

For more information, see the paper: de Pinna, MCC, JL Helmer, HA Britski and LR Nunes (2010) A new species of Trichogenes from the rio Itapemirim drainage, southeastern Brazil, with comments on the monophyly of the genus (Siluriformes: Trichomycteridae). Neotropical Ichthyology 8, pp. 707–717.