Typhlobelus

Typhlobelus is a genus of freshwater ray-finned fishes belonging to the family Trichomycteridae and the subfamily Glanapteryginae, the miniature pencil catfishes. The catfishes in this genus are found in South America.

Species

There are currently five recognized species in this genus:Typhlobelus auriculatus de Pinna & Zuanon, 2013Typhlobelus guacamaya Schaefer, Provenzano, de Pinna & Baskin, 2005Typhlobelus lundbergi Schaefer, Provenzano, de Pinna & Baskin, 2005Typhlobelus macromycterus W. J. E. M. Costa & Bockmann, 1994Typhlobelus ternetzi Myers, 1944

Distribution

T. guacamaya originates from the Cuao River in the Orinoco River basin of Venezuela. T. lundbergi inhabits the lower Orinoco River, between Ciudad Bolivar and Los Castillos de Guayana, Venezuela. T. macromycterus is known from the Tocantins River near Tucuruí, Pará State, Brazil. T. ternetzi lives in the upper Rio Negro basin, Brazil.

Description

Species of Typhlobelus share the extreme reduction of pigmentation, loss of the dorsal fin, the loss or extreme reduction of pectoral fins, a reduced lateral line, and the reduction or complete loss of eyes in some species. These fish are markedly miniaturized, yet retain a relatively well-ossified skeleton comparable in both bone differentiation and degree of calcification to that observed in larger trichomycterids.
T. guacamaya is distinguished from all congeners by the presence of three branchiostegal rays, posterior naris absent, and the lack of pleural ribs. T. lundbergi is distinguished from all congeners by the presence of four laterosensory pores on the head. Both T. guacamaya and T. lundbergi are distinguished from ternetzi and T. macromycterus by the absence of eyes ; between T. ternetzi and T. lundbergi, the distinction may be between the presence or absence of eyes or eyespots. T. macromycterus has one or two odontodes on the opercle and five branchiostegal rays, while T. ternetzi and T. lundbergi have no odontodes and four branchiostegal rays.
These fish have greatly elongate, slender bodies. These fish have three pairs of barbels, all similar in length and general appearance. The mouth is ventral. Typhlobelus has a long duck-billed rostrum that protrudes anteriorly well beyond the bases of the maxillary barbels.