Typhlobelus

Taxobox
name = "Typhlobelus"
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Siluriformes
familia = Trichomycteridae
subfamilia = Glanapteryginae
genus = "Typhlobelus"
genus_authority = Myers, 1944
type_species = "Typhlobelus ternetzi"
type_species_authority = Myers, 1944
subdivision_ranks = Binomial name
subdivision =
"Typhlobelus guacamaya"
Schaefer, Provenzano, de Pinna & Baskin, 2005
"Typhlobelus lundbergi"
Schaefer, Provenzano, de Pinna & Baskin, 2005
"Typhlobelus macromycterus"
Costa & Bockmann, 1994
"Typhlobelus ternetzi"
Myers, 1944

"Typhlobelus" is a genus of catfishes (order Siluriformes) of the family Trichomycteridae. It includes four species, "T. guacamaya", "T. lundbergi", "T. macromycterus", and "T. ternetzi".cite journal|url=http://silurus.acnatsci.org/ACSI/library/biblios/2007_Ferraris_Catfish_Checklist.pdf|title=Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types|first=Carl J., Jr.|last=Ferraris|journal=Zootaxa|volume=1418|pages=1–628|year=2007|format=PDF]

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, 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.cite journal|url=http://digitallibrary.amnh.org/dspace/bitstream/2246/5665/1/N3496.pdf|title=New and Noteworthy Venezuelan Glanapterygine Catfishes (Siluriformes, Trichomycteridae), with Discussion of Their Biogeography and Psammophily|first=Scott A.|last=Schaefer|coauthors=Provenzano, Francisco; de Pinna, Mario; Baskin, Jonathan N.|journal=American Museum Novitates|issue=3496|pages=1–27|date=November 29, 2005|format=PDF]

"T. guacamaya" is distinguished from all congeners by the presence of three branchiostegal rays (vs. four in "T. ternetzi" and "T. lundbergi", five in "T. macromycterus"), posterior naris absent (vs. present, nares bilaterally paired), and the lack of pleural ribs (vs. one pair of pleural ribs associated with the first free vertebra). "T. lundbergi" is distinguished from all congeners by the presence of four laterosensory pores on the head (vs. three). Both "T. guacamaya" and "T. lundbergi" are distinguished from " ternetzi" and "T. macromycterus" by the absence of eyes (vs. eyes present and vestigial); 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.

References