Pygidianops

Taxobox
name = "Pygidianops"
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Siluriformes
familia = Trichomycteridae
subfamilia = Glanapteryginae
genus = "Pygidianops"
genus_authority = Myers, 1944
type_species = "Pygidianops eigenmanni"
type_species_authority = Myers, 1944
subdivision_ranks = Binomial name
subdivision =
"Pygidianops cuao"
Schaefer, Provenzano, de Pinna & Baskin, 2005
"Pygidianops eigenmanni"
Myers, 1944
"Pygidianops magoi"
Schaefer, Provenzano, de Pinna & Baskin, 2005

"Pygidianops" is a genus of catfishes (order Siluriformes) of the family Trichomycteridae. It includes three species, "P. cuao", "P. eigenmanni", and "P. magoi".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

"P. eigenmanni" is from the Rio Negro basin in Brazil. "P. cuao" is known only from Cuao River drainage basin. "P. magoi" is known only from lower Orinoco mainstem between Ciudad Bolívar and Barrancas in Venezuela.

Description

Species of "Pygidianops" 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]

"P. cuao" is distinguished from congeners by the presence of diminutive eyes (vs. eyes absent in both other species), posterior naris absent (vs. nares bilaterally paired), and the presence of a triangular skin flap at mouth corner (vs. skin flap absent). "P. magoi" is distinguished from all congeners by the absence of pectoral and anal fins (vs. fins present), posterior naris absent (vs. present, nares bilaterally paired), four laterosensory pores on the head (vs. six), and by the presence of 9–10 caudal fin rays (vs. 12–13). With all of its fins lost except the caudal fin, "P. magoi" represents the most extreme fin loss among ostariophysans. "P. eigenmanni" lacks eyes but has its anal and pectoral fins.

References