Pygidianops

Life-forms

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Superclassis/Classis: Actinopterygii
Classis/Subclassis: Actinopteri
Subclassis/Infraclassis: Neopterygii
Infraclassis: Teleostei
Megacohors: Osteoglossocephalai
Supercohors: Clupeocephala
Cohors: Otomorpha
Subcohors: Ostariophysi
Sectio: Otophysa
Ordo: Siluriformes

Familia: Trichomycteridae
Genus: Pygidianops
Species: P. cuao – P. eigenmanni – P. magoi
Name

Pygidianops Myers, 1944
References

Carl J. Ferraris, Jr., 2007, Zootaxa 1418: 1–628 [1]

Pygidianops is a genus of pencil catfishes native to South America.
Species

There are currently four recognized species in this genus:[1]

Pygidianops amphioxus de Pinna & Kirovsky, 2011
Pygidianops cuao Schaefer, Provenzano, de Pinna & Baskin, 2005
Pygidianops eigenmanni Myers, 1944
Pygidianops magoi Schaefer, Provenzano, de Pinna & Baskin, 2005

Distribution

P. eigenmanni is from the Rio Negro basin in Brazil.[2] 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.[3]
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.[3]

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).[3] 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.[3] P. eigenmanni lacks eyes but has its anal and pectoral fins.[3]
References

Froese, Rainer and Pauly, Daniel, eds. (2012). Species of Pygidianops in FishBase. February 2012 version.
Ferraris, Carl J. Jr. (2007). "Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types" (PDF). Zootaxa. 1418: 1–628. doi:10.11646/zootaxa.1418.1.1.
Schaefer, Scott A.; Provenzano, Francisco; de Pinna, Mario; Baskin, Jonathan N. (November 29, 2005). "New and Noteworthy Venezuelan Glanapterygine Catfishes (Siluriformes, Trichomycteridae), with Discussion of Their Biogeography and Psammophily" (PDF). American Museum Novitates (3496): 1–27. doi:10.1206/0003-0082(2005)496[0001:NANVGC]2.0.CO;2. S2CID 19506818.