A New Species of Deep-channel Electric Knifefish Compsaraia (Apteronotidae, Gymnotiformes) from the Amazon River
The deep channels of large rivers throughout the humid Neotropics are occupied by diverse and abundant assemblages of electric knifefishes. Historically this habitat has been poorly sampled, but extensive benthic trawling efforts in the Brazilian Amazon in the 1990s produced large numbers of electric fishes especially in the family Apteronotidae. A large number of these specimens, initially identified as Porotergus, have been found to belong within Compsaraia, a genus with two species described from the Orinoco and western Amazon. From this material we describe a new species, from the Amazon River in Brazil, and provide a new diagnosis for the genus. This species is readily distinguished from congeners by a short, rounded snout and small, subterminal mouth with reduced dentition. This species inhabits large rivers in the Eastern and Central Amazon between Ilha Grande de Gurupá and the mouth of the Rio Içá. This description brings the total number of valid apteronotid species to 95.
Compsaraia iara, MZUSP 121514, 203 mm TL, holotype, Brazil, Pará, Rio Amazonas. Scale bar equals 1 cm.
(A) Compsaraia samueli, male, MUSM 54638, 199 mm TL, Peru, Loreto, Rio Nanay. (B) Compsaraia samueli, female, MUSM 54620, 137 mm TL, Peru, Loreto, Rio Amazonas. (C) Compsaraia compsa, ANSP 160194, paratype, 262 mm TL, Venezuela, Apure, Rio Meta. Scale bar equals 1 cm.
Detail of head and pigmentation for Compsaraia samueli (top), MUSM 37172, 241 mm TL, and Compsaraia iara, FMNH 128428, 235 mm TL in lateral view (A), dorsal view (B), and ventral view (C). Scale bar equals 1 cm.
Lateral view of neurocranium (A) and suspensorium and oral jaws (B) of Compsaraia iara, FMNH 115028, 208 mm TL. Cartilage shown in gray. Abbreviations: (A) bao, basioccipital; epo, epioccipital; exo, exoccipital; fro, frontal; let, lateral ethmoid; met, mesethmoid; obs, orbitosphenoid; par, parietal; pas, parasphenoid; pro, prootic; pto, pterotic; pts, pterosphenoid; soc, supraoccipital; spo, sphenotic; vet, ventral ethmoid; (B) aar, anguloarticular; ap, autopalatine cartilage; d, dentary; enp, endopterygoid; hm, hyomandibular; iop, interopercle; max, maxilla (detached from suspensorium); mco, mandibular canal ossicles; mpt, metapterygoid; op, opercle; pmx, premaxilla (in ventral view); pop, preopercle; q, quadrate; rar, retroarticular; sop, subopercle; sym, symplectic.
Neurocrania of juvenile and adult Compsaraia compsa, ANSP 163033, 119 and 285 mm TL (A) and Compsaraia iara, FMNH 115028, 147 and 208 mm TL (B).
Collection localities of Compsaraia iara. Star indicates type locality. Some localities not referenced in Material Examined were taken from Cox Fernandes (1995) and Crampton and Cella-Ribeiro (2013).
Collection localities of Compsaraia compsa (triangles) and Compsaraia samueli (squares). Some single points indicate more than one lot or collection from proximate localities.
Contributor Notes
Associate Editor: R. E. Reis.