Saturday, August 12, 2017

[Ichthyology • 2017] Taxonomic Assessment of the Hard-Nosed Thornycats (Siluriformes: Doradidae: Trachydoras Eigenmann 1925) with Description of A New Species, Trachydoras gepharti

Trachydoras gepharti Sabaj & Hernández, 2017

   DOI: 10.1635/053.166.0102 

Trachydoras is a genus of Doradidae (thorny catfishes) with five nominal valid species distributed in lowland areas of the Amazon, Orinoco, Paraná-Paraguay and Essequibo river basins of South America. A sixth species is described here as Trachydoras gepharti and diagnosed by five characteristics unique among congeners: mental barbels thick, tapered and profusely ornamented with many elongate fleshy papillae loosely arranged in 2–3 rows (vs. mental barbels thinner, papillae lacking or fewer, arranged in 1–2 rows); distinct columns of small, soft papillae along medial and lateral margins of gill filaments on all gill arches (vs. gill filaments lacking conspicuous papillae in congeners); gas bladder acorn-shaped (vs. cordiform) with smooth anterolateral shoulder (vs. shoulder with accessory diverticulum) and terminal diverticula medially united into singular, finger-like projection formed mostly by elongation of only one of the two posterior chambers (vs. both chambers elongated, contributing more or less equally to terminal diverticula in congeners or terminal diverticula absent or reduced in some specimens of T. nattereri and T. paraguayensis). Trachydoras gepharti is known from the Amazon and Orinoco basins where it often occurs syntopically with T. microstomus, T. nattereri and a separate undescribed species of Trachydoras. Like other species of Trachydoras, T. gepharti is specialized for vacuuming chironomid larvae from sandy substrates in medium to large river channels. Redescriptions and diagnoses are provided for the five nominal valid species of Trachydoras along with a key to identification and comments on characteristics used to diagnose the genus and delimit species. Designations include a lectotype (NMW 46375, 91.7 mm SL) for Trachydoras brevis (Kner 1853) and neotype (ANSP 178443, 100 mm SL) for T. nattereri (Steindachner 1881). The true holotype of T. microstomus (Eigenmann 1912) is identified as FMNH 118302 [ex. FMNH 53207, ex. CM 1650] and the specimen previously cataloged as the holotype (FMNH 53206) is identified as T. brevis.

Trachydoras Eigenmann 1925 
Hard-nosed thornycats

Etymology.— Generic name derived from the Greek words trachys, meaning rough, and dora, meaning animal hide (Jaeger, 1950). In his generic description, Eigenmann (1925:337) noted “granular” surfaces on the snout, opercle, preopercle and coracoid process. See Sabaj and Birindelli (2008) for discussion on etymology of Doras. The common name proposed here is inspired by the ossified nature of the snout.

Fig. 7. Trachydoras gepharti, n. sp. A. ANSP 203169 (60.6 mm SL, holotype) from río Ventuari, Raudales Tencua, Amazonas, Venezuela. B. INPA 35233 (50.7 mm SL) from río Teles Pires, Mato Grosso, Brazil. C. ANSP 179866 (37 mm SL) from río Nanay, Loreto, Peru. Scale bars = 1 cm. 

Trachydoras gepharti n. sp.  
 Sabaj & Hernández, 2017

Etymology.— Species name honors George W. Gephart, Jr., President & CEO of the Academy of Natural Sciences of Drexel University from 2010 to 2017, for his bold, deft and heartfelt leadership of a Glorious Enterprise into its third century.

Trachydoras brevis (Kner 1853) 
Trachydodras microstomus (Eigenmann 1912)
Trachydoras nattereri (Steindachner 1881)
Trachydoras paraguayensis (Eigenmann & Ward 1907) 
Trachydoras steindachneri (Perugia 1897) 
Trachydoras sp. “mancha-caudal” 

Mark Henry Sabaj and Mariangeles Arce Hernández. 2017. Taxonomic Assessment of the Hard-Nosed Thornycats (Siluriformes: Doradidae: Trachydoras Eigenmann 1925) with Description of Trachydoras gepharti, n. sp.  Proceedings of the Academy of Natural Sciences of Philadelphia. 166(1);1-53.   DOI: 10.1635/053.166.0102