Paracobitis rhadinaea

Common name. Giant crested loach.

Diagnosis. Distinguished from other species of Paracobitis by: ○ posterior narial opening slit-shaped / ○ body naked or with few, usually isolated and embedded scales / ○ usually a midlateral row of irregularly set and shaped large dark-brown blotches on flank posterior to dorsal base / ○ caudal emarginate or truncate / ○ pelvic origin below vertical of first to third branched dorsal ray / ○ axillary pelvic lobe large, well developed. Size up to 250 mm SL.

Distribution. Afghanistan and Iran: Sistan basin, including Helmand drainage, Chahnime reservoirs, and Hamun Lakes.

Habitat. Lakes and large rivers, but little-known about habitats.

Biology. Feeds on aquatic invertebrates and small fishes.

Remarks. Paracobitis macmahoni, P. ghazniensis, and P. vignai are synonyms for this species. Paracobitis rhadinaea shows remarkable variability in colour pattern, from spots to almost patternless, in scale cover, from scales on the caudal peduncle to being completely bare, and from an emarginate to a truncate or slightly rounded caudal.

Conservation status. LC; situation in Helmand is unknown. Strongly declined in Iran due to loss of wetlands.

Further reading. Regan 1906 (description); Bănărescu & Nalbant 1966 (diagnosis); Freyhof et al. 2014b (diagnosis); Mousavi-Sabet et al. 2014 (description); Mousavi-Sabet et al. 2016b (conservation); Sayyadzadeh et al. 2019a (variability, P. vignai).