Arabibarbus

A genus of three very large (A. grypus) to medium-sized species endemic to West Asia. These are hexaploid barbels of the yellowfish (Torini) group, distinguished by large, shield-shaped scales with numerous parallel radii. The last unbranched dorsal ray is weakly to strongly ossified, without serrae.They have two pairs of barbels,8½ branched dorsal rays, and 5½ branched anal rays. Their phylogenetic position has long been uncertain, but most authors categorised them in Barbus, as no alternative was available. One species, A. grypus, occurs in the Persian Gulf basin. Some authors have placed it in the Asian genus Tor. However, it has only recently become clear that these three species belong together, and with Carasobarbus, Mesopotamichthys, and Ptercapoeta form the sister group of the large African genus Labeobarbus. Both Arabian species are superficially similar but allopatric, and the molecular characters studied suggest that they have a long, isolated evolutionary history.

Further reading. Borkenhagen 2014 (description, phylogeny); Yang et al. 2015; Borkenhagen 2017 (phylogeny).

Key to species of Arabibarbus

1a - Body cylindrical; last unbranched dorsal ray weakly ossified; posterior barbel length 4−6 % SL; 29−36, usually 30−35, total lateral-line scales. ……………… A. grypus

1b - Body laterally compressed; last unbranched dorsal ray strongly ossified; posterior barbel length 7−12 % SL; 32−44, usually 35−41, total lateral-line scales. ………………2

2a - 29–36, usually 32−35, total lateral-line scales; head depth 14–17 % SL; pectoral length 18–22 % SL; pelvic length 15–19 % SL; head length 24–31 % SL. ……………… A. arabicus

2b - 29–32, usually 30–31, total lateral-line scales; head depth 16–18 % SL; pectoral length 20–24 % SL; pelvic length 17–20 % SL; head length 28–33 % SL. ……………… A. hadhrami