Loach previously misidentified in the aquarium hobby given name.

Nonn Panitvong/Siamensis.org

The fish previously known as Acanthocobitis rubidipinnis in the aquarium hobby is officially described as A. pictilis in the journal Zootaxa this week. It’s native to the Mae Klong watershed in western Thailand and the Ataran River, an affluent of the upper Salween basin flowing into Myanmar from Kanchanaburi province, Thailand.

Occurrences of ‘A. rubidipinnis‘ from the Hanthayaw River, another Salween tributary originating in Tak province, Thailand, presumably pertain to A. pictilis as well, but this remains to be confirmed. In Thailand the Ataran and Hanthayaw are known as the Kasat and Suriya, respectively.

A. pictilis can be told apart from congeners by colour pattern comprising dark brown, triangular-shaped, saddle-like markings in the upper half of the body, the anterior of which are strongly slanted, becoming straighter posteriorly. In large adults the saddles may be split and appear as two bars with a lighter interspace between, as in the specimen pictured.

It’s further distinguished by the following combination of non-unique characters: lateral line complete; 12½ or 13½ branched dorsal-fin rays; 8+8 or 7+8 branched caudal-fin rays; presence of suborbital slit in males; caudal-fin with 6–8 vertical lines or rows of spots; dorsal-fin with 6–7 longitudinal lines or rows of spots.

The former subspecies A. rubidipinnis mandalayensis is also considered valid as A. mandalaysensis and will be discussed further in an upcoming paper.

A. rubidipinnis is apparently restricted to the lower Irrawaddy River basin in Myanmar and differs from A. pictilis in possession of 14½ or 15½ branched dorsal-fin rays, a suborbital flap in males, and colour pattern comprising a series of blackish, vertically-elongated blotches on the lateral line with brown saddles on the dorsal surface which may or may not be connected to the lateral markings.

For more information please refer to the paper Kottelat, M. 2012. Acanthocobitis pictilis, a new species of loach from Myanmar and Thailand (Teleostei: Nemacheilidae). Zootaxa 3327: 45-52. The abstract is available here and we’ve also updated our profile of the species.