It is currently the only valid member of the genus but it is possible that additional taxa exist, particularly in Myanmar, while a number of former species are contained within the Laubuka assemblage, to which C. cachius is closely related. Phylogenetic studies suggest the existence of a monophyletic clade consisting of the genera Devario, Chela, Laubuca, Microdevario and Microrasbora plus the genus Betadevario.

The genus Amblypharyngodon currently contains five valid species, and A. chulabhornae can be distinguished from congeners by the following combination of characters: 42-50 (vs. 50-79) scales in the lateral row; lateral line incomplete with 6-7 (vs. 7-23) perforated scales; 4-5 scales on a transverse row between the lateral line and pelvic-fin base. All members of the genus lack barbels.

Apparently endemic to the upper Yangtze River basin, China.

Type locality is ‘mountain-stream fiowing into the Ichang gorge of the Yangtsze River’.

Members of the genus are characterised by possessing a particular number of dark vertical bar on each flank, and A. parallens belongs to a group of species with five or six such bars, each of which is two scales in width. Congeners sharing this pattern include A. fasciatus, A. hemispinus (in juveniles only), A. jishouensis, A. kreyenbergii, A. paradoxus, A. spinifer, A. wenchowensis, and A. wuyiensis.

Recorded from Fujian, Guangdong, and Guangxi provinces in southwestern China, plus the islands of Hainan and Hong Kong.

Type locality is ‘Lian-Xian and Yang-Shan, Guangdong, China’, corresponding to the Bei River drainage.

The genus Acrossocheilus is restricted to southern China, northern Vietnam and northern Laos. It can be distinguished from related genera by the following combination of characters: rostral fold present; lips fleshy and continuous around corners of mouth; lower lip with a median interruption; mouth inferior; horny sheath on lower jaw; two pairs of barbels; last simple ray of dorsal fin osseous with a serrated or smooth posterior margin.

A. iridescens and its closest relative A. longipinnis can be distinguished from all other barred species of Acrossocheilus by the following characters: wider (vs. narrower) black vertical bars on the flank in adults, each five to eight (vs. no more than four) scales in width; a horse-shoe shaped (vs. arched) mouth gape; rostral barbel located posteriorly (vs. anteriorly) to a horizontal line through the anteriormost margin of the lower jaw; two postlabial grooves extending anteromedially beyond (vs. away from) a horizontal line through the roots of the rostral barbels.

Appears to have a disjunct range with records from Pahang state in central Peninsular Malaysia, plus the Mae Klong and Chao Phraya river systems in Thailand, but it has not been recorded in Peninsular Thailand.

Type locality is ‘Pahang River, Kuala Tembeling, eastern slope of Sangka Dua Pass, Malaysia, elevation about 2000 feet’.

Bitterlings (see ‘Notes’) exhibit an unusual spawning symbiosis in which the interlamellar spaces of the paired inner and outer gills of living unionid mussels are used as a spawning substrate.

During the reproductive period females develop a long ovipositor which is used to deposit eggs through the mussel’s exhalant siphon. Males then move in to males release milt…

A. macropterus appears in the ornamental trade on an irregular basis and should only be considered by more experienced aquarists with sufficiently large facilities.

Given its wide geographical distribution there is a possibility that it represents a group of closely-related species, with genetic studies indicating the existence of several distinct clades.