Four new fish genera created in Rasbora split

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A study of the phylogeny of the cyprinid genus Rasbora by scientists based in the Naturhistoriska Riksmuseet in Stockholm has resulted in the erection of four new genera for some of its members.

Te Yu Liao, Sven Kullander and Fang Fang have published the results of a phylogenetic study of Rasbora in the most recent issue of the journal Zoologica Scripta, where they analyzed 41 characters in 29 species of Rasbora, as well as representatives of genera recently split from Rasbora (Boraras, Rasboroides and Trigonostigma) and Horadandia.  

The authors found the genus Rasbora as currently understood to be non-monophyletic and in order to maintain the monophyly of Boraras, Trigonostigma, Horadandia, Rasboroides and Rasbora, four new genera: Brevibora, Kottelatia, Rasbosoma and Trigonopoma are recognized.  

These four new genera are chiefly distinguished by osteological characters.

Brevibora
Named after the relatively few predorsal vertebrae characteristic of this genus (Latin brevis=short and -bora from Rasbora), this genus consists of only one species, B. dorsiocellata (although R. macrophthalma is the only other species that should be assigned to this genus should it be proven to be a valid species). 

Brevibora is distinguished from other rasborins in having a rectangular palatine process lacking a projection and with a narrow base, a black blotch in the middle of dorsal fin, and fewer (8–9) predorsal vertebrae.

Kottelatia
Named after Swiss ichthyologist Maurice Kottelat, this genus includes only a single species (K. brittani).  

Kottelatia is distinguished from other rasborins in having a slender palatine process with a narrow base, very elongate and without a projection, enlarged coronoid process and the lack of a plate-like anteroventral expansion on the dentary.

Rasbosoma
Named after its general resemblance to Rasbora (from Rasbora and the Greek soma=body), this genus includes only one species (R. spilocerca).  

Rasbosoma is distinguished from other rasborins in having the tip of the outer arm of suspensorium bent inward, forming a short horizontal process.

Trigonopoma
Named after the triangular shape of the opercle (Greek trigonos=triangle and poma=lid) that distinguishes members of this genus from other rasborins, this genus includes two species: T. gracile (formerly Rasbora gracilis) and T. pauciperforatum (formerly Rasbora pauciperforata).

For more information, see the paper: Liao, T-Y, SO Kullander & F Fang (2010) Phylogenetic analysis of the genus Rasbora (Teleostei: Cyprinidae). Zoologica Scripta 39, pp. 155–176.