Botiine loaches deserve own family


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The loaches in the subfamily Botiinae are so distinct that they deserve their own family, says new research.

The results of a new molecular study has suggested that botiine loaches are monophyletic - derived from a common ancestor - and so should be placed in a new family called the Botiidae.

Tang, Xiong, Yang and Liu of the Chinese Academy of Science and Huazhong Agricultural University produced an evolutionary family tree (phylogeny) for the fishes from their mitochondrial ctyochrome b gene sequences.

Their findings, which have just been reported in the journal Hydrobiologia, provide evidence to suggest that there are three botiine loach genera - Botia, Parabotia and Leptobotia, with each one forming a monophyletic group.

Last year, Maurice Kottelat completely reshuffled the botiine loaches into two tribes and seven genera.

In Kottelat's view, the tribe Botiini contains Botia, Chromobotia (the new genus erected for the Clown loach), Syncrossus and Yasuhikotakia, while the Leptobotiini contains Leptobotia, Parabotia and Sinibotia.

However, Kottelat's study wasn't based around a phylogenetic analysis of the relationships of the fish.

However, the three "Botia" used in the study (superciliaris, pulchra and robusta) are Sinibotia under Kottelat's classification.

Tang et al. reckon that their work shows these fishes are in fact a separate monophyletic group within the loaches:

"Our molecular analysis of loaches clearly demonstrates that the botiine fishes constitute a monophyletic group, supporting the previous study by Liu et al. (2002) using different data.

"Additionally, our molecular phylogenetic trees show that botiine loaches are only distantly related to Cobitis and Misgurnus.

"This provides support for the view of Nalbant (2002) to separate the botiine fishes as the family Botiidae but contradicts the classification of loaches proposed by Sawada (1982) who considered that the Botiinae were closely related to the Cobitidae."

For more details see the paper: Tang, Q., Xiong, B., Yang, X. and H. Liu (2005) - Phylogeny of the East Asian botiine loaches (Cypriniformes, Botiidae) inferred from mitochondrial cytochrome b gene sequences. Hydrobiologia (2005) 544: 249-258.