The relationships of the cobitoid loaches have been examined in a recent study and the familial placement of the genera Barbucca, Serpenticobitis and Vaillantella have been reassigned.
The study by Vendula lechtov, Jrg Bohlen and Heok Hui Tan is published in the latest issue of the journal Molecular Phylogenetics and Evolution.
Utilizing a 903-base pair fragment of the nuclear Recombination Activating Gene 1 (RAG-1), the authors examined the phylogentic relationships of the cobitoid loaches.
Based on their results, five families of loaches are recognized: the Nemacheilidae, Balitoridae, Cobitidae, Vaillantellidae and Botiidae.
The Nemacheilidae now includes loaches previously placed in the subfamily Nemacheilinae (e.g. Nemacheilus, Schistura) within the Balitoridae, while the Balitoridae now consists of loaches previously placed within the subfamily Balitorinae (e.g. Gastromyzon, Balitora, Homaloptera).
Barbucca, a loach from Southeast Asia previously thought to be closely related to nemacheilids, is found to be more closely related to other balitorid loaches, and is reassigned to the family Balitoridae.
Serpenticobitis, a loach from the Mekong River drainage previously thought to be a member of the Cobitidae is also reassigned to the Balitoridae in this study.
Vaillantella is another Southeast Asian loach genus thought to be closely related to the nemacheilids, but is found in this study to be the sister group of all nemacheilid, balitorid and cobitid loaches.
It is therefore reassigned to its own family, the Vaillantellidae.
The study also confirms the distinctiveness of the Botiidae, a family which includes popular aquarium loaches of the genera Botia, Yasuhikotakia and Syncrossus.
All other loaches (e.g. Cobitis, Misgurnus, Pangio, Acantopsis) make up the family Cobitidae.
For more information, see the paper: lechtov, V, J Bohlen and HH Tan (2007) Families of Cobitoidea (Teleostei; Cypriniformes) as revealed from nuclear genetic data and the position of the mysterious genera Barbucca, Psilorhynchus, Serpenticobitis and Vaillantella. Molecular Phylogenetics and Evolution 44, 1358"1365.