A new genetic study has shown that the Cobitis striata complex of loaches from Asia is monophyletic.
A team of Japanese and Korean ichthyologists studied the mitochondrial DNA (mtDNA) of a number of different populations of cobitine loaches in the Cobitis striata complex to determine how they were related to each other and to other loaches.
The results, which have just been published in the journal Ichthyological Research, provide evidence to suggest that the striata complex is monophyletic - all of the fish in the group evolved from a single ancestor - and that they all evolved in northeastern Asia.
The striata complex, which includes C. lutheria and C. tetralineata and a number of races in Japan which are considered subspecies, all have a characteristic dark stripe running along their flanks and reach an adult size of around 10cm/4".
For some time the Cobitis striata group has been considered to be closely related to taenia, which occurs in Europe and Asia.
However, this new research disproves this theory and has shown that there is, in fact, no sister-relationship with taenia.
For more details see the paper: Kitagawa, T., Jeon, SR., Kitagawa, E., Yoshioka, M., Kashigawa, M and T Okazaki. (2005) - Genetic relationships among the Japanese and Korean striated loach complex (Cobitidae: Cobitis) and their phylogenetic positions. Ichthyological Research, Vol. 52, No. 2. pp 111-122.