Phylogenetic position of the genus Bibarba as revealed from molecular genetic data (Teleostei: Cobitidae)

Phylogenetically, the family Cobitidae consists of an assemblage of lineages that are referred to as 'southern lineages', out of which stems a monophyletic bunch of lineages that is referred to as 'Northern Glade'. Up to now, 17 of the 21 valid genera have been included into genetic phylogenies. The present phylogenetic study analyses the only two known species of Bibarba using nuclear and mitochondrial DNA sequences. Both species together formed a monophyletic lineage that is sister to the Northern Glade of Cobitidae, but well-separated from the four other major lineages within the Northern Glade. The results support the validity of the genus and show it to represent a major lineage on its own. The morphological synapomorphy of the northern Glade is in the sexual dimorphism, with males bearing an ossified structure (lamina circularis or scale of Canestrini) on the second branched pectoral-fin ray in males. Bibarba was reported to have such structure on the third instead of second fin ray, but our observations reveal the presence of two lamina circularis, one on the second and one on the third fin ray (character doubling). Due to the presence of this synapomorphy in Bibarba and its distribution in the area of the Northern Glade we consider Bibarba as member of the Northern Glade. This Glade is enlarged by Bibarba forming a fifth major lineage.