Assessment of monophyly of the minnow genus Pteronotropis (Teleostei : Cyprinidae)

The North American cyprinid genus Pteronotropis contains five species distr ibuted in streams and swamps of the Atlantic and Gulf coastal plain. The ge nus is currently recognized even though previous explicitly phylogenetic an alyses have not supported the monophyly of this group. Of particular intere st is the relationship between Pteronotropis welaka and Pteronotropis hubbs i, both of which are nest associates with centrarchids, Although these spec ies are morphologically similar, there is limited support for a sister-grou p relationship between them, We performed phylogenetic analyses of all five species currently recognized in Pteronotropis and five outgroup taxa based on nucleotide sequences of the mitochondrial cytochrome b gene using both parsimony and maximum-likelihood analyses, Pteronotropis hypselopterus and Pteronotropis euryzonus were consistently resolved as sister taxa, as were, P welaka: and P. hubbsi. Pteronotropis signipinnis was sister to the P. we laka plus P. hubbsi clade in likelihood and parsimony analyses when rate va riation at third codon positions was taken into account. However, none of t he analyses resolved a monophyletic group inclusive of all five species. If Pteronotropis is actually a monophyletic group, our inability to resolve i t as such may be a result of sampling of outgroup taxa or the rate of evolu tion in cytochrome b in these taxa, Additional sampling of taxa, particular ly within the genus Notropis is needed to further resolve phylogenetic rela tionships within Pteronotropis and the relationships of the species to othe r North American cyprinid taxa. The sister-group relationship between P. we laka and P. hubbsi indicates a single origin of nest association rather tha n a dual origin as indicated by previous studies.