Phylogenetic Systematics of the Cyprinid Genera Mylopharodon and Ptychocheilus: Comparative Morphometry

Phylogenetic relationships among the western North American cyprinids Mylopharodon conocephalus and the four species of Ptychocheilus-P. grandis, P. lucius, P. oregonensis, and P. umpquae-were estimated from the perspective of an outgroup species, Hesperoleucus symmetricus. Canonical variate analysis (CVA) of 46 morphometric measures yielded scores that had group bivariate prediction ellipses with minimal overlap among species (95% prediction interval). These measures also indicated large phenetic differences between P. lucius and M. conocephalus, and other ingroup taxa. Ptychocheilus umpquae from the Umpqua and Siuslaw drainages was easily separable and may warrant recognition as separate taxa. Gap-coding of six counts and 35 measures yielded multistate characters that were then subjected to parsimony analysis. This analysis yielded a single tree with a consistency index of 0.868, with most of the homoplasy associated with P. lucius. The Wagner analysis supported the monophyly of the genus Ptychocheilus and the relationships within the genus of (oregonensis [umpquae (grandis, lucius)]) consistent with a north-to-south pattern of speciation. Given the ages of fossil taxa in the genus and their hypothesized relationships to extant members, the genus evolved prior to the Miocene. No taxonomic changes have been proposed for this group at this time, although additional study of the population currently recognized as P. umpquae inhabiting the Siuslaw drainage is warranted. A key to the species of Ptychocheilus has been provided.