Geographical intergradation in Proboscidea parviflora ssp. sinaloensis (Martyniaceae)

Ten characters were analyzed taximetrically to determine if morphological variation in P. parviflora ssp. sinaloensis from coastal Sonora and Sinaloa is geographically correlated. Principal component scores derived from all ten characters were strongly correlated with geographical latitude. The correlation of individual characters with latitude differed; some were uncorrelated but others were highly correlated. This pattern can be the result of introgression between P. parviflora ssp. sinaloensis and P. parviflora ssp. parviflora or primary differentiation along an environmental gradient. Several other angiosperms from Sonora and Sinaloa also displayed geographically correlated variation. The results of this study supported treatment of P. parviflora ssp. sinaloensis, P. parviflora ssp. parviflora, and P. parviflora ssp. gracillima as subspecies.