Morphological and genetic variation in Centrolepis paludicola and C-monogyna (Centrolepidaceae)

Centrolepis paludicola is a small cushion-forming herb which is listed as a n endangered species. However, some taxonomists have questioned its species status and treat it as a subspecies of the common C. monogyna. Morphologic al measurements were taken on plants from 50 cushions collected from 31 sit es throughout Tasmania, and included C. paludicola, C. monogyna and C. fasc icularis as an outgroup to resolve this taxonomic issue. While C. fascicula ris was distinct in all morphological analyses, the sympatric C. paludicola and C. monogyna could not be clearly distinguished on the basis of the rep roductive and vegetative characters that are supposed to separate them. Cen trolepis monogyna is henceforth interpreted as a morphologically variable s pecies which includes C. paludicola. Once it was shown that these are best treated as one species, RAPD molecular markers were used to analyse genetic variation between populations. This analysis revealed a high level of poly morphism between cushions. As in the multivariate analysis of morphological data, C. monogyna and C. paludicola containing cushions were indistinguish able. However, there was a strong geographical structure to the genetic var iation in the C. monogyna/C. paludicola group, consistent with a model in w hich gene flow between populations is limited and local differentiation has occurred.