Phylogenetic Relationships Among Species of Phillipsia Inferred from Molecular and Morphological Data

Abstract

The internal transcribed spacers (ITS) of the nuclear ribosomal DNA have been sequenced from 29 collections of <i>Phillipsia</i>, mainly from the New World. The <i>P domingensis</i> complex, collections with a range of colors but otherwise referable to <i>P domingensis</i> s.l. based on spore ornamentation, were studied. Three distinctive species of <i>Phillipsia</i> also were included. The sequences were analysed to infer phylogenetic relationships within <i>Phillipnsia</i>, using parsimony. Morphological features were studied separately, and then evaluated in the context of the ITS phylogeny. Four distinct rDNA lineages, supported by ascospore ornamentation, were identified: the <i>P. crispata</i> the <i>P. domingensis</i>, the <i>P. olivacea</i> and the <i>P. carnicolor</i> lineages. SEM photographs of the ascospores are presented. <i>Phillipsia lutea</i> and another yellow form were nested within the <i>P. dominagensis</i> complex, of those with reddish hymenial colors. Color has been emphasized in taxonomy of <i>Phillipsia</i>, but these results suggest that individuals with strikingly different coloration may be closely related. Levels of ITS sequence divergence in the <i>P. domingensis</i> lineage were low. Based on these data, and morphology as studied thus far; there is no justification for recognizing segregate species within the <i>P. domingensis</i> complex. The Old World collections of the <i>P. domingensis</i> complex were nested within the New World collections, which implies that the <i>P. domingensis</i> lineage is geographically widespread. <i>Phillipsia rugospora</i> is plated in synonymy with <i>P. olivacea</i> and a detailed description of this taxon is given. A lectotype is designated for <i>P. olivacea</i>.