PHYLOGENY OF LYCOPODIACEAE (LYCOPSIDA) AND THE RELATIONSHIPS OF PHYLLOGLOSSUM-DRUMMONDII KUNZE BASED ON RBCL SEQUENCES

A cladistic analysis based on rbcL sequences from a representative sam ple of 12 species yields a single most parsimonious tree that supports monophyly of Lycopodiaceae, Lycopodium, and Lycopodiella. Huperzia is resolved as paraphyletic to the morphologically divergent, monotypic Australasian Phylloglossum. The Huperzia-Phylloglossum clade is strong ly supported and is sister group to a Lycopodium-Lycopodiella clade. T hese results provide the first clear evidence for the relationships of the problematic Phylloglossum drummondii. Profound differences in lif e cycle and morphology between Phylloglossum and other Lycopodiaceae a re interpreted in terms of pedomorphosis (specifically. progenesis) an d are viewed as adaptive responses to drought and brush fur. Our resul ts show that rbcL sequence divergence among neotropical species of the supposedly ancient genus Huperzia is extremely low and that additiona l levels of sequence divergence indicate that most living species dive rsity within Lycopodiaceae ene is of relatively recent origin. Our res ults are consistent with a late Cretaceous or early Tertiary origin an d diversification of epiphytic species within Huperzia, and three even ts may be linked to the diversification of angiosperms.