SPECHT, CHELSEA D.1,2* and DENNIS W. STEVENSON2. 1New York University, Department of Biology. New York, NY 10003; 2New York Botanical Garden. Bronx, NY 10458. - A Phylogeny of Costaceae: Implications concerning floral morphology.
The phylogenetic relationships of Costaceae, a tropical
monocotyledonous family sister to the gingers (Zingiberaceae), were
investigated with a combination of two chloroplast loci (trnLF and
trnK) and one nuclear locus (ITS1 - 5.8s - ITS2). The resulting
parsimony analysis of selected taxa which demonstrate the range of
floral morphological variation in the family shows that the
Caldavena-type floral morphology is ancestral to the group and that
both Tapeinochilus species and a Monocostus +
Dimerocostus clade represent recent divergences. The genus
Costus is broadly paraphyletic but Costus subgenus
Costus represents a large monophyletic radiation with low
robustness at the species level. Within this clade, secondary analyses
suggest that pollination syndrome, traditionally used for taxonomic
and classification purposes within the genus Costus, is a
relatively plastic trait of limited phylogenetic utility. This
represents the first detailed investigation into intra-generic and
intra-specific evolutionary relationships within the family Costaceae
and presents some novel evolutionary trends with respect to floral
morphology and biogeography.
Key words: Costaceae, floral morphology, phylogenetics