Molecular systematics of the neotropical genus Psiguria (Cucurbitaceae): Implications for phylogeny and species identification.

Varying morphological features in many groups of tropical vines confound identification, requiring molecular tools for distinguishing species. Confusion is amplified in Psiguria, a small genus found in Central and South America and the Caribbean, because male and female flowers of these monoecious plants are widely separated by time and position on a branch. We present the first phylogeny of Psiguria utilizing a combination of eight chloroplast intergenic spacers, the internal transcribed spacer (ITS) regions of the nuclear ribosomal DNA repeat, and the intron of the low-copy nuclear gene serine/threonine phosphatase, for a total aligned length of 9456 base pairs. Analyses include multiple accessions of all species in the genus. The data support the monophyly of Psiguria and elucidate several species boundaries. Also presented are Psiguria-specific DNA barcodes, which include the chloroplast regions: ndhC-trnV, rps16-trnQ, rpoB-trnC, ndhF-rpl32, and psbZ-trnM. For the first time, systematists, ecologists, and evolutionary biologists will have the tools to confidently identify species of Psiguria with DNA barcodes that may be useful in other genera of Cucurbitaceae.