Psiguria Arn. is a small genus of Neotropical vines in the Cucurbitaceae that
grows in both wet and dry tropical forests from southern Mexico to Paraguay, and on
Caribbean islands. The genus is estimated to be very young with natural history
characteristics that have contributed to confusing species circumscriptions. The unique
relationship of plants in the group with their butterfly pollinators makes Psiguria an
interesting and important genus in tropical ecosystems. Both molecular and
morphological approaches were used to investigate the monophyly of Psiguria, to
elucidate the number of species in the genus, to discover sister relationships, and to
identify characteristics for delineating species. Toward that end, an intensive screening
of 141 primer combinations in search of phylogenetically informative low-copy nuclear
markers was conducted along with a molecular phylogenetic analysis and a complete
taxonomic revision of Psiguria. From the screening study, three potentially
phylogenetically informative low-copy nuclear markers were discovered for Psiguria, 11
were found to be potentially useful in rosids, and 32 in other angiosperms. DNA sequences for eight chloroplast intergenic spacers (ndhF-rpL32, ndhC-trnV, rps16-trnQ,
trnS-trnG, psbZ-trnM, psbM-trnD, rpoB-trnC, and psbE-petL), ITS, and the nuclear
serine/threonine phosphatase intron were obtained for 70 samples of Psiguria plus 14
outgroups. Phylogenetic analyses support the monophyly of Psiguria and a sister
relationship between P. umbrosa and P. warscewiczii. In the final chapter, two reviews
on the genus are presented – one encapsulating the nomenclatural history, and one
summarizing 35 years of ecological and natural history studies. In addition,
morphological characters were databased, descriptions were written, and maps of
geographic distribution were produced for all species. Considering both molecular and
morphological data, six species of Psiguria are defined. To distinguish those species
missing identifiable morphological characters, a set of DNA barcodes was developed. At
least four chloroplast regions are required to differentiate species (ndhC-trnV, rps16-
trnQ, rpoB-trnC, and ndhF-rpL32). Because of the absence of many morphological
characters, two taxonomic keys are presented – one using male flowers, and the other
using the set of DNA barcodes along with consistent leaf characteristics and geographic
distribution. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/6657 |
| Date | 23 October 2009 |
| Creators | Steele, Pamela Roxanne |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Format | electronic |
| Rights | Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. |
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