PENNEYS, DARIN S.1*, WALTER S. JUDD1, NORRIS H. WILLIAMS2, and W. MARK WHITTEN2. 1University of Florida, Dept. of Botany, 220 Bartram Hall, Gainesville, FL 32611-8526; 2University of Florida, Florida Museum of Natural History, Dept. of Natural History, P.O. Box 117800, Gainesville, FL 32611-7800. - A cladistic analysis of Charianthus (Miconieae: Melastomataceae) using morphological and molecular characters.
The absence of convincingly delimited monophyletic groups within the
Miconieae is well known to students of the family. The current
revision of Charianthus represents the first genus in the
Miconieae to be the subject of a molecular cladistic analysis.
Molecular data was combined with morphology to analyze hypotheses of
phylogeny within Charianthus using nine additional species as
outgroups. The internal transcribed spacer (ITS) region of 18S – 26S
nuclear ribosomal DNA was sequenced and provided important insights
into the evolutionary relationships of the taxa under investigation.
Each cladistic analysis supports the monophyly of Charianthus
when C. fadyenii is excluded. A combined analysis of the
morphological and molecular data sets resulted in a strongly supported
Charianthus clade with 100% bootstrap and a decay value of 12.
Charianthus fadyenii is in the Tetrazygia clade where
its position as sister to T. bicolor is supported by a bootsrap
value of 89% and decay of three. Inclusion of C. fadyenii in
Charianthus makes both Charianthus and Tetrazygia
non-monophyletic, therefore, this species is transferred to
Tetrazygia. Morphological adaptations to hummingbird
pollination have arisen independently in both Charianthus and
Tetrazygia. Charianthus purpureus, as defined by
previous taxonomists, is a polyphyletic species because of the
inclusion of the populations on the islands of Dominica and Grenada,
thus, two new species must be recognized. Charianthus is a
morphologically well-characterized clade of six species of hummingbird
pollinated shrubs and small trees found in the tropical montane rain
forests and elfin forests of the Lesser Antilles. The revised
circumscription of the group makes it the only plant genus endemic to
the Lesser Antilles. Ongoing studies will continue to concentrate on
the implementation of a phylogeny based on sequence data of both a
nuclear gene (ITS) and a chloroplast gene (trnL-F, matK,
or GBSSI) for all genera of Miconieae.
Key words: Charianthus, ITS, Lesser Antilles, Melastomataceae, Miconieae, morphology