GRANT1, JASON R.* AND LENA STRUWE2. 1 Laboratoire de phanérogamie, Institut de botanique, Université de Neuchâtel, ch. de Chantemerle 18, 2007 Neuchâtel, Switzerland, 2 The Lewis B. & Dorothy Cullman Program for Molecular Systematics Studies, The New York Botanical Garden, Bronx, NY 10458 USA. - Morphological evolution and neotropical biogeograpy in Macrocarpaea (Gentianaceae: Helieae).
The genus Macrocarpaea consists of 50-60 species of herbs,
shrubs (some epiphytic), and small trees restricted to the neotropics.
The majority of its species are distributed in mid- to
upper-elevation rain or cloud forests in the Andes. Additional
species occur in the mountains of southeastern Brazil, the Guayana
Highlands, Central America, and the Greater Antilles. A monographic
treatment of the genus based on over 1500 herbarium specimens on loan
from over 40 different herbaria has been initiated. Nomenclature
problems will be resolved, dozens of new species will be described,
and dubious taxa will be confirmed. Macrocarpaea is one of only
a few genera among that gentians that have hairy leaves in some
species. Scanning electron microscopy studies of indumentum anatomy
will be evaluated and presented. Large micromorphological variation
can also be found in seed and pollen anatomy, as well as in
macromorphological characters. Species level cladistic analyses based
on ribosomal 5s-NTS and nuclear ITS (internal transcribed spacer)
sequences are presented and will eventually be combined with
morphological data. Preliminary molecular data suggests that within
the distribution area of the genus, the most ancestral lineages are
present in the peripheral regions (i.e. Brazil and the Caribbean),
with the Andean species representing more recent and more species-rich
radiations.
Key words: biogeography, evolution, Gentianaceae, Macrocarpaea, molecular systematics, morphology