GRAHAM, SHIRLEY A. Department of Biological Sciences, Kent State University, Kent, OH 44242. - Biogeographic patterns of Antillean Lythraceae.
The Lythraceae are a family of 31 genera of world-wide distribution
growing primarily in wet to moist habitats of the subtropics and
tropics. The family is represented in the Antilles by seven genera and
39 species. Two genera, Ginoria and Haitia, and 21
species are endemic to the islands of the Caribbean. Ginoria
with 14 species and Cuphea with 10-15 species are best
represented. Cladistic analyses place Ginoria in an Afro-Asian
clade as sister to Tetrataxis of Madagascar. The ancestral
route of dispersion to the Caribbean is not clear, although a basal
member of the clade, Lawsonia, is known from the Middle Eocene
of British Columbia, suggesting an ancestral boreotropical route. The
center of origin for Cuphea is most likely eastern South
America. Cuphea has dispersed into the Greater Antilles from
Brazil a minimum of five times and into the Lesser Antilles from
northeastern South America twice. Lythrum and Heimia
have moved to the Antilles from North America. For Rotala and
Ammannia, a boreotropical dispersion route from Asia through
North America to the Caribbean, or oceanic dispersal of seeds from
Africa is equally likely. Seeds of all Antillean Lythraceae are minute
in size and have floats or mucilaginous hairs that enhance chances of
long distance dispersal by wind and water. Vicariance, although it may
have occurred, is not required to explain the distribution of
Lythraceae in the Antilles.
Key words: Antilles, biogeography, Cuphea, dispersal, Ginoria, Lythraceae