Two endemic Rubiaceae genera of the Caribbean, Erithalis P. Browne (Tribe Chiococceae) and Ernodea Swart (Tribe Spermacoceae), are composed of four to eight species, respectively. Each genus contains several species that appear to be single island endemics, in addition to one widespread species that is distributed throughout the Caribbean Basin. The pan-Caribbean species occur sympatrically with species of restricted distribution and/or endemics, and often are intermediate in morphology. The fruits of both genera are fleshy, potentially bird-dispersed, and float on sea water. One chloroplast intergenic spacer of trnF/L, and two nuclear non-coding spacer, ITS & ETS, were sequenced and analyzed phylogenetically for Erithalis. Analyses of the combined data set reveal two weakly supported clades: one consisting of the widespread species E. fruticosa and E. harrisi, and the other clade consisting of all remaining species. The two Jamaican endemic species, E. harrisi & E. quadrangularis, are each placed basally in these two clades. These species occur in the mountains, which suggests a migration to the coast and to other islands. The ITS were sequenced for Ernodea, however the data do not provide sufficient phylogenetic resolution with two exceptions: E. cokeri appears to be distinct and widespread E. littoralis appears paraphyletic. In conclusion, sequence divergence and phylogenetic resolution are low, suggesting that both genera are recently derived.

Key words: biogeography, Caribbean, Erithalis, Ernodea, phylogenies, Rubiaceae