The Genus Ernodea (Rubiaceae) in the Caribbean Basin. II. Morphological Analyses and Systematics

Abstract

The genus Ernodea, consisting of erect or prostrate shrubs, has been thought to consist of nine species, most of which are endemic to the Bahamian Archipelago. The classification of the genus is difficult because the original species descriptions are incomplete and include characters of great plasticity. Addition- ally, reproductive and genetic studies failed to provide evidence to support recognition of distinct species. We measured 30 floral and vegetative characters from samples representing all taxa and distributed across the entire range of the genus to delimit relationships at the specific level and to delineate morphological gaps within the genus. Phenetic analyses involving Principal Component Analysis and Canonical Discriminant Analysis provided consistent separation of two main clusters; each cluster separated into two subclusters. Vegetative characters provided better discrimination than floral characters. In contrast to the current literature, this study recognizes four morphological species: E. cokeri, E. littoralis, E. taylori and E. millspaughii. The morphological and ecological diversity of Ernodea in these islands suggest that there has been rapid divergence associated with adaptive radiation. A key to the species with descriptions and nomenclature is provided.