A New Species of Macrolobium (Fabaceae: Caesalpiniodeae) from Mesoamerica

MESOAMERICAIn the course of botanical exploration in the region of Cerro Coronel in northeastern Costa Rica in 1986 and 1987, botanists from the Missouri Botanical Garden and the Museo Nacional de Costa Rica made many collections from this isolated group of low rolling hills.Two species of Macrolobium were collected, M. costaricense W. Burger and an undescribed and closely related one which is here named in honor of Gerardo Herrera, an astute and energetic Costa Rican botanist and co-collector of the type gathering.In the last revision of the genus Macrolobium (Caesalpinioideae-Amherstieae) Cowan (1953) recognized 48 species.Since then, 22 additional species have been added, 19 of them by Cowan, the majority from previously unexplored areas of Venezuelan Guayana (TROPICOS, 1989).Macrolobium is considered to be wholly neotropical, the African taxa previously considered as part of the genus having been relegated mostly to the African genera Gilbertiodendron and Anthonotha by J. Léonard (see Cowan & Polhill, 1981).Of the 25 genera recognized for the tribe Amherstieae, only Macrolobium and Dicymbe are native to the New World.Although not a single Costa Rican specimen of Macrolobium was known to Cowan in 1953, two species from that country have since been described by Burger (1968) and Cowan (1985), M. costaricense and М. hartshornii, respectively.Both of these species, as well as the new taxon described herein, are members of sect.Stenosolen Harms and have leaves with few to many pairs of leaflets.Other closely related species are M. trinitense Urban from Trinidad, M. stenosiphon Harms of Pacific coastal Colombia and adjacent Ecuador, and М. colombianum (Britton & Killip) Killip, with six varieties, in northwestern South America and Panama.