A new species of Elvasia, E. bisepala, is described from Belize and Honduras. Elvasia bisepala possesses unique characters that help to clarify subgeneric classification in the genus and further expands the distribution of Elvasia from South America well into Central America. The new species is described and illustrated, and the subgeneric classification of Elvasia is reviewed and revised. The genus Elvasia has previously been considered to be exclusively South American and concentrated in the Amazon basin and the Guianas (Sastre & Lescure, 1978; Sastre, 1987), with a single species occurring in Bahia, Brazil (E. tricarpellata Sastre), and another recently collected in Panama and Costa Rica (E. elvasioides (Planchon) Gilg; pers. obs.). Currently there are 11 (including the new species described here) accepted species in the genus, which is distinguished from the rest of the Ochnaceae in the Neotropics by the uniovulate carpels that are united in fruit. During a review of material for the preparation of the Ochnaceae account for Flora Mesoamericana, a distinctive new species of Elvasia was found among recent collections from Belize and Honduras. The discovery of this taxon has clarified some previously ambiguous points about the infrageneric classification and biogeography of the genus. Infrageneric classification in Elvasia has been based primarily on either stamen number and ovary morphology or fruit characteristics. Planchon (1846) divided the genus into two subgenera: subg. Euelvasia Planchon with 8 stamens and a 4-locular ovary, and subg. Hostmannia Planchon, with 1820 stamens and a bilocular ovary. This same basic division was followed in Engler (1876). Van Tieghem (1902) elevated the genus to the rank of subfamily, and divided it into two tribes using fruit characteristics, the Elvasieae with star-shaped fruits and the Hostmannieae without star-shaped fruits. Gilg (1893, 1925) more or less followed earlier floral-morphology-based schemes in dividing the genus into two sections: sect. Euelvasia with 8 stamens (including E. calophyllea DC. & E. quinqueloba Spruce ex Engler) and sect. Hostmannia with 18-20 stamens (including E. hostmannia (Planchon) Gilg & E. essequibensis Engler). Revising the genus throughout its range, Dwyer (1943) described three sections based on various combinations of ovary locule and stamen number: sect. Euelvasia with 7-10 stamens and a 4-5-locular ovary (E. calophyllea, E. quinqueloba, and E. canescens (Van Tieghem) Gilg), sect. Eussequibensa Dwyer with 10-20 stamens and a 4-5-locular ovary (E. essequibensis and E. brevipedicellata Ule), and sect. Hostmannia with variable numbers of stamens and a bilocular ovary (E. elvasioides (Planchon) Gilg and E. caurensis Pittier). Cowan (1952) described E. sphaerocarpa, which he postulated was closely related to E. essequibensis. Due to its globose, unlobed fruit, he erected a new section for it, section Conjunctipora Cowan. Additional new species (Cuatrecasas, 1950; Sastre & Lescure, 1978) can be accommodated in Dwyer's subgeneric classification, with both E. macrostipularis Sastre & Lescure (closely related to E. sphaerocarpa but with only 2 carpels) and E. oligandra Cuatrecasas being placed in section Hostmannia. Placement of Elvasia tricarpellata Sastre (Sastre, 1981), with its 3-carpellate ovary and 10-15 stamens, in Dwyer's classification is problematic. With the discovery of E. bisepala, described here, a simpler and less ambiguous subgeneric classification of the genus Elvasia can be proposed with two sections: section Elvasia (= Euelvasia), characterized by star-shaped fruits, and section Hostmannia (Planchon) Gilg, characterized by globular fruits. The component species in each section, with their NovoN 9: 253-256. 1999. This content downloaded from 157.55.39.173 on Thu, 19 May 2016 05:43:20 UTC All use subject to http://about.jstor.org/terms