Two New Species of Hybanthus (Violaceae) from Central America and a Regional Key for the Genus

Abstract

Two morphologically and ecologically distinctive, woody Hybanthus species from Central America are described, illustrated, and mapped. Hybanthus denticulatus inhabits lowland rainforest from northern Nicaragua to eastern Panama and is allied to Mexican and Guatemalan H. elatus. Hybanthus hespericlivus is restricted to mid-elevation forest on the western mountain slopes of northern Costa and resembles Panamanian H. jefensis and northern Mesoamerican H. sylvicola. A key to Central American species of Hybanthus is provided. Systematic and nomenclatural studies of Mexican and Central American Violaceae for several flora projects, including the Manual de Plantas de Costa Rica and Flora Mesoamericana, have resulted in the discovery of two new species of Hybanthus commonly misidentified as H. guanacastensis Standley, a species of higher-elevation forest in northern and eastern Costa Rica. Both new species resemble H. guanacastensis and other members of Hybanthus subg. Hybanthus in their woody habit and axillary short shoots with one or more peduncles. However, their strongly zygomorphic flowers, with the bottom petal at least twice as long as the lateral and upper ones and strongly differentiated into a slender claw and greatly expanded blade, and free filaments of the stamens, suggest instead an alliance to subgenus lonidium (Ventenat) Schulze-Menz. The infrageneric relationships of the new species are as yet unresolved. Morton was the last to revise the genus Hybanthus in Mexico and Central America, through synoptical and piecemeal efforts (Morton, 1944, 1971). While he initially provided a pared-down key for herbaceous and semi-herbaceous species that he recognized in 1944, he left out woody shrubs and treelets in this earlier key and never published a more inclusive key in subsequent works in which he recognized additional species of Hybanthus. Exacerbating the situation are several names used in publications by Morton and his contemporaries that the first author has determined are synonyms. Since Morton's time, no single key or taxonomic resource has been available for Hybanthus species of Mexico and Central America. Consequently, approximately 25% of Hybanthus specimens from this region are misidentified. A treatment of Hybanthus for the entire region will be published in Flora Mesoamericana several years in the future. In the interim the following key will facilitate identification of dried flowering Central American specimens of Hybanthus. Synonyms in brackets represent names recognized as distinct species by Morton (1944, 1971). KEY TO THE SPECIES OF HYBANTHUS IN CENTRAL AMERICA la. Stems predominantly or entirely herbaceous; plant 0.1-0.5 m tall. 2a. Corollas 20-35 mm long; sepal margins dentate; plant densely and coarsely long-hirsute throughout H. calceolaria (L.) Schulze-Menz 2b. Corollas 9-17 mm long; sepal margins entire; plant glabrous or pubescent but not densely and coarsely long-hirsute throughout. 3a. Leaf blades 3.2-8.0 times as long as broad; at least the lowest leaf nodes opposite (lower leaves deciduous on H. attenuatus). 4a. Upper leaves alternate; leaf blades broadly lanceolate, widest at middle, tapering gradually to a cuneate or slightly convex base . . . H. attenuatus (Humboldt & Bonpland) Schulze-Menz NovoN 7: 221-226. 1997. This content downloaded from 207.46.13.114 on Thu, 26 May 2016 06:03:16 UTC All use subject to http://about.jstor.org/terms