Nomenclatural Changes in the Genus Mimosa (Fabaceae, Mimosoideae) in Southern Mexico and Central America

Abstract

As a result of a taxonomic study of the genus Mimosa L. for Flora de Nicaragua, Flora Mesoamericana, and Flora de M6xico, six new combinations at the infraspecific level, two new names at the specific level, and two changes of series category at the supraspecific level, are herein proposed. These taxa occur mainly in southeastern Mexico (states of Veracruz, Tabasco, Oaxaca, Chiapas, and the Yucatan Peninsula) as well as in Central America. RESUMEN. Como uno de los resultados del estudio taxon6mico del g6nero Mimosa L. para la Flora de Nicaragua, la Flora Mesoamericana y la Flora de MLxico, se proponen seis combinaciones nuevas a nivel infraespecffico, dos nombres nuevos a nivel especifico, asf como dos cambios en la categorfa de serie a nivel supraespeciffico, para los taxa existentes principalmente en el sureste de M6xico (estados de Veracruz, Tabasco, Oaxaca, Chiapas y la Peninsula de YucatAn) asf como en Centroam6rica. The genus Mimosa is characterized by biparipinnate leaves; haplostemonous or diplostemonous flowers, these disposed in capitate or spicate inflorescences; and articulate or unarticulate legumes with persistent margins. It comprises 480 to 500 species, of which 90% are American with the rest distributed in Africa and Asia. Most of the diversity is found in the tropics as well as in arid and semiarid regions at elevations from sea level up to 2250 m. Several species grow in temperate areas at 2000-2750 m (Grether, 1978; Lewis & Elias, 1981; Barneby, 1991). A taxonomic treatment of the genus for Flora Mesoamericana included 47 species with 28 varieties (Grether, 1997). In Nicaragua, 19 (40%) of these species have been found. Mexico is considered the second distributional center of the genus after Brazil: 100 to 110 species are known to occur in the country, and about 60% of them are endemic to different regions of it (Grether & Martfnez-Bernal, 1996). According to Barneby (1991), the genus in the New World comprises five sections: Mimadenia, Habbasia, Batocaulon, Calothamnos, and Mimosa; each of these includes series. Section Mimosa has been divided into three series, and series Mimosa into 37 subseries. The aim of this paper is to formalize and validate new combinations, new names, synonymies, and lectotypifications at the series, species, and variety level to accompany the taxonomic treatment of Mimosa in Flora de Nicaragua, Flora Mesoamericana, and Flora de Maxico. 1. Series Acantholobae Barneby Series Acantholobae is characterized by shrubby or arboreous species with lanceolate-oblong, oblong, or elliptic legumes, these 1-2.5 cm wide and with entire valves; the inflorescences are capitate or spicate. The group mainly occurs in Mexico and Central America, although Mimosa acantholoba (Humboldt & Bonpland ex Willdenow) Poiret var. acantholoba extends to Ecuador and Peru. Barneby (1991) considered series Acantholobae to comprise five varieties of M. acantholoba. Within this species, he accepted variation of inflorescences from globose to subglobose capitula or spikes and variation of legumes from lanceolate-oblong to oblong or elliptic, with valves glabrous, setose, or echinate. However, he described M. seticuspis as a distinct species. Within series Acantholobae, the following new combinations are proposed: Mimosa acantholoba (Humboldt & Bonpland ex Willdenow) Poiret var. seticuspis (Barneby) R. Grether, comb. et stat. nov. Basionym: Mimosa seticuspis Barneby, Mem. New York Bot. Gard. 65: 109. 1991. TYPE: El Salvador. Depto. Santa Ana: 15 km W of Metapan on low-lying ground N of Lago de Guija, 22 Feb. 1989, C. E. Hughes 1256 (holotype, NY; isotype, MEXU). In my opinion, this taxon should be treated at the infraspecific level because of its capitate inflorescences. The main difference with Mimosa acantholoba var. acantholoba is the narrower legume, NovoN 10: 29-37. 2000. This content downloaded from 157.55.39.11 on Fri, 25 Mar 2016 08:10:01 UTC All use subject to http://about.jstor.org/terms