Two New Species of Andira (Leguminosae) from Brazil and the Influence of Dispersal in Determining Their Distributions

Abstract

Andira contains approximately 30 species of trees and shrubs distributed throughout tropical America, with one in Africa. It is characterised by unusual drupaceous fruits and is one of the few genera of papilionoid legumes with fleshy fruits dispersed by vertebrates (Janzen, 1981). The majority of Andira species (such as A. cordata, described here) have fruit which rarely exceed 6 cm in length, are green or occasionally yellow when ripe, have a strong, sweet scent and a fibrous mesocarp. These fruit are dispersed by bats of the family Phyllostomidae Uanzen et al., 1976), probably of subfamilies Stenodermatinae and Phyllostominae, because these are the only neotropical fruit bats that are large enough to carry fruits of the size and weight of those of Andira (Emmons, 1990). Some of these bat-dispersed species such as A. inermis (W. Wright) DC, A. surinamensis (Bondt) Splitg. ex Pulle and A. anthelmia (Vell.) J. F. MacBr., may also be dispersed by water because they are often associated with riparian or lacustrine habitats. Other species of Andira (such as A. carvalhoi, described here) possess fruits that reach 12 cm in length, and weigh as much as 350 g (R. T. Pennington, unpublished data). This exceeds the 100 g estimated maximum weight that the largest neotropical fruit bats can carry (Fleming, 1986). These large fruits lack the strongly scented, fibrous mesocarp characteristic of the bat-dispersed fruits and they possess the "dry, large seeded, nut-like, green or brown, dehiscent or indehiscent" morphology described by van Roosemalen (1985: XVII) as characteristic of fruits dispersed by large rodents such as agouti (Dasyprocta spp.) and acouchy (Myoprocta spp.). Therefore, it appears likely that large Andira fruits are distributed by large rodents, which are important dispersers of large fruits in the neotropics (Emmons, 1990). However, their dispersal has never been directly observed.