Mimosa orthocarpa Spruce ex Benth

32. * Mimosa orthocarpa Spruce ex Benth

The occurrence of Mimosa orthocarpa in Bolivia represents a surprisingly large range extension for a species previously unrecorded from south of the Amazon and known to Barneby (1991) from the Amazon, northern South America and parts of Central America. Several collections ( J.R.I. Wood et al. 22861, LPB, K, USZ, J.R.I. Wood & D. Soto 27134, LPB, K, USZ and D. Villarroel et al. 2046, USZ) from two disjunct localities in Bolivia—ca. 50 km S of Concepcion (Las Trancas and El Encanto), and Cerro Mutún, German Busch—can be attributed here. Mimosa orthocarpa is characteristic of granite rock platforms, particularly in the Lomerio area, a habitat also mentioned by Barneby (1991) in his notes on this species from northern South America. The species is morphologically close to and easily confused with M. tobatiensis Barneby & Fortunato, another species here newly documented for Bolivia (see below). These two species, distinguished by details of leaflet venation, indumentum, and pod shape ( M. orthocarpa with larger, more robust and almost linear pods cf. the slightly falcate chartaceous pods of M. tobatiensis) and previously considered to be remotely allopatric putative sister species ( Barneby 1991), are thus now known to co-occur in Bolivia.