Two New Taxa of Mimosa (Leguminosae) from Oaxaca, Mexico

Abstract

Two new taxa of Mimosa from the Isthmus of Tehuantepec, Oaxaca, M6xico are de- scribed and illustrated. Mimosa torresiae is assigned to sect. Habbasia Benth. series Rubicaules Benth. and is closely related to M. leucaenoides Benth. The new variety, Mimosa antioquensis var. isthmensis is disjunct from var. antioquensis, which occurs in Colombia. Oaxaca, Mexico, has a great diversity of Mi- mosa species. About 45% of the mimosas occur- ring in Mexico have been collected in this state (Grether 1978). They occur in different primary vegetation types as well as in secondary vege- tation, at altitudes from sea level to 2500 m. Extensive collections by Mario Sousa and col- laborators for over a decade have resulted in the description of many new taxa of legumes, adding to important collections of others in the past, such as those made by Conzatti, Liebmann, and Galeotti. Correct names and synonymies for 16 species of Mimosa occurring in Oaxaca have been pub- lished (Grether 1987), and four new taxa have been discovered: Mimosa sousae R. Grether (se- ries Sensitivae), which was described from the region of Salina Cruz in the Isthmus of Te- huantepec and seems to be endemic to this area (Grether 1981); Mimosa albida Humb. & Bonpl. ex Willd. var. pochutlensis R. Grether (series Sen- sitivae) described from the region of Pochutla (Grether 1982); and the new species and variety described herein, also from the Isthmus of Te- huantepec.