A new polyploid species of Mimosa (leguminosae, mimosoideae) from the highlands of Southern Brazil

Abstract

Mimosa tucumensis (Leguminosae), a new species from M. sect. Mimosa ser. Mimosa subser. Mimosa is described and illustrated. This taxon is found in southern Brazil (Paran State), in "campos de altitude," an environment different from the typical habitat of other entities in this subseries. Mimosa tucumensis is morphologically close to M. debilis, M. velloziana, and M. sensibilis, but differs from these principally by the presence of humifuse stems with adventitious roots, considerably longer petioles and peduncles, and foliar venation. In addition, cytological characterization of this new taxon is provided and discussed in relation to the nearest species. This taxon appears to be narrowly restricted to grasslands on a handful of closely adjacent peaks in the Paran State adding to the notable endemism of this area. On the basis of morphological, cytological, and geographical data, some evolutionary considerations are inferred.