Tradescantia sect. Mandonia D.R.Hunt, Kew Bull. 35(2): 441. 1980.

Pellegrini, Marco O. O., Forzza, Rafaela C. & Sakuragui, Cassia M., 2017, Novelties in Brazilian Tradescantia L. (Commelinaceae), PhytoKeys 80, pp. 1-31 : 9-10

Tradescantia sect. Mandonia D.R.Hunt, Kew Bull. 35(2): 441. 1980.

Diagnosis.

The section is characterized by perennial herbs, with tuberous roots, definite base, without rhizomes, leaves with symmetric or slightly asymmetric base, inflorescences mainly axillary, sessile, cincinni bracts much reduced or rarely leaf-like in the terminal inflorescences, bracteoles inconspicuous, flowers flat, rarely tubular, sepals equal, free, not keeled, petals free, sessile, stamens 6 and equal, free or epipetalous, filaments coiling at post anthesis, medially sparsely bearded with moniliform hairs, connectives quadrangular to rectangular, rarely rhomboid, anther sacs C-shaped, ovary pubescent, stigma truncate to capitulate, seeds scrobiculate to rugose, rarely costate, embryotega conspicuous and dorsal ( Hunt 1980; Pellegrini 2015).

Comments.

Tradescantia sect. Mandonia is a poorly understood group, currently represented by 12 species ( Hunt 1980, 1986b, 2007; Grant 2000, 2004; Zamudio et al. 2013). This section possesses a very interesting disjunctive distribution, being restricted to Seasonally Dry Tropical Forests throughout the Neotropics. Species delimitation is especially complicated in this this group, due to great vegetative plasticity within species, and conserved reproductive features. Most species can be easily identified based on their allopatric distributions, but hardly differentiated based solely on their morphological features (Pellegrini, unpublished data). In South America, T. sect. Mandonia is currently represented exclusively by two species, T. ambigua Mart. ex Schult. & Schult.f. and T. boliviana . Tradescantia boliviana has hitherto been considered exclusive to Argentina, Bolivia, Paraguay, and Peru ( Grant 2004). However, after analyzing several herbaria we came across specimens representing T. boliviana that reached the Brazilian territory, in the state of Mato Grosso do Sul. Thus, we present an identification key differentiating both species, illustrations, a distribution map, and the needed comments and typifications.