NOVON 15: 282–285. 2005. Ditassa obscura (Apocynaceae: Asclepiadoideae, Asclepiadeae), a New Combination from Minas Gerais State, Brazil Maria Ana Farinaccio Departamento de Bota ˆnica, Instituto de Biocie ˆncias, Universidade de Sa ˜o Paulo, Caixa Postal 11461, CEP 05422-970, Sa ˜o Paulo, SP, Brazil. mafarinaccio@hotmail.com Tatiana U. P. Konno Instituto de Bota ˆnica de Sa ˜o Paulo, Divisa ˜o de Fitotaxonomia, Sec ¸a ˜o Curadoria do Herba ´rio, Av. Miguel Este ´fano 3687, Caixa Postal 4005, CEP 04301-012, Sa ˜o Paulo, Brazil. tkonno@uol.com.br ABSTRACT. Ditassa obscura (E. Fournier) Farinac- cio & T. U. P. Konno (Apocynaceae: Asclepiadoi- deae, Asclepiadeae), a new combination from Mi- nas Gerais State, Brazil, is proposed, and its relationships are discussed. Key words: Apocynaceae, Asclepiadeae, Ascle- piadoideae, Brazil, Ditassa, Minas Gerais, Neotrop- ics. Ditassa R. Brown is a Neotropical genus of the large tribe Asclepiadeae (Asclepiadoideae, Apocy- naceae), containing approximately 100 species (Konno & Fontella-Pereira, 2004). It is one of the most species-rich genera in Brazil, with a center of diversity in the states of Bahia and Minas Gerais (Fontella-Pereira et al., 1987, 1989; Rapini et al., 2001; Farinaccio & Mello-Silva, 2004a). The genus has a problematic delimitation (Fari- naccio & Mello-Silva, 2004a, 2004b), but can usu- ally be recognized by its subaxillary umbelliform cymes and flowers with a double corona, in which the outer segments are united at least at the base. During the preparation of a monograph of the subfamily Asclepiadoideae for the Serra da Can- astra National Park, in the state of Minas Gerais, southeastern Brazil (Farinaccio & Mello-Silva, 2004a), a specimen came to light that exhibited the same set of characters as the type collection of Me- tastelma obscurum E. Fournier. Its clear affinity with Ditassa tomentosa (Decaisne) Fontella, espe- cially in relation to floral morphology and also veg- etative features such as indument and leaf venation, justify its transfer to Ditassa (Fontella-Pereira, 1979). Therefore, we propose the new combination Ditassa obscura (E. Fournier) Farinaccio & T. U.P. Konno. Ditassa obscura (E. Fournier) Farinaccio & T. U. P. Konno, comb. nov. Basionym: Metastelma obscurum E. Fournier, in Martius, Fl. Bras. 6(4): 208. 1885. TYPE: Brazil. ‘‘In prov. Min- arum in Serra de Araxa,’’ s.d., St. Hilaire C1- 449 (holotype, P). Figure 1. Vines, densely tomentose; leaves opposite, pat- ent; petiole 2–7 mm long, somewhat sulcate, dense- ly tomentose; leaf blade 2–4.7  0.6–1.5 cm, el- liptic to obovate, apex acute, mucronate, base cuneate, discolorous, opaque, chartaceous, adaxial surface tomentose, abaxially pubescent, margins strongly revolute, venation brochidodromous, mid- rib abaxially prominent, secondary veins conspic- uously parallel, approximately perpendicular to the midrib, 2 to 4 colleters at the base on the adaxial side; inflorescence subaxillary, glomerulate, alter- nate, 5- to 10-flowered, erect; peduncles 0.3–1 mm long, densely tomentose, bracts 1.1–1.5  0.2–0.6 mm, lanceolate, abaxial surface tomentose, adaxial surface glabrous. Pedicel 0.3–0.5 mm long, tomen- tose. Calyx light green to green, lobes 1.7–2  0.55–0.6 mm, lanceolate to ovate, apex acuminate, abaxial surface tomentose, adaxial surface gla- brous, with 1 colleter present below each sinus; corolla white to cream, subcampanulate, tube 0.7– 0.75 mm long, abaxial surface glabrous, adaxial surface barbellate, glabrous only in the proximal region; lobes 1.5–2  0.7–0.95 mm, ovate, erect, recurved from about the middle, apex acute, ab- axial surface glabrous, adaxial surface incanous-se- riceous, barbellate in the proximal region, margins hyaline; corona white to cream, in 2 series: outer corona with 5 lobes joined at the base or free, not attached to the corolla tube, each lobe 0.64–0.8  0.35–0.4 mm, oblong to ovate, asymmetric, apex cuspidate, apiculate to unguiculate, shorter than the gynostegium; inner segments strongly reduced