A New Species of Ditassa (Asclepiadaceae) from Espírito Santo, Brazil

Abstract

Ditassa oberdanii, a new species of Asclepiadaceae from remnant patches of Atlantic rainforest in Espirito Santo state, southeastern Brazil, is described, illustrated, and compared to D. oxyphylla Turczaninow, a similar species that is found in Brazil, Colombia, and Venezuela. A survey of the Asclepiadaceae of Espirito Santo, Brazil, turned up 44 species belonging to 16 genera. The largest genus is Ditassa with 11 species, including D. oberdanii. This species is found in remnant patches of lower montane rainforest in southeastern Brazil, in the Atlantic forest biome which is seriously threatened by human activities. Ditassa oberdanii Fontella & Alvarez, sp. nov. TYPE: Brazil. Espfrito Santo: Santa Teresa, Rio Saltinho, 500 m, 26 Apr. 1984, Pizziolo 22 (holotype, MBML; isotype, HB). Figure 1. Species nova D. oxyphyllae Turczaninow affinis, sed imprimis foliis linear-lanceolatis angustioribus, corollae lobis extus glabris et longioribus, caudiculis non geniculatis, polliniis ellipticis vel subellipticis et latioribus differt. Vines; stems hirsute-tomentose. Leaves with flattened petioles, hirsute above, glabrescent beneath, 7-10 mm long; blade linear-lanceolate, glabrous to glabrescent with secondary nerves rectilinear, base cuneate with two glands at petiole juncture, apex acuminate, 61-69 X 10-13 mm. Inflorescence an umbelliform cyme, extra-axillary, 3-6-flowered; peduncles hirsute-tomentose, 1-2 mm. Flowers white; pedicels hirsute, 2-4 mm long. Calyx deeply lobed; lobes ovate-lanceolate, hirsute outside, glabrous inside, margins hyaline, 2-2.5 X 1-1.5 mm, with 1-2 minute inside glands at base of each sinus; corolla subcampanulate; tube glabrous outside, pubescent inside, 0.8-1.0 mm long; lobes linear-lanceolate, glabrous outside, pubescent inside on upper half at margin, with longer hairs at apex, 4-5 X 1-1.3 mm. Corona lobes filiform, twice the length of the gynostegium, upper part papillose, the outer 3-3.2 X 0.1-0.3 mm, apex slightly curved, the inner 3.5-4 X 0.2-0.3 mm, apex curving inward. Anthers rectangular or subrectangular, ca. 0.75 x 0.57 mm, appendages membranaceous, suborbicular, ca. 0.42 mm long. Corpusculum ovate, 0.20-0.22 x 0.08-0.09 mm; translator arms filiform, 0.06-0.09 mm long; pollinia elliptic or subelliptic, longer than corpusculum, slightly curved, 0.24-0.28 x 0.09-0.17 mm. Stigmatic appendix apiculate. This new species is related to Ditassa oxyphylla Turczaninow, from which it differs mainly by the linear-lanceolate leaves, longer corolla lobes (4-5 mm), which are glabrous outside, straighter translator arms, and wider (0.09-0.17 mm), elliptic to subelliptic pollinia. In contrast, D. oxyphylla has ovate-lanceolate to elliptic leaves, corolla lobes 23 mm long, geniculate translator arms, and oblong to subclavate pollinia (0.06-0.08 mm wide). Ditassa oxyphylla is found in Colombia, Venezuela, and Brazil, where it occurs in Pernambuco, Alagoas, and Bahia states; in Bahia it is found in caatinga, remnant liana forest (Mata de Cip6) and pastures, from 500-600 m above sea level (Pereira & Silva, 1973; Pereira et al., 1989). Ditassa oberdanii is named in honor of Oberdan Jose Pereira, Professor of Botany at the Espirito Santo Federal University (UFES), who has contributed greatly to the study of the flora of Espirito Santo, Brazil. Acknowledgments. We thank the CNPq for Jorge Fontella-Pereira's research fellowship, the curators of R, RB, GUA, MBML, VIES, and CVRD, Dorothy Sue Dunn de Araujo for the translation of the text into English, and Gloria Gongalves for the sketch.