Meibomia riedelii Schindl., Repert., 2014

Lima, Laura Cristina Pires, Queiroz, Luciano Paganucci De, Tozzi, Ana Maria Goulart De Azevedo & Lewis, Gwilym Peter, 2014, A Taxonomic Revision of Desmodium (Leguminosae, Papilionoideae) in Brazil, Phytotaxa 169 (1), pp. 1-119 : 75-76

24. Desmodium riedelii ( Schindl.) Burkart, Darwiniana 3(2): 195. 1939. Meibomia riedelii Schindl., Repert. Spec. Nov. Regni Veg. 23: 281. 1926. Lectotype (designated by Lima et al. 2012a):— BRAZIL. Mato Grosso do Sul: Ribas do Rio Pardo , September 1926, L. Riedel 526 (lectotype K!, isolectotype LE![2 sheets]). Fig. 26 .

Erect?, branched subshrub, lacking stolons rooting at the nodes, xylopodium not seen; stems virgate, slender, cylindrical, striate, glabrescent or sparsely puberulous-uncinate, not glaucous; internodes 2.2–5.2 cm long. Stipules ca. 2 × 1 mm, ovate, not auriculate, not amplexicaul, inserted perpendicularly at the base of the leaf petiole, free from each other, apex caudate, margin straight, glabrescent, veins conspicuous, caducous. Leaves trifoliolate; petiole 2–4 mm long, cylindrical, sulcate, sparsely uncinate; rachis 3–6 mm long; stipels 1–1.5 mm long, subulate, margin straight, uncinate on the outer surface, persistent; leaflets concolorous, chartaceous, venation eucamptodromous, primary and secondary veins prominent, tertiary veins flush with the abaxial surface, indumentum sparsely tomentose on the primary, secondary and tertiary veins on the abaxial surface, adaxial surface glabrous, uncinate hairs covering on the abaxial surface, terminal leaflet 2.9–4.9 × 0.6–1.7 cm, lanceolate or oblong, base oblique or obtuse, apex acute, subacute, obtuse or retuse, lateral leaflets 1.8–2.9 × 0.7–1.3 cm, the same shape as the terminal leaflet. Inflorescence a terminal paniculate; the main axis longer than the adjacent leaves, 9–22 cm long, sparsely tomentose and uncinate, 2 flowers per node; primary bract ca. 2 mm long, ovate, margin ciliate, hirsute on the outer surface, caducous, veins inconspicuous on the outer surface; secondary bract ca. 1 mm long, narrowly lanceolate, margin ciliate, hirsute on the outer surface, caducous, veins inconspicuous on the outer surface; pedicel 2–4 mm long, densely hirsute. Flowers 8–10 mm long; calyx bilabiate, tube campanulate, 2–2.5 mm long, hirsute and uncinate on the outer surface; upper lip entire, oblong, apex obtuse, ca. 2 mm long; lower lip trifid, lateral tooth lanceolate a ovate, 1.5–2 mm long, central tooth lanceolate, ca. 2 mm long; corolla lilac, standard ca. 7 × 6 mm, orbicular, apex emarginate, maculate at the base, claw ca. 1 mm long; wing petals ca. 7 × 3 mm, oblong, apex obtuse, without callosities, claw ca. 1.2 mm long; keel petals 7 × 2.5 mm, narrowly obovate, apex subacute, without callosities, claw ca. 2 mm long; androecium monadelphous, 8–10 mm long, vexillary stamen partially fused with the other from the base 1.5–2 mm; ovary 5–6 mm long, glabrous stipe ca. 2 mm long, glabrous. Loment 1.1–1.3 cm long, stipe 4–6 mm long, glabrescent, isthmus central, both margins sinuate; articles uniform 1–2, 11–13 × 5.5–6 mm, obovate-depressed, not tortuous, indehiscent, membranaceous, veins slightly conspicuous, densely puberulous-uncinate. Seed not seen.

Specimens examined:— BRAZIL. Mato Grosso do Sul. Ribas do Rio Pardo, s. loc., s.d., L. Riedel 78 (K, LE); s.d., L. Riedel 91 (K, LE); s.d., L. Riedel s.n. (LECB, OXF).

Distribution and Ecology:— restricted to the State of Mato Grosso do Sul in Brazil.

Conservation Assessment:— Data deficient (DD) ( IUCN 2001).

Phenology:— flowering and fruiting from September.

Etymology:— first named by Schindler in honour of the naturalist Ludwig Riedel, who collected the type material of the species.

Common Name:— unknown.

Taxonomic notes:— lanceolate or oblong leaflets, flowers 8–10 mm long and obovate-depressed fruit articles are diagnostic characters of D. riedelii . The species is similar to D. platycarpum with obovate-depressed articles, but can be distinguished by the number of leaflets and their shape (see notes under D. platycarpum ).

For more than seventy years D. riedelii was considered to occur in Argentina ( Burkart 1939; Vanni 2001), but after fieldwork in northeastern Argentina and central Brazil and examination of herbarium specimens (including types) we conclude that Argentinian specimens considered to be Desmodium riedelii by Burkart (1939) and Vanni (2001) belong to another species, Desmodium burkartii ( Lima et al. 2012a).

Desmodium riedelii is similar to D. burkartii in its pseudoracemose inflorescences and flower length (8–10 mm long), but can be distinguished by oblong or elliptic leaflets (vs. elliptic-lanceolate in D. burkartii ), short petiole and pedicel, up to 4 mm long (vs. greater than 7 mm long), ovate primary bracts (vs. lanceolate) and loment with 1–2 obovate-depressed articles (vs. 2–6 oblong articles).

DESMODIUM (LEGUMINOSAE, PAPILIONOIDEAE ) IN BRAZIL

Phytotaxa 169 (1) © 2014 Magnolia Press • 75 76 • Phytotaxa 169 (1) © 2014 Magnolia Press

LIMA ET AL.

Figures

FIGURE 26. Desmodium riedelii. A. Flowering branch. B. Stipules inner surface. C. Face abaxial do folíolo. D. Detail of adaxial surface of leaflet. E. Calyx inner surface (opened). F. Fruit. (A–F: Riedel 526).