Desmodium microcarpum (Rusby) L.C.P. Lima, A.M.G. Azevedo & L.P. Queiroz, 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 : 62-64

19. Desmodium microcarpum (Rusby) L. C. P. Lima, A. M. G. Azevedo & L. P. Queiroz , comb. nov. Meibomia microcarpa Rusby, Mem. New York Bot. Gard. 7: 263. 1927. Type :— BOLIVIA. Beni: Reyes , 100 feeets, 25 October 1921, H. H. Rusby 1318 (holotype NY00016321 !, isotypes BKL *!, K!, NY000163220 !, US!). Fig. 21 .

Desmodium pachyrhizum var. latifolium Micheli, Bull. Herb. Boissier 6, App. 1: 34. 1898. Type:— PARAGUAY. Cordillera dos Altos: January, E. Hassler 1812 (holotype G!), syn. nov.

Desmodium hickenianum Burkart, Darwiniana 3: 217. 1939. Type:— ARGENTINA. Santa Fé: Malabrigo, A. Burkart 5881 (holotype SI!), syn. nov.

Desmodium hickenianum var. major Burkart, Darwiniana 3: 220. 1939. Type:— ARGENTINA. Tucuman: cumbre de San Javier, Tafi, 08 February 1933, A. Burkart 5566 (holotype SI!, isotype P!), syn. nov.

Prostrate, ascendent or decumbent, branched subshrub, lacking stolons rooting at the nodes, with a xylopodium; stems virgate, slender, cylindrical, striate, glabrescent or sparsely puberulous-uncinate, not glaucous; internodes 2.3–3.5 cm long. Stipules 2–3 × 0.5–1 mm, ovate-lanceolate, not auriculate, semi-amplexicaul, inserted perpendicularly at the base of the leaf petiole, free from each other, apex caudate, margin straight, tomentose, veins inconspicuous, caducous. Leaves unifoliolate; petiole 2–8 mm long, cylindrical, sulcate, uncinate or sparsely or densely tomentose; stipels 2–3 mm long, subulate, margin straight, sparsely tomentose, persistent; leaflet concolorous, chartaceous, venation brochidodromous, primary, secondary, tertiary and quaternary veins prominent on the abaxial surface, indumentum tomentose on the primary, secondary and tertiary veins on the abaxial surface, adaxial surface puberulous-uncinate, uncinate hairs covering both surfaces, leaflet (2.5–)3.4–4.5(–6.5) × 1.1–2.6(–4.3) cm, elliptic, ovate or ovate-lanceolate, oblong, base obtuse, truncate or subcordate, apex subacute, mucronate, retuse or obtuse. Inflorescence a terminal pseudoraceme or paniculate; the main axis longer than the adjacent leaves, 13.5–33.5(–43.5) cm long, sparsely or densely hirsute–uncinate, 2 flowers per node; primary bract 3–4 mm long, lanceolate, margin straight, hirsute and uncinate on the outer surface, caducous, veins conspicuous on the outer surface; secondary bract ca. 1 mm long, linear, margin straight, hirsute–uncinate on the outer surface, caducous, veins inconspicuous on the outer surface; pedicel 3–6 mm long, sparsely or densely hirsute–uncinate. Flowers 5–7 mm long; calyx bilabiate, tube campanulate, 1–1.5 mm long, hirsute on the outer surface; upper lip bifid, slightly fused, the 2 teeth joined for a ca. ¾ of their length, acute, 0.5 mm long; lower lip trifid, lateral tooth

62 • Phytotaxa 169 (1) © 2014 Magnolia Press

LIMA ET AL. DESMODIUM (LEGUMINOSAE, PAPILIONOIDEAE ) IN BRAZIL

Phytotaxa 169 (1) © 2014 Magnolia Press • 63 lanceolate, 1.5–2 mm long, central tooth lanceolate, 2–2.5 mm long; corolla lilac, standard 6–7 × 5–6 mm, broadly obovate, apex retuse or obtuse, maculate at the base, claw 0.1–0.5 mm long; wing petals 5–6 × 1.5–2 mm, obovate, apex obtuse, without callosities, claw 1–1.5 mm long; keel petals 4–5 × 1.5–2 mm, narrowly obovate, apex subacute, with callosities, claw 1.5–2 mm long; androecium monadelphous, 5–7 mm long, vexillary stamen partially fused with the other from the base ca. 1 mm long; ovary 3–4 mm long, sparsely pubescent, stipe 0.4–0.6 mm long, glabrous. Loment 1.2–2.5 cm long, stipe 1–2 mm long, glabrescent, isthmus subcentral, upper suture straight or slightly sinuate and lower suture sinuate; articles uniform 3–6, 3–4 × 2.5–3 mm, obovate-depressed or elliptic, slightly tortuous, indehiscent, subcoriaceous, veins inconspicuous, uncinate or sparsely hirsute. Seed 2–2.2 × 1.2–1.5 mm, obovate, hilum subcentral.

Selected specimens examined:— BRAZIL. Goiás: Itajá: Córrego Enterrado, rodovia BR-483, 56 km Norte do rio Aporé (divisa MS / GO), 16 November 2004, fr., A . Pott et al. 12357 ( CGMS) . Mato Grosso do Sul: Aquidauana : BR-262, ao longo da pista de aviação, 23 September 2008, fl., fr., L . C . P. Lima et al. 423 ( HUEFS); Piraputanga , 4 June 1994, fl., fr., G . Hatschbach et al. 60672 ( PAMG) .

Distribution and Ecology:— Tropical and Subtropical South America in Argentina, Bolivia, Brazil, Paraguay and Uruguay ( Chodat & Hassler 1904, Rusby 1927, Izaguirre & Beyhaut 1998, Vanni 2001, Lima et al. 2010). In Brazil D.microcarpum occurs in areas of Cerrado and in the Pantanal biome in the States of Goiás, Mato Grosso do Sul, and Paraná.

Conservation Assessment:— Least Concern (LC), not endangered ( IUCN 2001).

Phenology:— flowering and fruiting from June to November.

Etymology:— from the Greek micro (= small) + carpus (= fruit), in reference to the small-fruits.

Common Name:— unknown.

Taxonomic notes:— D.microcarpum is characterised by a combination of characters including a decumbent or prostrate-ascending habit, ovate stipules, unifoliolate leaves, and obovate-depressed or elliptic articles. It is morphologically similar to D. craspediferum (see notes under that species), D. pachyrhizum , and D. venosum . In leaflet shape (elliptic or ovate) and pedicel length (3–6 mm long) D. microcarpum resembles D. pachyrhizum . However, the decumbent or prostrate-ascending habit of D. microcarpum (vs. erect in D. pachyrhizum ), the pubescent ovary (vs. tomentose), and the obovate-depressed articles (vs. elliptic) help to differentiate these two species. With elliptic or ovate-lanceolate leaflets, prominent venation on the abaxial leaflet surface, and flowers 5–7 mm long, D. microcarpum is very similar to D. venosum . However, it can be differianted on the basis of the decumbent or prostrate-ascending habit (vs. erect in D. venosum ), leaves that are always unifoliolate (vs. trifoliolate or rarely unifoliolate next to the base of the inflorescence), pubescent ovary (vs. tomentose), and the inconspicuous veins of the articles (vs. conspicuous).

In accordance with article 11 of the ICBN ( McNeill et al. 2006), a validly published name has priority over others of the same rank published later. Considering that the name Meibomia microcarpa is older than Desmodium hickenianum , the epithet microcarpa is here used to establish the new combination Desmodium microcarpum .

Desmodium pachyrhizum var. latifolium Micheli was synonymised by Schindler (1928) with Meibomia venosa . However, the article shape, length, and pattern of venation and the indumentum of the pedicel show morphological similarities with Desmodium microcarpum . For that reason a new synonym is here proposed. Most specimens examined in European herbaria and identified by Schindler (1915–1927) as D. venosum or M. venosa are recognised in this study as D. microcarpum .

Figures

FIGURE 21. Desmodium microcarpum. A. Habit. B. Stipules inner surface. C. Calyx inner surface (opened). D. Parts of the corolla from the bottom to top: keel petals, wing petals, and standard. E. Androecium monadelphous (opened). F. Gynoecium. G. Fruit. H. Seed. (A, G–H: Hatsbach 60672; B–F: Lima 423).