Urochloa nana (Stapf) Voronts.

Vorontsova, Maria S., 2022, Revision of some Malagasy forage grasses and their relatives within Brachiaria, Echinochloa, Moorochloa, and Urochloa, Candollea 77 (2), pp. 199-236 : 229-230

25. Urochloa nana (Stapf) Voronts. , comb. nov.

Brachiaria nana Stapf in Bull. Misc. Inform. Kew 1919: 264. 1919.

Holotypus: MADAGASCAR. Reg. Atsimo-Andrefana [Prov. Toliara]: Onilahy, near Sakomdy river , VI.1910, Perrier de la Bâthie 117 [“ 107 ”] or 11202 ( K [ K000244719 ]!; iso-: P [ P00450185 , P00450186 ]!) .

Loosely tufted stoloniferous perennial, ascending to erect, to 20 cm high, culms much branched, rooting at lower nodes, culms glabrous or pubescent, nodes finely hirsute. Leaf sheath glabrous or sparsely pubescent with ciliate margins. Ligule a line of hairs. Leaf blade ovate, basally cordate, thickly chartaceous, 1–4 × 0.4–1 cm, glabrous to sparsely hirsute on both sides, sometimes with bulbous-based trichomes near base. Inflorescence racemose, contracted or sometimes open, rarely fully exserted, 3–5 cm long. Racemes 3–5, 2–3 cm long, roughly even in length, often appressed, frequently bare towards apex on a common axis 0.5–1.5 cm long, with no secondary branching, rhachis triquetrous to narrowly winged, 0.6 –0.8 mm wide, scaberulous, spikelets overlapping untidily with adjacent spikelets, paired, subsessile, in 2 untidy rows. Spikelets elliptic, apically apiculate, 2.7–3 mm long, whiteish. Lower glume ¼–⅓ as long as spikelet, membranous, obtuse to acute, 1–3-veined, glabrous, orientation relative to rhachis variable. Upper glume as long as spikelet, membranous, 5–7-veined, with cross veins towards apex, glabrous. Lower floret infertile, palea absent or ⅓–½ as long as lemma. Lower lemma membranous, 5– 7-veined, with cross veins towards apex, glabrous. Upper lemma obtuse, rugulose.

Distribution and ecology. – Endemic to the northern, western, and southern parts of Madagascar. Dry forest and spiny forest and savanna, roadsides, cultivation, often on limestone, at elevations of 0–800 m (F ig. 16).

Notes. – Urochloa nana can be recognised by its visibly thick leaf blades, and frequently bare apices of racemes. It is somewhat similar to U. ramosa but its spikelets are smaller, upper lemma less rugose, lower glume more membranous, and its leaf blades thicker. Urochloa nana also resembles U. reptans (L.) Stapf with its leaf blades and racemes crowded at the apex of the culms and slightly curved upwards; U. nana can be distinguished from U. reptans by its larger spikelets, a 3-veined lower glume, and the absence of a mucro on the upper lemma. Urochloa nana seems to be related to U. distachyos as its chloroplast DNA sequences were identical (HACKEL et al., 2018).

The collection series of Perrier de la Bâthie are labelled with five-digit numbers at P , with duplicates of the same series marked with three-digit numbers at K . It is sometimes possible to establish a correspondence between these two series when both numbers are cross-referenced on a sheet at P , such as the isotype sheet P00450185 . Thus, the type collection is marked with two alternative numbers: Perrier de la Bâthie 117 and 11202. It seems clear the number 107 in the protologue is an error, because the holotype sheet is numbered 117, annotated by Oto Stapf , and is the only historic collection of this species held at K.

Selected specimens examined. – MADAGASCAR. Reg. Atsimo-Andrefana [Prov. Toliara]: Sakaraha, II.1956, Bosser 9000 ( P); Sakaraha , forêt de Zombitsy , III.1955, Humbert et al. 29663 ( P); Morondava Airport , 9.III.1953, Porteres s.n. ( P). Reg. AIANA [Prov. Antsiranana]: Ambilobe , Sosumav, XII.1964, Morat 1271 ( P); Andrafiabe , Ankarana , I.1969, Morat 3111 ( P). Reg. Melaky [Prov. Mahajanga]: lisière de la R.N. 9, Antsalova, I.1975, Morat 4851 ( P). Reg. SAVA [Prov. Antsiranana]: Sambava , Marojejy NP office, 14.X.2011, Hall et al. 28 ( K, TAN) .