Brachiaria antsirabensis A. Camus

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 : 202-203

1. Brachiaria antsirabensis A. Camus in Bull. Soc. Bot. F rance 77: 640. 1931.

Lectotypus (designated here): MADAGASCAR. Reg. Amoron’i Mania [Prov. Fianarantsoa]: env. d’Ambositra , 1500 m, I.1914, Perrier de la Bâthie 10758 ( P [ P00450157 ]!; isolecto-: K [ K000244724 fragm.]!, P [ P00450158 ]!) .

Loosely tufted stoloniferous perennial, ascending to erect, to c. 30 cm high, culms weakly branched, wiry, glabrous. Leaf sheath glabrous or with ciliate margins. Ligule a truncate membrane. Leaf blade linear, flat or rolled, chartaceous, 3–7 × 0.3–0.6 cm, glabrous to pubescent on both sides, retrorse at maturity. Inflorescence racemose, often condensed, ascendent, 2–7 cm long, peduncle pubescent. Racemes 2–6, 0.5–1.5(–2.5) cm long, roughly even in length, on a common axis 1–5 cm long, with no secondary branching, rhachis narrow, ciliate, spikelets overlapping untidily with adjacent spikelets, single or paired, subsessile. Spikelets laterally compressed, ovate, apiculate, 2.7 –3.3 mm long, olive green. Lower glume ⅔– ¾ as long as spikelet, herbaceous, keeled, pinched at apex, 7-veined, glabrous to pubescent, orientation relative to rhachis variable. Upper glume ¾ as long as spikelet, herbaceous, 7-veined, glabrous to pubescent. Lower floret male, palea as long as lemma, anthers 3.2– 2.3 mm long. Lower lemma herbaceous, 7-veined, glabrous to pubescent. Upper lemma acute, smooth, shiny, white to brown.

Distribution and ecology. – Endemic to open highland savanna with Loudetia simplex (Nees) C.E. Hubb. and secondary grassland in central Madagascar, often on rocky slopes, near ericoid vegetation, or under tapia, at elevations of 800–1800 m (F ig. 1).

Notes. – This distinctive species is easy to recognise by its dense untidy inflorescences of overlapping spikelets. It shares laterally compressed spikelets and short upper glumes with its closest relative Brachiaria dimorpha A. Camus , another highland endemic (HACKEL et al., 2018). Not fire resistant (Perrier de la Bâthie 10758). Somewhat swollen stolons may act as food storage. Not common or locally abundant, does not seem to become ecologically dominant.

The specimen designated here as the lectotype [P00450157] has superior quality flowering material than the duplicates, and it has previously been labelled as the holotype.

Additional specimens examined. – MADAGASCAR. Reg. Alaotra-Mangoro [Prov. Toamasina]: rte. de Moramanga-Lac Alaotra , PK 15, VI.1959, Bosser 13044 ( P) ; sur le Mongoro, XII.1927, Perrier de la Bâthie 18344 ( P) . Reg. Amoron’i Mania [Prov. Fianarantsoa]: F andriana, I.1953, Bosser 5073 ( TAN) ; Marovitsika ( Anjiro ), XI.1953, Bosser 7135 ( P) ; ibid. loco, III.1953, Bosser 7140 ( TAN) ; Ambositra , Imerina-Imady , I.1961, Bosser 14884 ( P) ; F aliarivo, env. d’Ambositra , III.1934, Humbert 14518 ( P) ; 6 km from Ivato towards Ambatofinandrahana , 24.II.2013, Vorontsova et al. 992 ( K, TAN) . Reg. Analamanga [Prov. Antananarivo]: Ankazobe , Manerinerina, rte. de Majunga, PK 135, I.1967, Morat 2657[b] ( P) ; entre Arivonimamo et Soamananety , 29.I.1960, Peltier 1826 ( P) . Reg. Itasy [Prov. Antananarivo]: Nanisana , 14.I.1951, Benoist 698 ( P) ; ibid. loco, 14.I.1951, Benoist s.n. ( P) ; Arivonimamo , Antongona, I.1956, Bosser 8933 ( P, TAN) ; massif de l’Antongona , 4.XII.1959, Peltier & Peltier 1573 ( P) . Reg. Vakinankaratra [Prov. Antananarivo]: Ambatolampy , I.1953, Bosser 4748 ( TAN) ; ibid. loco, II.1953, Bosser 4782 ( TAN) ; ibid. loco, II.1953, Bosser 4810 ( P, TAN) ; ibid. loco, II.1953, Bosser 5062 ( TAN) ; F aratsiho, Ankaratra , I.1955, Bosser 7633 ( P) ; Behenjy, Andosy, Cornet 13 ( TAN) ; Amboasary ( Behenjy ), 28.XII.1963, Peltier 4517 ( P) . Sine loco: “Central Madagascar”, Baron 3713 (K, P).