Digitaria abyssinica (Hochst. ex A. Rich.) Stapf (1907: 213)

Boonsuk, Boonchuang, Chantaranothai, Pranom & Hodkinson Abstract, Trevor R., 2016, A taxonomic revision of the genus Digitaria (Panicoideae: Poaceae) in mainland Southeast Asia, Phytotaxa 246 (4), pp. 248-280 : 254

2. Digitaria abyssinica (Hochst. ex A. Rich.) Stapf (1907: 213) .— Panicum abyssinicum Hochst. ex A. Rich. (1851: 360) . Type :— ETHIOPIA, W. Schimper 82 (holotype P!; isotypes B! ( B100167794 ), K!, L!).

Digitaria hentyi Veldkamp (1980: 391) , syn. nov. Type:— PAPUA NEW GUINEA, East Highlands, Aiyura , E. Henty NGF 20994 (holotype L!; isotypes A, BISH, BRI, CANB, E, K!, LAE, M, NSW).

Digitaria effusa Veldkamp (1999: 447) , syn. nov. Type:— VIETNAM, Lam Dong, J.B. Hacker 1613 (holotype L!).

Annual or short-lived perennial. Culms geniculately ascending, 20–35 cm high; nodes and internodes glabrous; cataphylls present. Sheaths 1.2–3 cm long, densely pilose on upper part. Ligules 1–1.5 mm long. Blades lanceolate to linear, 2–8 by 0.5–1 cm, chartaceous, apex acuminate, crenulate at one side of margin, both surfaces densely pilose. Inflorescences composed of racemes; peduncles glabrous; common axis 1.5–3 cm long. Racemes 4–8, longest 3.5–5.5 cm long, subdigitate or alternate along the common axis; rachis filiform, triquetrous, not winged, 0.2–0.3 mm wide, serrate. Pedicels triquetrous, serrate; abscission truncate to slightly discoid. Spikelets binate, homomorphous, elliptic, 2–2.2 mm long, glabrous. Lower glume ovate, 0.3–0.4 mm long, chartaceous, apex obtuse, nerveless. Upper glume elliptic, 1.4–1.6 mm long, chartaceous, apex acute, nerves 3. Lower lemma elliptic, as long as the spikelet, chartaceous, apex acute, nerves 7, equidistant. Upper lemma 1.8–2 mm long, chartaceous, apex acute, yellowish. Anthers not seen. Caryopsis oblong-ellipsoid, 1.3–1.4 mm long, brownish.

Distribution: —America, Africa, Vietnam, Malaysia, Papua New Guinea, Australia,

Selected specimens examined: —PENINSULAR MALAYSIA. Pahang: Cameron highlands, 8 March 2010, M.Y. Chew, H. Duistermaat & A. Mohd. Nazri FRI 70435 (KEP, L). VIETNAM. Lam Dong: Da Lat, 14 November 1998, J.B. Hacker 1613 (L).

Ecology: —Roadsides, pine tree woodlands; elevation 1,200–2,000 m.

Conservation status: —This species is widely distributed and found in most continents even though only two specimens were from mainland SE Asia. The status of D. abyssinica is assessed as LC, according to IUCN (2012) criteria.

Note: —We have examined characters such as inflorescence type, filiform and triquetrous rachis, binate spikelets, truncate pedicels and absolutely glabrous spikelets of D. effusa (from Vietnam), D. hentyi (from Papua New Guinea) and D. abyssinica (from Africa) and detected no significant differences between them. Therefore, D. effusa and D. hentyi are reduced to synonyms of D. abyssinica and also presented as the first record of this species for SE Asia. It is distinguished by its glabrous spikelets with ovate and nerveless lower glume.