Mnesithea cancellata (Ridl.) Ridl.

Veldkamp, J. F., Heidweiller, J., Klaauw, M. A. F. van der, Koning, R. de, Kraaijeveld, A. R., Sosef, M. S. M. & Strucker, R. C. W., 2013, A revision of Mnesithea (Gramineae - Rottboelliinae) in Malesia and Thailand, Blumea 58 (3), pp. 277-292 : 279-280

1. Mnesithea cancellata (Ridl.) Ridl. — Fig. 1

Mnesithea cancellata (Ridl.) Ridl. (1925) 206. — Rottboellia cancellata Ridl. (1911b) 228. — Rottboellia foveolata Holttum (1947) 297,nom.superfl. — Coelorachis foveolata (Holttum) Jansen (1953) 256, nom superfl. — Coelorachis cancellata (Ridl.) Bor (1962) 168. — Type: Ridley 15231 (holo SING; K, sh. no. 290024), see note.

[ Rottboellia striata auct.non Nees: Balansa (1890) 110. — Coelorachis striata auct.non A.Camus:A. Camus (1922) 383, quoad Balansa s.n. — Coelorachis clathrata Henrard (1941) 519, t., nom. inval, sine Lat. — Voucher: Balansa s.n. (‘holo’ L, sh. no. 908.94-1206, -1207, -1208; P, sh. no. 953.347-274)].

Plants perennial. Culms 0.4–1.1 m long, glabrous to pilose. Cataphylls ovate to ovate-oblong, (3–)6–17(–27) by 0.8–3.5 mm, puberulous to pilose to ciliate along the margin, apex acute to acuminate. Nodes puberulous to setose. Sheaths glabrous to setose, margin pilose to ciliate. Ligule 0.2–1.5 mm long, margin setose. Contra-ligule absent. Blades flat to folded, (13–)27–37(–41) cm by 3–9 mm, margins at base glabrous to pectinate, glabrous to hairy on both sides or hairy below to glabrescent, glabrous to setose behind the ligule, smooth. Peduncles solitary or paired, glabrous to hairy. Spatheoles 5.5–16 cm long. Spikes 2.5–12 cm by 2–2.8 mm. Spikelets paired. Joints 4.5–5.8 mm long, glabrous, smooth. Sessile spikelets 4.3–5.8 mm long (incl. callus), shorter to longer than the joint. Callus glabrous. Lower glume convex, ovate to ovate-oblong, glabrous, apex rounded, winged or not, coriaceous, cancellate, greenish yellow, sometimes with purplish margins, 6–7-nerved, lower part at keel smooth; upper glume boat-shaped, ovate to ovate-oblong, 3.3–5.1 mm long, glabrous, margin infolded, apex acute, 3-nerved, nerves anastomosing or not. Lemmas ovate to ovate-oblong, 2.8–4.4 mm long, glabrous, apex acute; first lemma epaleate or paleate, 3.1–4.4 mm long, 3–4-nerved. Second lemma 3-nerved. Paleas 2–3-nerved, glabrous; first palea (when present) ovate-oblong, 0–3.2 mm long; second palea ovate-oblong to -lanceolate, 2.8–3 mm long. Anthers 1.5–1.7 mm long. Pedicel free from the joint, 3.7–5.5 mm long, glabrous, smooth. Pedicelled spikelets reduced to 2 glumes, laterally flattened, 1.1–2.1 mm long. Lower glume apex obtuse to winged, chartaceous, glabrous to margins ciliolate. 2n =?

Distribution — Thailand (NE: Loei; E: Chaiyaphum, Si Sa Ket; Peninsular: Satun Prov.), S Vietnam (Dalat, Kiên Giang, Nhatrang Prov.), Malesia: Bangka.

Habitat — Open grassy pine, dry dipterocarp, Tectona forests, on sand, roadsides, 120–1400 m altitude.

Notes — Distinct because of the glabrous callus, sessile spikelet 4.3–5.8 mm long (incl. callus), glabrous and cancellate lower glume and the 1.1–2.1 mm long pedicelled spikelets.

Rottboellia cancellata and derivatives were based on the collection in SING, while R. foveolata etc. was based on the isotype in K and thus the names are not strictly homotypic, but Art. 9 Note 2 makes them superfluous.

Differs from the Malesian / Thai congeners in: Culms 0.4–1.1 m long. Cataphylls puberulous, pilose, or ciliate along the margin. Sessile spikelet 4.3–5.79 mm long (incl. glabrous callus); lower glume of sessile spikelet glabrous, sculptured. Pedicelled spikelets 1.1–2.1 mm long.

Most similar is M. glandulosa :

1. Sessile spikelet callus glabrous. Lower glume of sessile spikelet glabrous, greenish yellow, margins purplish.....

................................... M. cancellata 1. Sessile spikelet callus puberulous. Lower glume of sessile spikelet hairy, yellowish................ M. glandulosa