Trichanthecium pusillum Zuloaga, comb. nov.
Creators: name: Zuloaga, Fernando Omar
name: Aliscioni, Sandra
name: Delfini, Carolina
name: Salariato, Diego Leonel
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Poales
Poaceae
Trichanthecium
Trichanthecium pusillum

description: 11. Trichanthecium pusillum (Hook.f.) Zuloaga, comb. nov.
Panicum pusillum Hooker (1864: 227).
Lectotype (designated as “holotype” by Clayton & Renvoize 1982: 490):— CAMEROON. Cameroon Mountains, 7000–8000 ft, December 1882, G. Mann 2090 (K [K000182419!]). Fig. 10
Panicum tylanthum Hack ex Engler (1891: 118).
Lectotype (here designated):— ETHIOPIA. “ Abyssinien auf Felsen am Hedscha, G. H. W. Schimper 1095 (K [000255571!]).
Panicum nymphoides Renvoize (1989a: 545).
Type:— MALAWI. Mount Mulanje, 4 February 1971, O. M. Hilliard & B. L. Burtt 6396 (holotype K [000318207!]), syn. nov.
Annual; culms (2–) 15–30 cm tall, decumbent, branching and rooting at the lower nodes, rarely erect; internodes cylindrical, 1–3 cm long, hollow, glabrous; nodes dark, pilose. Sheaths striate, 1–2 cm long, hirsute, with tuberculate hairs. Ligule membranous, 0.4 mm long. Blades ovate-lanceolate, 0.5–4(4.2) × 0.2–0.6 cm, narrowed at the base, flat, membranous, pilose, the apex acuminate. Inflorescence a terminal, short-exserted lax panicle 1–2(4.5) × 1–3 cm, peduncle cylindrical, 2–4 cm long; main axis flexuous, hispid, first-order branches alternate, divergent, deflexed or not, spikelets solitary on flexuous pedicels, 1–3 mm long; axillary inflorescences present, similar to the terminal one. Spikelets ellipsoid, 1.5–2 × 0.7–0.8 mm, hirsute, with tuberculate hairs, occasionally glabrous, greenish, acute; lower glume 1.2–1.5 mm long, 1/2 to 4/5 the length of the spikelet, 3-nerved, acuminate, membranous; upper glume and lower lemma subequal, 5–7-nerved, acute, membranous, upper glume early deciduous; lower palea reduced, hyaline, glabrous; lower flower absent. Upper anthecium narrowly ovoid, 1.5–1.8 × 0.6–0.8 mm, smooth, shiny, indurate. Caryopsis ovoid, 1.2 × 0.6 mm; hilum punctiform, embryo 1/3 the length of the caryopsis.
Distribution and habitat: —Widely distributed from Ethiopia to Kenya, Malawi, and Tanzania in Tropical East Africa. It is found in clefts, mountain grassland or bushland and forest margins; at 1350–3300 m elevation (Clayton & Renvoize 1982).
Chromosome number: —2n = 18 (Morton 1993).
Typification: —The protologue of P. tylanthum mentions a single specimen, Schimper 1095. Since no material was found at B or W, relating it to Hackel or Engler, a specimen of from K [0000255571!] is here selected as the lectotype.
Note: — Brown (1977) reported that this is a non-Kranz species with a δ13C value of –26.8.
Representative material examined: — BURUNDI. Prov. Muramwya: Mugongomanga, 14 May 1982, Reekmans 11225 (MO); Teza, 31 May 1978, Bouharmont 11329 (BR). CAMEROON. Cameroon Mountains, Maitland 1218 (K, US). DEMOCRATIC REPUBLIC OF CONGO. Kabare, Mugigo, 9 May 1959, Leonard 4097 (BR); Kivu, Kalehe, Petit s.n. (BR). KENYA. 15 miles SSW of Nyeri, 14 November 1956, Bogdan 4347 (K, US); Nakuru, 21 September 1929, Hitchcock 25113 (US); Nakuru, 4 miles W of Nakuru, 10 October 1951, Bogdan 3283 (K, US). MALAWI. Northern Province. Nyika Plateau, below main bridge Dam 1, 22 March 1976, Phillips 1518 (MO). NIGERIA. Obudu cattle ranch, Birnas 222 (K); Chappal Waddi, Gangirwal, Jackson et al. 2023 (K). RWANDA Montagnes a l’Est de Kisenyi, May 1929, Humbert 8478 (BR). TANZANIA. Kilimanjaron; Peters Hut to Marangu, 6 September 1929, Hitchcock 24649 (US). Nyassa Hochland, Kyimbala, 15 May 1912, Stolz 1271 (US).
description: Published as part of Zuloaga, Fernando Omar, Aliscioni, Sandra, Delfini, Carolina & Salariato, Diego Leonel, 2024, Old World species of Trichanthecium (Poaceae: Panicoideae: Paniceae) including a new species from the Democratic Republic of Congo, pp. 230-264 in Phytotaxa 646 (3) on pages 251-253, DOI: 10.11646/phytotaxa.646.3.2, http://zenodo.org/record/13215433