Rhipidocladum cordatum C.D. Tyrrell & L.G. Clark, 2013

Tyrrell, Christopher D. & Clark, Lynn G., 2013, Three new species of Rhipidocladum (Poaceae: Bambusoideae: Arthrostylidiinae) from South America, Phytotaxa 98 (2), pp. 55-64 : 58-61

Rhipidocladum cordatum C.D. Tyrrell & L.G. Clark , sp. nov., Fig 3

Type:— ECUADOR. Morona-Santiago: 16 km W of Limon on the road to Gualaceo, 2110 m, 4 June 1980 (fl), S. M. Young 164 (holotype: QCA!; isotypes: AAU!, ISC!, US!) .

Diagnosis:— Rhipidocladum cordatum differs from R. harmonicum by its cordate culm leaf blades, greater number (70–100) of branchlets per node, greater number of florets (9–10) per spikelet, and more closely (4–9 mm) spaced spikelets per synflorescence.

Description:— Culms 8 m tall; internode length unknown, 20–25 mm diameter, hollow. Culm leaves 13.5–22.5 cm long; sheaths 7–10 cm long, abaxially glabrous, margins glabrous; blades cordate, pleated near the base, 8–13 cm long, abaxially glabrous, margins glabrous. Branch complements with 70–100 branchlets, branchlets 23–30 cm long, often rebranching from the base. Foliage leaves 3–4 per flowering branchlet; sheaths 20–30 mm long, abaxially glabrous with a row of hispid hairs along one side, margins glabrous; fimbriae 4.5–5.0 mm continuing down sheath shoulder becoming 2 mm long, basally fused, reddish-brown to golden; pseudopetioles 2–3 mm long, abaxially sparsely puberulent, adaxially hispidulous, purple to brown; inner ligules 0.2–0.4 mm long, truncate; blades 6.0– 7.5 cm long, 7–11 mm wide, L:W ratio 7–9, lanceolate, abaxially glabrous, adaxially pubescent with a row of hispid hairs along one side, base slightly asymmetrical and attenuate, apex acute, margins smooth. Synflorescences 4–6 cm long, spicate, bearing 4–6 spikelets spaced 4–9 mm apart; rachis geniculate. Spikelets 4.8–5.0 cm long, comprising 3–4 glumes and 9–10 fertile florets; rachilla internodes 4.0– 4.5 mm long. Lowest glume 3–4 mm long, 1-nerved, ovate-lanceolate, apex acuminate, abaxially glabrous, mucronate; upper glumes ovate-lanceolate, apex acuminate, abaxially glabrous, adaxially puberulent: second glume 3.5–4.0 mm long, 3–5-nerved, mucronate; third glume ca. 6 mm long, 5-nerved, mucronate. Lemmas 7.5–8.0 mm long, 5–7-nerved, lanceolate, apex acuminate, abaxially glabrous, mucronate. Paleas 6.5–7.0 mm long, abaxially glabrous, stramineous. Flowers and fruit unknown.

Distribution and Habitat:— Cloud forests in the Cordillera Oriental of Ecuador, at 2100–2900 m elevation.

Etymology:— The name is descriptive of the heart-shaped (cordate) culm leaf blades.

Additional Specimens Examined:— ECUADOR. Morona-Santiago: road Gualaceo-Limón (Gral. L. Plaza Gutierrez), 33.1 km E of Gualaceo , 7.8 km E of the pass, ca. 41.2 km W of Limón , 2885 m, 18 February 1996 (fl), Clark & Asimbaya 1464 ( AAU!, ISC!, QCA!, US!); 32 km E of pass on the road from Gualaceo to Limón (Gral. L. Plaza Gutierrez), 2080 m, 30 May 1992 (fl), Clark et al. 1092 ( ISC!, MO!, QCA!, US!). Zamora-Chinchipe: 22.9 km E of Loja on the new road to Zamora 2250 m, 10 February 1996 (fl), Clark & Asimbaya 1415 ( AAU!, ISC!, MO!, QCA!, US!); Valle de San Francisco near casa de INEFAN at road Loja- Zamora, 2150 m, 9 March 1998 (fl), Laegaard et al. 18521 ( AAU!, LOJA) .

Figures

FIGURE 3. Rhipidocladum cordatum. A. Branch complement, B. Apsidate branching pattern, C. Culm leaf, D. Close up of culm leaf blade base showing “pleats” (a folding or puckering of the blade tissue across the venation) illustrated with stippling, E. Foliage leaf ligular area, F. Synflorescence, G. Spikelet. Illustration by Anna B. Gardner; A, C, D, and E based on Clark et al. 1092, B based on Clark & Asimbaya 1415, F and G based on Young 164.