Rhipidocladum rubrofimbriatum C.D. Tyrrell, L.G. Clark & Judz., 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 : 61-64

Rhipidocladum rubrofimbriatum C.D. Tyrrell, L.G. Clark & Judz. , sp. nov., Fig 4

Type:— VENEZUELA. Bolívar : Distrio Cendeño, planicie aluvial, piedemonte y altiplanicie entre el margen derecho del Río Orinoco medio y el borde NW de la Serrania de Los Pijiguaos (Bajo Río Suapure ), laja y sus alrededores en piedemonte al borde de caño Trapichote, 6° 18’– 6° 48’ N, 66° 30’– 67° 11’ W, 260 m, 21 March 1987 (fl), F. Guanchez and O. Huber 4583 (holotype: VEN!; isotypes: MYF, TFAV, US!) .

Diagnosis: — Rhipidocladum rubrofimbriatum differs from R. sibilans in its reddish to coppery-colored fimbriae 1.8-6 mm long borne on the foliage leaf sheaths, fewer (20–60) branchlets per node, lanceolate and relatively wider (L:W ratio 5–6) foliage leaf blades and awnless lemmas.

Description: — Culms 2–5 m tall; internodes 12–24 cm long, 3–15 mm diameter, hollow. Culm leaves 8– 9 cm long; sheaths 5.0– 5.5 cm long, abaxially glabrous, margins glabrous; blades 3.0– 3.5 cm long, abaxially glabrous, margins glabrous, apex involute into an awn-like tip. Branch complements with 20–60 branchlets, branchlets 15–35 cm long, occasionally rebranching. Foliage leaves lacking on flowering branchlets (4–7 per vegetative branchlets); sheaths 10–25 mm long, abaxially pubescent-pilose to glabrous, margins ciliate; fimbriae 1.8–6.0 mm long, rubescent, apically wavy to curly; pseudopetioles 0.5–1.0 mm long, abaxially and adaxially glabrous to pubescent, yellow; inner ligules ca. 0.1 mm long, truncate; blades 3.2–8.5 cm long, 6–14 mm wide, L:W ratio 5–6, lanceolate, abaxially puberulent, adaxially glabrous, base often slightly asymmetrical and rounded-attenuate, apex acute, margins finely serrulate. Synflorescences 4.5–8.0(–10.0) cm long, spicate, bearing 3–5 non-secund spikelets spaced 10–20(–40) mm apart; rachis straight. Spikelets 2.0– 2.5 cm long, comprising 2 glumes and 1–2 fertile florets; rachilla internodes 6–7 mm long. Lowest glume 6–7 mm long, 3-nerved, narrowly lanceolate, apex attenuate, abaxially glabrous, awnless to mucronate; upper glume 8–10 mm long, 5-nerved, narrowly lanceolate, apex attenuate, abaxially glabrous, adaxially glabrous, awnless to mucronate. Lemma 9–13 mm long, 7-nerved, narrowly lanceolate, apex attenuate, abaxially glabrous, awnless or mucronate. Palea 9–13 mm long, abaxially glabrous, stramineous, sulcus shallower than congeners. Lodicules 3, the anterior pair 2.0– 2.2 mm long, the posterior one 1.0– 1.3 mm long, ovate. Anthers 4.5–5.5 mm long. Ovary 1.5 mm long, brown to cream. Fruit unknown.

Distribution and Habitat:— Apparently endemic to southwestern Venezuela, growing in savannas in the foothills of a granitic outcrop region along the middle stretch of the Río Orinoco. Found at 85–260 m elevation

Etymology:— The name denotes the coppery red fimbriae which are characteristic of this species: (rubro- = red, fimbriatum = fimbriae).

Comments:— This is the species referenced by Judziewicz in Davidse et al. (2004) as “ Rhipidocladum sp. A ” and “ Rhipidocladum sp. B .”

Additional Specimens Examined:— VENEZUELA. Bolivar [as Territorio Federal Amazonas]: Depto. Atures, 22 km S of Puerto Ayacucho along road to Samariapo, near Garcitas , 85 m, 5°28’ N 67°36’ W, 16 April 1978 (fl), Davidse & Huber 15183 ( MO!, US!) ; carretera de Los Pijiguaos hacia Pto. Ayacucho, km 78; Cerro Gavilan al Norte de la carretera, 6°13’N 67°12’W, en una grieta ancha de 2 m de profundidad, 3 March 1993 (fl), Gröger 836 ( MO!) ; Dpto. Atures, Río Sipapo, 5 km de su desembocadura al Río Orinoco , Cerro Caldero , 5°1’N 67°46’ W, 17 May 1992 (fl), Gröger & Bancroft 416 ( MO!) ; Dpto. Atures, carretera Samariapo-Puerto Ayacucho, Km 5.5, laja al oeste de la carretera, 5°17’N 67°48’ W, 4 June 1992 (fl), Gröger & Meier 483 ( MO!) ; forest E of Río Parguaza bordering savanna 1 km S of Quebrada La Flore, affluent of Río Ore, affluent of Río Parguaza , 6°17’N 67°5’W, 85 m, 9 September 1985 (fl), Steyermark et al. 131610 ( MO!) .

Figures

FIGURE 4. Rhipidocladum rubrofimbriatum. A. Culm internode with flowering branch complement showing leafless branches bearing terminal synflorescences, B. Culm leaf, C. Floret, lateral view, D. Floret, ventral view, E. Foliage leaf complement, F. Foliage leaf ligular area showing fimbriae. Illustration by Christa Adler; A based on Guanchez & Huber 4583, B based on Steyermark et al. 131610, C, D and F based on Gröger & Meier 483, E based on Davidse & Huber 15183.