Merostachys ramosa E.M. Pianissola, R. Vinicíus-Silva & L.G. Clark, 2016

Parma, Daniele F., Pianissola, Evandro M., Vinícius-Silva, Ronaldo, Clark, Lynn G. & Santos-Gonçalves, Ana Paula, 2016, Two new species of Merostachys (Poaceae: Bambusoideae) from the Brazilian Atlantic forest, Phytotaxa 267 (3), pp. 219-227 : 220-223

Merostachys ramosa E.M. Pianissola, R. Vinicíus-Silva & L.G. Clark , sp. nov. ( Fig. 1 )

This species can be distinguished from all other species of the genus by a combination of these characters: the occurrence of scabrous midculm internodes and 125–850 branches 16–87 cm long in the branch complement.

Type:— BRAZIL. Minas Gerais: Araponga, Parque Estadual da Serra do Brigadeiro, Trilha do Carvão, 20º41’58”S, 42º27’33”W, 1292 m, 09 September 2013 (veg.), M. M. Picanço, D. F. Parma & E. P. Machado 24 (holotype VIC, isotypes BHCB, ISC, SP, US).

Plants with culms initially erect then clambering on vegetation. Culms 11–20 m tall; internodes 44–98 cm long, 0.8– 3.5 cm in diam., hollow, cylindrical, green with yellow stripes, scabrous, walls 2.7–4 mm thick, ratio of wall thickness: culm diam. 0.13–0.35, very thin to moderately thick, lumen 0.6–3.2 cm in diam., large, not filled by a pith; nodes not prominent, brown, without a fringe of trichomes at the nodal line. Culm leaves 28–53.7 cm long; sheaths 16–41 × 6.5–10 cm, glabrous on the adaxial surface, shiny, sparsely sericeous on the abaxial surface, apex scabrous, sometimes hirsute, margins apically fimbriate; auricles absent; fimbriae 3.6–7.8 mm long, not fused, straight to sinuous, entangled at the apex, yellowish; inner ligule 0.6–1.4 mm long, membranous, apex ciliate; blades 12–12.7 × 1 cm, scabrous on the adaxial surface, hirsute on the abaxial surface, margins scabrous, apex scabrous. Branch complement with 125–850 branches, the branches 16–87 cm long, 0.7–1.8 mm in diam., rebranching from the lower nodes of the first order branches; nodes not prominent, brown to black, without a fringe of trichomes at the nodal line. Foliage leaves 3–10 per branch; sheaths 1.5–4.3 cm × 1.4–3.8 mm, glabrous, the overlapping margin ciliate; auricles absent; outer ligule 0.1–0.2 mm long, apex ciliate; inner ligule 0.1–0.3 mm long, membranous, apex ciliate; fimbriae 2–7 mm long, not fused, straight to sinuous, generally entangled at the apex, yellowish to brownish, often yellowish at the base and becoming brownish toward the apex; pseudopetiole 2–3.8 mm long, dark green to black, glabrous to pubescent, twisted; blades 5–13 × 0.7–1.7 cm, L: W = 6–14.6, lanceolate, with 3–5 scabrous marginal ribs toward the apex on the adaxial surface, apex glabrous, scabrous elsewhere, acuminate, abaxial surface with a tuft of hispid trichomes at the base, apex scabrous, glabrous elsewhere, base symmetric to asymmetric, the apex acuminate, margins scabrous. Inflorescence not seen.

Comments:— Merostachys ramosa with its large number of branches (125–850) per node resembles M. exserta , which has 20–497 branches per node ( Vinícius-Silva 2015), but differs by a few characteristics ( Table 1). In overall aspect, including the relatively narrow leaf blades, M. ramosa most closely resembles M. leptophylla . These two species have foliage leaf blades without a band of minute antrorse strigose trichomes on the abaxial surface, between the marginal stripe and the rest of the blade. However, M. ramosa differs from M. leptophylla by the presence of a tuft of hispid trichomes at the base of the foliage leaf blade on the abaxial surface, internodes green with yellow stripes and mostly scabrous, a large number of branches (125–850) per node, and it occurs at a higher altitudinal range (1290–1520 m). Merostachys leptophylla has foliage leaf blades without a basal tuft of hispid trichomes on the abaxial surface, internodes yellowish-green and glabrous, fewer branches (20–72) per node, and its altitudinal range is completely lowland (240–300 m) ( Table 1).

Distribution and habitat:— Merostachys ramosa is known only from the state of Minas Gerais, Brazil. It is known from five populations in the Parque Estadual da Serra do Brigadeiro at 1290–1520 m elevation, along the borders of the vegetation locally known as Floresta Atlântica Estacional Semidecidual Montana ( Veloso et al. 1991).

Conservation:— We applied the IUCN criteria (2015) and propose an IUCN red list category of vulnerable (VU = D2) given the low occupancy area of 20 km ² and the number of locations in the same conservation unit equal to five.

Etymology:— The specific epithet ramosa refers to the large number of branches in the branch complement of this species.

Additional specimens examined:— BRAZIL: Minas Gerais: Araponga, Parque Estadual da Serra do Brigadeiro, Serra das Cabeças , trilha do mamute, 21 January 2014, veg., E. M. Pianissola & D. F. Parma 38 ( VIC) ; Trilha da Toca da Onça , 04 December 2013, veg., E. M. Pianissola 19 ( VIC) ; Trilha do Carvão , 06 August 2013, veg., M. M. Picanço & E. P. Machado 12 ( VIC) ; ibidem, 09 September 2013, veg., M. M. Picanço, D. F. Parma & E. P. Machado 21 ( VIC) ; ibidem, 09 September 2013, veg., M. M. Picanço, D. F. Parma & E. P. Machado 23 ( VIC) ; ibidem, 09 September 2013, veg., M. M. Picanço, D. F. Parma & E. P. Machado 27 ( VIC) ; ibidem, 10 October 2013, veg., M. M. Picanço, D. F. Parma & E. P. Machado 32 ( VIC) ; Trilha do Panelão dos Muriquis , 21 October 2013, veg., E. M. Pianissola, A. L. Fontes & M. N. Moura 09 ( VIC) ; Trilha do Pico do Boné , 05 december 2013, veg., E. M. Pianissola 24 ( VIC) .

Figures

FIGURE 1. Merostachys ramosa. A (Pianissola & Parma 38) A. Culm leaf. B–C (Picanço et al. 24). B. Branch complement with foliage leaves. C. Ligular area of a foliage leaf with fimbriae. (Illustration by Reinaldo Pinto).