Cephalocarpus marahuacensis S. M. Costa 2024, sp. nov.

2. Cephalocarpus marahuacensis S.M.Costa, sp. nov. (Figures 1B, 2B, 3B) Similar to Cephalocarpus rigidus due to its head-like inflorescence, but clearly distinguished by its narrower leaf blade without main midrib and achene with round apex and linear beak without a narrow neck between main body and beak. Type specimen:— VENEZUELA. Amazonas: Atabapo, Cerro Marahuaca, cumbre, sección suroriental, vecinidades de zanjón, 2685 m, 3°37’N 65°21’W, 15 January 1981, B. Maguire 65631 & J.A. Steyermark, C. Brewer-Carías, C.K. Maguire, V.C. Espinosa (NY02480927! – holotype, VEN?). Monoecious herb: sexes intermingled at paracladia, monomorphic. Caudex 4.5–6 mm diam. including sheaths remains and adventitious roots. Leaf: sheath greenish, margin glabrous or sparse-pubescent; blade 3–5 cm × 0.08–0.13 cm, linear, no main midrib, margin and midrib glabrous or sparse pubescent, concolorous, greenish. Inflorescence reduced, panicle-like, single at each prophyll, 2 paracladia; culm 1.3–1.5 × 0.05–0.07 cm, compressed, glabrous. Paracladia (lowermost) 0.5–1.5 cm long, 1–2 orders; peduncle up to 1cm, compressed, glabrous. Involucral bract (lowermost) leaf-like: sheath 0.3 cm, mouth pubescent, yellowish/reddish-brown; blade 1–1.2 × 0.09 cm, “M”-shaped, glabrous to sparse and long ciliate, yellowish/reddish-brown. Male spikelet 3.5–4 × 0.7–0.8 mm, 1–2 flowers, 5–6 glumes; glume (outermost) –2,5 mm long, margin ciliate, mucronate (ciliate mucron up to ~ 0.6mm long); stamens 2, connective projection short ciliate. Female spikelet ~4 × ~ 1mm, 4–5 glumes; glume (outermost) –2,5 mm long, margin ciliate, mucronate (ciliate mucron up to ~ 0.6mm long); stigmas 3. Fruit 2–4 × ~ 1 mm, obovoid, smooth, apex ciliate, light brown to brown, apex rounded; hypogynous scale – 1.2 mm long, orbicular or obtriangular, trichome – 1mm long; beak – 0.8 mm long, linear, glabrous. Etymology:—The name of the species refers to the type-locality, the Cerro Marahuaca (Amazonas, Venezuela). Distribution:—Only registered from its type-locality and probably restricted to Cerro Marahuaca (Amazonas, Venezuela) at altitudes above 2400m. Taxonomic notes:—This species is easily distinguishable by its leaf blades (without conspicuous midrib) and rounded achene apex with a linear beak, without the constriction zone between the beak and the main body. Examined Material (additional):— VENEZUELA. Amazonas. Cerro Marahuaca: Huha. Cumbre altiplanice no arbolada, más o menos plana, com piedras expuestas, rio abajo, altitud 2580 metros, Lat. 3°40’N, 65°30’O, 31 de enero de 1982, J.A. Steyermark 125922 & M. Guariglia, N. Holmgren, J. Luteyn, S. Mori (US!, VEN?). (cumbre), 3-4 February 1982, J.A. Steyermark 126085 & M. Guariglia, N. Holmgren, J. Luteyn, S. Mori (NY!, US!).