Olyra caudata Trinius (1836: 292). Fig. 7 A–B.

Type:— PERU. Tocache, in sylvis densis, 1834, Poeppig [(holotype LE-TRIN-1118.01, isotype US-2877958 (fragment ex LE)].

Rhizomes not seen. Culms ca. 2m tall, erect, internodes 14–28 cm long, hollow, smooth, glabrous; nodes dark brown, glabrous. Leaf sheath pubescent, margins short-ciliate; ligules 4–6 mm, membranous-ciliate; pseudopetioles 3–4 mm, flat, shortly to densely pilose; blades 18–23 × 3.8–5.2 cm, ovate-lanceolate, short-pilose on both surfaces, asymmetrical, base obtuse, margins scabrous, apex acuminate. Synflorescences (12–)15–18 × (13–) 15–20 cm, umbelliform, the lower branches whorled, the upper branches alternate or verticillate, each branch with male spikelets on short pedicels basally and a single terminal female spikelet, rachis scabrous, the pedicels of male spikelets 1–2 mm, thin, the apex clavate, short-pilose, the pedicels of female spikelets 6.7–7.9 cm, longitudinally ridged, one side flattened, the apex clavate, densely pilose. Male spikelets 2.8–3.1 × 0.3 mm, lanceolate, brownish, hispid, falling entire; lemma 3-nerved, hispid in the apex and margins, apex short-aristate; palea 2-nerved, glabrous to shortly pilose toward the apex, apex short-aristate; stamens 3, included, filaments 0.3–0.5 mm, glabrous, anthers ca. 1.6 mm, black (in siccus). Female spikelets 23–32 × 4–5 mm, ovoid, stramineous (in siccus), glabrous, dispersion above the glumes, tardily caducous; the glumes subequal, 9-nerved, glabrous, apex awned, the awn 13–24 mm long; anthecium ca. 6–8 × 3–4 mm, ovoid, stramineous (in siccus), becoming black at maturity, smooth and shiny, deciduous, shortly stipitate at its base, stipe ca. 0.4 mm long; lemma with prickle trichomes in the upper margins, apex acute; palea glabrous, apex acute; lodicules not seen; ovary not seen, stigma 2, plumose. Caryopsis not seen.

Specimens examined: — BRAZIL. Pará: Altamira, Reserva Biológica Nascentes da Serra do Cachimbo, ramal principal da REBIONSC, entrada a 65km de Cachoeira da Serra, 592 m, 9°04’26.7”S, 54°45’14.6”W, 25 May 2021, Lopes-Neto et al. 685 (MG). Itaituba, BR-163, Cuiabá-Santarém Highway, Km 867, Rio Vermelho, 11 November 1977, Silva 209 (INPA, MG, MO, US); Km 877, Cachoeira da Luz, Rio Curuá, margem esquerda, 02 May 1983, Amaral et al. 1077 (INPA, MO, NY).

Distribution and habitat: —This species occurs in Central and South America, in Bolivia, Brazil, Colombia, Costa Rica, Guyana, Panama, Peru, Suriname and Trinidad and Tobago (Soderstrom & Zuloaga 1989, Vorontsova et al. 2016). In Brazil, it is registered in the Amazon Forest, between 150 to 1.100 meters, in the states of Acre, Amazonas, Pará, Rondônia and Mato Grosso (Oliveira et al. 2020b). In the Serra do Cachimbo, it was found in Open ombrophilous forest.

Comments: — Olyra caudata and O. latifolia Linnaeus (1759: 1261) share culms ca. 2 m tall, ovate-lanceolate leaves, asymmetrical, shortly pilose on both surfaces, female spikelets awned and anthecium ovoid and smooth. However, this species has umbelliform synflorescences, the female spikelets are larger (23–32 × 4–5 mm) and the glumes are subequal, with awns 13–14 mm long, while O. latifolia has pyramidal synflorescences, the female spikelets are smaller (10–12 × 1.4–2.2 mm) and the glumes are unequal, with awns 3.8–4.8 mm long.