Paspalum cachimboense Davidse, Morrone & Zuloaga (2001: 389)

Delfini, Carolina, Souza, Vinicius Castro & Zuloaga, Fernando Omar, 2017, Taxonomic revision and nomenclatural update of Paspalum sect. Pectinata (Poaceae, Panicoideae, Paspaleae), Phytotaxa 323 (1), pp. 1-26 : 8-9

2. Paspalum cachimboense Davidse, Morrone & Zuloaga (2001: 389) . Fig. 1E–J

Type:— BRAZIL. Mato Grosso: Colider, estrada Santarém–Cuiabá, BR 163, km 762, Serra do Cachimbo a 30 km de Guarantã. Cerrado, campo aberto, solo pedregoso, 09°35’S 54°55’W, 19 April 1983, M.N. Silva 24 et al. (holotype MO 3313433!, isotypes INPA 113144!, RB 373949!).

Densely caespitose annual, 30–60 cm tall. Culms erect, compressed, nodes geniculate, glabrous; aestivation conduplicate. Sheaths usually longer than the internodes, predominantly basal, striated, pilose toward the apical third, with hyaline trichomes, 1–2 mm long. Ligules 1–3 mm long, spatulate, membranous, brown, the margins serrate. Blades 12–20 × 0.4–0.7 cm, linear, flat, hirsute to densely hirsute; the apex acuminate, the margins entire to slightly undulated, papillose-ciliate, hyaline cilia, 1–3 mm long; nerves conspicuous; adaxial and abaxial surfaces hirsute to densely hirsute, with simple and hyaline papillose-trichomes, 1–3 mm long. Inflorescences (5–) 9–15 cm long, 2–4 racemes, racemes 5–7 cm long, subdigitate, axillary inflorescences absent; peduncle 5–20 cm long, glabrous. Rachis 1.8–2.4 mm wide, ending in a naked point, linear to slightly sinuous, glabrous, apical spikelet absent. Spikelets 4–4.4 × 1–1.2 mm, solitary, arranged into two series along the rachis, pedicellate, pedicels glabrous; lower anthecium ca. 1 mm larger than the upper anthecium; upper glume pale brown, lanceolate, not winged, 3-nerved, the nerves conspicuous, midnerve present, the apex acute to obtuse, the margins papillose-ciliate, hyaline cilia 1–1.5 mm long, the base acute to rounded, the surface slightly pilose at the base, simple whitish trichomes, ca 1mm long; lower lemma subequal or slightly smaller than the upper glume, pale yellow, lanceolate, not winged, 3-nerved, the nerves conspicuous, midnerve present, the apex acute to obtuse, the margins ciliate, hyaline cilia 1–1.5 mm long, the base acute to rounded, the surface delicately pilose to papillose-pilose at the base, whitish trichomes, ca. 1 mm long; upper anthecium 3–3.2 × 0.9–1.1 mm, pale yellow, sessile, elliptic, with a conspicuous tuft of trichomes at the apex of the upper lemma; upper lemma and upper palea minutely papillose, the midnerve absent, the apex acute. Anthers 1–1.5 mm long, purple. Styles 2, stigmas plumose, purple. Lodicules 2. Caryopsis ca. 1.5 mm long, elliptic to oblong, brown.

Distribution and habitat: —Restricted to Brazil, and endemic to Serra do Cachimbo, occurring along the border between Pará and Mato Grosso states, between 300 and 570 meters ( Fig. 3 ). Paspalum cachimboense grows in poor quartzite soil nutrient, in a small transition area between the Amazon forest and cerrado. This species was previously known only from the type collection; however, we found one additional sheet collected in the same area as the original specimens. There are no records of recent gatherings of P. cachimboense .

Comments: — Paspalum cachimboense can be separated from all other species of section Pectinata by its typical densely caespitose habit and geniculate nodes. The closest species is P. lanciflorum , from which it mainly differs by having a thinner rachis (1.8–2.4 mm wide vs. 3.5–7 mm wide), smaller spikelets (4–4.4 mm long. vs. 4.8–7.3 mm long) and an annual life cycle (vs. perennial).

Davidse et al. (2001) commented that the annual life cycle is unusual within subgenus Ceresia , having been observed previously only in P. longiaristatum , an endemic species from Niquelândia, region of Chapada dos Veadeiros in Brazil (Goiás state).

Specimens examined: — BRAZIL. Mato Grosso: Colider, Rodovia Cuiabá–Santarém (BR 163) entre Peixoto de Azevedo e divisa MT/PA, km 53, complexo da Serra do Cachimbo, latossolo vermelho amarelo, 320 m. s.m., 30 August 1984, L. Coradín 18520 et al. (CEN).

Figures

FIGURE 1. A–D: Paspalum aspidiotes: A. Upper glume; B. Spikelet, view of the lower lemma; C. Upper lemma; D. Upper palea. E–J: Paspalum cachimboense: E. Habit; F. Node detail; G. Spikelet, view of the upper glume; H. Lower lemma; I. Upper anthecium, view of the upper lemma; J. Upper palea. K–N: Paspalum cordatum: K. Upper glume; L. Lower lemma; M. Upper lemma; N. Upper palea. O–R: Paspalum imbricatum: O. Upper glume; P. Spikelet, view of the lower lemma; Q. Upper lemma; R. Upper palea. S–V: Paspalum lanciflorum: S. Spikelet, view of the upper glume; T. Lower lemma; U. Upper lemma; V. Upper palea. W–Z: Paspalum pectinatum: W. Upper glume; X. Spikelet, view of the lower lemma; Y.Upper lemma; Z. Upper palea. A’–D’: Paspalum reticulinerve: A’. Upper glume; B’. Spikelet, view of the lower lemma; C’. Upper lemma; D’. Upper palea. [A–D: N.A. Rosa 2369 (INPA); E–J: M.N. Silva 24 et al. (RB); K–N: H.M. Longhi-Wagner 8963 et al. (ICN); O–R: T.S. Filgueiras 970 (IBGE); S–V: A. Chase 11402 (RB); W–Z: A. Rizzo 4470 (RB); A’–D’: T. Killeen 4824 et al. (SI)]. Drawn by Maíra Mezzacappa.

FIGURE 3. Distribution map of Paspalum cachimboense and P. imbricatum.