Syngonanthus weddellii Moldenke var. gracilis Moldenke, Phytologia 25: 224. 1973. TYPE: BRAZIL. Goiás. Pirenópolis: Serra dos Pirineus, ca. 18 km E of Pirenópolis town, 1000 m alt., 15 Jan. 1972, H. S. Irwin, W. R. Anderson, M. Stieber & E. Y. Lee 34259 (holotype, LL!; isotype, NY!).

Herbs, 20–40 cm long. Aerial stem 10–20 cm long, pilose with long curled filamentous trichomes ca. 1 cm long, bearing distal inflorescences; after the flowering period, the stem elongates and ramifies distally to the inflorescences, giving rise to other inflorescences in the next fertile period. Leaves spirally disposed along the elongated stem, persistent, linear, flat, patent, 2.0–4.0 × 0.1–0.2 cm, villous in both surfaces, with pedicellate filamentous erect to curled trichomes ca. 0.7 cm long, sheath enlarged, up to 2–3 mm, semi-amplexicaul, apex acute to acuminate. Spathes 2.5–3.5 cm long, abaxial surface pubescent as the leaves, oblique opening, apex acute. Scapes 10–45 per fertile branch, 15–25 cm long, pubescent with short adpressed simple trichomes, early glabrescent. Capitula 5–8 mm diam., spherical; involucral bracts in 5–8 series, oblong, concave, ca. 3.0 × 1.0 mm, external series completely glabrous in both surfaces, internal series densely tufted and ciliated at the apex, with trichomes ca. 0.3 mm long, with clavate apical cells, golden, apex obtuse; receptacle semi-spherical, hairy. Flowers dimerous, ca. 150 per capitulum, ca. 4 times more staminates than pistillates. Floral bracts linear, flat, ca. 1.5 mm long, hairy toward the apex to glabrescent, trichomes with clavate apical cells, brown to dark, apex acute. Staminate flowers ca. 1.5–2.0 mm long, including the pedicel; pedicel ca. 0.5 mm long, with long (ca. 1 mm) trichomes; sepals navicular, ca. 1.0–1.5 mm long, hairy toward the apex, soon glabrescent, trichomes with clavate apical cells, brown to dark in the apex, cream at the base, apex truncate, membranaceous; antophore ca. 0.5 mm long, cream, membranaceous; corolla tubular, ca. 1.0 mm long, glabrous, with the same color as the sepals, membranaceous, involute after anthesis; stamens ca. 1.0 mm long, anthers white; pistillodes 2, ca. 0.1 mm long, papillose, hyaline. Pistillate flowers ca. 1.5–2.0 mm long, including the pedicel; pedicel ca. 0.5 mm long, with trichomes ca. 1 mm long; sepals navicular, ca. 1.0–1.5 mm long, hairy toward the apex, soon glabrescent, trichomes with clavate apical cells, brown to dark in the apex, cream at the base, apex truncate, membranaceous; petals free, ca. 1.0 mm long, densely pilose toward the apex, trichomes with clavate apical cells, hyaline, membranaceous; gynoecium ca. 0.5 mm long, ovary ca. 0.2 mm long, style ca. 0.2 mm, appendages ca. 0.05 mm long, hyaline, inserted at the same point of the stigmatic branches, stigmatic branches 0.2 mm long, bifid. Seeds not seen.

Syngonanthus weddellii var. gracilis Moldenke was misplaced in Syngonanthus as this taxon has truly free petals on the pistillate flower and bifid stigmatic branches. It is therefore transferred at the species level to Paepalanthus, a genus encompassing such morphological traits. The epithet gracilis , however, has been previously used in Paepalanthus by Koernicke (1863). Thus, since it is not available, we propose the new name Paepalanthus rectifolius, referring to straight and ascending leaves, which differ the species from the most similar ones. Paepalanthus rectifolius is known only from the type specimens collected in the mountains east of Pirenópolis, in the Serra dos Pirineus, Goiás, Brazil (Fig. 2). During our research on Eriocaulaceae systematics, we studied collections from several herbaria (B, BHCB, BM, BR, BRLU, C, CESJ, ESA, ESALQ, F, G, HUEFS, INPA, K, L, LE, LL, M, MO, NY, OUPR, OXF, P, R, RB, S, SP, SPF, UEC and UPS; acronyms in Thiers continuously updated). However, despite the presence of several collections from the Serra dos Pirineus, we did not find other specimen of Paepalanthus rectifolius besides the type. Individuals with immature as well as old inflorescences were collected in January.

The morphologically related species are Paepalanthus flaccidus (Bong.) Koern. (1863), Paepalanthus trichophyllus (Bong.) Koern. (1863), and Paepalanthus strictus Koern. (1863), three species with dimerous flowers recently excluded from Paepalanthus sect. Diphyomene Ruhland (1903) (Trovó and Sano 2010). As mentioned above, Paepalanthus rectifolius differs from these three species by its ascending and straight leaves (vs. recurved). It is easily differentiated from Paepalanthus strictus and Paepalanthus trichophyllus by its linear leaves (vs. lanceolate), golden involucral bracts (vs. dark castaneous), and linear floral bracts (vs. oblong). Paepalanthus flaccidus is the most similar species, due to the linear leaves, to the golden involucral bracts, whose internal series might also be tufted in the apex, and to the villous pubescence, with long pedicellate trichomes. Both may be considered sympatric as they are reported to Goiás and occur in the same habitats. Paepalanthus rectifolius is distinguished from Paepalanthus flaccidus by its much longer leaves (2.0–4.0 cm vs. 0.5–1.5 cm), linear floral bracts (vs. oblong), and staminate flowers without lobes (vs. markedly lobed).