Dicranopteris flexuosa Underw., Bull. Torrey Bot.

8.1. Dicranopteris flexuosa (Schrad.) Underw., Bull. Torrey Bot. Club 34: 254 (1907). Fig. 4 b-c Plants terrestrial. Stem long-creeping, with multicellular, reddish-brown hairs. Fronds 16–142.5 cm long, monomorphic, 2–4 forked, erect or scandent; petiole 8.1–39.8 cm long, paleaceous, cylindrical, glabrous; rachis paleaceous, cylindrical, glabrous; laminae 7.9–53.2 cm long, isotomically branched, buds between the bifurcations covered by hairs, reddish-brown; pinnae (ultimate segments) dichotomously branched, pectinate, chartaceous, with globose hairs only on the secondary veins, margins slightly revolute, apex pectinated to pinnatifid, accessory pinnae present at the base; veins free. Sori rounded, medial to supramedial; indusia absent. Examined material: MARANHÃO: Alto ParnaÍba, PNNRP, 10°10’09’’S, 45°55’27’’W, 21.IV.2022, P. H. C. Aguiar et al. 36 (CCAA, UB); Cachoeira do Sussuapara, 10°09’56’’S, 45°55’39’’W, 425 m, 15.XII.2022, P. H. Castro-Aguiar et al. 179 (CCAA, UB); acampamento Várzea Grande, 10°00’21’’S, 46°20’03’’W, 437 m, 17.III.2023, P. H. Castro-Aguiar et al. 277 (CCAA). PIAUÍ: Barreiras do PiauÍ, PNNRP, Cachoeira do Pintado, 10°11’28’’S, 45°51’12’’W, 21.IV.2022, P. H. C. Aguiar et al. 43 (CCAA, UB); P. H. Castro-Aguiar et al. 63 (CCAA); P. H. Castro-Aguiar et al. 67 (CCAA, UB); P. H. Castro-Aguiar et al. 71 (CCAA); Cachoeira do Urubu, 10°11’45’’S, 45°47’48’’W, 470 m, 14.XII.2023, P. H. Castro-Aguiar et al. 105 (CCAA); margem do Rio ParnaÍba, 09°53’23’’S, 45°51’38’’W, 390 m, 18.III.2023, P. H. Castro-Aguiar et al. 293 (CCAA, UB); P. H. Castro-Aguiar et al. 294 (CCAA). Dicranopteris flexuosa has a Neotropical distribution, occurring from Mexico to Paraguay (Lima & Salino 2018). In Brazil, it is a widely distributed species occurring in all biomes (Lima & Salino 2023) and considered in the present study as a new occurrence for PiauÍ. PiauÍ is one of the least sampled states of the Northeastern region, which might explain the absence of records of the species until this present moment. In the PNNRP it was discovered in a wide range of environments, occurring close to waterfalls, on the edges of streams, and in the gallery forest. This species is characterized by 2–4 forked fronds, with unicellular, globose glandular hairs on the secondary veins, abaxially. Dicranopteris flexuosa is morphologically related to D. rufinervis (Mart.) Ching, a species more commonly found in campo rupestre, all with pseudostipules and accessory branches opposite the principal branches, however D. rufinervis differs due to the white to reddish multicellular hairs on the central vein of the segments abaxially, whereas D. flexuosa has glabrous central veins (Lima & Salino 2018).