Telmatoblechnum serrulatum Perrie, D. J. Ohlsen & Brownsey

3.1. Telmatoblechnum serrulatum (Rich.) Perrie, D.J.Ohlsen & Brownsey, Taxon 63(4): 755 (2014). Fig. 3g Plants terrestrial. Stem long-creeping, scales lanceolate, 2.6–3.1 mm long, pale brown to blackish. Fronds (41.1–) 62.9–82.9 cm long, subdimorphic, 1-pinnate; petiole (12.6–) 22.5–41.5 cm long, paleaceous to pale brown, adaxially sulcate; rachis adaxially sulcate, glabrous; laminae 28.5–52.6 × 6.2–18.7(–23.2) cm, oblong-linear, truncate base; pinnae 1.7–12.7 × 0.7–1.3 cm, 16–32 pairs, oblong-linear, chartaceous to coriaceous abaxially, with scales on the costae, articulate to rachis, ascending, ascending, margin conspicuously serrate, apex acute to acuminate; veins free. Sori linear, parallel to the costae; indusia linear, introrse. Examined material: MARANHÃO: Alto ParnaÍba, PNNRP, Povoado Curupá, 09°53’05’’S, 45°53’20’’W, 380 m, 19.IV.2022, P. H. C. Aguiar et al. 05 (CCAA, UB); P. H. C. Aguiar et al. 09 (CCAA); Brejo ruim, 09°51’18’’S, 46°16’33’’W, 406 m, 19.VII.2023, P. H. Castro-Aguiar et al. 312 (CCAA, UB). PIAUÍ: Barreiras do PiauÍ, PNNRP, Passagem do Padre Velho, 10°08’34’’S, 45°49’12’’W, 407 m, 16.XII.2022, P. H. Castro-Aguiar et al. 239 (CCAA, UB). Telmatoblechnum serrulatum is widely distributed in the Neotropical region, occurring from Mexico to Argentina (Gasper et al. 2016). In Brazil, it has been recorded in almost all the states, except Acre and Ceará (Gasper & Dittrich 2023). In the study area it was found growing preferentially along the edge of the vereda, in areas where it would be exposed to light, or in the interior of the vereda, in shaded areas. It is characterized by having 1-pinnate frond, pinnae articulated at the spine, with scales on the costae abaxially, and a conspicuously serrate margin.