Blechnum areolatum V.A.O.Dittrich & Salino

Castro-Aguiar, Pedro Henrique, Fernandes, Rozijane Santos & Zappi, Daniela Cristina, 2025, Ferns of the Parque Nacional das Nascentes do Rio Parnaíba Brazilian Cerrado, Rodriguesia (e 00612024) 76, pp. 1-24 : 8

2.1. Blechnum areolatum V.A.O.Dittrich & Salino , Syst. Bot. 37(1): 40, f.1-3 (2012). Fig. 3 d-e

Plants rupicolous. Stem erect or decumbent, scales lanceolate, 2.4–4.3 cm long, pale brown. Fronds 7.5–30.2 cm long, monomorphic, 1-pinnate, the fertile longer than the sterile; petiole (2.1–) 3.8–16.8 cm long, paleaceous to brown, adaxially sulcate, with scales at the base similar to those on the stem; rachis adaxially sulcate, with short hairs abaxially; laminae 4.7–13.6 × 1.9–10.3 cm, 1-pinnate, triangular to deltoide, truncate at base; pinnae (2.4–)3–11 × 0.8–1.6 cm, 1–2 pairs, lanceolate, membranaceous, with short hairs abaxially; sessile to adnate, finely denticulate margins, obtuse to acute apex; veins partially anastomosing, form areoles along costae lent free towards the margin. Sori linear, parallel to the costae; indusia linear, introrse.

Examined material: Alto ParnaÍba, PNNRP, 10°10’09’’S, 45°53’27’’W, trilha em direção à Cachoeira do Sussuapara , 407 m, 21.IV.2022, P. H. C. Aguiar et al. 21 ( CCAA, UB); 15.XII.2022, P. H. Castro-Aguiar et al. 171 ( CCAA) .

Blechnum areolatum is endemic in Brazil and has been recorded in the states of Pará and Mato Grosso (Dittrich & Gasper 2023). In the present study it has been recorded for the first time in the Cerrado, in the state of Maranhão, and is found growing on shaded rock formations, inside gallery forest.

This species can be characterized by pinnae with only one row of areoles (occasionally two) along the sides, with inconspicuously denticulated margins (apparently entire) and without auricules in the acroscopic portion. Hairs minute and sparse, found principally at the base of the pinnae and are present only beneath the lamina.

Blechnum areolatum resembles B. heringeri Brade e B. longipilosum V.A.O. Dittrich & Salino due to the partially anastomosed veins. Blechnum heringeri differs in its acroscopic basal portion of the auriculate pinnae, pubescent adaxially (vs. the acroscopic basal portion of the pinnae are truncated, glabrous adaxially in B. areolatum ), whereas in B. longipilosum the laminae have 4–7 pairs of pinnae, densely pubescent on both surfaces (vs. laminae with 1–2 pairs of pinnae, with minute hairs abaxially in B. areolatum ) ( Dittrich et al. 2012).

Figures

Figure 3 – a. Anemia buniifolia – habit. b. Anemia oblongifolia - habit. c. Anemia presliana – habit. d-e. Blechnum areolatum – habit. f.Blechnum asplenioides – habit. g. Telmatoblechnum serrulatum – habit. h. Pteridium esculentum var.harpianum – habit. i. Cyclodium meniscioides – habit. (a. P.H. Castro-Aguiar et al. 280; b. P.H. Castro-Aguiar et al. 290; c. P.H. Castro-Aguiar et al. 170; d. P.H.C. Aguiar et al. 21; e. P.H. Castro-Aguiar et al. 171; f. P.H. Castro-Aguiar et al. 168; g. P.H.C. Aguiar et al. 05; h. P.H. Castro-Aguiar et al. 243; i. P.H. Castro-Aguiar et al. 160).