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Family:

Dryopteridaceae (Pteridophyta)

Primary Citation:

Amer. Fern J. 99: 10-11, Figs. 2B, 7A, 9E–H. 2009

Accepted Name:

This name is currently accepted.

Type Specimens:

Specimen 1: Isotype -- P. H. Labiak E.

Description:

by: R.C. Moran, J. Prado, and P.H. Labiak

Type: Brazil. Paraná: Mun. Morretes, Serra da Graciosa, Caminho dos Jesuítas, 29º59'23"S, 52º22'41"W, 1000 m, 20 Oct 2003, Labiak & Goldenberg 3011 (holotype: UPCB; isotypes: NY, SP).

Description: Leaves to 2 m long; scales of the petiole bases ca. 1.5-2 × 0.04-0.1 cm, linear, sparsely denticulate, yellowish to golden brown, flat (not twisted), en masse not forming a woolly tuft; laminae 1.5 m long, to 3-pinnate-pinnatisect at base, 2-pinnate-pinnatifid medially; basal pinnae to 45 cm long, stalks to 2 cm long, strongly inequilateral, pinnules acroscopically slightly reduced toward the bases of pinnae; pinna rachises abaxially non-glandular, sparsely pubescent, very sparsely scaly, hairs 0.3-0.6 mm long, 3-5-celled, scales 1-2 mm long, linear, brown, denticulate, flat (not bullate), slightly spreading, adaxially non-glandular, densely pubescent, hairs ca. 0.3-0.6 mm long, 3-5-celled, patent (not strigose); costules abaxially non-glandular, pubescent, hairs of relatively uniform length, ca. 0.8-1.0 mm long, 5-8-celled, acicular, whitish, scaly, scales small (ca. 0.5-1 mm long), subentire to denticulate, linear, subappressed, adaxially non-glandular, pubescent, hairs ascending to antrorsely strigose, ca. 0.5 mm long, 3-5-celled; laminar tissue between veins abaxially non-glandular, densely pubescent, sparsely scaly, hairs ca. 1-1.5 mm long, 6-9-celled, erect, scales ca. 0.1 mm long, uniseriate, linear, appressed, reddish, inconspicuous, adaxially pubescent, hairs 0.4-0.7 mm long, 4-7-celled, spreading to erect, very sparse scaly, scales ca. 0.2-0.4 mm long, uniseriate, appressed, light reddish, both surfaces dull; veins visible on both surfaces, non-glandular, pubescent and scaly, hairs ca. 1-1.5 mm long, 6-9-celled, adaxially densely pubescent, hairs 0.4-0.7 mm long, 4-7-celled; lamina margins ciliate, non-glandular, hairs ca. 0.2-0.3 mm long, 2-3-celled; indusia absent.

Distribution: SE Brazil (Paraná and São Paulo); 0-1000 m.

Comments: Megalastrum albidum has linear scales on costae abaxially, these mixed with whitish hairs 0.4-0.6 mm long. Also characteristic are the laminae pubescent on both surfaces between the veins. It resembles M. canescens, a species that differs by glandular, stalked hairs on the abaxial lamina surfaces, hairs of mixed length on the costules, and generally shorter hairs on the laminar tissue between the veins (shorter than those along the veins). Furthermore, the laminae of M. canescens are 2-pinnate-pinnatisect at base, 2-pinnate-pinnatifid medially, whereas the laminae of M. albidum are 3-pinnate-pinnatisect at base, 2-pinnate-pinnatifid medially. Megalastrum albidum is named for the dull whitish hairs on both surfaces of the laminae.