Megalastrum costipubens R.C.Moran & J.Prado

Description

by: R.C. Moran, J. Prado

Type: Costa Rica. Limón: Cantón de Pococi, R.N.F.S. Barra del Colorado, Llanura de Tortuguero, Sardinas, 10°38'38"N, 83°44'10"W, 15-20 m, 6 Jun 1996, F. Araya & A. Rojas 919 (Holotype: INB; Isotypes: MO-2 sheets, NY-2 sheets).

Description: Rhizomes erect to decumbent; leaves up to 1.5 m long; scales of the petiole bases 10-20 × 0.4-0.5 mm, linear, spreading to ascending, twisted, the apices filiform and uniseriate for a short distance light brown, shiny, conspicuously denticulate on the margins,; laminae 1.0-1.2 m long, up to 3-pinnate-pinnatisect at the base, 2-pinnate-pinnatisect medially; basal pinnae up to 0.5 m long, strongly inequilateral; pinna rachises abaxially non-glandular (lacking both stipitate or sessile glands), pubescent, sparsely scaly, the scales 1.0-1.5 × ca. 0.2 mm, linear, the apices filiform, firm, spreading-ascending, brown, shiny, denticulate, the hairs 0.2-0.6 mm long, 2-5-celled, spreading, adaxially densely pubescent, non-glandular, sparsely scaly, the hairs 0.3-0.5 mm long, 3-5-celled, spreading, the scales like those of the abaxial surfaces; costules abaxially sparsely pubescent and scaly, non-glandular, subglabrous to sparsely puberulent, sparsely scaly at the base, the hairs 0.2-0.3 mm long, 2- or 3-celled, acicular, erect, the scales 0.3-0.5 × ca. 0.1 mm, brown, twisted, adaxially non-glandular, densely pubescent, hairs ca. 0.5 mm long, 3-5-celled, strigose, sparsely scaly; laminar tissue between veins abaxially glabrous to subglabrous, the hairs 0.1-0.2 mm long, 1-3-celled, erect, acicular, adaxially glabrous; veins visible on both surfaces, non-glandular, abaxially sparsely sparsely pubescent, the hairs like those of the costules, adaxially glabrous to sparsely pubescent, the hairs 0.2-0.3(-0.5) mm long, 2-4-celled; hydathodes evident; lamina margins ciliate, the hairs 0.1-0.3 mm long, 1- or 2-celled, ascending, acicular, non-glandular; indusia minute, fugacious, apparently consisting of a cluster of reddish proscales, ca. 0.1 mm long, protruding from the center of the sorus.

Distribution: Nicaragua, Costa Rica, Panama; wet forests, 15-1150 m.

Comments: Megalastrum costipubens resembles M. galeottii and differs only by the pubescent pinna rachises abaxially. Future researchers might conclude that they are the same, but the difference is so striking that we feel it best to name this species to call attention to the variation. Also similar is M. longipilosum (see below), which can be distinguished by the characteristics given in the key.

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