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Family:

Dryopteridaceae (Pteridophyta)

Primary Citation:

Amer. Fern J. 77(4): 128. 1987

Accepted Name:

This name is currently accepted.

Description:

by: R.C. Moran, J. Prado

Lectotype: (designated by Smith & Moran, 1995): Costa Rica. San José: La Palma, [10°03'N 83°59'W], 1400 m, 20 Mar 1909, A. Brade & C. Brade 215 (UC; duplicates: BM, NY, GH).

Description: Rhizomes erect, the scales 5-10 mm long, entire, golden, flaccid; leaves up to 1.5 m long; scales of the petiole base 1-7 x 0.2-1 mm, generally inconspicuous, linear to lanceolate, flaccid, tightly appressed to the petiole, brown, dull, entire to denticulate or erose on the margins; laminae up to 1.5 m long, 3-pinnate-pinnatifid at base, 2-pinnate-pinnatifid medially; basal pinnae ca. 0.4 m long, strongly inequilateral (elongated basiscopically); pinna rachises abaxially non-glandular (lacking both stipate and sessile glands), densely puberulent, sparsely scaly, the scales to 6 mm long, ovate to oblong, flaccid, appressed, dull brown, entire to erose, the hairs ca. 0.1 mm long, 1- or 2(-4)-celled, spreading; adaxially densely and evenly puberulent, the hairs 0.1 mm long, 1- or 2-celled, spreading to antrorsely strigose; costules abaxially sparsely pubescent and scaly, the hairs and scales like those on the rachis, adaxially pubescent, the hairs 0.1 mm long, 1-3-celled, spreading to antrorsely strigose; laminar tissue between the veins on both surfaces non-glandular, glabrous, procales present, sparse; veins obscure on both surfaces, non-glandular, glabrous; hydathodes evident; lamina margins ciliate, the hairs 0.1-0.2 mm long, 1-3-celled, non-glandular; indusia absent.

Distribution: Costa Rica, Panama; wet forests, 1100-2700 m.

Comments: Megalastrum palmense can be distinguished from nearly all its congeners by the short (ca. 0.1 mm long) hairs on both surfaces of the pinna rachises and costules. These hairs are often antrorsely strigose. Having hairs of the same length on both surfaces of the pinna rachises is unusual; nearly all other species of Megalastrum have longer hairs on the adaxial surfaces. The only species of Megalastrum in Central America with similar hairs on the pinna rachises and costae is M. heydei, endemic to Guatemala. Megalastrum heydei belongs to the M. pulverulentum group, which differs from M. palmense (and other species of Megalastrum) by large leaves (3-4 m long), more highly divided laminae (up to 4-pinnate-pinnatisect), and strongly and conspicuously dentate scales on the pinna rachises and costules. Also distinctive of Megalastrum palmense are its scales on the petioles, rachises, and costules. These scales are lax, flaccid, dull brown, and entire. Upon drying, they often conform closely to the surface. Often the petiole scales appear to be absent, but in fact they are present and tightly appressed to the petiole base. No other species of Megalastrum has similar scales. Megalastrum palmense also lacks hairs and glands (both stalked and spherical) on the both surfaces of the laminae. These characters will serve to distinguish it from many congeners in Costa Rica and Panama, such as M. apicale, M. galeottii, and M. lunense. An unusual specimen that will key to Megalastrum palmense is Moran & Triana-Moreno 8015, from Costa Rica. It differs from typical M. palmense by its petiole scales that are spreading, linear, firm, and denticulate. Its lamina pubescence resembles that of M. palmense except that the costules abaxially are sparsely and minutely acicular pubescent (vs. glabrous) and the hairs on the adaxial surface of the rachis and costae are longer than the hairs on the abaxial surfaces. The scales on the abaxial surface of the rachis and costae resemble those of M. palmense, but some are longer, denticulate, and ascending-spreading, not appressed. This specimen might represent a hybrid involving M. palmense, but we are not sure what species the other parent is. The protologue of Dryopteris palmensis lists Brade 215a as one of the syntypes. This specimen is not at S or UC where Rosenstock types are often found. We have examined three specimens collected on the same date, locality, and elevation that are Brade 215, and consider these specimens as syntypes. Both are annotated in Rosenstock's hand as "palmensis var. nov." The other syntype cited (Costa Rica, La Palma, 1450 m, 17 Mar 1910, A. Brade & C. Brade s.n.) was not found among the specimens requested on loan. For these reasons, we select Brade 215 (NY) as the lectotype.