Taxon Details: Megalastrum squamosum A.Rojas
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Protologue of Megalastrum squamosum A. Rojas
Protologue of Megalastrum squamosum A. RojasFamily:
Dryopteridaceae (Pteridophyta)
Dryopteridaceae (Pteridophyta)
Scientific Name:
Megalastrum squamosum A.Rojas
Megalastrum squamosum A.Rojas
Primary Citation:
Brenesia 45-46: 42, f. 6.. 1996
Brenesia 45-46: 42, f. 6.. 1996
Accepted Name:
This name is currently accepted.
This name is currently accepted.
Description:
by: R.C. Moran, J. Prado
Type: Costa Rica. Limón: Cordillera de Talamanca, Reserva Indígena Hitoy Cerere, siguiendo la fila entre Río Hitoy and Río Cerere, 9º38'35"N, 83º05'30"W, 300 m, 26 Feb 1989, G. Herrera & Solís 2458 (Holotype: INB; Isotypes: CR, MO).
Description: Rhizomes erect; leaves up to 2 m long; scales of the petiole base 10-25 × 0.2-1 mm, dense, spreading to deflexed, linear, flat (not twisted), yellowish brown, often shiny, denticulate throughout,; laminae up to 1.5 m long, 3-pinnate-pinnatifid at base, 2-pinnate-pinnatisect medially; basal pinnae ca. 0.4 m long, strongly inequilateral (elongated basiscopically); pinna rachises abaxially non-glandular (neither stalked or sessile glands present), sparsely pubescent to glabrescent, the hairs 0.2-0.4 mm long, 3-5-celled, moderately to densely scaly, the scales to 2-4 × 0.2-0.3 mm, linear, flat (not twisted), spreading, yellowish brown, often shiny sparsely denticulate throughout; adaxially densely pubescent, the hairs 0.5-1 mm long, 5-8-celled, whitish, spreading to antrorsely strigose; costules abaxially sparsely pubescent and scaly, the hairs like those on the rachis, the scales 1.0-1.2 × ca. 0.1 mm, filiform, brown, shiny, adaxially the hairs like those on the pinna rachises, scales absent; laminar tissue between the veins abaxially non-glandular (neither stipitate nor sessile glands present), abaxially sparsely puberulent, the hairs ca. 0.1-0.2 mm long, 1-celled, erect, acicular, adaxially glabrous; veins visible on both surfaces, abaxially non-glandular, pubescent, the hairs 0.1-0.2 mm long, 2 or 3-celled, adaxially glabrous or with 1-3 hairs, the hairs 0.3-0.4 mm long, 3- or 4-celled, spreading, proscales present, appressed, reddish; hydathodes evident; lamina margins ciliate, the hairs 0.1-0.3 mm long, 1-3-celled, non-glandular; indusia minute, fugacious, apparently consisting of a cluster of reddish proscales protruding from the center of the sorus.
Distribution: Talamanca region of Costa Rica and Panama; wet forests, 140-800 m.
Comments: Megalastrum squamosum is distinguished by densely and conspicuously scaly petioles, rachises, and costae. No other Central American species is as densely or conspicuously scaly. Sometimes the scales on the leaf axes are rubbed off and therefore absent, but the typical dense scales can be seen on the petiole bases. The scales are unlike those of many species in the genus by being firm, flat (not twisted even toward the apex), and yellowish brown. By these characteristics they resemble the scales of M. atrogriseum, but are much larger. The scales of many other species in Central America differ by being dull, narrower, shorter, filiform, and twisted or tortuous toward the apex. Another helpful distinguishing character is the minute (0.1 mm long), acicular hairs on the abaxial surface of the laminae between the veins. Because these hairs are erect, they are easily overlooked when viewed from above. Similar fine pubescence occurs in M. galeottii, a species that differs by its laminar scales that are shorter and filiform and far less abundant scales on the petioles, rachises, and costae. See Megalastrum dentatum for comparison with that species.
by: R.C. Moran, J. Prado
Type: Costa Rica. Limón: Cordillera de Talamanca, Reserva Indígena Hitoy Cerere, siguiendo la fila entre Río Hitoy and Río Cerere, 9º38'35"N, 83º05'30"W, 300 m, 26 Feb 1989, G. Herrera & Solís 2458 (Holotype: INB; Isotypes: CR, MO).
Description: Rhizomes erect; leaves up to 2 m long; scales of the petiole base 10-25 × 0.2-1 mm, dense, spreading to deflexed, linear, flat (not twisted), yellowish brown, often shiny, denticulate throughout,; laminae up to 1.5 m long, 3-pinnate-pinnatifid at base, 2-pinnate-pinnatisect medially; basal pinnae ca. 0.4 m long, strongly inequilateral (elongated basiscopically); pinna rachises abaxially non-glandular (neither stalked or sessile glands present), sparsely pubescent to glabrescent, the hairs 0.2-0.4 mm long, 3-5-celled, moderately to densely scaly, the scales to 2-4 × 0.2-0.3 mm, linear, flat (not twisted), spreading, yellowish brown, often shiny sparsely denticulate throughout; adaxially densely pubescent, the hairs 0.5-1 mm long, 5-8-celled, whitish, spreading to antrorsely strigose; costules abaxially sparsely pubescent and scaly, the hairs like those on the rachis, the scales 1.0-1.2 × ca. 0.1 mm, filiform, brown, shiny, adaxially the hairs like those on the pinna rachises, scales absent; laminar tissue between the veins abaxially non-glandular (neither stipitate nor sessile glands present), abaxially sparsely puberulent, the hairs ca. 0.1-0.2 mm long, 1-celled, erect, acicular, adaxially glabrous; veins visible on both surfaces, abaxially non-glandular, pubescent, the hairs 0.1-0.2 mm long, 2 or 3-celled, adaxially glabrous or with 1-3 hairs, the hairs 0.3-0.4 mm long, 3- or 4-celled, spreading, proscales present, appressed, reddish; hydathodes evident; lamina margins ciliate, the hairs 0.1-0.3 mm long, 1-3-celled, non-glandular; indusia minute, fugacious, apparently consisting of a cluster of reddish proscales protruding from the center of the sorus.
Distribution: Talamanca region of Costa Rica and Panama; wet forests, 140-800 m.
Comments: Megalastrum squamosum is distinguished by densely and conspicuously scaly petioles, rachises, and costae. No other Central American species is as densely or conspicuously scaly. Sometimes the scales on the leaf axes are rubbed off and therefore absent, but the typical dense scales can be seen on the petiole bases. The scales are unlike those of many species in the genus by being firm, flat (not twisted even toward the apex), and yellowish brown. By these characteristics they resemble the scales of M. atrogriseum, but are much larger. The scales of many other species in Central America differ by being dull, narrower, shorter, filiform, and twisted or tortuous toward the apex. Another helpful distinguishing character is the minute (0.1 mm long), acicular hairs on the abaxial surface of the laminae between the veins. Because these hairs are erect, they are easily overlooked when viewed from above. Similar fine pubescence occurs in M. galeottii, a species that differs by its laminar scales that are shorter and filiform and far less abundant scales on the petioles, rachises, and costae. See Megalastrum dentatum for comparison with that species.