Taxon Details: Megalastrum heydei (C.Chr.) R.C.Moran & J.Prado
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Narratives:
Family:
Dryopteridaceae (Pteridophyta)
Dryopteridaceae (Pteridophyta)
Scientific Name:
Megalastrum heydei (C.Chr.) R.C.Moran & J.Prado
Megalastrum heydei (C.Chr.) R.C.Moran & J.Prado
Accepted Name:
This name is currently accepted.
This name is currently accepted.
Synonyms:
Dryopteris karsteniana var. heydei C.Chr.
Megalastrum pulverulentum var. heydei (C.Chr.) A.R.Sm. & R.C.Moran
Ctenitis pulverulenta var. heydei (C.Chr.) Stolze
Dryopteris karsteniana var. heydei C.Chr.
Megalastrum pulverulentum var. heydei (C.Chr.) A.R.Sm. & R.C.Moran
Ctenitis pulverulenta var. heydei (C.Chr.) Stolze
Description:
by: R.C. Moran, J. Prado
Lectotype: (designated here): Guatemala. Santa Rosa: Río de los Esclavos, E. T. Heyde & Lux s.n. [Donn. Sm. 3249, pro parte] (US-258590; duplicates: GH, MO, US-246305).
Description: Rhizomes not seen; leaves up to 4 m long (estimate); scales of the petiole base not seen; laminae up to 2.5 m long (estimate), 4-pinnate-pinnatifid at base, 3-pinnate-pinnatisect medially; basal pinnae ca. 0.7 m long, strongly inequilateral (elongated basiscopically); pinna rachises glabrescent but when young with sparse glands, hairs, and scales, the glands spherical, ca. 0.1 mm wide, the hairs ca. 0.2 mm long, 2- or 3-celled, spreading, the scales to 1.0-1.8 mm long, lanceolate to linear, loosely appressed to spreading, brown, distinctly toothed, the margins sometimes slightly darker than the scale body, adaxially sparsely glandular, densely puberulent, the glands spherical, sessile, the hairs 0.1-0.2 mm long, 1-3-celled, dense, spreading, brown to reddish brown; costules with indument like that of the pinna rachises; laminar tissue between the veins non-glandular, glabrous on both surfaces, proscales present abaxially, sparse; veins abaxially evident, sparsely puberulent, the hairs 0.2-0.3 mm long, 2- or 3-celled, adaxially obscure, sparsely glandular, subglabrous, the glands ca. 0.1 mm long, spherical, sessile; hydathodes evident; lamina margins sparsely ciliate to subglabrous, the hairs 0.1-0.2 mm long, 1- or 2-celled, 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: Guatemala; known only from two collections; presumably in wet forests, 800-2200 m.
Comments: Based on its large, highly divided leaves (up to 4 m long) and distinctly dentate laminar scales, Megalastrum heydei resembles M. pulverulentum and M. semipubescens. It differs from these two species by minute (ca. 0.1 mm long), often strigose hairs on both surfaces of the pinna rachises and costules. In contrast the hairs on the pinna rachises and costules of M. pulverulentum and M. semipubescens are 1-2 mm long. The short hairs on the axes of M. heydei resemble those of M. palmense, a species that differs by broad, flaccid, dull brown, entire laminar scales and less divided laminae (2-pinnate-pinnatisect medially). Megalastrum heydei is endemic to Guatemala, whereas M. palmense occurs only in the mountains of Costa Rica and Panama. In the two specimens available, the lamina has dried nearly black on the adaxial surface. As pointed out by Stolze (1981), the type collection is mixed. Some Heyde and Lux specimens bearing Donnell-Smith's distribution number 3249 represent Ctenitis excelsa (for instance, US sheet numbers 258596 and 830988). Martínez 12943 (MO) was cited by Moran and Smith (1995) as this taxon from Honduras. It actually represents our new species, M. sparsipilosum.
by: R.C. Moran, J. Prado
Lectotype: (designated here): Guatemala. Santa Rosa: Río de los Esclavos, E. T. Heyde & Lux s.n. [Donn. Sm. 3249, pro parte] (US-258590; duplicates: GH, MO, US-246305).
Description: Rhizomes not seen; leaves up to 4 m long (estimate); scales of the petiole base not seen; laminae up to 2.5 m long (estimate), 4-pinnate-pinnatifid at base, 3-pinnate-pinnatisect medially; basal pinnae ca. 0.7 m long, strongly inequilateral (elongated basiscopically); pinna rachises glabrescent but when young with sparse glands, hairs, and scales, the glands spherical, ca. 0.1 mm wide, the hairs ca. 0.2 mm long, 2- or 3-celled, spreading, the scales to 1.0-1.8 mm long, lanceolate to linear, loosely appressed to spreading, brown, distinctly toothed, the margins sometimes slightly darker than the scale body, adaxially sparsely glandular, densely puberulent, the glands spherical, sessile, the hairs 0.1-0.2 mm long, 1-3-celled, dense, spreading, brown to reddish brown; costules with indument like that of the pinna rachises; laminar tissue between the veins non-glandular, glabrous on both surfaces, proscales present abaxially, sparse; veins abaxially evident, sparsely puberulent, the hairs 0.2-0.3 mm long, 2- or 3-celled, adaxially obscure, sparsely glandular, subglabrous, the glands ca. 0.1 mm long, spherical, sessile; hydathodes evident; lamina margins sparsely ciliate to subglabrous, the hairs 0.1-0.2 mm long, 1- or 2-celled, 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: Guatemala; known only from two collections; presumably in wet forests, 800-2200 m.
Comments: Based on its large, highly divided leaves (up to 4 m long) and distinctly dentate laminar scales, Megalastrum heydei resembles M. pulverulentum and M. semipubescens. It differs from these two species by minute (ca. 0.1 mm long), often strigose hairs on both surfaces of the pinna rachises and costules. In contrast the hairs on the pinna rachises and costules of M. pulverulentum and M. semipubescens are 1-2 mm long. The short hairs on the axes of M. heydei resemble those of M. palmense, a species that differs by broad, flaccid, dull brown, entire laminar scales and less divided laminae (2-pinnate-pinnatisect medially). Megalastrum heydei is endemic to Guatemala, whereas M. palmense occurs only in the mountains of Costa Rica and Panama. In the two specimens available, the lamina has dried nearly black on the adaxial surface. As pointed out by Stolze (1981), the type collection is mixed. Some Heyde and Lux specimens bearing Donnell-Smith's distribution number 3249 represent Ctenitis excelsa (for instance, US sheet numbers 258596 and 830988). Martínez 12943 (MO) was cited by Moran and Smith (1995) as this taxon from Honduras. It actually represents our new species, M. sparsipilosum.