Megalastrum galeottii (M.Martens) R.C.Moran & J.Prado
Descripción
Rhizomes erect to decumbent; leaves up to 1.5 m long; scales of the petiole bases 10–20 × 0.4–0.5 mm, linear, light brown, shiny, conspicuously denticulate on the margins, twisted, the teeth often bifid, the apices filiform and 1-celled for a short distance; 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 (elongated basiscopically); pinna rachises abaxially non-glandular (lacking both stipitate or sessile glands), sparsely scaly, hairs absent, the scales 1.0–1.5 × 0.05–0.2 mm, linear to filiform, spreading-ascending, brown, shiny, denticulate, adaxially pubescent, sparsely scaly, the hairs 0.3-0.5 mm long, 3- or 4-celled, spreading, the scales like those of the abaxial surfaces; costules non-glandular, subglabrous to sparsely puberulent, sparsely scaly at the base, the hairs 0.1–0.2 mm long, 1–3-celled, acicular, erect, adaxially non-glandular, densely pubescent, hairs c. 0.5 mm long, 3–5-celled, strigose to spreading; laminar tissue between veins abaxially glabrous to (more commonly) densely puberulent, the hairs 0.1–0.2 mm long, 1–3-celled, erect, acicular, adaxially glabrous; veins visible on both surfaces, abaxially sparsely pubescent to glabrous, the hairs like those of the costules, adaxially glabrous to sparsely pubescent, the hairs 0.3-0.4 mm long, 1–3-celled, strigose to spreading; hydathodes evident; lamina margins ciliate, the hairs 0.2–0.3 mm long, 1- or 2-celled, acicular, ascending, non-glandular; indusia minute, fugacious, apparently consisting of a cluster of reddish proscales, c. 0.1 mm long, protruding from the centre of the sorus.A
Elevación
400 – 2800 mA
Categoría IUCN
No incluidaB
Categoría NOM-059-SEMARNAT-2010
No incluidaC
Discusión taxonómica
Megalastrum galeottii is characterised by pinnae rachises abaxially with filiform to linear scales and without hairs. Furthermore, most specimens are puberulent between the veins abaxially with hairs 0.1–0.2 mm long, erect, and acicular (specimens glabrous between the veins abaxially are Grayum et al. 5008, Correaet al. 3978, Jiménez 446, Cook & Doyle 157, and Wercklé s.n.). We consider this absence of hairs between the veins abaxially as part of the variation within the species because no other character appears to correlate with it. Also variable in M. galeottii is the length of the hairs on the adaxial surface of the laminae. Some specimens (e.g., Mickel 6396, Molina R. 8084) have longer hairs (0.8-1.2 mm, 4–6-celled) than usual (0.3–0.4 mm long, 1–3-celled).
Megalastrum costipubens is similar but differs by dense puberulence on the pinna rachises and costae abaxially. M. longipilosum also differs by pubescent pinna rachises abaxially and further differs by longer (0.6–1.3(–2) mm, 4–7(–12)-celled) hairs on the laminae adaxially.
Megalastrum galeottii can be confused with M. dentatum. The best way to distinguish them is by the scales on the abaxial surface of the pinna rachises and costae. In M. galeottii these scales are inconspicuous because they are generally sparse and ascending to appressed. In M. dentatum, however, the scales are widely spreading and immediately conspicuous to the naked eye (also along the petiole and rachises). With magnification, the scales of M. galeottii appear linear to filiform, c. 0.2 mm wide, with the cells obscure, whereas those of M. dentatum appear decidedly lanceolate, 0.3–0.4 mm wide, with more evident cells (nearly subclathrate). If large laminae of both species are compared, M. galeottii can be seen to be less finely divided, being only 2-pinnate-pinnatisect medially in contrast to M. dentatum which is 3-pinnate-pinnatisect medially.
Croat 27413 might represent a hybrid between Megalastrum galeottii and M. atrogriseum. It is minutely glandular on the laminae abaxially and has golden brown, firm scales like M. atrogriseum, but it resembles M. galeottii by the minute acicular hairs on the lamina abaxially and glabrous pinna rachises abaxially. Its spores appear misshapen and irregular. The indument of the abaxial surface between the veins only occurs in the soriferous parts of the leaf, not in the nonsoriferous portions.
In a few specimens, stipitate-glandular hairs can be found between the veins abaxially (e.g., Conzatti 615, P). Such hairs are rare and occur among the typical acicular, erect hairs, from which they seem modified and differ only by their glandular apices.
Mickel 1077 is a typical by veins pilose adaxially (the c. 0.5–1.5 mm long). This suggests Megalastrum longipilosum from Costa Rica and Panama, but the specimen is otherwise typical of M. galeottii.
A
Megalastrum costipubens is similar but differs by dense puberulence on the pinna rachises and costae abaxially. M. longipilosum also differs by pubescent pinna rachises abaxially and further differs by longer (0.6–1.3(–2) mm, 4–7(–12)-celled) hairs on the laminae adaxially.
Megalastrum galeottii can be confused with M. dentatum. The best way to distinguish them is by the scales on the abaxial surface of the pinna rachises and costae. In M. galeottii these scales are inconspicuous because they are generally sparse and ascending to appressed. In M. dentatum, however, the scales are widely spreading and immediately conspicuous to the naked eye (also along the petiole and rachises). With magnification, the scales of M. galeottii appear linear to filiform, c. 0.2 mm wide, with the cells obscure, whereas those of M. dentatum appear decidedly lanceolate, 0.3–0.4 mm wide, with more evident cells (nearly subclathrate). If large laminae of both species are compared, M. galeottii can be seen to be less finely divided, being only 2-pinnate-pinnatisect medially in contrast to M. dentatum which is 3-pinnate-pinnatisect medially.
Croat 27413 might represent a hybrid between Megalastrum galeottii and M. atrogriseum. It is minutely glandular on the laminae abaxially and has golden brown, firm scales like M. atrogriseum, but it resembles M. galeottii by the minute acicular hairs on the lamina abaxially and glabrous pinna rachises abaxially. Its spores appear misshapen and irregular. The indument of the abaxial surface between the veins only occurs in the soriferous parts of the leaf, not in the nonsoriferous portions.
In a few specimens, stipitate-glandular hairs can be found between the veins abaxially (e.g., Conzatti 615, P). Such hairs are rare and occur among the typical acicular, erect hairs, from which they seem modified and differ only by their glandular apices.
Mickel 1077 is a typical by veins pilose adaxially (the c. 0.5–1.5 mm long). This suggests Megalastrum longipilosum from Costa Rica and Panama, but the specimen is otherwise typical of M. galeottii.
A