Taxon Details: Megalastrum lanatum (Fée) Holttum
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Combination for Megalastrum lanatum (Fée) Holttum
Combination for Megalastrum lanatum (Fée) HolttumFamily:
Dryopteridaceae (Pteridophyta)
Dryopteridaceae (Pteridophyta)
Scientific Name:
Megalastrum lanatum (Fée) Holttum
Megalastrum lanatum (Fée) Holttum
Primary Citation:
Gard. Bull. Singapore 39(2): 161. 1986
Gard. Bull. Singapore 39(2): 161. 1986
Accepted Name:
This name is currently accepted.
This name is currently accepted.
Description:
by: G. Rouhan & R.C. Moran
Type: La Réunion. S.d., De Montbrison s.n. (holotype, P!).
Description: Rhizomes short-creeping, scaly, the scales up to 20 mm long; fronds up to 2 m long; scales of the petiole bases 8-11 × 0.8-2.0(-3.0) mm, linear, subentire, dark brown, spreading; rachises with few similar but smaller scales in the proximal half; laminae up to 1.2 m long, deltoid; bipinnate-pinnatifid at base and medially; basal pinnae 18-30 cm long, the stalk up to 1.5 cm long, inequilateral, the pinnules on the acroscopic side slightly reduced toward the base of the pinna, the first basiscopic pinnules with lobes lobulate, other pinnules with lobes crenate to subentire toward the apex of the pinna; pinna rachises abaxially pubescent, not glandular, the hairs erect, 0.5-1.2 mm long, to 6-celled, scaly, the scales 2.0-4.0 × 0.2-0.5 mm long, linear, entire, flat (non-bullate), dark brown, adaxially densely pubescent, the hairs erect, 1.2-1.7 mm long, 6-8-celled, septate, non-glandular; costules abaxially puberulent, not glandular, the hairs spreading to erect, 0.3-0.6 mm long, 3-5-celled, scaly, the scales 0.3-0.7 × ca. 0.2 mm, flat, entire, adaxially densely pubescent, the hairs erect to spreading, 0.6-1.0(-1.5) mm long, 5-7-celled, non glandular, septate; laminar tissue between veins pubescent on both surfaces, abaxially rarely glandular, the glands spherical, sessile, clear or translucid yellowish, up to 0.1 mm diam., hairs erect to spreading on both surfaces, 0.3-0.6 mm long, 3-5-celled; veins to 7 pairs per pinnules lobe, visible on both surfaces, ending behind laminar margins in enlarged clavate tips (conspicuous hydathodes), pubescent with hairs like those of the laminar tissue; laminar margins sparsely ciliate, the hairs similar to those of the laminar surfaces; indusia absent, or if present (rarely), reduced, pubescent, pale brown, dull, up to 0.5 mm diam., hairs mostly on the margins, ca 0.5 mm long.
Etymology: From the Latin lana, wool, referring to the conspicuous, dense, whitish pubescence on both faces of the laminae.
Distribution: Endemic to La Réunion, terrestrial in wet forests, 800-1400 m. Although one specimen (Bréon s.n. in 1834) with 'Madagascar' written on it, we believe this to be in error. There is no other collection of M. lanatum from Madagascar, and Bréon collected M. lanatum in La Réunion in the same year.
Comments: Megalastrum lanatum differs from M. canacae by the laminae between veins pubescent on both surfaces and longer hairs on the pinna-rachises and the abaxial surfaces of costules. The lack of indusia will distinguish M. lanatum from the other two species of the Old World; however, small indusia can rarely be found on a few specimens. Also, indusia may be present but so fugacious that it is only rarely observed. When present, indusia have to be very carefully looked for: they are reduced, pubescent, and often almost completely hidden by sporangia, the only evidence of their prescence being marginal hairs exceeding the sporangia. As for M. canacae, recent observations and collections made in La Réunion demonstrate that the length of the basal basiscopic pinnules of basal pinnae is not necessarily shorter than the pinnules next to them as was claimed by Holttum (1983). The holotype of Phegopteris lanata Fée (M. lanatum), collected by De Montbrison s.n. according to Fée, could have never been found considering that usually, specimens seen by Fée and used by him in his descriptions bear his handwriting including his signature. And indeed, the only specimen De Montbrison s.n. does not have such signature or his handwriting. Nevertheless, it accords well with the original description by Fée. For this reason, we treated the specimen De Montbrison s.n. as the holotype, arguing that Fée forgot to annotate this specimen. The following name applies to M. lanatum: Aspidium oppositum var. subglandulosum Mett. ex Kuhn, Filic. Afr.: 138. 1868, nom. nud. quoad Boivin 814 (P!).
by: G. Rouhan & R.C. Moran
Type: La Réunion. S.d., De Montbrison s.n. (holotype, P!).
Description: Rhizomes short-creeping, scaly, the scales up to 20 mm long; fronds up to 2 m long; scales of the petiole bases 8-11 × 0.8-2.0(-3.0) mm, linear, subentire, dark brown, spreading; rachises with few similar but smaller scales in the proximal half; laminae up to 1.2 m long, deltoid; bipinnate-pinnatifid at base and medially; basal pinnae 18-30 cm long, the stalk up to 1.5 cm long, inequilateral, the pinnules on the acroscopic side slightly reduced toward the base of the pinna, the first basiscopic pinnules with lobes lobulate, other pinnules with lobes crenate to subentire toward the apex of the pinna; pinna rachises abaxially pubescent, not glandular, the hairs erect, 0.5-1.2 mm long, to 6-celled, scaly, the scales 2.0-4.0 × 0.2-0.5 mm long, linear, entire, flat (non-bullate), dark brown, adaxially densely pubescent, the hairs erect, 1.2-1.7 mm long, 6-8-celled, septate, non-glandular; costules abaxially puberulent, not glandular, the hairs spreading to erect, 0.3-0.6 mm long, 3-5-celled, scaly, the scales 0.3-0.7 × ca. 0.2 mm, flat, entire, adaxially densely pubescent, the hairs erect to spreading, 0.6-1.0(-1.5) mm long, 5-7-celled, non glandular, septate; laminar tissue between veins pubescent on both surfaces, abaxially rarely glandular, the glands spherical, sessile, clear or translucid yellowish, up to 0.1 mm diam., hairs erect to spreading on both surfaces, 0.3-0.6 mm long, 3-5-celled; veins to 7 pairs per pinnules lobe, visible on both surfaces, ending behind laminar margins in enlarged clavate tips (conspicuous hydathodes), pubescent with hairs like those of the laminar tissue; laminar margins sparsely ciliate, the hairs similar to those of the laminar surfaces; indusia absent, or if present (rarely), reduced, pubescent, pale brown, dull, up to 0.5 mm diam., hairs mostly on the margins, ca 0.5 mm long.
Etymology: From the Latin lana, wool, referring to the conspicuous, dense, whitish pubescence on both faces of the laminae.
Distribution: Endemic to La Réunion, terrestrial in wet forests, 800-1400 m. Although one specimen (Bréon s.n. in 1834) with 'Madagascar' written on it, we believe this to be in error. There is no other collection of M. lanatum from Madagascar, and Bréon collected M. lanatum in La Réunion in the same year.
Comments: Megalastrum lanatum differs from M. canacae by the laminae between veins pubescent on both surfaces and longer hairs on the pinna-rachises and the abaxial surfaces of costules. The lack of indusia will distinguish M. lanatum from the other two species of the Old World; however, small indusia can rarely be found on a few specimens. Also, indusia may be present but so fugacious that it is only rarely observed. When present, indusia have to be very carefully looked for: they are reduced, pubescent, and often almost completely hidden by sporangia, the only evidence of their prescence being marginal hairs exceeding the sporangia. As for M. canacae, recent observations and collections made in La Réunion demonstrate that the length of the basal basiscopic pinnules of basal pinnae is not necessarily shorter than the pinnules next to them as was claimed by Holttum (1983). The holotype of Phegopteris lanata Fée (M. lanatum), collected by De Montbrison s.n. according to Fée, could have never been found considering that usually, specimens seen by Fée and used by him in his descriptions bear his handwriting including his signature. And indeed, the only specimen De Montbrison s.n. does not have such signature or his handwriting. Nevertheless, it accords well with the original description by Fée. For this reason, we treated the specimen De Montbrison s.n. as the holotype, arguing that Fée forgot to annotate this specimen. The following name applies to M. lanatum: Aspidium oppositum var. subglandulosum Mett. ex Kuhn, Filic. Afr.: 138. 1868, nom. nud. quoad Boivin 814 (P!).