Megalastrum subincisum (Willd.) A.R.Sm. & R.C.Moran

  • Family

    Dryopteridaceae (Pteridophyta)

  • Scientific Name

    Megalastrum subincisum (Willd.) A.R.Sm. & R.C.Moran

  • Primary Citation

    Amer. Fern J. 77(4): 129. 1987

  • Description

    by: R.C. Moran, J. Prado, and P.H. Labiak

    Type: Type: Venezuela. Federal District: Caracas, [10°30'N, 66°55'W], s.d., F. Bredemeyer s.n. (holotype: B-W 19701).

    Description: Leaves up to 2 m long; scales of the petiole bases 2.0-2.5 × 0.1-0.2 cm, linear-lanceolate, denticulate, brown; laminae up to 1.5 m long, 3-pinnate-pinnatisect at base, 2-pinnate-pinnitisect medially; basal pinnae 0.4-0.6 m long, inequilateral; pinnules short-stalked, 4-15 cm long; pinna rachises abaxially non-glandular, without hairs, scaly, the scales 5-6 mm long, lanceolate, light brown, denticulate, non-bullate, rachises adaxially non-glandular, densely pubescent, the hairs 0.5-0.8 mm long; 4- or 5-celled, the scales like those on the abaxial surface; costules on the abaxial surface eglandular, sparsely pubescent (especially distally) and scaly, the hairs 0.2-0.5 mm long, 2-4-celled, acicular, erect to spreading or substrigose, the scales like those on the pinna rachises abaxially but smaller, 3-5 × 0.3-0.7 mm, lanceolate, enlarged basally, the adaxial surface pubescent, the hairs 0.5-1.0 mm long, 4- or 5-celled, substrigose; laminar tissue between veins glabrous on both surfaces, or near the costules and sinuses very sparsely puberulent abaxially, the hairs ca. 0.1 mm long, acicular; veins visible on both surfaces, abaxially non-glandular, sparsely pubescent, non-scaly, the hairs ca. 0.5-0.8 mm long, 2- or 3-celled, the scales ca. 0.3 mm long, uniseriate, appressed, reddish, adaxially non-glandular, sparsely pubescent, the hairs 0.8-1.0 mm long, 2-4-celled; laminar margins ciliate, non-glandular, the hairs 0.2-0.3 mm long, 1- or 2-celled, spreading to substrigose; indusia absent.

    Distribution and ecology: Mexico, Honduras, Cuba, Jamaica, Haiti, Dominican Republic, Guadeloupe, Dominica, Venezuela, Colombia; wet forests, shady ravines, 900-1700 m.

    Comments: Megalastrum subincisum is characterized by lanceolate, bright brown, shiny scales on the pinna rachises and costules abaxially. Hairs are absent on the laminar surfaces abaxially and pinnae rachises abaxially, being only sparsely present on the costules distally. Christensen (1920) construed Megalastrum subincisum in the wide sense, occurring from Mexico to Bolivia. He admitted a great deal of variation in the presence versus absence of hairs and glands and the type of laminar scales. We find, however, that indument characteristics can be used to divide M. subincisum in the broad sense (and other species in the genus) into additional species that often correspond to elevation and geography. Two such instances are M. caribaeum and M. martinicense, both recognized here but lumped by Christensen under M. subincisum. In our view, M. subincisum is far more narrowly distributed than conceived by Christensen, occurring only in Mexico, Honduras, the West Indies and northern Venezuela and Colombia.

  • Floras and Monographs

    Megalastrum subincisum (Willd.) A.R.Sm. & R.C.Moran: [Article] Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.