Megalastrum martinicense (Spreng.) R.C.Moran, J.Prado & Labiak

  • Description

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

    Lectotype: Lectotype (effectively designated by Proctor, 1989): Martinique. s.d., F. Kohaut s.n. (Sieber Syn. Fil. no. 162) (L-n.v.; photos MICH, NY, US-n.v. ex L; duplicates of the lectotype: K, P)

    Description: Leaves up to 2.5 m long; scales of the petiole bases 1.5-2.0 × 0.05 cm, linear-lanceolate, copiously denticulate, light brown; laminae up to 2 m long, 3-pinnate-pinnatisect at base, 2-pinnate-pinnisect medially; basal pinnae ca. 0.5 m long, inequilateral; pinnules short-stalked, 3-12 cm long; pinna rachises abaxially non-glandular, non-pubescent, scaly, the scales 1.5-3 mm long, linear, brown, denticulate, non-bullate, rachises adaxially non-glandular, densely pubescent, the hairs 1.0-1.2 mm long 4-6-celled, scales sparse, like those on the abaxial surface; costules on the abaxial surface eglandular, sparsely pubescent and scaly, the hairs 0.3-0.5 mm long, 2- or 3-celled, acicular, erect to spreading, the scales like those on the pinna rachises abaxially but smaller, 1.5-2.5 × 0.1-0.3 mm, linear to linear-lanceolate, parallel sided, scarcely enlarged basally, the adaxial surface densely pubescent, the hairs 0.5-1.0 mm long, 4- or 5-celled, substrigose; laminar tissue between veins glabrous on both surfaces, rarely with a few scattered hairs abaxially, the hairs ca. 0.1 mm long; veins visible on both surfaces, abaxially non-glandular, sparsely pubescent, non-scaly, the hairs ca. 0.3-0.5 mm long, 2- or 3-celled, the scales ca. 0.3 mm long, uniseriate, appressed, reddish, adaxially non-glandular, sparsely pubescent, the hairs 0.5-1.0 mm long, 4- or 5-celled; laminar margins ciliate, non-glandular, the hairs 0.3-0.5 mm long, 3- or 4-celled, spreading to substrigose; indusia absent.

    Distribution and ecology: Cuba, Jamaica, Haiti, Dominican Republic, Puerto Rico, Martinique, St. Vincent, St. Lucia, Dominica, Saba, Trinidad; wet forests, shady ravines, 0-1600 m.

    Comments: Megalastrum martinicense is characterized by linear denticulate scales, and hairs along the costules abaxially 0.3-0.5 mm long, 3- or 4-celled. The hairs on the laminar margins tend to be more spreading than in other species, which are typically ascending or appressed. Only rarely does this species have a few scattered glands on the abaxial surface of the lamina between the veins (e.g., Wright 1012); it is typically glabrous between the veins. It resembles M. caribaeum but differs by narrow, filiform denticulate scales on the pinna rachises and costules abaxially. Megalastrum gilbertii has similar hairs and scales on the pinna rachises and costules abaxially but differs by glandular pubescence between the veins abaxially. Besides the characters presented on the key, Megalastrum martinicense and M. subincisum can be distinguished by the following characters: M. martinicense has pinna rachises scales linear, 1.5-3.0 mm long and hairs of the lamina margins 0.3-0.5 mm long, 3- or 4-celled, whereas M. subincisum has pinna rachises scales lanceolate, 5-6 mm long and hairs of the lamina margins 0.2-0.3 mm long, 1- or 2-celled. The type of Phegopteris epieroides represents a less pubescent form of M. martinicense. It is pubescent only along the costules distally.

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