Megalastrum connexum (Kaulf.) A.R.Sm. & R.C.Moran

  • Family

    Dryopteridaceae (Pteridophyta)

  • Scientific Name

    Megalastrum connexum (Kaulf.) A.R.Sm. & R.C.Moran

  • Primary Citation

    Amer. Fern J. 77(4): 127. 1987

  • Basionym

    Polypodium connexum Kaulf.

  • Description

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

    Neotype: (designated by Moran et al, 2009): Brazil. Santa Catharina: Ilha de Santa Catarina (Florianópolis), Sertão da Lagoa, [27º35'49''S, 48º48'56''W], 26 Jun 1948, Rohr 1071 (US; isoneotypes: HB, HBR, NY).

    Description: Leaves to 1.5-2.5 m long; scales of the petiole bases ca. 2 × 0.15 cm, linear to lanceolate, sparsely denticulate, light brown to yellowish or golden, twisted or crispate, en masse forming a dense wool; laminae 1-2 m long, to 3-pinnate at base, 2-pinnate medially; basal pinnae ca. 30-50 cm long, stalks to 2 cm long, strongly inequilateral, pinnules acroscopically slightly reduced toward pinna bases; pinna rachises abaxially non-glandular, glabrous or nearly so, with a few (usually at pinna base) scales, these 2.5 mm long, linear, denticulate, adaxially densely pubescent, non-glandular, hairs 0.1-0.3 mm long, 1-4-celled; costules abaxially non-glandular, pubescent or lacking hairs, sparsely scaly, hairs 0.2-0.3 mm long, 2-4-celled, scales 1-2 mm long, filiform to narrowly lanceolate, non-bullate, adaxially pubescent, hairs 0.1-0.6 mm long, 3-5-celled; laminar tissue between veins abaxially non-glandular, glabrous, sometimes with sparse uniseriate scales, these ca. 0.2 mm long, appressed, brown, adaxially glabrous; veins adaxially glabrous or with scattered hairs, visible, abaxially glabrous or pubescent, hairs ca. 0.2 mm long, 1-3-celled, with sparse uniseriate, filiform scales, these ca. 0.2 mm long, appressed, brown; lamina margins non-glandular, sparsely ciliate or apparently eciliate, hairs ca. 0.1 mm long, 1(2)-celled; indusia absent.

    Distribution: Brazil, Argentina, Paraguay, and Uruguay; 0-1000 m.

    Comments: Megalastrum connexum is characterized by glabrous pinna rachises abaxially and filiform scales on the costules and veins abaxially. Both surfaces of the lamina between the veins are glabrous. The costular indument is variable. In all specimens there are hairs and scales on the costules abaxially, but some specimens have more scales than hairs, and vice-versa. Judging from the number of specimens, this is one of the most common species in Brazil. Megalastrum brevipubens has similar laminar cutting but differs by minute (ca. 0.1-0.2 mm long), erect, acicular hairs on the laminar tissue between the veins. Two specimens from Paraguay (Hassler 12203, 12942a) are unusual in lamina cutting. The pinnae are extremely large, with ultimate segments widely spaced and slightly acute and falcate; however, we find no differences in the indument with typical plants, and no other differences correlate with lamina division. Therefore, we consider the specimens part of the variation within M. connexum. Both Christensen (1920) and we were unable to find Kaulfuss's type specimen of Polypodium connexum (Brazil, Sta. Catarina, s.d., Chamisso s.n.), which should be housed at B or LE. For this reason, we are neotypifying this long-used name. The neotype chosen is from the island of Santa Catarina where the Chamisso specimen was collected.

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