A new species of Thelypteris subgenus Amauropelta (Thelypteridaceae) from Southeastern Brazil.

ABSTRACT.--Thelypteris soridepressa, known only from the type collection, is described and illustrated. The species belongs to subg. Amauropelta sect. Apelta A.R. Sm. It is superficially similar to Thelypteris micula from Peru in its small, very thin-textured leaves and short trichomes on the adaxial surface of the veins, but can be distinguished by the lack of resinous dots and indusia, as well as by its sunken sori. It has no close relatives in Brazil.

KEY WORDS.--Ferns, pteridophytes, Thelypteridaceae, Thelypteris, Amauropelta, Brazil

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Thelypteris subg. Amauropelta (Kunze) A.R. Sm. comprises more than 200 Neotropical species, besides one species in Hawaii and a few species in Africa, Madagascar, and Mascarene Islands (Smith, 1992). The subgenus can be distinguished from other New World subgenera by the reduced pinnae at the base of blades, veins reaching the margins above the sinuses, finely reticulate sporoderm, and x=29 (Mickel and Smith, 2004). The main center of diversity of the subgenus is the region of the equatorial Andes, notably Colombia, Ecuador, and Peru (Smith, 1983, 1992). According to Salino (2003), in Brazil there are 33 species.

Thelypteris soridepressa Salino & V. Dittrich, sp. nov. TYPE.--BRAZIL. Minas Gerais: Ouro Preto, Sao Bartolomeu, 20[degrees]17'39,68"S, 43[degrees]33 36,67"W, 1050 m, V.A.O. Dittrich et al. 1484 (holotype, BHCB!). Fig. 1.

Species nova ad subg. Amauropeltam sect. Apeltam A.R. Sm. pertinens. Superficialiter T. miculae A.R. Sm. foliis diminutis, membranaceis, trichomatibus brevibus supra nervos superficiei adaxialis dispostis similis, sed soris in cryptis immersis et absentia glandularum resinosarum et indusiorum abunde differt.

Stem erect, with rare scales 0.63 x 0.2 mm, brown, narrowly triangular, with hyaline acicular trichomes. Leaves few to many, clustered, 4.36-9.16 cm long. Lamina membranaceous, 1-pinnate-pinnatifid, 3.06-5.69 x 1.05-1.48 cm, not reduced at base or proximal 1-3 pairs reduced, the lowermost pair 3.25.9 mm long. Petiole 1.34-3.45 cm x 0.3 mm, bisulcate, light green, except at the base, lacking scales, rarely with few scales at the base, pubescent with unicellular to multicellular acicular trichomes, 0.2-0.3 mm. Rachis with acicular trichomes mostly 0.3-0.5 mm on both surface. Pinnae sessile, 0.5-0.72 x 0.28-0.42 cm, lobed or shallowly pinnatifid less than 1.5 mm from margin. Segments 1.2-2 mm wide. Aerophores lacking. Buds lacking. Veins forked or simple towards apex. Indument on costae and veins adaxially, margin of segments, rarely on laminar tissue adaxially of spreading acicular trichomes mostly 0.2-0.5 mm, costal scales lacking, resinous glands lacking. Sori medial to supramedial, round, without indusia, receptacle glabrous and slightly to moderately sunken, sporangia glabrous, spores monolete, ellipsoidal, reticulate.

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Thelypteris soridepressa is the first Brazilian species of Amauropelta sect. Apelta A.R. Sm. According to Smith (1974), the species of this section occur from Hispaniola, southern Mexico, Central America, Venezuela, and British Guiana to Peru, and the number of species is unknown. This species is the smallest of the subg. Amauropelta in Brazil. Thelypteris soridepressa is similar to T. micula A.R. Sm. (sect. Amauropelta) from Peru in its small, very thin-textured leaves and short trichomes on the adaxial surface of the veins, but differs mainly by lacking the resinous glands and indusia, as well as by its sunken sori. The thin-textured leaves and epipetric stem resemble those of some specimens of T. stierii (Rosent.) C.F. Reed (from Brazil and Argentina), but this species differs by the size of the leaves (19-55 cm long), pinnae more numerous and incised, indument of resinous glands on abaxial side of laminar tissue, and setose sporangia.

ACKNOWLEDGMENTS

The authors thank T. S. Filgueiras for the Latin diagnosis, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) for a research fellowship grant to A. Salino (302594/20051), and Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG) for a post-doctoral grant to V.A.O. Dittrich (00176/07), and Miryan Morato Duarte for preparing the illustration. This contribution derives from the research project Riqueza, distribuicao geografica e conservacao das pteridofitas no estado de Minas Gerais, Brasil, supported by resources from the Fundacao O Boticario de Protecao a Natureza (FBPN).

LITERATURE CITED

MICKEL, J. and SMITH, A. R. 2004. The pteridophytes of Mexico. Memoirs of the New York Botanical Garden 88:1-1054.

SALINO, A. 2003. New species and combinations in Thelypteris subg. Goniopteris (Thelypteridaceae). Brittonia 54(4):331-339.

SMITH, A. R. 1974. A revised classification of Thelypteris subgenus Amauropelta. Amer. Fern Journal 64:83-95.

SMITH, A. R. 1983. Polypodiaceae-Thelypteridoideae. In: G. HARLING. G and B. SPARRE, EDS, Flora of Ecuador, 18:18-148.

SMITH, A. R. 1992. Thelypteridaceae. In: R. M. Tryon and R. G. Stolze, eds. Pteridophyta of Peru. Part III. Fieldiana Bot. n.s. 29:1-80.

ALEXANDRE SALINO and VINICIUS ANTONIO DE OLIVEIRA DITTRICH

Departamento de Botanica, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Caixa Postal 486, 30123-970, Belo Horizonte, MG, Brasil; e-mail: [e-mail]