The curious distribution of the dwarf Brazilian tree fern, Neoblechnum brasiliense (Blechnaceae): New country records an
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Wild Earth Allies, 2 Wisconsin Circle, Suite 900, Chevy Chase, MD 20815, USA; e-mail: [email protected] 2 Laboratorio de Ecología y Sistemática Vegetal, Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Antigua carretera a Pátzcuaro No. 8701, Col. San José de la Huerta. C.P, 58190, Morelia, Michoacán, Mexico; e-mail: [email protected]; e-mail: [email protected]
Abstract. Neoblechnum brasiliense (Blechnaceae) is common and widespread in South America but has been known from Mesoamerica by only one collection from Guatemala by Julian Steyermark in 1939. We discovered two new occurrences of the species, in Belize and Mexico, extending the range of the species over 1000 km north and west into northern Mesoamerica. We discuss possible explanations for the rarity of the species in Mesoamerica and its disjunction from South America. Keywords: Belize, Blechnum, floristics, Mexico.
The Blechnaceae comprises ca. 250 species of ferns worldwide (Kramer et al., 1990 Smith et al., 2006; Rothfels et al., 2012; Perrie et al., 2014; Gasper et al., 2016, 2017), of which about 200 have been classified in Blechnum. This genus is well known to be polyphyletic (e.g., Cranfill & Kato, 2003; Schuettpelz & Pryer, 2007; Rothfels et al., 2012; Perrie et al., 2014; Gasper et al., 2017), and recently 25 genera have been recognized for the family (Molino et al., 2019). Five of these genera may have trunk-like, arborescent rhizomes: the monotypic Brainea J. Sm. (China, southeast Asia, Malesia) and Neoblechnum Gasper & V.A.O. Dittrich (Neotropical), plus Oceaniopteris Gasper & Salino [O. gibba (Labill.) Gasper & Salino of Oceania], some Lomaria Willd. (South America, South Africa, Australia, New Caledonia), Lomariocycas (J. Sm.) Gasper & V.A.O. Dittrich (Neotropics, Africa, and Madagascar), and Sadleria Kaulf. (Hawaii). Neoblechnum brasiliense (Desv.) Gasper & V. A. O. Dittrich (Blechnum brasiliense Desv.) differs from other Blechnaceae by the combination of stout, erect rhizomes forming caudices to c. 1
m, monomorphic sterile and fertile fronds, free veins, indusiate sori, serrulate pinnae adnate to and strongly decurrent onto the leaf rachis, and linear-lanceolate, bicolored but mostly glossyblack scales at the base of the stipe (Gasper et al., 2016).
Distribution Neoblechnum brasiliense has an unusual distribution: it is almost exclusively South American except for one disjunct occurrence in Guatemala that was first documented by a collection by Julian Steyermark in 1939. In his description of the species for Guatemala, Stolze (1981) remarked that “The species is aptly named, as it is far more abundant in Brazil than anywhere else. It is found as far north as Colombia but heretofore has not been found in the West Indies, or in Central America except for the one Steyermark specimen collected in Chiquimula in 1939. This is curious, in that the plants are large and conspicuous and not likely to be overlooked even by general collectors. It should not be confused with any ot
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