Elaphoglossum Schott ex J.Sm., J. Bot. (Hooker)

Kessler, Michael, Moran, Robbin C., Mickel, John T., Matos, Fernando B. & Smith, Alan R., 2018, Prodromus of a fern flora for Bolivia. XXXV. Dryopteridaceae, Phytotaxa 353 (1), pp. 448-450 : 448-450

Elaphoglossum Schott ex J.Sm., J. Bot. (Hooker) 4: 148. 1841.

= Peltapteris Link, Fil. Spec. 147. 1841.

The largest fern genus in Bolivia, with 127 species. In humid montane forests over a dozen species may grow side-by-side. Elaphoglossum belongs to the bolbitidoid clade of the Dryopteridaceae . This clade is characterized by sterile-fertile leaf dimorphism; acrostichoid sori; lack of hairs (rarely present in Elaphoglossum ); creeping rhizomes (infrequently erect in Elaphoglossum ), and an elongate (as seen in cross-section) ventral meristele ( Rouhan et al. 2004, Moran et al. 2010a, b). Within this clade, Elaphoglossum is sister to Mickelia and can usually be recognized by the presence of phyllopodia, simple blades, and free veins ± perpendicular to the midrib. In a few species, the veins are anastomosing, and six species have divided leaves that are either pedate, pinnate, or flabellate ( Vasco et al. 2013). Occasionally, individuals of simple-bladed species produce 1-forked blades or have cristate blade apices (especially E. orbignyanum ).

The genus is taxonomically difficult due to the low number of useful characters and the intraspecific variability of such characters as plant size, blade shape, scale color, and scale type. The distinction between scales, hairs, and resinous dots is sometimes difficult in Elaphoglossum , with transitional forms occurring. While fertile leaves add a number of useful characters, all species can be identified based on sterile material alone. Unfortunately, many botanists are hesitant to collect sterile specimens, and rarely fertile species are accordingly under-collected. Hybrids are infrequently documented in Elaphoglossum , but this may be largely a result of the similarity of the species, the paucity of useful characters, and the corresponding difficulty of detection.

Mickel & Atehortúa (1980) recognized six sections based on morphological grounds. These groups have largely been confirmed by more recent molecular studies, although a few species groups have been slightly rearranged ( Rouhan et al. 2004, Skog et al. 2004, Vasco et al. 2015) and a seventh monospecific section, endemic to Cuba, has been recognized recently ( Lóriga et al. 2014). The sections are mostly easily distinguished in the field and herbarium. They are the starting point for the classification and identification of Elaphoglossum .

Elaphoglossum is a pantropical genus with over 600 species, over 450 in the Americas. Since Christ’s (1899) monograph of the genus, the number of recognized species has more than tripled (e.g., Mickel 1980, 1985, 1987, 1991, 1993, Rojas-Alvarado 2002, Moran & Mickel 2004, Kessler & Mickel 2006, Kessler 2008, 2013, Matos & Mickel 2014, Matos & Moran 2017). Alston (1958a) wrote an account for the Brazilian species, and Mickel (1991) treated those in Peru; other Andean countries need a modern account, and many species remain undescribed. Modern revisionary treatments are available for only a few clades, most of which are comparatively distinct and species-poor (e.g., Vasco et al. 2009 a, Vasco 2011, 2013).