New records of Megalastrum in the northeastern Atlantic Forest

Megalastrum indusiatum R. C. Moran et al. and Megalastrum umbrinum (C. Chr.) A. R. Sm. & R. C. Moran are reported for the first time in the Northeastern Atlantic Forest, extending the distribution of species in the Brazilian Atlantic Forest in about 680 and 1080 km to the north, respectively. Information on taxonomy and species distribution are provided.

Megalastrum Holttum has about 90 species, mainly Neotropical, three of which occur in Africa-Madagascar region and six on islands of the Atlantic, Pacific, and Indian oceans (Moran and Prado 2010;Sundue et al. 2010;Rouhan and Moran 2011).The genus comprises terrestrial plants (rarely saxicolous), medium to large-sized, rhizomes erect to decumbent, 1-4 pinnate-pinnatifid (Moran and Prado 2010;Moran et al. 2014).It has important features for its distinction in the cutting blade, nervation, and axis indumentum in the adaxial part (Moran et al. 2009a(Moran et al. , 2009b)).The basal basiscopic pinnules gradually become decurrent and broadly adnate to the pinna rachis and it is supplied by a vein arising from the costa instead of the costula (Moran et al. 2009a(Moran et al. , 2009b)).Moran et al. (2009a) pointed out that the veins in most Megalastrum species end in hydathodes, before the lamina margins.Hairs in axes are coarse, whitish, multiseptate, with pointed tips, and antrorsely strigose or spreading (Smith and Moran 1987).
Megalastrum is a member of a clade informally recognized as the "lastreopsid ferns", which also includes Lastreopsis, Parapolystichum and Rumohra (Labiak et al. 2014).In Brazil there are 18 recorded species, 13 of which are endemic.All the species occur in Atlantic Forest areas and are absent from Amazonia (Moran et al. 2009a).The species are mainly distributed along the eastern coast of the southeast and southern regions of Brazil, and the complex of Serra do Mar stands out, a location considered as a center of endemism and diversity for the genus (Moran et al. 2009a).Megalastrum stands out in the country as the genus with the highest percentage of endemic species (72.2%) (Prado and Hirai 2014).In the Atlantic Forest region, north of São Francisco river or the Northeastern Atlantic Forest, the occurrence of only one species was previously registered, Megalastrum eugenii (Brade) A. R.This species resembles M. adenopteris (C.Chr.) A. R. Sm. & R. C. Moran, but it differs by laminae adaxially glabrous between veins or sparsely pubescent with a few hairs near the margins; rachis scales spreading, conspicuous, and absence of indusia (vs.laminae adaxially dense and evenly pubescent between veins; rachis scales appessed, inconspicuous and minute fugacious indusia in M. adenopteris) (Moran et al. 2009a).In addition, distinctively, M. adenopteris have 4-pinnate-pinatisect laminae at base, 3-pinnate-pinnatifid medially (Moran et al. 2009a).
In short, the distribution of M. indusiatum and M. umbrinum in the Brazilian Atlantic Forest, which was delimited up to southern Bahia (or the occurrence was restricted to this region, in the case of M. indusiatum), is extended here in about 680 and 1,080 km to the north, respectively (Figures 1 and 2).The interrupt pattern of distribution observed in occurrence of the new records has been shown to other ferns species, for example Pecluma recurvata (Kaulf.)M.G.Price (Santiago et al. 2014), Pteris schwackeana Christ (Prado, 2015), M. eugenii and Cyathea praecincta (Kunze) Domin (Matos et al. 2010).Usually, these species are widely distributed in Forest Atlantic areas from south and/or southeast to the south of the Bahia, with disjunct populations in the Northeastern Atlantic Forest.However, some forests indusiatum may be distinguished by persistent indusia (small sized) and lamina tissue between the veins adaxially glabrous (vs.indusia minute and fugacious; and laminae adaxially densely and evenly pubescent between veins in M. adenopteris).Also distinctive are the non-bullate scales on the pinna rachises abaxially (vs.indusia conspicuous, scales bullate on the pinna rachises abaxially; and lamina tissue between the veins adaxially glandular in M. crenulans) (Moran et al. 2009a;Prado and Hirai 2010).
Comments: Megalastrum umbrinum is characterized by 3-pinnate-pinatisect laminae at base, 2-pinnatepinnatisect medially; abaxial surfaces of axes densely puberulent with short glandular hairs, and acicular (nonglandular) hairs of various sizes (Moran et al. 2009a).remaining that occur in this interrupt area of distribution (Sergipe and/or Alagoas states) are undersampled in relation to ferns flora.Thus, only through the increase in sampling efforts on these areas will be possible to confirm this pattern of disjunct distribution.The species include new records for the Northeastern Atlantic Forest, demonstrating the importance of carrying out further inventories of ferns within this biogeographical unit.Finally, we highlight the need to keep the conservation efforts regarding both of these protected areas of the Northeastern Atlantic Forest, as well as the need to add new records for them, since these areas are rich in flora, there are 82 fern species in RPPN D'Antas (unpublished data) and 107 species in ESEC Murici (Pereira et al. 2013).

Figure 2 .
Figure 2. Distribution of Megalastrum umbrinum in Brazil (based on records shown by speciesLink Project; CRIA 2014).The red circles represents the new record (Lagoa dos Gatos-Pernambuco).