608 M. Arana et al.
reproductive stages), growing as an epiphyte on horco molle Blepharocalyx salicifolius (Kunth) O. Berg (Plate 1a,b). Here we re-evaluate its status as a lost species, to support conservation action and to prevent its extinction. We compiled a database of all known specimens (pre-
served and living) and published records of the species, including those summarized in Arana et al. (2022), and generated a map of all records (Fig. 1) superimposed on a map of biogeographical provinces (Arana et al., 2021a). Using GeoCAT (Bachman et al., 2011) and a 2 × 2 km grid as recommended in the IUCN guidelines (IUCN, 2012a), we estimated the area of occupancy (AOO) of the known population to be 4 km2. We were unable to calcu- late the extent of occurrence as only one living population is known. Wepropose that the fern of Achala should be categorized
as Critically Endangered, based on criterion B2ab(i,ii,iii,iv, v); i.e. an AOO of ,10 km2 (B2), a single location (a), and a continuing decline (b) in the extent of occurrence (i), area of occupancy (ii), area, extent and quality of habitat (iii), number of locations (iv), and number of mature indi- viduals (v). Along with assessing the risk of species becom- ing globally extinct, it is also important to assess species at regional and national levels (IUCN, 2012b), and the fern of Achala should be considered Regionally Extinct in its locus classicus in Comechingones biogeographical province. The rediscovered population of the fern of Achala lies
centrally within its historical range, suggesting that an- thropogenic pressures on the species are strongest at the periphery of its range (Channell & Lomolino, 2000). The Comechingones grasslands have been degraded by the al- most annual setting of intentional fires, with the almost 40,000 ha fire in 2020 being the most extensive since 2010 (Oggero et al., 2020; Arana et al., 2021b; Mari et al., 2021). The Yungas in Argentina has lost more than 31% of its original extent as a consequence of intense anthropogenic disturbance associated with oil exploitation, extensive ranching, and agricultural and urban expansion (Malizia et al., 2012). Securing the survival of the fern of Achala in the short
PLATE 1 (a) Epiphytic habit of the fern of Achala Asplenium achalense; (b) the fern’s habit; (c) typical environment of the Yungas biogeographical province; (d) typical environment of the Comechingones biogeographical province.
to places potentially suitable for the fern of Achala in the Yungas and Comechingones biogeographical provinces, we did not relocate it in places where it had been collected previously or in places with microhabitats similar to the locus classicus in Pampa de Achala, and it was therefore considered a lost species (Romagnoli et al., 2023). However, in August 2022 we found a living population of the species in the Yungas (eight individuals, in different
term and restoring the species to the wild in the long term in an environment in which almost all habitats have been severely modified by human activities will be a challenge. Overlaying all fern of Achala records on a map of the Integral System of Protected Areas in Argentina (not shown) indicates that only five of the species’ historical re- cords were within protected areas and that the rediscovered population does not lie within a conservation unit. We rec- ommend further surveys for the species in the protected areas where it has been recorded historically, and reintro- duction of the species into optimal habitats within protected areas. To facilitate reintroduction, studies of spore germin- ation, gametophyte development and cultivation of sporo- phytes are required (Ibars & Estrelles, 2012; Ballesteros &
Oryx, 2024, 58(5), 607–610 © The Author(s), 2024. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605324000486
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