Rediscovering Andreaea subulata Harv., a critically endangered moss in Brazil

Andreaea subulata is a moss species that occurs throughout the Southern Hemisphere. In Brazil, it is restricted to high-altitude fields in the state of Rio de Janeiro. The last recorded collection of this species in the country was made 95 years ago in the Itatiaia National Park (INP). It was never seen or collected again since then and it was, therefore, considered ‘probably extinct’ in Brazil. Here we report the rediscovery of this species in the INP and provide information on its ecology and conservation status in Brazil (Critically Endangered) as well as conservation recommendations. The newly found population is very small and grows on granitic rocks in humid areas. The principal threat to the species in Brazil is habitat loss.

The genus Andreaea Hedw. is cosmopolitan but restricted to temperate regions and mountain tops in tropical regions, exclusively on granite outcrops (Schultze-Motel 1970;Peralta 2020).Few localities in Brazil have been found to provide favorable conditions for the occurrence of the genus, namely, the Serra da Mantiqueira and Serra do Mar mountain chains at elevations between 1,000 and 2,880 m a.s.l.within the Atlantic Forest phytogeographic domain (Peralta 2020).
In Brazil, Andreaea subulata Harv.was known only from three collections made ca.100 years ago in the state of Rio de Janeiro (Flora do Brasil 2020).The While surveying the endemic and threatened moss species from high-altitude fields in the INP, we rediscovered A. subulata.The species is, thus, not extinct as previously assumed.
The methodological procedures of collection and herborization followed Glime & Wagner (2017) and the identification followed Peralta (2020).The map was elaborated using QGis software (QGIS Development Team 2020).
According to information provided by our field guide, the newly found population in Agulhas Negras is exactly in the course of a small intermittent stream, which is the only one along the trail that provides access to the Agulhas Negras peak.This stream is used by alpinists to obtain potable water during the dry season (May through September, when fires in the region are more frequent [personal information]).There was no evidence of recent wildfires in the locality.
The gametophytes of A. subulata are small (from 1 to 4 cm long) and have a reddish brown color in the field; the apices of the gametophytes are greenish (Fig. 2).It differs from A. rupestris -the most common species of the genus in high-altitude fields in the INP -by having falcate, costate leaves with a subulate base. A. subulata also resembles young individuals of other genera, such as Campylopus Brid.and Atractylocarpus Mitt.The species has a dioicous or autoicous sexual system (Peralta 2020).We found no evidence of sporophytes or sexual reproductive structures in the population seen in the field, nor among herbarium specimens, only the fragmentation of leaves that could constitute an asexual reproductive strategy.The absence of sporophytes in the population is likely related to the highly restricted distribution of A. subulata in high-altitude fields in the INP, because if sporophytes were frequent, there should be several other populations due to the ability of moss spores to disperse over long distances.Future phenological studies will greatly contribute to the understanding of the reproductive biology of A. subulata.
The population we encountered was formed by few small clumps along vertical fissures with dripping water.The gametophytes form cushions, a life form tolerant to high solar radiation levels and adapted to conserve water (Glime 2007).
According to Schultze-Motel (1970), A. subulata occurs in Brazil at 2,000 m a.s.l. in Serra dos Órgãos mountains and between 2,800 and 2,900 m in Serra da Mantiqueira mountains -INP.Its rediscovery in a single locality at 2,700 m of altitude indicates that its elevational range in the INP has narrowed over the last 95 years, maybe in response to climate change.Bergamini et al. (2009) demonstrated that climate warming can provoke alterations in the distributions of bryophyte species typical of cooler environments (cryophilous) and that they tend to migrate from mountainous sites to areas more favorable to their establishment and growth.
Concerning the conservation status, A. subulata was previously considered Vulnerable (VU) by Costa et al. (2005) in Rio de Janeiro State, but its conservation status in Brazil was not evaluated.In light of the extremely restricted distribution in the country, with only two recent samples (collected in October 31, 2020) from the same population in localities where they went unnoticed in the frequent surveys conducted during the last years, and the decline of habitat quality observed in those localities, we indicate that the conservation status of A. subulata in Brazil is Critically Endangered (CR).This classification is suggested on the ground of the small area of occupancy of the species (less than 10,000 km²), its occurrence in areas intensely visited by tourists, and the fact that it is only known from two localities (Serra dos Órgãos and Serra da Mantiqueira mountains) in high-altitude fields (fragile ecosystems threatened by climate change).
first collection was made by Dusén in Itatiaia in 1902 and is deposited in R Herbarium.Then, it was collected by Lützelburg in 1916 in Serra dos Órgãos (Serra do Mar) mountains and by Maria do Carmo Vaughan Bandeira in 1925 in Itatiaia National Park (INP) (Serra da Mantiqueira mountains).The latter two collections were analyzed by Schultze-Motel (1970).Due to its rare occurrence, Costa et al. (2005) classified A. subulata as vulnerable (VU) in Rio de Janeiro State (RJ).As it was never collected again after 1925 despite numerous recent floristic studies of bryophytes in and around the INP, Peralta (2020) considered it as probably regionally extinct.

Figure 1 .
Figure 1.Location of the new record of A. subulata in the Itatiaia National Park, Rio de Janeiro State, Brazil.(A) Gametophytes of A. subulata.(B) Agulhas Negras peak.

Figure 2 .
Figure 2. Rock fissures on the Agulhas Negras peak, where A. subulata was collected.