New records and range extension of Habenaria dutrae Schltr . ( Orchidaceae ) in southern Rio Grande do Sul , Brazil

We describe 4 new records of Habenaria dutrae Schltr., a threatened orchid species that is endemic of Rio Grande do Sul state, Brazil. The new record, from Pontal da Barra, increases the distribution of H. dutrae by approximately 180 km south and represents the southernmost known location for the species. We also re-evaluate the conservation status of the species including the new records, finding it to be Endangered under criteria B2ab(iii); D.


Introduction
The family Orchidaceae, the most diverse family among the angiosperms, comprises 899 genera and approximately 27,801 species (The Plant List 2015, Givnish et al. 2016).Its distribution is cosmopolitan, except for dry deserts and the Antarctic continent (Hágsater and Dumont 1996).In Brazil, it is represented by approximately 221 genera and 2,472 species (Flora do Brasil 2018).
The genus Habenaria Willd.has approximately 870 species, and within subfamily Orchidoideae, it has the highest number of species (Govaerts et al. 2017) and is the largest genus of terrestrial orchids in the world (Batista et al. 2011).With approximately 153 species in Brazil Habenaria is the genus of Orchidaceae with high-est species richness in the county (Flora do Brasil 2018).In Rio Grande do Sul state there are 33 species recorded (Batista et al. 2012).
Habenaria dutrae Schltr. is considered rare and endemic to Rio Grande do Sul (Batista et al. 2012).Its occurrence is predominantly associated with swamp forests (Rocha and Waechter 2006) and wetlands of the coastal plain (Pedron et al. 2014).This species is considered Critically Endangered (criteria B1ab(iii) + 2ab(iii); D) in Rio Grande do Sul (FZB 2014), but it is not included in the Red Book of the Flora of Brazil (Martinelli and Moraes 2013).Habenaria dutrae was previously evaluated according to the categories and criteria of the Red List of the International Union for Conservation of Nature by Pedron et al. (2014) as Endangered (criteria B1ab(iii) + 2ab(iii); D).This species was recorded in only 5 municipalities, as shown in Table 1.
In this study, we expand the geographic distribution of H. dutrae and characterize the environments where the species occurs.We also re-evaluate the conservation status of the species based on the IUCN categories and criteria and including the new records.

Methods
The first author coincidentally found a population of H. dutrae in Altos do Laranjal, Pelotas, Rio Grande do Sul.In the following months, between January and May of 2018, we undertook field trips in search of other populations in Altos do Laranjal and other humid areas in Rio Grande do Sul.The geographic coordinates were obtained in the field using Garmin GPSMAP ® 64.To create the geographic distribution map (Fig. 1) we used the points of observation of H. dutrae from our field trips and information available in SpeciesLink (http://splink.cria.org.br/),Reflora (http://reflora.jbrj.gov.br), and Global Biodiversity Information Facility (http://www.gbif.org/).We used a portable photo studio to get detailed pictures of the inflorescence and flowers.Botanical collections were not undertaken due to delay in emission of specific licenses by the environmental agencies in Brazil (Sistema de Autorização e Informação em Biodiversidade; http://  www.icmbio.gov.br/sisbio/).As a geophyte species, the aerial part dehydrates from apex to base, starting in April and becomes unavailable to collect after that.For re-evaluation of the conservation status of H. dutrae we used the IUCN Red List categories and criteria (IUCN 2012).We calculated the Extent of Occurrence (EOO) and Area of Occupancy (AOO; grid size = 4 km²).Spatial analysis (EOO and AOO) and the distribution map (Fig. 1) were done using the software QuantumGIS v. 3.2.3(QGIS Development Team 2018).

Habenaria dutrae
According to Pedron et al. (2014), H. dutrae differs from H. ekmaniana Kraenzl., the most morphologically similar species, because: In H. dutrae the lateral lobes of the lip are linear and longer than the median lobe, and the anterior lobe of the petals is longer than the posterior one, whereas, in H. ekmaniana, both petal and labellum lobes are similarly sized and the lip lobes are oblanceolate in shape.
However, their key, Rocha and Waechter (2006) considered that the middle segment of the labellum has approximately the same length as the side ones.
Distribution and conservation.This species is presently considered rare by Rocha and Waechter (2006).Natural The locality of Altos do Laranjal (Fig. 3A) is characterized by a transition between coastal wetlands and swamp forests (locally known as "Mata de restinga paludosa").The population of Pontal da Barra locality (Fig. 3B) occurs in the lower areas, in a swamp vegetation dominated by Androtrichum trigynum (Spreng.)H. Pfeiff.interspersed with dunes and sandy forests (locally know as "Mata de restinga arenosa").In these two localities the species was associated with populations of Eryngium pandanifolium Cham.& Schltdl.These types of vegetation are increasingly rare in the coastal plains of southern Rio Grande do Sul, due to agriculture and real estate speculation (Burger and Ramos 2006).The Cascata population (Fig. 3C) was also associated with E. pandanifolium, and at Coqueiral (Fig. 3D) the species was found among veg-etation composed by Cyperus sp.Both populations were found in wetlands among seasonal forests.
The EOO of the species, based on the new records, is 26,852 km² and the AOO is 36 km².The species AOO is less than 500 km², and populations described before 1960 occur in heavily modified areas.Current records are composed of less than 250 mature individuals.Although the orchids show a great production of seeds of anemocoric dispersion, the most seeds fall and develop in the proximity of the maternal plant (Chung et al. 2005), presenting significant genetic clustering on a scale of approximately 5 m (Chung et al. 2004).Considering the low mobility of this species, the small and relatively isolated subpopulations, subjected to strong anthropogenic pressure, we consider populations "severely fragmented" as more than half of the individuals are under these conditions (IUCN Standards and Petitions Subcommittee 2017).Therefore the category remains the same as that proposed by Pedron et al. (2014), even though there were changes in the evaluation criteria: Endangered under criteria B2ab(iii); D.

Discussion
The occurrence of Habenaria dutrae was originally thought to relate to vegetation of humid environments in Rio Grande do Sul coastal plains (Rocha and Waechter 2006) and specifically to areas of the metropolitan region of Porto Alegre and the northern coast of Rio Grande do Sul.The records from Pontal da Barra (Pelotas) extend the geographic distribution of H. dutrae by approximately 180 km south of the southernmost known location (Porto Alegre municipality).This occurrence and the record in Vacaria municipality (C.Buzatto and M. Nervo, cited by Pedron et al. 2014) demonstrate that H. dutrae is not restricted to the metropolitan region of Porto Alegre and the northern coast of Rio do Sul, as previously suggested.Some of the newly reported populations of H. dutrae are from humid areas at the edge of Semideciduous Seasonal Forest fragments on the hillsides of the Serra do Sudeste at Cascata (Pelotas municipality) and in the Central Depression, at Coqueiral (Pareci Novo municipality).
The geophyte habit of H. dutrae, its adaptation to humid areas, and its association with other species that together form dense populations make it difficult to find.The scarcity of records might be associated more with a scarcity of sampling than with rarity of the species.Recently, Singer et al. (2018) rediscovered Codonorchis canisioi (Brogn.)Lindl., another rare and endemic orchid species from Rio Grande do Sul and mentioned that habitat characteristics, morphological aspects of plants, and anthropic activities can make it more difficult to locate rare species.This corroborates our observations for H. dutrae.
Our data considerably increases the number of records and area of occurrence, which are useful for updating this species' conservation status.The description of habitats and the occurrence map may be useful to modeling the distribution of H. dutrae with the goal to locate additional populations.

Figure 2 .
Figure 2. Habenaria dutrae: A. General appearance.B. Leaves.C. Inflorescence.D. Inflorescence detail.E. Frontal view of the flower.F. Lateral view of the flower.G. Mature fruits.Locality for A, B: Altos do Laranjal; C-G, Cascata.

Figure 3 .
Figure 3. Vegetation types of the new records.A. Transition between coastal wetlands and swamp forests; Altos do Laranjal.B. Swamp vegetation interspersed with dunes and sandy forests; Pontal da Barra.C. Wetlands among seasonal forests; Cascata.D. Wetlands among seasonal forests; Coqueiral.