Eremitis clarkiae and E. vinacea (Poaceae, Bambusoideae): two new species of herbaceous bamboos endemic to the Atlantic Forest of southern Bahia, Brazil increase the diversity of the genus in this hotspot

Background and aims – We here describe two new species of Eremitis from Bahia, Brazil, and compare them with morphologically similar species. We also provide illustrations, photos, a distribution map, and notes on habitat and conservation status of the new species. Material and methods – This study was based on fieldwork, analysis of herbarium specimens, and literature review. Specimens collected were analyzed and photographed during fieldwork and observed in cultivation in a greenhouse. The conservation assessment is based on field observations and spatial analyses, following the IUCN guidelines and criteria. Results – Eremitis clarkiae sp. nov. occurs in southern Bahia and has been collected only twice, in the municipality of Floresta Azul. The new species is similar to E. jardimii and E. robusta, both also endemic to Bahia, but can be distinguished by several vegetative and reproductive structures longer than those observed in these species, such as leafy culms, ligules, decumbent culm inflorescences, and pedicels of the staminate spikelets of the staminate whorls. Eremitis vinacea sp. nov. was collected in three localities in southern Bahia, but only the type population was found during recent field trips, in the municipality of Camacã. It is similar to E. afimbriata, a species endemic to Espírito Santo state, being differentiated by its leaf sheaths with persistent fimbriae (vs absent), leaf blades with green adaxial surface (vs bluish green with a blue iridescence), and a single inflorescence on decumbent culms (vs multiple). Both new species are endemic to the Bahian Coastal Forests subregion and should be considered Critically Endangered (CR), according to the IUCN guidelines and criteria.


INTRODUCTION
The Atlantic Forest was originally continuous, covering around 1.5 million km 2 along the Brazilian coast (Galindo-Leal & Câmara 2003;Ribeiro et al. 2009), also reaching into Paraguay and Argentina (Fundação SOS Mata Atlântica 2013). The Atlantic Forest is extremely heterogeneous, especially due to its latitudinal-longitudinal range (3-30° S and 35-60° W), altitudinal variation (0-2,900 m a.s.l.), and soil-climatic gradients (1,000-4,200 mm annual rainfall) (Ribeiro et al. 2011). These abiotic characteristics have favoured high plant diversity and endemism (Mittermeier et al. 2004). According to the Flora do Brasil (2020), the Brazilian Atlantic Forest encompasses 15,569 species of angiosperms, of which 7,628 are endemic. Based on this high level of endemic and threatened species, associated with the destruction suffered in the past, the Atlantic Forest is considered a biodiversity hotspot (Myers et al. 2000). Despite this, it is now confined to only ca 11% of its original extent in Brazil (Ribeiro et al. 2009), and most of it is represented by small fragments (Ranta et al. 1998).
Based on its floristic composition (e.g. Oliveira-Filho & Fontes 2000;Oliveira-Filho et al. 2005;Martins 2011), the Atlantic Forest can be divided into two regions, North and South, with the Doce river as the limit between these two regions. Murray-Smith et al. (2009) recognized three main centres of endemism in the Atlantic Forest: the northern (Pernambuco and Alagoas states), the central (southern Bahia and Espírito Santo states), and the southern ones (from Rio de Janeiro to Santa Catarina states). Saiter et al. (2016), based on the composition of tree species, divided the central region into three subregions: Bahian Coastal Forests (BCF), Bahian Interior Forests (BIF), and Krenák-Waitaká Forests (KWF). The Bahian Coastal Forests subregion encompasses the northern extreme of Espírito Santo and most of the coast of the state of Bahia (Saiter et al. 2016), a region with a great biodiversity, presenting a high incidence of endemic species (Thomas et al. 2003;Martini et al. 2007;Ostroski et al. 2018).
The Bahian Coastal Forests (BCF) subregion encompasses a great diversity and endemism of bamboos, which are members of the grass subfamily Bambusoideae (Soderstrom et al. 1988;Clark 1990;Judziewicz et al. 1999). According to recent data (Flora do Brasil 2020), the state of Bahia, and particularly the BCF subregion, contains 23 genera and 90 species of bamboos, with 10 genera and 54 species included in the tribe Bambuseae (woody bamboos), and 13 genera and 36 species included in the tribe Olyreae (herbaceous bamboos). Four genera and 37 species of these tribes are endemic to Bahia (Flora do Brasil 2020).
Among the herbaceous bamboos, a lineage strongly supported by molecular phylogenetic analyses (Ferreira et al. 2019) occurring in Bahia is represented by the subtribe Parianinae, which includes three genera: Eremitis Döll with 14 described species, all of them endemic to the Atlantic Forest (five endemic to the BCF subregion) (Ferreira et al. 2013a(Ferreira et al. , 2016(Ferreira et al. , 2019(Ferreira et al. , 2020a(Ferreira et al. , 2020b(Ferreira et al. , 2020c(Ferreira et al. , 2020d(Ferreira et al. , 2021; Parianella Hollowell, F.M.Ferreira & R.P.Oliveira with two species, both endemic to the BCF subregion (Ferreira et al. 2013b); and Pariana Aubl. with 27 species restricted to southern Central America and northern South America, especially in the Amazon region (Ferreira et al. 2013b(Ferreira et al. , 2019. Eremitis is a very singular genus that was poorly known until some years ago, and whose diversity has been increasing every year with the description of new species, especially from Bahia (Ferreira et al. 2016(Ferreira et al. , 2020b(Ferreira et al. , 2020c(Ferreira et al. , 2020d(Ferreira et al. , 2021. It is characterized by five morphological synapomorphies: truly underground culms, sympodial inflorescences on leafy culms, gynecandrous and staminate spikelet whorls in the same inflorescence, staminate spikelet pedicels elongated and laminar only in the terminal whorl, and pubescent styles (Ferreira et al. 2019).
During our systematic studies on Eremitis, two new species from Bahia, Brazil were detected and are described herein, increasing the number of species described in this genus to 16 (Ferreira et al. 2013a(Ferreira et al. , 2016(Ferreira et al. , 2019(Ferreira et al. , 2020a(Ferreira et al. , 2020b(Ferreira et al. , 2020c(Ferreira et al. , 2020d(Ferreira et al. , 2021. In addition, these new species increase the number of bamboo species in the state of Bahia to 92 species (Flora do Brasil 2020). These findings confirm previous propositions (Soderstrom et al. 1988;Clark 1990;Judziewicz et al. 1999) that the forests of southern Bahia hold the greatest diversity of bamboos in the Neotropics. Thus, in the present study we provide morphological descriptions, illustrations, in situ photographs, a distribution map, and notes on habitat and conservation status of the two new species.

MATERIAL AND METHODS
This study was based on extensive fieldwork in all known localities of occurrence of Eremitis in Brazil, from 2008 to 2018. In addition to the data obtained in the field, specimens were observed in cultivation since 2008 in a private greenhouse in the municipality of Baependi, Minas Gerais, Brazil. Morphological and geographical data of the described species of Eremitis were obtained from specimens deposited in the following herbaria: ALCB, BHCB, CEPEC, CVRD, ESA, GUA, HUEFS, HUFU, IAN, INPA, ISC, K, LE, MBM, MBML, MG, MO, NY, P, PEUFR, R, RB, RBR, SP, SPF, UEC, UESC, US, and VIC (acronyms according to Thiers continuously updated). Morphological terminology follows Hollowell (1987) and Ferreira et al. (2013a). Measurements of both vegetative and reproductive characters were made on herbarium specimens with a digital calliper with a precision of 0.1 mm. In inflorescences enclosed by spathaceous bracts (modified leaves), measurements were taken after removing them. In addition, web-based resources such as Tropicos (www.tropicos.org), SpeciesLink system (www.splink.org. br), and Flora do Brasil 2020 (www.floradobrasil.jbrj.gov. br) were accessed in order to check additional specimens and update the geographical distribution of the genus. The distribution map was made using ArcMap v.9.3 (ESRI 2008) and the website SimpleMappr (Shorthouse 2010). The classification adopted for the Atlantic Forest of southern Bahia followed Jardim (2003), Thomas et al. (2003), and Saiter et al. (2016).