Introduction

The Atlantic Forest is considered a biodiversity hotspot due to the occurrence of a high number of endemic and threatened species (^{Myers et al. 2000}). The natural distribution of the Atlantic Forest was originally continuous along the Brazilian coast and extended to some areas in Argentina and Paraguay (^{Fundação SOS Mata Atlântica 2013}). Nowadays, it is one of the eight most critically endangered hotspots, as only 12,5% of the original forest remains (^{Fundação SOS Mata Atlântica 2014}). Nevertheless, it is the richest Brazilian phytogeographic domain in plant diversity, with 8,728 endemic species of angiosperms (^{Flora do Brasil 2020, under construction}).

Some studies have emphasized the division of the Atlantic Forest in northern and southern regions (^{Cracraft 1985}, ^{Colombi et al. 2010}, ^{Martins 2011}) with a limit along the Doce river, in the north of Espírito Santo state. The floristic differences between these two regions were highlighted by ^{Oliveira-Filho & Fontes (2000)} and ^{Oliveira-Filho et al. (2005)}, who observed several taxa with Amazonian affinities occuring in the northern region, while taxa with subtropical Andean affinities are mostly found in the southern region (^{Berry et al. 2004}, ^{Santos et al. 2007}, ^{Menini Neto et al. 2016}). Other authors recognize three main centers of endemism in the Atlantic Forest: northern (Pernambuco and Alagoas states), southern (from Rio de Janeiro to Santa Catarina states), and central (southern Bahia and Espírito Santo states) (^{Murray-Smith et al. 2009}, ^{Thomas et al. 1998}).

Recently, ^{Saiter et al. (2016a)} divided the central region of the Atlantic Forest in three subregions based on the composition of tree species, indicating the most important abiotic factors affecting that division. Contrary to previous knowledge, the rivers did not play an important role in this division, which lies about 100 km north of the Doce river and is best explained by climatic factors, such as moisture, elevation and temperature (^{Saiter et al. 2016a}). One of the regions, referred to as Bahia Coastal Forests (BCF) by ^{Saiter et al. (2016a)}, encompasses the northern extreme of Espírito Santo and most of the coast of the state of Bahia. Due to high biodiversity and the incidence of endemic and threatened species, this region has been designated as a hot-point within the Atlantic Forest hotspot (^{Martini et al. 2007}). Many studies to this date on different groups of organisms support this claim, as the region is considered an area of endemism for frogs (^{Carnaval et al. 2009}), birds (^{Silva et al. 2004}), Myrtaceae (^{Murray-Smith et al. 2009}) and trees in general (^{Thomas et al. 2003}).

An estimate of endemic vascular plant species present in two protected areas in southern Bahia showed that the distribution of 59% of the species is restricted to Bahia and Espírito Santo states (^{Thomas et al. 1998}). These results motivated the compilation of a preliminary list of endemic angiosperm species in the region comprising Espírito Santo to the north of the Doce river and the south of Bahia, including inland Seasonal Dry Forests (^{Thomas et al. 2003}) (Figure 1a). This list consisted of 395 endemic species of angiosperms in the region (^{Thomas et al. 2003}), among which several are known to occur only in dry forests, such as Chrysophyllum subspinosum Monach. (Sapotaceae) and Colicodendron bahianum Cornejo & Ilts (Capparaceae). That study reported eight endemic genera in this area: Arapatiella R.S.Cowan, Brodriguesia R.S.Cowan and Harleyodendron R.S.Cowan (Fabaceae), Atractantha McClure, Anomochloa Brogn., Alvimia Calderón ex Soderstr. & Londoño, and Sucrea Soderstr. (Poaceae), and Trigoniodendron E.F.Guim & Miguel (Trigoniaceae) (^{Thomas et al, 2003}).

Figure 1 a) Study area in which ^{Thomas et al. (2003)} based their list of endemic species. b) Bahia Coastal Forest (BCF) according to ^{Saiter et al. (2016a)}. c) Municipalities with at least 50% of its area within the BCF (light grey), and those added to the study area based on ^{IBGE (1993)} (dark grey). Coordinates: UTM. Datum WGS 84. 

Checklists of endemic taxa are critical to overcome issues that hinder conservation strategies in highly biodiverse regions, such as: 1) basic taxonomic information (Linnean shortfall, or "which species are there?"), and 2) lack of geographic information (Wallacean shortfall, or "where do these species occur?") (^{Whittaker et al. 2005}). Both shortfalls are part of reality in Bahia Coastal Forests, world-renowned as one of the highest diversity areas in tree species (^{Thomas et al. 1998}, ^{Martini et al. 2007}, ^{Murray-Smith et al. 2009}).

We aimed to provide a list of endemic species of angiosperms in Bahia Coastal Forest following ^{Saiter et al. (2016a)} to verify whether the current list agrees with the preliminary checklist by ^{Thomas et al. (2003)}. We expect this updated list to further highlight the importance of BCF as a critical area for biodiversity conservation in the Brazilian Atlantic forest.

Material and Methods

Results

The final checklist consisted of 547 angiosperm taxa endemic to BCF (535 species, six subspecies, and six varieties) in 69 families (none endemic) and 230 genera (Table 1). Seven genera are endemic to BCF: Bahiella J.F.Morales (Apocynaceae), Santosia R.M.King & H.Rob. (Asteraceae), Harleyodendron (Fabaceae, Figure 2f), Cubitanthus Barringer (Linderniaceae), Anomochloa and Parianella Hollowell, F.M.Ferreira & R.P.Oliveira (Poaceae), and Andreadoxa Kallunki (Rutaceae). The genera with the highest number of endemic species in the BCF were Aechmea Ruiz & Pav. (Bromeliaceae) (33 spp.), Pavonia Cav. (Malvaceae) and Myrcia DC. (Myrtaceae), each with 16 species. The three families with the highest numbers of endemic taxa (species + infraspecific taxa) were Bromeliaceae (108), Fabaceae (41) and Myrtaceae (32).

Figure 2 Some species found in the checklist of endemic angiosperms of BCF: a) Kuhlmanniodendron macrocarpum (Achariaceae). b) Quesnelia koltesii (Bromeliaceae). c) Dichorisandra leucophtalmos (Commelinaceae). d) Tapura zei-limae (Dichapetalaceae). e) Arapatiella psilophylla (Fabaceae). f) Harleyodendron unifoliolatum (Fabaceae). g) Pavonia goetheoides (Malvaceae). h) Pleiochiton amorimii (Melastomataceae). i) Anomochloa marantoidea (Poaceae). Photos: a, b, d, g, h) A.Amorim; c) L.Aona; e, f) D.Cardoso; i) J.Jardim. 

Discussion

The families with the highest numbers of endemic taxa in BCF are also among the ten richest angiosperm families in Brazil and in the Atlantic Forest (^{BFG 2015}). ^{Thomas et al. (2003)} reported Fabaceae (53 spp.) as the richest family of a total of 65 families in the previous list. Compared with the ^{BFG (2015)}, it is remarkable that Orchidaceae, one of the three richest families in Brazil and in the Atlantic Forest, was not among the richest families in this study, with only 25 taxa. This may be due to the lack of geographic records for 14 species in this family, which had to be discarded.

Among the 20 richest angiosperm genera in Brazil (^{BFG 2015}), Aechmea and Myrcia are also among the genera with the highest number of endemic species in the BCF. In a preliminary list of the endemic angiosperm species from southern Bahia and northern Espírito Santo, ^{Thomas et al. (2003)} cited Conchocarpus J.C.Mikan (Rutaceae) (19 spp.) as the richest genus, followed by Pavonia Cav. (Malvaceae) (13 spp.), Couepia Aubl., and Erythroxylum P.Browne (seven spp. each). The occurrence of only 12 endemic species of Conchocarpus in the present checklist probably indicates that several endemic species of this genus are exclusively found at more inland seasonally dry forests (^{Kallunki & Pirani 1998}).

Among the endemic genera from southern Bahia and northern Espírito Santo reported by ^{Thomas et al. (2003)}, such as Arapatiella and Brodriguesia (Fabaceae), Atractantha, Alvimia and Sucrea (Poaceae), and Trigoniodendron (Trigoniaceae), several are not endemic to BCF. For example, Brodriguesia, Atractantha and Trigoniodendron have been recorded outside our study area, respectively, in Sergipe, Amazonas, and near the Doce River. Similarly, Physeterostemon R.Goldenb. & Amorim (Melastomataceae), a recently described endemic genus from the Atlantic Forest of Bahia state (^{Amorim et al. 2014}, ^{Goldenberg et al. 2016}, ^{Goldenberg & Amorim 2006}), was not considered endemic to BCF in this checklist, as among its species P. gomesii Amorim & R.Goldenb. occurs in the municipality of Boa Nova (^{Amorim et al. 2014}), which lies slightly outside our study area.

In comparison with the preliminary list of ^{Thomas et al. (2003)}, which included 395 endemic angiosperm taxa from an area that covered a larger part of northern Espírito Santo state, as far as the Doce River, and the southern Bahia Atlantic Forest, including more inland areas, and almost reaching the municipality of Salvador (i.e., an area ca. 20% larger than ours) (Figure 1a), the list presented here surprisingly shares only 143 taxa (Table 1). If we had used the Doce River as our area southern limit, it would have included at least 45 additional species restricted to the Linhares region, such as Cryptanthus beuckeri E.Morren (Bromeliaceae), Rourea luizalbertoi Forero, L.A.Vidal & Carbonó (Connaraceae), Simira eliezeriana Peixoto (Rubiaceae) and the endemic genus Riodocea Delprete (^{Thomas et al. 2003}, ^{Rolim et al. 2016}). Despite being geographically close and having several species in common (^{Saiter et al. 2016b}), the vegetation of Linhares and the Doce River floodplain are ecologically different from the BCF (^{Rolim et al. 2005}, ²⁰⁰⁶). In floristic terms, the Linhares region may be more similar to northern Rio de Janeiro, southern Espírito Santo (^{Silva & Nascimento 2001}, ^{Saiter et al. 2016b}) and eastern Minas Gerais states (see Krenák-Waitaká Forests sensu^{Saiter et al. 2016a}).

Another difference between the two checklists is due to the time gap of about 15 years between studies. A total of 174 species in our checklist were described after 2003, probably due to increased efforts in collecting and studying plants in the Atlantic Forest in Bahia. For instance, about 41.5% of all new angiosperms in the Brazilian flora described between 1990 and 2006 are endemic to the Atlantic Forest (^{Sobral & Stehmann 2009}). Moreover, 23 species of angiosperms endemic to BCF were described between 2015 and 2017 (e.g., ^{Araújo et al. 2015}, ^{Santos et al. 2015}, ^{Abreu & Giulietti 2016}, ^{Amorim et al. 2016}, ^{Côrtes et al. 2016}, ^{Ferreira et al. 2016}, ^{Marinho & Lucas 2016}, ^{Popovkin et al. 2016}, ^{Ribeiro et al. 2016}, ^{Terra-Araujo et al. 2016}, ^{Daly & Melo 2017}, ^{Gonçalez et al. 2017}).

Compared to the results of a search in the Brazilian Plant List (^{Flora do Brasil 2020, under construction}) using the following filters: "group: angiosperms", "endemism: only endemic to Brazil", "occurrence: only occurs in", "origin: native", "state: Bahia", and "phytogeographic domain: Atlantic Forest", the number of species in our checklist (547 spp.) was much smaller than the 795 species identified by the search engine. Among the reasons for this large difference (248 spp.) it is worth mentioning that a) more than 50 taxa from our list had to be removed due to lack of precise geospatial data, such as the municipality name, which precluded us from citing them as endemic to BCF; b) among the taxa exclusive to the Brazilian Plant List (^{Flora do Brasil 2020, under construction}) that are not restricted to BCF, several occur in more inland seasonally dry forests in the Atlantic Forest, such as Chrysophyllum subspinosum Monach. (Sapotaceae) and Colicodendron bahianum Cornejo & Iltis (Capparaceae); and c) at least 29 species exclusive to the Brazilian Plant List search occur close to, but outside the study area, such as Canistrum camacaense Martinelli & Leme (Bromeliaceae), Inga grazielae (Vinha) T.D.Penn. (Fabaceae), and Bertolonia carmoi Baumgratz (Melastomataceae), all from the municipality of Boa Nova, and Aechmea bicolor L.B.Sm. (Bromeliaceae), Heteropterys jardimii Amorim (Malpighiaceae), and Passiflora timboensis T.S.Nunes & L.P.Queiroz (Passifloraceae), from the municipality of Santa Teresinha.

There are additional reasons to anticipate that the difference in species numbers between the Brazilian Plant List and our list could be even greater, as the list presented here includes 84 taxa that also occur in northern Espírito Santo and in a small area in northeastern Minas Gerais (Figure 1c). Moreover, the Brazilian Plant List (^{Flora do Brasil 2020, under construction}) is an ongoing project on which new taxa can be continuously added and identified as endemic, what could bring the total number of endemic angiosperm species using the same filters even larger. Alternatively, if the native distribution of several taxa is shown to extend beyond the Atlantic Forest domain in Bahia, the difference between the lists could decrease, as fewer species from the Brazilian Plant List would appear as endemic while applying the same search filters.

Developing knowledge on patterns of endemism for plant species is extremely important and must be taken into account in conservation strategies. This information is relevant for the establishment of new protected areas (^{Kerr 1997}), restoration policies (^{Chazdon 2008}) and in directing additional studies (^{Francisco-Ortega et al. 2010}). Considering the key role of endemic species in the design of conservation policies (^{Myers et al. 2000}, ^{Van Der Werff & Consiglio 2004}, Moraes et al. 2005, ^{Lamoreux et al. 2006}, ^{Martinelli et al. 2008}, ^{Essl et al. 2009}, ^{Nowak & Nobis 2010}), we expect this checklist could guide future studies and conservation strategies, as well as emphasize the importance of the BCF region as a key area for plant conservation.