Identification key for anuran amphibians in a protected area in the northeastern Atlantic Forest

The identification of anuran amphibians is still a challenge in megadiverse assemblages. In the Neotropics, the Atlantic Forest harbors more than 600 anuran species, and many studies in this ecoregion report anuran assemblages surpassing 30 species. Taxonomic keys facilitate the identification of biological diversity, however only a few are available for anuran assemblages in the Atlantic Forest. Herein we present an identification key for 40 anuran species distributed across 20 genera and nine families, occurring in the Environmental Protection Area of Catolé and Fernão Velho, northeastern Atlantic Forest. Thirty-five morphological characteristics were used in the key, all of which can be easily observed in living and museum specimens. This pioneer study provides the first identification key for an amphibian assemblage in the northeastern Atlantic Forest and this baseline information acts as the starting point for the development of evolutionary and ecological research in this conservation unit.


INTRODUCTION
To accurately identify a species, the first step is to assess the diversity of an area, which acts as the baseline for further ecological and evolutionary studies (e.g., Narvaes & Rodrigues, 2009;Pereyra et al., 2016). Furthermore, species lists can be used for conservation purposes (ICMBio, 2018). The correct identification of a species can be facilitated when taxonomic keys are available. These tools use the diagnostic characteristics of species to guide the user, whose goal is to identify the lowest hierarchical level to which that individual belongs.
The identification of anuran amphibians in megadiverse assemblages is very challenging (Fouquet et al., 2007a;Cassini et al., 2013;Peloso et al., 2014Peloso et al., , 2018Taucce et al., 2018). Anurans display a great morphological similarity between species and cryptic species (those marked by pronounced morphological conservatism) are com-monly found in this group (Camargo et al., 2006;Fouquet et al., 2007aFouquet et al., , 2007bWalker et al., 2018;Taucce et al., 2018). Additionally, the imprecise diagnostic characteristics for some species, along with a plethora of polymorphic traits hamper the accurate diagnosis of many taxa.
Despite the importance of taxonomic keys in facilitating the identification of biological diversity, these tools are still a greatly lacking for Neotropical anurans. For example, the Brazilian Atlantic Forest ecoregion harbors over 600 anuran species (Rossa-Feres et al., 2017), and currently there are only six available identification keys for adult anurans that are published in books or scientific journals (Eterovick & Sazima, 2004 for Serra do Cipó, Minas Gerais state; Loebmann, 2005 for the coastal region of southernmost Brazil, Rio Grande do Sul state; Ribeiro et al., 2005 for the Serra do Japí, São Paulo state; Kwet et al., 2010 for the Serra Gaúcha, Rio Grande do Sul state; Provete et al., 2011 for the northwest region of São Paulo state; and Pimenta et al., 2014 for the municipalities of Alvorada de Minas, Conceição do Mato Dentro and Dom Joaquim, Minas Gerais state). All these keys include anuran assemblages from the southern part of Atlantic Forest.
The aim of the present study was to develop an identification key for 40 anuran species occurring in the Environmental Protection Area of Catolé and Fernão Velho in the northeastern Atlantic Forest of Brazil.

MATERIAL AND METHODS
The elaboration of identification keys was based on adult anurans obtained in the Environmental Protection Area of Catolé and Fernão Velho (EPACFV), a conservation unit in the Northeastern Atlantic Forest. The area covers 37.12 km² and presents a mosaic of phytophysiognomies that vary from ombrophylous forest to mangroves (sensu Assis, 2000;Oliveira et al., 2014). All specimens were collected from 1994 to 2018 and are housed in the Herpetological Collection of the Museu de História Natural da Universidade Federal de Alagoas (MUFAL; Appendix 1).
Absence ing family and genus level terminals wherever possible. The taxonomic nomenclature followed the current phylogenetic proposals (e.g., Faivovich et al., 2005;De-Sá et al., 2014;Duellman et al., 2016). The key was tested by people with varying degrees of knowledge on anuran morphology, ranging from undergraduate biology students (not familiar with herpetology) to expert taxonomists of this group.
Thirty-five morphological characteristics were used in the key, as follows: 14 related to the presence/absence of structures, five related to shape, six related to proportion (size), nine related to color patterns, and one related to skin texture. The characteristics used can be easily observed in both living individuals or preserved specimens and apply to both sexes. Some of these traits may vary with ontogeny and defining characteristics were determined for adult individuals and thus, may not be easily applicable to juvenile individuals. Species terminals are highlighted in bold. 10a. (7b) Finger I longer than finger III (Fig. 2K) (12a) A light colored band anteriorly delimited from the snout to the intraorbital region and extending laterodorsally (Fig. 2N)  Tympanic annulus distinct (Fig. 3M)  Rounded-snout in lateral view (Fig. 3F) (Fig. 4D)  Absence of marbled spots on gular and pectoral regions (Fig. 4I)   The Environmental Protection Area of Catolé and Fernão Velho contain important forest remnants in the state of Alagoas. Of the 40 species recorded, three are topotypical of this conservation unit (Chiasmocleis alagoana, Phyllodytes edelmoi and Ololygon skuki), four are currently considered threatened (Allobates olfersioides, Chiasmocleis alagoana, Hylomantis granulosa, and Ololygon skuki) and one species are lacking sufficient data for the assessment of their threatened status (Gastrotheca fissipes; Dubeux et al., 2020). This area represents one of the few forest remnants of the northeastern Atlantic Forest, with a long term herpetofauna survey and approximately 26 years of research led by different researchers.
This pioneer study provides the first identification key for an anuran assemblage in the northeastern Atlantic Forest. This study will certainly facilitate the identification of anurans in this Environmental Protection Area. Moreover, this baseline information can act as a starting point for the development of evolutionary and ecological research as well as providing a framework for the improved management of the fauna found in this conservation unit.