Zaretis Hübner, [1819]

Dias, Fernando Maia Silva, Janzen, Daniel, Hallwachs, Winnie, Chacón, Isidro, Willmott, Keith, Ortiz-Acevedo, Elena, Mielke, Olaf Hermann Hendrik & Casagrande, Mirna Martins, 2019, DNA barcodes uncover hidden taxonomic diversity behind the variable wing patterns in the Neotropical butterfly genus Zaretis (Lepidoptera: Nymphalidae: Charaxinae), Zoological Journal of the Linnean Society 185, pp. 132-192 : 132-133

Zaretis Hübner, [1819] is a neotropical genus of leafwing butterflies widely distributed throughout the Central and South Americas (Comstock, 1961; Willmott & Hall, 2004). More than 40 years after the preceding revision of the genus (Comstock, 1961), and 50 years since the previous description of a new species ( Bryk, 1953), the taxonomy of Zaretis was succinctly reviewed by Willmott & Hall (2004), and three new species ( Willmott & Hall, 2004; Choimet, 2009; Dias, Casagrande & Mielke, 2012) and two subspecies ( Brévignon, 2006) were described. Additionally, two taxonomic names, one previously in synonymy and another recognized as a subspecies, were recognized as valid species ( Dias et al., 2012, 2015), increasing the number of valid species to ten. Nevertheless, only three of those ten species are easily recognizable: Zaretis syene ( Hewitson, 1856) , Zaretis callidryas (R. Felder, 1869) and Zaretis delassisei Choimet, 2009 . The identification of the remaining species is complicated by a lack of consistent external diagnostic characters, owing to the high level of intraspecific variation in both sexes that occurs both within a single locality and throughout the distributional range of these species ( Pyrcz & Neild, 1996; Willmott & Hall, 2004). D’Abrera (1988) regarded Zaretis as ‘the most variable of the neotropical butterflies’. A lack of obvious interspecific differences in male genitalia and the marked sexual dimorphism complicate identification further ( Willmott & Hall, 2004). In the past, these issues caused differing views on the number of valid species and resulted in the description of 27 debatable species-level taxonomic names (e.g. Comstock, 1961; Vane-Wright, 1975; Lamas, 2004; Willmott & Hall, 2004). Despite recent efforts to facilitate the identification of some taxa ( Willmott & Hall, 2004; Dias et al., 2012, 2015), the correct association of most of those names and the species diversity within the genus have remained uncertain.

Traditional morphological taxonomic studies can be extremely time consuming or even unproductive in certain groups, especially when the subject species are superficially similar or highly variable. Such is the case with most of the species of Zaretis . To overcome these shortcomings in taxonomy as a whole, Hebert et al. (2003a) suggested the use of ‘DNA barcodes’; a short, standardized DNA fragment from the mitochondrial cytochrome c oxidase subunit I (COI) gene to facilitate the identification and discovery of new species based on differences in their sequences. Although there is some dispute on both practical and theoretical grounds about the exclusive use of this method in taxonomic studies and difficulties caused by hybridization, gene introgression and Wolbachia infections (e.g. Brower, 2006; Cong et al., 2017), the effectiveness of DNA barcodes has been confirmed repeatedly by the successful identification and discovery of species in numerous animal groups (e.g. Hebert, Ratnasingham & deWaard, 2003b; Huemer et al., 2014; Dumas et al., 2015). The use of standard phylogenetic analyses and novel statistics to infer species delimitation with single-locus molecular data, such as Poisson-tree-processes (PTP; Zhang et al., 2013) and generalized mixed Yule coalescent (GMYC) methods ( Fujisawa & Barraclough, 2013), provides further statistical support for DNA barcode species delimitation. Thus, the aim of this study was to complement morphological and molecular data and use different statistical methods to resolve the chaotic species-level taxonomy of the genus Zaretis .