J Zool Syst Evol Res. 2019;00:1–8. wileyonlinelibrary.com/journal/jzs | 1 © 2019 Blackwell Verlag GmbH 1 | INTRODUCTION The family Anhingidae contains the birds known colloquially as snakebirds (due to their appearance when swimming—with their body submerged all that is visible is a snake‐like elongated neck, non‐differentiated elongated head and slender beak), anhingas (“devil bird” or “snake bird” in Brazilian Tupian language), and dart‐ ers (due to their unique foraging behavior, spearing fish and other aquatic prey using their beaks). These active fish hunters are found in freshwater habitats in most parts of the tropics and subtropics. Like their close relatives the cormorants (family Phalacrocoracidae) and the gannets and boobies (Sulidae), with which they form the Suliformes, they exhibit a remarkable degree of morphological con‐ servatism, to the point where the number of species recognized has varied among different authorities. The New World species, the Anhinga or American Darter Anhinga anhinga (Linnaeus, 1766), is clearly separable from the remaining Old World forms. The latter are variously treated as a single species, the Darter Anhinga mela‐ nogaster (Pennant, 1769), with three subspecies (Christidis & Boles, 1994; Clements, 2007; Cramp & Simmons, 1977; Dickinson, 2003; Harrison, 1978; Johnsgard, 1993; Nelson, 2005; O'Brien, 1990; Orta, 1992; Worthy, 2012), or, perhaps less often, as three separate species, the Oriental or Indian Darter ( A. melanogaster), the African Darter Anhinga rufa (Daudin, 1802), and the Australasian Darter Anhinga novaehollandiae (Gould, 1847) (Clements et al., 2017; del Hoyo, Collar, Christie, Elliott, & Fishpool, 2014; Ogilvie‐Grant, 1898; Peters, 1931; Schodde, Kirwan, & Porter, 2012; Sibley & Monroe, 1990; Vaurie, 1965). The more recent treatments by some of these Received: 17 December 2018 | Revised: 2 May 2019 | Accepted: 5 May 2019 DOI: 10.1111/jzs.12299 ORIGINAL ARTICLE Sorting out the Snakebirds: The species status, phylogeny, and biogeography of the Darters (Aves: Anhingidae) Martyn Kennedy 1 | Sampath S. Seneviratne 2 | Ushawarni K. Mendis 2 | Hamish G. Spencer 1 1 Department of Zoology, University of Otago, Dunedin, New Zealand 2 Avian Evolution Node, Department of Zoology & Environment Sciences, University of Colombo, Colombo, Sri Lanka Correspondence Martyn Kennedy, Department of Zoology, University of Otago, Dunedin, New Zealand. Email: martyn.kennedy@otago.ac.nz Funding information American Museum of Natural History, Grant/Award Number: 3, 2, 41 and 14; University of Otago; Allan Wilson Centre Contributing authors: Sampath S. Seneviratne (sam@sci.cmb.ac.lk), Ushawarni K. Mendis (mushawarni@gmail.com), Hamish G. Spencer (hamish.spencer@otago.ac.nz) Abstract Although the avian family Anhingidae is unequivocally monophyletic, the number and relationships of the component species within the single genus ( Anhinga) have long remained unclear. Here, we use extensive mitochondrial and nuclear DNA se‐ quence data (8,878 bp) to show that four species should be recognized. Our fully resolved and well‐supported tree shows that the American Anhinga ( Anhinga an‐ hinga) is sister to the three Old World species, with the Oriental ( A. melanogaster) and African ( A. rufa) Darters sister within the Old World clade, which also includes the Australian Darter ( A. novaehollandiae). We estimate that the divergence between the New World and Old World branches occurred 19–22 mya, with the Australian Darter separating from its Old World congeners 14–16 mya and the Oriental and African species splitting ~10 mya. The genus is yet another example of osteological conserva‐ tism in the Suliformes, which is comparable to that shown by the cormorants and shags. Nevertheless, the relationships we infer are congruent with recent plumage studies and are biogeographically plausible. We suggest that further investigation of the variation within the African and Australian Darters would be of interest. KEYWORDS Anhinga, Anhingidae, Darters, phylogeny, taxonomy