A hidden finch from the Galapagos Islands: a genetically and morphologically distinctive woodpecker finch from San Cristobal Island

Abstract

The Galapagos finches represent a rapid radiation of birds across the remote oceanic archipelago that vary morphologically, behaviourally, and genetically. The level of diversity and rapid rate of speciation have created taxonomic difficulties in resolving phylogenetic relationships. While much of the phylogeny has recently been clarified with modern genomic methods, some of the diversity has been overlooked by under-sampling across islands within presumed species. The woodpecker finch, Camarhynchus pallidus Sclater and Salvin, 1870, represents one such lineage, as all three recognized subspecies have never been fully phylogenetically assessed in regard to their species’ status and relationship with their close sister-species, the mangrove finch (C. heliobates; Snodgrass and Heller 1901). Using genetic and genomic tools, along with morphological analyses, we show that the San Cristobal woodpecker finch (C. p. striatipecta; Swarth 1931) is genetically distinct and paraphyletic with the mangrove finch, compared to all other woodpecker finch subspecies. Given these results we propose that the San Cristobal woodpecker finch be prioritized for further research, as our results hint that it should be given full species’ status as Camarhynchus striatipecta Swarth, 1931.