Taxonomic implications of recent molecular analyses of Spectacled (Symposiachrus trivirgatus) and Spot-winged (S. guttula) Monarchs (Passeriformes: Monarchidae)

Genomic approaches to phylogeography routinely reveal that our estimates of species level diversity within island systems are woefully underappreciated. A recent analysis of population genetics, phylogeography and historical demography of two pied monarchs (Monarchidae), the Spectacled (Symposiachrus trivirgatus) and Spot-winged Monarchs (S. guttula), uncovered unexpected instances of paraphyly and genetic diversity. Here, we discuss the taxonomic implications for these species complexes and recommend recognising three species within what has been considered S. trivirgatus. We defer the naming of a genetically distinct and admixed population of S. guttula on Gag Island, Indonesia, and, pending further study, we advocate continued recognition of this species as monotypic. This study highlights cryptic diversity in the Indo-Pacific species complex and the need for thoroughly sampled phylogenomic datasets to reconcile taxonomy with the complex evolutionary history of birds in this region.