What Is an Eared Nightjar? Ultraconserved Elements Clarify the Evolutionary Relationships of Eurostopodus and Lyncornis Nightjars (Aves: Caprimulgidae)

Nightjars (Aves: Caprimulgidae) are a species-rich family of birds, with the “eared nightjars” (Eurostopodinae) being an early-branching group endemic to the Indo-Pacific. While much research has focused on species-rich nightjar genera and their higher-level relationships, the evolutionary history of Eurostopodinae (Eurostopodus, Lyncornis) remains understudied. We generated a genome-scale dataset to produce the first fully sampled phylogeny of all Eurostopodus and one Lyncornis species, including sequencing two type specimens of critically endangered and extinct species. Tree-building methods inferred concordant, well-resolved topologies that reveal intriguing biogeographic patterns within Eurostopodus. Our results show Eurostopodus as sister to all other nightjars, while Lyncornis, previously considered related, is more closely allied with other caprimulgids. We propose that the term “eared nightjars” should apply only to the two Lyncornis species, which should be classified within the subfamily Caprimulginae. Accordingly, since only Eurostopodus species remain in Eurostopodinae, we recommend renaming this subfamily “Indo-Pacific nightjars” to reflect their geographic distribution in this significant region.