Species limits and biogeography of Rhynchospiza sparrows

ARETA JI; DEPINO EA; SALVADOR SA; CARDIFF SW; EPPERLY K; HOLZMANN I

Journal of Ornithology

Springer

Año: 2019 vol. 160 p. 973 - 991

2193-7206

The genus Rhynchospiza comprises two species, the monotypic Tumbes Sparrow (R. stolzmanni) and the Stripe-crowned Sparrow (R. strigiceps) with subspecies strigiceps and dabbenei. We evaluate their taxonomic status and discuss key features involved in speciation. All three taxa exhibited multiple differences in plumage, morphology, and vocalizations, supporting the recognition of three species in Rhynchospiza. The very large billed R. stolzmanni has a song composed of a succession of faster complex trilled phrases, shows a small black loral line, dark chestnut head stripes with large dark central-stripe to individual feathers and is resident in the Tumbes region. The large and heavy dabbenei has a song consisting of a series of simple chirping notes, has a large black loral crescent, chestnut head stripes with reduced to absent dark center to feathers, and inhabits the Austral Yungas as a year-round resident. The small and pale strigiceps has a song consisting of a succession of complex trilled phrases, shows a small black loral line, rufous-brown head stripes with large dark central-stripe to feathers and inhabits Dry and Sierran Chaco where it is a partial migrant. Locality data and ecological niche modelling show that. dabbenei and strigiceps are allo-parapatric and use different altitudinally segregated habitats at their zone of parapatry. Molecular-phylogenetic analyses (ND2 gene) found R. stolzmanni as sister (11.5% divergent) to a recently diverged dabbenei and strigiceps clade (1.6% divergent). We conclude that the genus Rhynchospiza is comprised of three species-level entities, each restricted to a major biogeographic region, and that vocalizations and facial patterns provide key evidence on species-limits in these otherwise similarly plumaged taxa. The evolutionary-cultural differences in songs, complex phrases in R. strigiceps and R. stolzmanni and single notes in R. dabbenei, suggest changes in the innate vocal learning template during speciation in the latter.