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| male [back] and female [front] individuals of Sakesphoroides niedeguidonae Cerqueira, Gonçalves, Quaresma, Silva, Pichorim & Aleixo, 2024 Illustration by Eduardo Brettas |
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| [Pattern 1] Sakesphoroides niedeguidonae Cerqueira, Gonçalves, Quaresma, Silva, Pichorim & Aleixo, 2024 [Pattern 2] Sakesphoroides cristatus (Wied, 1831) |
Abstract
The Caatinga is the largest patch of Seasonal Dry Tropical Forest in the Neotropics, located in northeastern Brazil and characterized mainly by deciduous vegetation and extreme rainfall seasonality. It has historically been treated as a biologically impoverished domain, but recent studies uncovered new diversification patterns and several new taxa of frogs, mammals, insects, and fishes. Here we employed a dense sampling regime to evaluate whether the São Francisco River (SFR) would have promoted genetic diversification and fixed phenotypic differences and how Quaternary climatic oscillations shaped distribution and population sizes in a Caatinga endemic species, the Silvery-cheeked Antshrike (Sakesphoroides cristatus). We adopted an integrative approach using multilocus genetic, plumage, vocal data, and ecological niche modelling (ENM) to characterize evolutionary units and niche suitability in past scenarios. We recovered strong genetic structure across the SFR that was congruent with plumage and vocal variation, revealing a yet undescribed species named herein as Sakesphoroides niedeguidonae, sp. nov.. The splitting time estimated between the newly described species and S. cristatus is consistent with the establishment of the modern course of SFR, with a more recent course shift apparently promoting the secondary contact between the two species in the Raso da Catarina region. After their split, both species experienced increases in population sizes and range sizes at similar times during the Last Glacial Maximum. We expect other Caatinga avian endemic lineages to show similar patterns of genetic differentiation across the SFR that were enhanced by Quaternary climatic oscillations.
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| Geographic distribution of diagnostic plumage characters in Sakesphoroides cristatus females. Green and blue circles represent diagnostic patterns numbered 1 and 2, respectively, recovered from plumage analyses using study skins and digital photographs (see text for details). The dark-blue line represents the modern course of the São Francisco River (SFR), with the red dashed lines representing the estimated position of abandoned meanders of a Late Pleistocene paleocourse of the SFR. The colour gradient represents altitudinal variation. Credit photos: Rocílio Ribeiro Rocha (pattern 1) and Oberdan Nunes (pattern 2). |
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Once we defined S. cristatus as the applicable name for clade 2 and no taxon name is available for clade 1 birds, herein we describe the latter group as a new species:
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| male [back] and female [front] individuals of Sakesphoroides niedeguidonae Illustration by Eduardo Brettas, from Cerqueira et al., 2024) |
Sakesphoroides niedeguidonae, sp. nov. Cerqueira, Gonçalves, Quaresma, Silva, Pichorim & Aleixo
Northern Silvery-cheeked Antshrike (English).
Choca-do-nordeste-de-cauda-barrada (Portuguese).
Diagnosis:
Morphology: The new species is assigned to the genus Sakesphoroides based on its morphological diagnostic characters as described by Grantsau (2010), and its sister relationship to Sakesphoroides cristatus.
Males of Sakesphoroides niedeguidonae are similar in plumage to Sakesphoroides cristatus, but females differ from the former by distinct crown, back, and tail colours, (Table 1). Sakesphoroides niedeguidonae has an overall lighter (Amber) colour rather than Chestnut as S. cristatus. The back is olive brown in S. niedeguidonae, whereas that of S. cristatus is Cinnamon-Brown. The overall tail colour in S. niedeguidonae is darker than in S. cristatus, with the most conspicuous difference being the black and white barring, replaced in S. cristatus only by discreet dull brown and rufous bars and complete absence of white barring (Figure S1).
Voice: The loudsong of S. niedeguidonae is slightly similar in general pattern to that of S. cristatus, but differs conspicuously by the shape of the first notes. While the loudsong of S. niedeguidonae has initial notes with an ascending–descending pattern of frequency modulation, looking visually like an inverted ‘U’ letter on sound spectrograms, that of S. cristatus has initial ascending notes reaching quickly a high frequency (~2300 Hz) and then descending to the maximum amplitude and continuing to descend further to a lower frequency (~580 Hz), which confers to it a sigmoid shape on spectrograms (Figure 2). Additionally, the loudsong of S. niedeguidonae differs from that of S. cristatus by a significantly greater number of notes, longer overall duration, and slower pace in total song (see Table 3). Female recordings present noticeable higher pitched songs than males (ML579640291; Macaulay Library of Natural Sounds, Cornell Laboratory of Ornithology, Ithaca).
Etymology:
It is our pleasure to name this species in honour of Niède Guidon, a Brazilian archaeologist who in 1970's explored the largest and oldest concentration of prehistoric sites in the Americas. Niède's efforts helped to create the Serra da Capivara National Park in Piauí state, where her research found evidence of artefacts that have provoked a re-evaluation of the traditional theories about human settlement in the Americas. Moreover, she is a symbol of power and persistence in preserving the Caatinga environment not just for archaeological purposes but also considering biodiversity and local human communities, highlighting the Caatinga as a singular place in the world, which has inspired us every day.
The English name (Northern Silvery-cheeked Antshrike) is a reference to its range in the Caatinga domain and the sister taxon S. cristatus (now called Southern Silvery-cheeked Antshrike). The Portuguese name (Choca-do-nordeste-de-cauda-barrada) highlights the main plumage feature in females distinguishing the new species from S. cristatus (Choca-do-nordeste in Portuguese). Both names maintain in its composition the name used in S. cristatus for an easy reference to their close phylogenetic relationship.
Pablo Cerqueira, Gabriela R. Gonçalves, Tânia F. Quaresma, Marcelo Silva, Mauro Pichorim and Alexandre Aleixo. 2024. A New Antshrike (Aves: Thamnophilidae) endemic to the Caatinga and the Role of Climate Oscillations and Drainage Shift in Shaping Cryptic Diversity of Neotropical Seasonal Dry Forests. Zoologica Scripta. DOI: 10.1111/zsc.12672
Nova espécie de ave da Caatinga é descoberta e tem origem em variações históricas do São Francisco
https://abori.com.br/ambiente/aves-da-caatinga-mudancas-climaticas-nova-especie/
