Sakesphoroides niedeguidonae, Cerqueira & Gonçalves & Quaresma & Silva & Pichorim & Aleixo, 2024

Sakesphoroides niedeguidonae , sp. nov. Cerqueira, Gonçalves, Quaresma, Silva, Pichorim & Aleixo

Northern Silvery-cheeked Antshrike (English).

Choca-do-nordeste-de-cauda-barrada (Portuguese).

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3.7.1 | Holotype

MPEG 84680 , field number PVC 275, adult female from Serra Vermelha , surroundings of Serra da Capivara National Park , São Raimundo Nonato, Piauí ( 08°52′47.5”S, 42°43′32.8”W); elevation c. 525m; collected on 11 January 2019 by P. V. Cerqueira, G. R. Gonçalves and A. Aleixo; study skin and tissue prepared by P. V. Cerqueira (Tissue accession number PVC275 ); audio recorded by P. V. Cerqueira ( ML579640291 ; Macaulay Library of Natural Sounds, Cornell Laboratory of Ornithology, Ithaca, New York).

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3.7.2 | 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).

3.7.3 | Description of holotype

See cover plate (Supplementary Material). Crown, forehead, and nape Amber Colour (36), forming a crest. Sides of head, neck, and throat pale horn Colour (92). Back/mantle olive brown (28), presence of weak white interscapular patch. Rump and uppertail coverts olive brown, as in the back/mantle. Breast, belly, and undertail coverts Buff (124), slightly contrasting with upperparts. Primary and secondary feathers olive brown colour (28), tertials olive brown with white on outer vane edge. Secondary coverts Dusky Brown colour (19) with white and Cinnamon colour (123A) on distal portion. Greater primary coverts Dusky Brown colour (19) with white and Cinnamon colour (123A) on outer vane edge and distal portion of feathers. Central rectrices darker than outer rectrices, showing marginal black and white spots sometimes washed Amber (36) close to the five bars formed by white spots in both vanes. Soft parts in life: iris dark brown; maxilla black; mandible with a grey proximal portion and a black distal portion; tarsus and feet dull bluish grey.

3.7.4 | Measurements of holotype

Exposed culmen from cranium insertion 17.83mm; bill length from anterior edge of nostrils 9.85 mm; bill width at anterior edge of nostrils 3.87 mm; bill depth at anterior edge of nostrils 4.83 mm; wing chords 64.42mm (left) and 64.13mm (right); tail 54.8mm; tarsus 24.18mm (left) and 24.37mm (right); body mass 15.0 g; Skull 100% ossified; ovary 6 × 3mm.

3.7.5 | Allotype

MPEG 84480 , field number PVC 272, adult male from Serra Vermelha , surroundings of Serra da Capivara National Park , São Raimundo Nonato, Piauí ( 08°52′47.5”S, 42°43′32.8”W); elevation c. 525m; collected 09 January 2019 by P. V. Cerqueira, G. R. Gonçalves and A. Aleixo; study skin and tissue prepared by P. V. Cerqueira (Tissue accession number PVC272 ); audio recorded by P. V. Cerqueira ( ML579595301 ; Macaulay Library of Natural Sounds, Cornell Laboratory of Ornithology, Ithaca, New York).

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3.7.6 | Description of allotype

See cover plate (Supplementary Material). Crown, forehead, and central portion of nape Jet Black Colour (89), forming a crest. Supercilium and lores Jet Black. Sides of head Pale Neutral Grey (86) with Jet Black just behind the eyes, and black in the anterior portion of the malar region. Back/ mantle Raw Umber colour (23), with presence of a weak white interscapular patch. Rump and uppertail coverts Raw Umber, as the back/mantle. Throat and breast black as crest and lores; the black colour is restricted to the central portion of breast, continuous from the throat and narrowing towards the belly. Belly and undertail coverts White, flanks Light Neutral Grey (85). Primary and secondary feathers olive brown (28), tertials olive brown with white on the edges of outer vanes. Marginal and lesser secondary coverts Jet Black with white distal portions. Median and greater secondary coverts Jet Black with white distal portions. Greater primary coverts Jet Black with white on outer vane edges and distal portion of feathers. Some secondary and primary coverts present Raw Umber colour, probably related to moult limit. Tail Jet Black with white spots on each vane of rectrices. Soft parts in life: iris dark brown; maxilla black; mandible black; tarsus and feet dull bluish grey.

3.7.7 | Measurements of allotype

Exposed culmen from cranium insertion 17.65 mm; bill length from anterior edge of nostrils 10.45 mm; bill width at anterior edge of nostrils 4.21 mm; bill depth at anterior edge of nostrils 5.74 mm; wing chords 68 mm (left) and 67 mm (right); tail 59.11 mm; tarsus 26.91 mm (left) and 27.29 mm (right); body mass 15.0 g; Skull 100% ossified; left testis 4.0 × 2.0 mm.

3.7.8 | Distribution

The new species is almost restricted to the left/northern bank of the São Francisco River, with one population occurring on the right bank at ‘Raso da Catarina’ region in Bahia state (Figure 5). This population found on the right/ southern bank of the São Francisco River could have been ‘transferred’ across the river due to paleocourse shifts, as discussed in detail below in discussion section.

3.7.9 | Specimens examined (skins)

See Table S1 for detailed information on the specimens examined below.

Sakesphoroides niedeguidonae : Brazil; Piauí: 10 females ( MPEG 68001 , 75,501 , 84,680 GoogleMaps [ holotype], PVC285 , 84,481 , GoogleMaps UFRN 410 , 546 , 550 , 567 , GoogleMaps UFPE 4936 ) GoogleMaps , 10 males ( MPEG 68000 , 68,002 , 75,506 , 76,052 , 76,752 , 76,753 , 84,466 , 84,480 [ allotype], UFRN 376 , 521 ) ; Ceará: 5 females ( MPEG 82876 , 82,885 , 82,886 , GoogleMaps UFPE 4988 , 4998 ) GoogleMaps , 6 males ( MPEG 72194 , 82,890 , 82,893 , 82,894 , UFPE 4953 , 4993 ); Rio Grande do Norte: 1 female ( UFRN 167 ) , 7 males ( UFRN 160 , 166 , 252 , 275 , 296 , 302 , 321 ); Paraíba: 1 female ( UFPE 4546 ); Pernambuco: 10 females ( UFPE 934 , 943 , 972 , 1228 , 1301 , 4162 , 4748 , 4749 , 4750 , 4751 ) , 11 males ( UFPE 213 , 214 , 936 , 969 , 1252 , 4223 , 4691 , 4744 , 4745 , 4746 , 4747 ); Bahia: 8 females ( MPEG 83581 , 83,590 , 83,592 , 83,852 , UEFS DA220 , DA336 , DA443 , UFPE 4844 ), 14 males ( MPEG 83583 , 83,584 , 83,586 , 83,589 , 83,591 , 83,615 , 83,616 , UEFS DA675 , DA238 , DA347 , DA577 , DA497 , DA240 , UFPE 4848 ).

Sakesphoroides cristatus : Brazil; Bahia: 2 females ( MPEG 83595 , 83,620 ), 17 males ( MPEG 83596 , 83,597 , 83,598 , 83,599 , 83,602 , 83,603 , 83,611 , 83,612 , 83,613 , 83,617 , 83,618 , 83,619 , UEFS DA028 , DA039 , DA835 , DA995 , DA254 ) .

3.7.10 | Specimens examined (tape recordings)

See Table S2 View TABLE for detailed information of examined tape recordings.

Sakesphoroides niedeguidonae : Brazil; Piauí ( 3), Ceará ( 18), Rio Grande do Norte ( 1), Paraíba ( 1), Pernambuco (7), Bahia ( 6) .

Sakesphoroides cristatus : Brazil; Bahia ( 41), Minas Gerais ( 18).

3.7.11 | 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 reevaluation 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.

3.7.12 | Habitat, ecology, and behaviour

Sakesphoroides niedeguidonae is restricted to Caatinga vegetations, occurring in woody deciduous forest, arid lowland scrub Caatinga, coastal sandy scrub vegetation in Ceará and Rio Grande do Norte states and in enclaves of ‘cerradão’ (forested savannas) in the Chapada do Araripe region. Sometimes it occurs close to anthropogenic landscapes whenever natural ecosystems are available nearby, supporting a medium adaptative capacity status to human impacts like the sister S. cristatus ( De Araujo & Da Silva, 2017) .

Commonly seen in pairs or small familiar groups. In March 2018 during one of our collecting expeditions at Formosa do Rio Preto (western Bahia), we observed a familiar group with two adults (male and female) and two juveniles with incomplete male plumage. It forages in pairs or sometimes in mixed-species flocks in low and middle strata of woodland and scrub vegetation, catching insects in short flights between close branches, dropping to the ground where it scans for prey while tossing dry leaves. Ants, spiders, termites, beetles, and caterpillars are the main food items in Sakesphoroides niedeguidonae , and we expect a similar diet to that reported for S. cristatus , which includes Formicidae, Isoptera , and Coleoptera during dry season, with the proportion of Isoptera, Coleoptera and Lepidoptera (larvae) increasing and that of Formicidae decreasing during the rainy season ( Buainain et al., 2016). Additional studies focused on feeding biology of S. niedeguidonae are needed to corroborate similar patterns reported for S. cristatus .

Similar to most antshrikes, Sakesphoroides niedeguidonae is a territorial species. During collecting expeditions at the type locality and in western Bahia, males were commonly observed on top of vegetation and exposed branches showing a clear territory defence behaviour in response to playback. Females in contrast were more secretive in low strata of dense vegetation, perching on horizontal and vertical branches when stimulated by playback or scanning for prey, with discrete tail movements. We located several adjacent territories during linear transects distancing at least 50 m from each other, with similar observations made in the Serra Vermelha area ( Santos et al., 2012), suggesting small territories in S. niedeguidonae .

Little is known about the breeding biology of Sakesphoroides niedeguidonae . Lima et al. (2010) described a nest in the Raso da Catarina region found in April (see WA1109656 and WA1109655 at www.wikiaves.com.br) as an open cup c. 45 mm deep, 50 × 60 mm diameter and 50 mm in total height. Clutch size consisted of 2 eggs with creamy colour variably blotched with vinaceous-brown markings concentrated on the larger pole of eggshell (based on photographs provided in Lima et al., 2010). Eggs weighed 3 g and measured 22 × 17 mm. Both male and females incubate the eggs ( Lima et al., 2010).

3.7.13 | Conservation

The Caatinga region has been strongly disturbed by human activities and main threats are large-scale conversion of native vegetation areas for commercial agriculture, livestock farms, and continuous overexploitation of native vegetation by firewood collecting and slash-andburn agriculture ( Da Silva et al., 2017). Moreover, the absence of a large protected area system connected by corridors, plus the intensification of desertification and climate change exacerbate the impacts of main threats in this region.

Sakesphoroides niedeguidonae is a common species in most of its distribution, occurring in different habitats in the Caatinga, including secondary growth vegetations but the capacity to tolerate anthropogenic landscape without natural vegetation nearby seems to be very low ( De Araujo & Da Silva, 2017). The extent of occurrence (EOO) is estimated at 630,000 km 2, not approaching the threshold for a Vulnerable status under the IUCN range size criterion (< 20,000 km 2). Although no data on population size is available, we expect a number greater than 10,000 mature individuals, so this species is best placed as Least Concern (LC). However, new approaches using niche modelling for future climate scenarios support a significant reduction in range size of S. cristatus (including S. niedeguidonae , as treated before this study); applying IUCN criteria to these future estimated range sizes can change its threat category to Near Threatened (NT) and even Vulnerable (VU) depending of the future global change scenario (i.e. RCP 4.5 and RCP 8.5, respectively; Gonçalves et al., 2023). To improve extinction risk evaluations for this species, more precise estimates of population sizes and a better understanding of landscape fragmentation and climate change effects on the species' range are needed.