Aves: Trogonidae) 1.54 1.55 1.5 JEREMY KENNETH DICKENS1,2,*, PIERRE-PAUL BITTON3, GUSTAVO A
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applyparastyle “fig//caption/p[1]” parastyle “FigCapt” CE: JE QC: RA Zoological Journal of the Linnean Society, 2021, XX, 1–42. With 7 figures. Species limits, patterns of secondary contact and a new 1.52 species in the Trogon rufus complex (Aves: Trogonidae) 1.54 1.55 1.5 JEREMY KENNETH DICKENS1,2,*, PIERRE-PAUL BITTON3, GUSTAVO A. BRAVO4, and LUÍS FÁBIO SILVEIRA1 1 Museu de Zoologia da Universidade de São Paulo, 481 Av. Nazaré, Ipiranga, São Paulo, 04263-000, 1.60 1.10 Brazil 2Fundación Para La Tierra, 321 Mariscal José Félix Estigarribia, Pilar, 2800, Ñeembucú, Paraguay 3Department of Psychology, Memorial University of Newfoundland, 232 Elizabeth Avenue, St. John’s, NL A1B 3X9, Canada 4Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard 1.65 1.15 University, Cambridge, MA 02138, USA Received 6 May 2019; revised 13 October 2020; accepted for publication 8 November 2020 1.70 1.20 The black-throated trogon, Trogon rufus, is a widespread, polytypic species-complex with a convoluted taxonomic history. Here, we integrated morphological, vocal and genetic datasets, including spectral data and digital quantification of barred plumage, to assess and redefine its species limits according to the foremost species concepts. We suggest the recognition of four named and one new species. Trogon tenellus and T. cupreicauda are divergent across Central and South America without geographic overlap or intermediates. Trogon chrysochloros in the Atlantic 1.75 1.25 Forests of Brazil is phenotypically, genetically and ecologically distinct. In Amazonia, Trogon rufus consists of three phenotypically distinct subspecies intergrading with each other in a ring-like formation around central Amazonian rivers. Trogon rufus rufus in the Guiana Shield, Trogon rufus amazonicus in south-eastern Amazonia and Trogon rufus sulphureus in western Amazonia, with contact across the Lower Amazon and Madeira rivers, likely due to secondary contact between incompletely diverged lineages. The unique combination of song, morphology and mtDNA 1.80 1.30 features of an unnamed, isolated population in the Atlantic Forest of north-eastern Brazil resulted in its description as a new species, known only from the type locality and considered here as Critically Endangered, requiring urgent conservation actions. ADDITIONAL KEYWORDS: species boundaries– Neotropical – sibling species – divergence – alpha taxonomy – 1.85 species delineation – taxonomic revision – evolutionary trends – new species – Aves. 1.35 INTRODUCTION (Collar, 2001), and are among the most colourful 1.90 birds in the world. Males are patterned with hues of 1.40 The trogons and quetzals (Trogoniformes) are a iridescent green, blue, violet and purple above (except pantropically distributed order of birds consisting in the Asian Harpactes Swainson, 1833), and a bright of a single family, the Trogonidae, which contains 43 red, yellow or orange abdomen. Females have grey or species and 109 subspecies (Gill & Donsker, 2019). brown plumage where males are iridescent They are identified by the possession of a heterodactyl 1.95 Originating in Eurasia during the Palaeogene 1.45 foot, in which digits one and two point posteriorly (Kristoffersen, 2002; Mayr, 2005; Oliveros et al., 2019), they are thought to have been widespread across Laurasia and Africa before becoming fragmented *Corresponding author. E-mail: [email protected] between the African, Asian and American tropics due 1.100 1.50 [Version of record, published online XX XXXX XXXX; to global cooling and changes in habitat during the http://zoobank.org/ urn:lsid:zoobank.org:pub:BD62F699- Oligocene–Miocene (Oliveros et al., 2019). Today, they AA76-4EE3-8B78-C4007112F103] are most diverse in the Neotropics with 29 species, 1.104 © 2021 The Linnean Society of London, Zoological Journal of the Linnean Society, 2021, XX, 1–42 1 2 J. K. DICKENS ET AL. of which 24 species and 66 subspecies belong to the which varies notably between populations (Gould, genus Trogon Brisson, 1760 (Gill & Donsker, 2019). 1838; Ridgway, 1911; Todd, 1943; Zimmer, 1948; Pinto, This relatively high diversity is a result of their rapid 1950), whilst the dimensions of the barred patterning, diversification in South America following the ‘Great collar presence/absence and body size have also 2.60 2.5 American Interchange’ coinciding with the closing featured prominently. Nevertheless, most accounts of the Isthmus of Panama (DaCosta & Klicka, 2008). are highly speculative, usually because of the limited Although diversification is mostly attributed to material available, leading to high levels of uncertainty divergence across geographic barriers, its sympatric in classifications. occurrence in multiple lineages yielded classic The first new species to be split from the nominate 2.65 2.10 patterns of trait sorting amongst South American was Trogon sulphureus Spix, 1824, described from a species (Bitton, 2015). This is especially notable in single male collected in Tabatinga, on the Rio Solimões, the characteristic undertail pattern (black, white or Brazil, which was distinguished by its shiny coppery barred), presence/absence of a white breast band and (versus green) uppertail. A second coppery-tailed form head colour. from Santa Maria, on the left bank of the upper Amazon 2.70 2.15 Differences in these traits are, therefore, likely in Peru, was described as Aganus devillei Cabanis & associated with taxonomic differences and they have Heine, 1863, but most authors found it to be consistent featured prominently in trogon taxonomy, along with in morphology with T. sulphureus. Nevertheless, slight differences in tonality of iridescent plumage patches, differences in the intensity of the copper sheen of the bareparts’ coloration (especially eye-ring) and wing uppertail between specimens led to its intermittent 2.75 2.20 panel patterning (plain or barred) (Gould, 1838; resurrection (Stone, 1928; Zimmer, 1930; Gyldenstolpe, Ridgway, 1911; Todd, 1943; Zimmer, 1948; Pinto, 1950; 1945) until Gyldenstolpe (1951) noted that the close Collar, 2001). In particular, the distinctiveness of the proximity between the type localities, both on the left undertail pattern between species has long raised bank of the Rio Solimões, made it almost impossible suspicions over its involvement in species recognition for them to be different. 2.80 2.25 (Collar, 2001). This was recently confirmed by Bitton The Central American form was then described as & Doucet (2016), whilst Bitton & Doucet (2014) linked Trogon tenellus Cabanis, 1862, based on an immature it to the tail-raising display – a multifunctional visual male with a brown tail. However, since Grant (1892) display that targets both con- and heterospecifics in first noted the uniquely bluer tail colour of the adult the closely related species, Trogon elegans Gould, 1834. male and the broader barring on the undertail and 2.85 2.30 In terms of the tonality of iridescent plumage, this is wing panel compared to the nominate it has been known to be produced by the coherent scattering of recognized as valid by most subsequent authors. light by melanosomes in the feather filaments (Durrer Similarly, Trogonurus curucui cupreicauda Chapman, & Villiger, 1966). However, the variability in tonality 1914, from the Chocó and Magdalena Valley, was and barring dimensions has never been investigated distinguished from tenellus and the nominate by its 2.90 2.35 at the meta-population level but would likely offer copper-bronze uppertail with greenish reflections. The insight into species limits. undertail and wing panel barring were also noted as In this context, Trogon rufus Gmelin, 1788 is widely similar to tenellus but broader than the nominate, distributed in the understory and mid-levels of humid whilst it lacked the white breast band of these taxa forests from Honduras to northern Argentina, up and had a more deeply yellow abdomen. Subsequent 2.95 2.40 to 1100 m above sea level (Collar, 2001). It was first authors have consistently upheld the validity of this described by Gmelin (1788) from female birds depicted taxon but maintained its subspecies status due to and described by Buffon and d’Aubenton (1765–81) as uncertainty over the fact that these distinctions ‘Le Courucou à queue rousse’ and Latham (1782) as represented species-level differences. ‘Rufous Curucui’ from French Guiana and named after Unlike the aforementioned taxa, there has been wide 2.100 2.45 their reddish-brown colored upperparts. The male was disagreement about the validity and status of Trogon initially described as Trogon atricollis Vieillot, 1817, chrysochloros Pelzeln, 1856, described from a series of until Gould (1838) realized that Trogon rufus and specimens from São Paulo state, Brazil. Pelzeln (1856, T. atricollis were in fact the same species. 1868) distinguished it from the nominate by its larger It is easy to distinguish from its congeners by the body size, presence of a vague white breast band and 2.105 2.50 unique combination of a green head in males, brown the finer barring of the upperwing coverts and outer in females, and a yellow belly. However, with the tail secondaries, although he noted overlap in the collection of more material, it soon became recognized coarseness of the barring and that the breast band as notoriously variable across its distribution and could not yet be regarded as diagnostic due to the resulted in the description of nine taxa. Of particular small sample size. Seemingly unaware of this, Bertoni 2.110 2.55 interest to past authors