Blue-crowned Manakin Lepidothrix coronata is a widely distributed frugivorous passerine. It ranges from southern Central America (Costa Rica and Panama) to northwestern South America south to northern Ecuador, and across western Amazonia from southern Venezuela and south-east Colombia to Peru and Bolivia (Kirwan & Green 2012). Males possess two plumage patterns. In some populations males are black and in others they are predominantly green. Both black and green males have a blue crown. Females and juveniles are uniform green. Amazonian populations are divided into the coronata group (black males) including L. c. coronata, L. c. carbonata and L. c. caquetae, and the exquisita group (with green males) comprising L. c. exquisita, L. c. caelestipileata and L. c. regalis (Kirwan & Green 2012). The exquisita group is restricted to south-west Amazonia in the Inambari centre of endemism (Cracraft 1985, Silva et al. 2005), with L. c. exquisita considered endemic to Peru, L. c. regalis endemic to Bolivia, and L. c. caelestipileata restricted to southeast Peru and adjacent Acre and Amazonas states in Brazil (Kirwan & Green 2012). Here, I present evidence of the presence of L. c. exquisita in Brazil and Bolivia, in sympatry with caelestipileata in this part of south-west Amazonia.

To obtain historical records of the distribution of three subspecies of L. coronata in southwest Amazonia (Fig. 1), I consulted VertNet ( http://www.vertnet.org; accessed 15 December 2021) and GBIF ( https://doi.org/10.15468/dl.evws4u; accessed 28 December 2021), as well as specimens in the Museu Paraense Emílio Goeldi (MPEG), Belém. Photos of the holotypes of L. c. exquisita (AMNH 493004) and L. c. caelestipileata (NMBE 1006262) were provided by the American Museum of Natural History, New York, and Naturhistorisches Museum Bern, respectively (Fig. 2). A photo of an L. c. caelestipileata (MZUSP 35743) collected in Acre in 1951 was provided by the Museu de Zoologia da Universidade de São Paulo (MZUSP) (Fig. 3C). I took photos of specimens at MPEG in Belém (Fig. 3A–B) and I was later sent additional photos of these individuals by the museum's curators (Fig. 4).

The compilation of records indicated the occurrence of L. c. coronata on the south bank of the Solimões and left bank of the Juruá in the west of the Inambari centre of endemism (see Cracraft 1985; Fig. 1). On the upper Juruá, this subspecies reaches the right bank and extends across central-west Acre (Fig. 1). L. c. caelestipileata is present throughout the Madeira–Juruá interfluvium in the state of Amazonas (Brazil) extending to the border region between Brazil, Bolivia and Peru, south of the Inambari (Fig. 1). L. c. exquisita occurs in the Andean foothills of northern Peru to the Amazon lowlands of Peru, Brazil and Bolivia (Fig. 1). In eastern Acre, Brazil, in dpto. Pando in Bolivia and dpto. Madre de Dios in Peru L. c. exquisita and L. c. caelestipileata occur in sympatry (Fig. 1).

Figure 1.

Distribution of three subspecies of Blue-crowned Manakin Lepidothrix coronata in south-west Amazonia. The rectangle indicates the region where the taxa exquisita/caelestipileata occur in sympatry.

Identification of specimens in the area of sympatry between exquisita and caelestipileata was confirmed by comparison with their relevant holotypes (Fig. 2). Four specimens from Acre and one from Bolivia (Figs. 3A–B and 4; Table 1) have the crown paler blue and correspond to exquisita (Figs. 2B and 4), whereas another collected in the same part of Acre (Fig. 3C; Table 1; Pinto & Camargo 1954) has the brighter blue crown indicative of caelestipileata (Figs. 2D and 4; Pinto & Camargo 1954). The straight-line distance between the closest localities of exquisita and caelestipileata in Acre is only 50 km (Fig. 1). In addition, a specimen at the Museum of Vertebrate Zoology, Berkeley, CA, from dpto. Madre de Dios, Peru, is assigned to caelestipileata (Table 1), extending the distribution of this subspecies to the southern boundary of the Inambari (Fig. 1).

Figure 2.

Holotypes of two subspecies of Blue-crowned Manakin Lepidothrix coronata. (A–B) L. c. exquisita (Hellmayr 1905) (Paul Sweet, © American Museum of Natural History, New York); (C–D) L. c. caelestipileata (Goeldi 1905) (Manuel Schweizer, © Naturhistorisches Museum Bern). Note the difference in the blue crown: pale turquoise in exquisita and darker and shinier in caelestipileata.

Figure 3.

Evidence of sympatric occurrence among two geographic races of Blue-crowned Manakin in south-west Amazonia. (A) L. c. exquisita, eastern Acre, Brazil (MPEG 63656) (Edson Guilherme); (B) L. c. exquisita, dpto. Pando, northern Bolivia (MPEG 54188) (Edson Guilherme); and (C) L. c. caelestipileata, eastern Acre, Brazil (MZUSP 35743) (Luís Fábio Silveira, © Museu de Zoologia da Universidade de São Paulo). Note the difference in crown colour between the specimen of caelestipileata (C) versus those of exquisita (A–B).

Hellmayr (1905) described exquisita as having the ‘crown of the head beautiful sky blue’ and Goeldi (1905) described caelestipileata in German as having the crown ‘Himmelblauen’ (sky blue), but there is a difference between the blue of exquisita (turquoise/lighter; Figs. 2A–B and 4) and that of caelestipileata (darker/brighter; Figs. 2C–D and 4), which makes it possible to clearly distinguish them (Fig. 4; Hellmayr 1906, 1929) and to state that they occur in sympatry in south-west Amazonia (Fig. 1). The presence of caelestipileata in Madre de Dios in Peru was already known (Schulenberg et al. 2007, Snow 2020).

Figure 4.

Specimens of L. c. exquisita from eastern Acre and L. c. caelestipileata from Amazonas, Brazil, at MPEG, showing differences in crown colour, and matching their respective holotypes, taken under the same light conditions (Lincoln Silva Carneiro, © Museu Paraense Emílio Goeldi, Belém)

TABLE 1

Material evidence of sympatry of two subspecies of Blue-crowned Manakin Lepidothrix coronata in south-west Amazonia; see Fig. 1 (rectangle). * MPEG = Museu Paraense Emílio Goeldi, Belém; MZUSP = Museu de Zoologia da Universidade de São Paulo; MVZ = Museum of Vertebrate Zoology, Berkeley, CA.

Although Guilherme (2009, 2012) reported the presence of exquisita in eastern Acre based on the four specimens collected in 2006–07 (Table 1; Figs. 3A and 4), the Brazilian Committee on Ornithological Records (CBRO) (Piacentini et al. 2015) did not accept this taxon's occurrence in Brazil, alleging that eastern Acre ‘comprises precisely the type locality of L. c. caelestipileata’. Guilherme (2016) reaffirmed the presence of exquisita in eastern Acre based on a comparison of four specimens collected there (Table 1; Figs. 3A and 4) with material attributed to exquisita from central Peru. However, the recent version of the CBRO checklist (Pacheco et al. 2021) again argued for excluding exquisita, ignoring the specimens from Acre (Table 1; Figs. 3A and 4), and also noted that Del-Rio et al. (2021) had confirmed that birds east of the Juruá are caelestipileata. Del-Rio et al. (2021) sampled a restricted region (Carauari) of the middle Juruá River c.550 km distant from locations where specimens in Acre were collected (Fig. 1).

Phylogeographic studies of Blue-crowned Manakin indicate that the current geographic distribution of the group is related to different vicariance events, such as the uplift of the Andes and formation of the modern drainage network in the Amazon lowlands (Cheviron et al. 2005, Reis et al. 2019). Some have defended the idea that it is floodplains (várzea) along main rivers that limit the occurrence of taxa in the L. coronata group (Del-Rio et al. 2021), however, neither vicariance nor the presence of floodplains can explain the sympatric presence of these two taxa in the south-east Inambari. Both must have reached the region by dispersing from their core areas, namely the Andean foothills (exquisita) and north-central Inambari (caelestipileata). This type of biogeographic encounter between parapatric taxa is not uncommon in Acre (Guilherme 2012) and corresponds to the southernmost contact zone in the south-west Amazonian lowlands proposed by Haffer (1997). Maintenance of this distribution pattern among sister taxa in this region may be related to environmental gradients (Tuomisto et al. 2003, 2019). In east Peru, north-west Bolivia and south-west Brazilian Amazonia (Acre and Amazonas), terra firme ecosystems are predominantly dominated by two forest typologies, those dominated by bamboo and forests with palms (Silveira et al. 2008, Carvalho et al. 2013). When these taxa meet due to dispersal, they appear to have adapted to use these different habitats thereby avoiding direct (interspecific) competition, occurring in the same geographic region but occupying different habitats (Carneiro et al. 2022). Increased ornithological knowledge of the region has shown that some species thought to occur only in the Andean foothills also occur in the adjacent lowlands in Peru, Brazil and Bolivia (Guilherme & Aleixo 2007, Tobias et al. 2008, Rego et al. 2009, Plácido et al. 2018), as well as species known only in the central-northern Inambari that have been recorded further south (Souza et al. 2018), just as suggested by Haffer (1997: 283).

Sympatric occurrence of these two subspecies of Blue-crowned Manakin in the southeast Inambari has biogeographic and phylogenetic implications. Relationships and species limits are still under debate within the genus Lepidothrix (Dias et al. 2018), in particular in the L. coronata group (Cheviron et al. 2005, Reis et al. 2019). If both taxa occur in the same geographic area and maintain their diagnosable morphological characteristics, it is possible that they have already completed their speciation process and are, in fact, species.