Cercomacroides hypomelaena (Sclater 1890) Cavarzere & Silveira, 2024

Cavarzere, Vagner & Silveira, Luis F., 2024, Integrative taxonomy of Cercomacroides serva (Sclater, 1858) demonstrates the validity of C. hypomelaena (Sclater, 1890) comb. nov. (Aves: Thamnophilidae), Vertebrate Zoology 74, pp. 235-247 : 235

Cercomacroides hypomelaena (Sclater 1890) comb. nov.

Southwestern black antbird (suggested English name)

Chororó-preto-do-sudoeste (suggested Portuguese name)

Chresonymy.

Cercomacra hypomelaena Sclater, 1890, Catalogue of the Birds in the British Museum 15: 268. Cosnipata, S.W. Peru.

Pyriglena serva [non Pyriglena serva Sclater, 1858] - Allen (1889), Bulletin of the American Museum of Natural History 2: 96.

Cercomacra serva [non Pyriglena serva Sclater, 1858] - Berlepsch and Stolzmann (1906), Ornis, Internationale Zeitschrift für die gesamte Ornithologie 13: 117.

Cercomacroides serva - Tello et al. (2014), Zoological Journal of the Linnean Society 170: 555.

Holotype.

BMNH 1889.7.10.574 (male). Cosnipata, Peru.

Diagnosis.

Males indistinct from C. serva . Females with brown upperparts, which are concolorous with the eyebrows, a white interscapular patch, brown tail, reddish brown primaries, and an orange belly, concolorous with the auriculars and fimbriae on the outer wing coverts. The loudsong is Type 2.

Distribution.

It can be found on the southern bank of the Marañon River and on both banks of the Ucayali River, in Peru. Its westernmost limit is the base of the Andes. It also ranges south of the Amazon River east to the Madeira River, in Brazil, and its southernmost range is in northwestern Bolivia.

Although the Ucayali is an important barrier to several taxa, the upper and middle sections of the Ucayali do not segregate the C. serva and C. hypomelaena comb. nov. This was already noted in a comprehensive biogeographic study, which documented only Cercomacra hypomelaena on both banks of that river ( Harvey et al. 2014). Cercomacroides hypomelaena comb. nov. occurs on both banks of the Yavarí (Javari) River, being limited to the north by the Marañon-Amazonas River complex. We found no indication of clinal variations of female plumage coloration across the ranges of C. serva and C. hypomelaena comb. nov. (Fig. 1C, D ) in contrast to what has been suggested ( Zimmer and Isler 2003). The coloration of the upperparts was constant in females of each species, and from Colombia, south to Peru and Brazil, the female upperparts did not gradually fade into the lighter southwestern form ( Zimmer and Isler 2003). This is especially valid when considering specimens that are separated by approximately 100 km in northwestern Peru. Female MUSM 10208 from Rio Cenepa is perfectly distinguished from female AMNH 240187 from Santa Rosa. These populations are probably not in contact, since the Marañon River apparently acts as a barrier, even in its narrower upper region (Fig. 5B ). It has been shown that the width of a river near the headwater may not act as a barrier ( Harvey et al. 2014), and the fact that those females are clearly distinguishable corroborates their specific status. Furthermore, the recordings from the northern (XC335224) and southern (XC89140) banks of the Amazon River on the borders of Colombia and Brazil, which are ~30 km apart (Fig. 5C ), further corroborate the absence of intergradation. Via spectrogram analyses, both male loudsongs can be diagnosed as C. serva and C. hypomelaena comb. nov., respectively, indicating that the river is a geographic barrier. From these few contact areas where we could assess the identify of Cercomacroides species, gene flow may be reduced or absent, reaffirming their specific status under the Biological Species Concept ( Mayr 2000).

Our study indicates that Cercomacra tyrannina (sic) atrogularis Lletget, 1918 is not a valid taxon. The holotype, a male from Archidona, Ecuador, was collected by Marcos Jiménez de la Espada during his visits from Guayaquil to Tabatinga between 1862-1866 (J. Barreiro in litt. 2013). We evaluated this specimen via photographs, but due to the similarity of male plumages of C. serva and C. hypomelaena comb. nov. we could not distinguish this specimen from C. serva on plumage alone. Lletget’s type specimen originated from within the distribution of C. serva . Thus, we suggest that, pending molecular analysis, atrogularis is best synonymized with C. serva (Sclater, 1858).

The type locality of C. serva , Napo, is imprecise, but the banks of this river do not act as barriers to other species of Thamnophilidae (e.g., Cavarzere et al. 2012). Records from Ecuador merit a few comments. The presence of the species in the Ecuadorian Chocó is based on only two specimens (MNHN 1936n117, 1936n118) collected by Carlos Olalla and sons, and this information is neglected without explanation in some references ( Zimmer and Isler 2003). There is a great deal of discussion about some of the specimens collected by the Olalla family and kept in the American Museum of Natural History (AMNH), as well as in other museums ( Wiley 2010). Few errors in locations can be attributed to the Olalla family, especially Alfonso, who contributed thousands of bird and mammal specimens, which are currently kept in dozens of institutions. His work significantly shaped the field of zoological studies of neotropical fauna ( Wiley 2010). It is possible that these two specimens (as well as two other specimens of C. cinerascens , from the same locations and from similar dates) might be the result of a location error. This is partly because the species is restricted to the Amazon Basin, but also because among all the specimens examined in this study, only these two came from this location. For C. Vaurie, the former curator of ornithology at the AMNH, some specimens sold by Olalla exclusively to the Natural History Museum in Stockholm, then curated by N. Gyldenstolpe, were also traded with other buyers, which had incorrect information on their labels ( Wiley 2010). Some of these specimens were found in the Muséum National d’Histoire Naturelle, Paris, and may include the examples cited here. P. E. Vanzolini, then curator of herpetology at the Museu de Zoologia da Universidade de São Paulo (MZUSP), was confident of the Olalla locations, and in a letter to Vaurie, dated 1965, explained that Olalla had more employees that collected on opposite riverbanks, at least for the Amazonian cases. This would explain why the collection includes taxa that inhabit different localities collected on the same day ( Wiley 2010).

The altitude of Carondelet, in the province of Esmeraldas, Ecuador, was questioned, since the amphibian species collected there normally occur at much higher elevations and further west than where this location was said to be, according to the gazetteers ( Hoogmoed 1989, Paynter Jr. 1993). Hoogmoed (1989: 15) refrained from contradicting the locality itself, because Olalla specimens are generally reliable. These two specimens were collected by Manuel Olalla in February 1952, today held at MZUSP. For bats of the genus Sturnira , which inhabit western Ecuador and Colombia, nothing unusual has been reported for rio Cachabi, the location for S. ludovici , where a male of this species was collected by Carlos Olalla on 9 August 1935 (McCarthy et al. 2006). This date coincides with two specimens of C. serva (1 and 6 August 1935) and another two C. cinerascens (27 July and 5 August 1935).

There is a record of a young male C. hypomelaena comb. nov. from the right bank of the Madeira River (MZUSP 109098) collected on 8 November 2010. At the time of this collection in Porto Velho, Rondônia state, Brazil, all collected specimens were processed on the same day by a person accustomed to specimen tagging. This strongly suggests that there is no location error (E. Machado, pers. comm. 2015). There were no other records available for this species on the right bank of the Madeira River. Specimens and recordings from the left (southern) bank of the Marañon River near its headwater, and from the right (eastern) bank of the Ucayali River are warranted to further elucidate if those rivers impose barriers or whether the two taxa might form a hybridization zone.

Figures

Figure 1. Dorsal view of (A) Cercomacroides serva (ANSP 189169 - N Lumbagui, Sucumbios, Ecuador; ANSP 176140 - Rio Maniti, Santa Cecilia, Loreto, Peru), and (B) Cercomacroides hypomelaena comb. nov. (ANSP 103221 - La Pampa, Sandia, Peru; ANSP 120221 - Teoponte, Rio Kaka, La Paz, Bolivia). The lack of intergradation of plumage coloration along their range is demonstrated for (C) C. serva (ANSP 83291 - R. Suno Abajo, Orellana, Ecuador; ANSP 159994 - Umbria, Putumayo, Colombia; ANSP 83292 - Abajo San Jose, Coca, Ecuador; ANSP 168085 - Montallo, Oriente, Ecuador; ANSP 176140 - Rio Maniti, Santa Cecilia, Loreto, Peru), and (D) C. hypomelaena comb. nov. (ANSP 92202 - Puerto Yessup, Junin, Peru; ANSP 120226 - Huanay, Rio Mapiri, La Paz, Bolivia; INPA 1962 - km 260, BR 319, modulo 5 do PPBio (Igapo-acu), Amazonas, Brazil; MZUSP 109099 - Left bank of Madeira River, Abuna, Rondonia, Brazil).

Figure 5. (A) Distribution of specimens (triangles), and recordings (circles) of Cercomacroides serva (black), and Cercomacroides hypomelaena comb. nov. (orange), examined in this study. A diamond in SE Peru represents the type-locality of C. hypomelaena comb. nov.; there is no precise type locality for C. serva (see text). Insets indicate potential contact areas in which species are separated by the Maranon (B) or the Amazon (C) River. Range map (light grey) from IUCN (2023).