Xiphocolaptes albicollis

Vasconcelos, Marcelo Ferreira de, 2018, First avifaunal survey of a Cerrado dry forest enclave on the right bank of the São Francisco River, Minas Gerais, Brazil, with insights on geographic variation of some species, Papéis Avulsos de Zoologia 58, pp. 1-18 : 7-8

Xiphocolaptes albicollis (White-throatedWoodcreeper)

This was a medium frequent species during our survey (IFL = 6.2%), recorded exclusively in dry forest. We collected a pair in the study area (MCNA 5203, MCNA 5204). The plumage features of the specimens collected in the study area matches the description of the subspecies X. a. bahiae. So far, X. a. bahiae has been reported to occur only in the state of Bahia (Cory, 1919; Marantz et al., 2003). In comparison with specimens of the nominotypical subspecies from Três Rios (Rio de Janeiro) and Bertioga, São Paulo, they are generally paler ( Fig. 7 ), with crown and nape very dark brown (10YR 2/2) to very dark grayish brown (10YR 3/2) with streaks varying between very pale brown (10YR 7/3.5) and light pale brown (10YR 6/3). In comparison to nominotypical specimens, crown and nape contrast less with brown (10YR 4/2.5) back. Cheeks are unstreaked, varying between pale yellow (2.5Y 8/2) and light gray (2.5Y 7/2). These cheeks form a continuous moustachial stripe to a loral spot of the same color, a pattern that resembles X. falcirostris . Breast and sides varies between brown (10YR 5/3) and light olive brown (2.5Y 5/3), with streaks light yellowish brown (2.5Y 6.5/3), without dark spots on their borders. Belly is less barred in comparison to specimens of nominotypical race. Another character that approaches these specimens to X. falcirostris is their more pronounced decurved bills ( Fig. 7 ).

Studied specimens from humid (Atlantic) forests of the nominotypical subspecies are generally dark- er than specimens from Curral de Pedras ( Fig. 7 ). Head and nape are black (10YR 2/1), with streaks varying between very pale brown (10YR 7/4) and light yellowish brown (10YR 6/4), contrasting deeply with back that varies between very dark grayish brown (10YR 3/2) and dark yellowish brown (10YR 3/4). Cheeks are usually white (2.5Y 8/1) striped black (10YR 2/1) or very dark brown (10YR 2/2). Breast varies between dark grayish brown (10YR 4/2), brown (10YR 4/3), and dark yellowish brown (10YR 4/4), with streaks pale yellow (2.5Y 7/3 and 2.5Y 7/4) bordered by spots very dark grayish brown (10YR 3/2). Belly presents a denser barring pattern than those specimens of dry forests.

It is noteworthy that in specimens collected in semideciduous forests, between areas of humid and dry forests, the plumage pattern appears to be intermediate between X. a. albicollis and X. a. bahiae. They present dark head and striped cheeks similar to specimens of the nominotypical subspecies. Nevertheless, the breast streaks are never bordered by dark spots and belly barring is less pronounced, similar to X. a. bahiae. The background color of breast and upperparts present a wide variation among specimens, with some resembling those of X. a. albicollis and others with a pattern closer to that of X. a. bahiae ( Fig. 7 ).

We checked photographs of the type of X. a. bahiae, housed in the Field Museum of Natural History (FMNH 65976), and its overall plumage pattern is similar to specimens collected at Curral de Pedras, except for its more streaked back and its rump that appears more rufescent. We also analyzed a photograph of a topotypical specimen, which presents a similar plumage pattern of both specimens collected in the study area ( Silva, 2015). Pinto & Camargo (1961), based on the analysis of the two specimens of X. a. villanovae used in the original description of this subspecies, suggested a relationship of this taxon to X. a. bahiae. We checked photographs of the type of X. a. villanovae, housed in the Museu de Zoologia da Universidade de São Paulo (MZUSP 7593) and it differs from X.a. bahiae by presenting a very strong streaked pattern on the back and a densely barred belly. Nevertheless, since both type localities of X. a. villanovae and X. a. bahiae are located east to the EspinhaÇo Range in Bahia state, it is possible that X. a. villanovae is just an extreme of the cline occurring in its northern range.

These results also suggest a geographical variation in X. albicollis following the Gloger’s ecogeographic rule, with darker specimens from the humid coastal forests and paler specimens from dry forests.Intermediate specimens do occur between these regions in semideciduous forests. Also, the less contrasting head and nape with back, the conspicuous moustachial stripe,the less barred abdomen, and the more decurved bill of specimens from Curral de Pedras approach them to X.falcirostris , known to occur only in the opposite (left) bank of the São Francisco River ( Silva & Oren, 1997). Cory & Hellmayr (1925) were the first to note that “by the lighter, less blackish pileum, less distinctly streaked auriculars, and absence of black barring underneath X.a. bahiae seems to form the transition to X.falcirostris , of northeastern Brazil ”.This suggests a possible gene flow between both species. Thus, we strongly suggest that further detailed taxonomic revisions and phylogeographic studies must be conducted to access the possible clinal variation in X. albicollis and to test possible hybridization of this species with X. falcirostris , which also shows a not well resolved pattern of geographic variation ( Silva & Oren, 1997). In future studies it would be extremely important to collect specimens from intermediate localities between the known range of these taxa, including the subspecies X. a. villanovae, sometimes treated as a subspecies of X. falcirostris (Cory & Hellmayr, 1925 – but see Meyer de Schauensee, 1966; Pinto, 1938), and X. f. franciscanus, previously considered closer to X.albicollis ( Pinto, 1978) .

Figures

Figure 7. From left to right: specimens of Xiphocolaptes albicollis albicollis fromTrês Rios,Rio de Janeiro(MCNA2061);intermediatespecimens between X. a. bahiae and X. a. albicollis from Conceição do Mato Dentro, Minas Gerais (MCNA 2903) and Mariana, Minas Gerais (DZUFMG 6536); and specimens of X.a. bahiae from Curral de Pedras,Minas Gerais (MCNA 5203,MCNA 5204) in lateral (A) and dorsal (B) views.