Xiphorhynchus guttatus (M.H.C. Lichtenstein, 1820 )

Raposo, Marcos A., Kirwan, Guy M., Fonseca, Odirlei, Selvatti, Alexandre Pedro, Höfling, Elizabeth & Stopiglia, Renata, 2025, Towards a more coherent taxonomy for the woodcreepers Xiphorhynchus guttatus and X. guttatoides (Aves: Passeriformes: Dendrocolaptidae), Zootaxa 5683 (4), pp. 492-512 : 502-503

Xiphorhynchus guttatus (M.H.C. Lichtenstein, 1820)

Dendrocolaptes guttatus M.H.C. Lichtenstein, 1820: 201

Type material: A specimen housed at the Museum für Naturkunde, Berlin, registration number ZMB 9207, collected by Georg Wilhelm Freyreiss in “Bahia” is identified on the label and in the registration book as the type of Dendrocolaptes guttatus Lichtenstein, 1820 . In the original description of Dendrocolaptes guttatus, Lichtenstein (1820: 201) cited two prior indications for his nomen: “ Le Pic grimpereau commun Azara 242” and “ Dendr. nigrirostris . Illig.”. Azara’s 242 was also previously used by Vieillot (1818) to describe what is now Lepidocolaptes angustirostris ( Vieillot, 1818) (originally described as Dendrocopus angustirostris ) whilst D. nigrirostris is a name from an unpublished manuscript of J.K.W. Illiger, and is a nomen nudum according to the Code ( ICZN 1999). That Illiger’s name was available only in manuscript form was confirmed by Lichtenstein (1821: 264) in a subsequent publication as follows: “Dendr. nigrirostris Illig in Mscpt.”. Lichtenstein (1820: 201) also described a specimen with a straight blackish-brown bill ( D. rostro rectiusculo cultrato nigrescente). The first mention in the original description is to “ Le Pic-Grimpereau commun Azar. 242”, probably in reference to Cuvier (1809: 472), who described Félix de Azara’s material collected in Paraguay and along the Rio de La Plata, specifically a specimen with a reddish-brown bill ( le bec supérieur, brun rougeätre em dessus). Specimen ZMB 9207, collected by Georg Wilhelm Freyreiss in “Bahia”, clearly cannot be equated with Azara’s material. It might be related to the other prior indication cited by Lichtenstein ( Dendr. nigrirostris Illiger ) in the original description, but our search for confirmation of this remains inconclusive. Lichtenstein (1820) went on to mention that “ Azara’s description perfectly matches 2 specimens on display in the Berlin museum ”, which could indicate that ZMB 9207 is a syntype, given that it was presumably one of the two specimens in Berlin that Lichtenstein (1820) was referring to when he described Dendrocolaptes guttatus . In his catalogue of the Zoological Museum of the Royal University of Berlin, Lichtenstein (1823: 16) corroborated this hypothesis by his mention of three specimens from Bahia identified as Dendrocolaptes guttatus . Based on this, it seems that Xiphorhynchus guttatus (M.H.C. Lichtenstein, 1820) is based on a mixed type series, the nomenclatural consequences of which will be discussed in greater detail by Raposo et al. (unpubl. data).

Diagnosis: Xiphorhynchus guttatus is extremely similar in plumage to the allopatric X. polystictus ( Salvin & Godman, 1883) but is distinguished by having a more chestnut-washed plumage, different measurements, and a totally different vocalization (Fonseca et al. in prep.), involving a longer and structurally more complex song, with on average 48.75 notes. On a sonogram, the inter-note intervals for X. guttatus are much shorter than for X. polystictus , with a tendency for the terminal notes to be more hook-shaped. The notes throughout the song are strongly asymmetrical in frequency variation which converges in a convex-convex geometric arrangement in the song’s architecture. It is similar to a trill, which progressively slows down, resulting in longer intervals between notes at the end of the song. On the other hand, X. polystictus has shorter and more homogeneous vocalizations in which note shape and inter-note interval do not change as the song progresses, with on average 21.6 less distorted and compressed notes in the song. Its notes are symmetrical in relation to their frequency variation with a concaveconvex geometric arrangement in the song’s architecture. The song of X. polystictus is more melodic and uttered at a regular pace, with intervals between notes more regular and longer than in X. guttatus , providing three major points of divergence between the species in this character. Xiphorhynchus guttatus is also readily separated from X. eytoni (P.L. Slater, 1854) , geographically the closest species, in having the throat and breast, particularly the spots, deep ochraceous (123B), whereas X. eytoni has the throat and underparts spotting white. The same is true of the dorsal markings and supercilium, which are ochre in X. guttatus but much whiter in X. eytoni , rendering the supercilium distinctly more obvious in X. eytoni . Compared to those populations of X. guttatoides that are closest geographically to X. guttatus , on the central Brazilian Planalto ( Fig. 3 ), the present species is separable based on its black bill, and better-defined (dark-bordered) spots on both the upper- and underparts, whereas X. guttatoides has a paler bill, ventral spots without any black border or only narrowly so, and upperparts spotting rather reduced and fine on the mantle. Compared to western populations of X. guttatoides (e.g., in Acre, Brazil, and Peru, Ecuador, and Colombia), X. guttatus has a darker bill, and more spotted belly and flanks lacking any hint of cinnamon, unlike X. guttatoides .

Variation: Juveniles have a smaller and blacker bill, their overall colouration is darker cinnamon, as well as having shorter and more diffuse spots in the shape of small teardrops.

Morphometrics: Males of X. guttatus have mean values larger than females for culmen, wing and tail lengths. This species has the culmen and wing lengths significantly shorter than in X. eytoni and X. polystictus , respectively. Mean tail length is shorter than in X. vicinalis and X. eytoni but the differences are not statistically significant (see Tables 2 and 3).

Range: Endemic to the Atlantic Forest of Brazil, in humid littoral forests from Paraíba south to Rio de Janeiro, in which latter state its occurrence was first mentioned by Cory & Hellmayr (1925), and where it is apparently restricted to lowland forests in the north of the state (see Figs. 3‒4 ) .

Figures

FIGURE 3. Map depicting the distribution of plumage analyses: black circles, morphotype 1, green area, Atlantic Forest area of endemism (AE); white triangles, morphotype 2, purple area, Guiana AE; black diamonds, morphotype 3, red and grey areas, Napo-Inambari AE and Cerrado Biome, respectively; and grey squares, morphotype 4, yellow and blue AEs, Xingu-Belém and Rondônia-Tapajós, respectively, and grey and light green areas, Cerrado and Caatinga Biomes, respectively.

FIGURE 4. Map depicting results of taxognosis analyses and the taxonomic proposal: black circles, Xiphorhynchus guttatus; white triangles, X. polystictus; black diamonds, X. guttatoides; white stars, X. vicinalis; and grey squares, X. eytoni.