Xiphorhynchus guttatoides ( Lafresnaye, 1850 )

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 : 504-506

Xiphorhynchus guttatoides ( Lafresnaye, 1850)

Nasica guttatoides Lafresnaye, 1850: 387

Nasica dorbignyanus Pucheran & Lafresnaye, 1850: 420

Picolaptes subguttatus Reichenbach, 1853: 187

Dendrornis rostripallens Des Murs 1855: 45

Xiphorhynchus guttata rimarum Cherrie, 1916: 391

Xiphorhynchus guttatus marginatus Griscom, 1927: 7

Type series: Under article 73.2 of the International Code of Zoological Nomenclature ( ICZN 1999), all specimens on which an original author bases a new species-group taxon constitute the type material. For Nasica guttatoides Lafresnaye, 1850 , there were at least two syntypes, potentially representing a mixed series, which may explain the long-standing disagreement and confusion among subsequent authors ( Ménégaux & Hellmayr 1906a: 99; 1906b: 432; Allen 1906: 351; Cory & Hellmayr 1925: 295; Bangs 1930: 256; Peters 1951: 43). One syntype is at the Muséum national d’Histoire naturelle, Paris (MNHN-ZO-MO-1847-1019), identified as a female, collected at Pebas, Loreto, Peru, during the Castelnau & Deville expedition. The second syntype, MCZ 77146, is at the Museum of Comparative Zoology, Cambridge, MA, and is labelled Colombia ( Bangs 1930). This aligns with Lafresnaye (1850: 387): “ Cette espèce a été rapportée de Lorette, au Musée, par l’expédition Castelnaud; mais nous la possédions déjà dans notre collection, l’ayant achetée d’un marchand avec quelques oiseaux de Colombie.” Translated this reads: “This species was brought back from Lorette to the Museum by the Castelnaud expedition; but we already had it in our collection, having bought it from a merchant with some birds from Colombia.”. Despite this, by the late 19th and early 20th centuries, curiously most authors agreed that Lafresnaye had based his description on a single specimen but disagreed as to which of the two specimens mentioned above was “the type” ( Elliot 1890; Sclater 1890; Ménégaux & Hellmayr 1906 a, 1906b; Allen 1906; Cory & Hellmayr 1925; Bangs 1930; Peters 1951).

The original description of Nasica guttatoides ( Lafresnaye 1850: 387) refers to a bird with a short, straight, black bill (rostro subrecto, brevi, nigro), which trait is emphasized: “ Un peu moins grande que le Guttatus , cette espèce semble tenir le milieu entr’elle et le Flammeus; mais elle diffère de toutes deux par son bec, beaucoup plus court et tout noir. ” The syntype from Colombia ( MCZ 77146) has a black bill, consistent with the description. However, this character is not present in populations currently assigned to X. guttatoides (see Table 4), which match the other syntype, from Peru (MNHN-ZO-MO-1847-1019), that has a Drab-Gray (119D) maxilla. Some authors have suggested that one of the syntypes is a juvenile, although there is no consensus as to which. Ménégaux & Hellmayr (1906 a, 1906b) and Cory & Hellmayr (1925) proposed that the Peruvian specimen was immature, whereas Allen (1906), Bangs (1930), and others considered that the Colombian specimen is the juvenile. Our current understanding of populations attributed to X. guttatoides point to the specimen from Peru as more representative of adults of the taxon. The morphology of the Colombian specimen could represent a young of X. guttatoides or that of a congeneric (e.g., X. susurrans rosenbergi Bangs, 1910 ).

To avoid further confusion and unnecessary nomenclatural instability, we consider that the Peruvian syntype would be the most appropriate lectotype of Nasica guttatoides Lafresnaye, 1850 . However, a lectotype has already been selected in accordance with the ICZN Code. Under the Code, article 74.5 “In a lectotype designation prior to 2000, either the term “ lectotype ”, or an exact translation or equivalent expression (e.g. “the type”), must have been used or the author must have unambiguously selected a particular syntype to act as the unique name-bearing type of the taxon.” ( ICZN 1999). Ménégaux & Hellmayr (1906a: 99) purposely selected MNHN-ZO-MO-1847-1019 as the “ Type de la sous-espèce ” and the “ vrai type ” of Nasica guttatoides Lafresnaye, 1850 , thereby providing a valid lectotypification. They reiterated their selection in a second commentary published the same year ( Ménégaux & Hellmayr 1906b). No prior author (e.g., Des Murs 1856: 43; Sclater 1862: 164; Salvin 1885: 422; Elliot 1890: 186; Sclater 1890: 128) made a selection between the two specimens. Consequently, MCZ 77146 is the paralectotype of Nasica guttatoides Lafresnaye, 1850 , and has “no name-bearing function and does not regain status as a syntype if the lectotype is lost or destroyed” (article 73.2.2, ICZN 1999).

Diagnosis: Xiphorhynchus guttatoides closely resembles X. polystictus , but can be distinguished by having less marked streaking both above and below, and for having most of the bill silvery gray instead of the blackish bill of X. polystictus . Compared to X. guttatus , X. eytoni and X. vicinalis Todd, 1948 the present species is immediately separable based on its paler bill. Xiphorhynchus eytoni and X. vicinalis also differ in their whitish underparts when compared to X. guttatoides .

Variation: We have not detected any sexual dimorphism in colouration in this species. However, X. guttatoides presents a spectrum of geographical variation, which has led to the naming of some subspecies in the past. The majority of specimens from central Brazil, and south of the range of X. eytoni (e.g., the Ilha do Bananal, São Domingos, Aragarças, Colinas, Chapada dos Guimarães, and Chavantina) possess less well-marked plumage, with the breast streaking only indistinctly bordered pale brown, less contrasting upperparts streaking, and a pale grey to bluish-grey bill. The same is true of specimens we have examined from Bolivia. Notably, specimens closely resembling those formerly referred to as X. g. dorbignyanus , recently collected in the area of Porto Franco PCH (Small Hydropower Plant), Tocantins (MN 53756 and 53757), less than 200 km from Baião, also in Tocantins, from where typical specimens of X. eytoni (e.g., MN 13253) are available, also suggest the possibility of sympatry (though not necessarily syntopy) between these species.

Morphometrics: Males of X. guttatoides possess mean values larger than females in culmen, wing and tail lengths. Wing length of X. guttatoides is significantly shorter than other species except X. guttatus , the culmen is significantly smaller than X. eytoni and X. polystictus , and the tail is significantly shorter than X. eytoni (see Tables 2 and 3).

Range: Occurs in Bolivia, Peru, Ecuador, and Colombia, where it extends west to the east slope of the East Andes, at Villavicencio and Bogotá, reaching 2,590 m, as well as in Brazil throughout the Negro-Madeira interfluvium, in the Napo (including Jau) and Inambari areas of endemism, and in central Brazil in the Cerrado biome, in southern Mato Grosso and Goiás (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.