Proposal (542) to South American
Classification Committee
Split Drymophila caudata into
four species
Effect on SACC: If adopted, three species would
be added to the South American checklist by splitting Drymophila caudata into four species, as recommended by Isler and
colleagues (2012): D. klagesi Hellmayr
and Seilern, 1912, D. hellmayri Todd,
1915, D. caudata (Sclater, 1854), and D. striaticeps Chapman, 1912.
Background on a taxonomic conundrum: Not
included in the Isler et al. paper is a full description of the taxonomic
history of Drymophila caudata.
Sclater (1854) described Formicivora
caudata based on ÒBogotaÓ trade skins. He described the male as having the
middle of pileum and nape solid black and a heavily streaked plumage overall.
These characteristics are clearly depicted in the plate of the description (http://bit.ly/RDy9Os). Isler
et al. (2012) had access to the syntypes at BMNH and could confirm these
diagnostic traits.
Almost six decades after the
description of caudata, Hellmayr and
Seilern (1912) described Drymophila
caudata klagesi from Venezuela, a taxon that also has a solid black middle
pileum as in D. c. caudata but that
differs in other respects. However, Hellmayr and Seilern used as comparative
material for nominate caudata three
male specimens with striped crowns: two ÒBogot‡Ó skins and one from Santa
Elena, Antioquia, Colombia (Central Andes). Clearly, Hellmayr assumed that the
ÒBogot‡Ó skins in front of him (sent by A. Menegaux from the Paris Museum)
corresponded to true caudata (i.e.
topotypical), but this was not the case. There is no a single indication in the
literature that the syntypes of caudata
at the BMNH were actually examined for this or any other descriptions or
studies that followed.
That same year Chapman (1912)
described D. c. striaticeps as a
subspecies distinct from D. c. caudata
as his specimens from the Western and Central Andes of Colombia exhibited
completely striped (black and white) crowns unlike what the SclaterÕs
description indicated for nominal caudata.
Chapman was looking at male specimens that appeared as those that Hellmayr and
Seilern assumed to be of the nominal form. Although Chapman did not inspect the
syntypes of caudata at the BMNH
directly, he was guided by SclaterÕs description and thought that two adult
males from Santa Marta, which also have black crowns, corresponded to nominate caudata (Chapman 1912, p. 146). Chapman
was in the right direction but apparently was not aware at that point of the
interpretations of Hellmayr and Seilern written in the D. c. klagesi description.
In 1915, Todd described D. c. hellmayri from Santa Marta as a
subspecies of D. caudata (Todd 1915,
p. 80) and argued that its diagnostic characters included the black middle
crown and nape indicating that, according to a personal comment by C. E.
Hellmayr, Òin typical D. c. caudata these
parts are always prominently streaked with white, except in worn plumageÓ.
This assertion clearly contradicted SclaterÕs original description (of caudata) and casted doubts on the
validity of ChapmanÕs striaticeps.
Further data on Santa Marta birds resulted in a better characterization of the
local form of this antbird (D. c.
hellmayri) by Todd and Carriker (1922), particularly, for its unique
rufous-brown tone of the tail. A long quote of C. E. Hellmayr in Todd and
CarrikerÕs monograph (p. 307) reveals a number of conclusions that were not
verified at the time but that resulted in a great deal of confusion, ultimately
obscuring the diversity of this group of antbirds: ÒDrymophila caudata striaticeps
Chapman is simply D. c. caudata redescribed. Mr. Chapman was misled by the
original description and accompanying figures. Adult males from Bogota
(topotypical) and the Western Andes of Colombia (striaticeps), [for which] I
have examined a series in the Paris Museum, are perfectly identical inter
se and have the top of the head regularly
streaked with white. In breeding time the white edges sometimes become nearly
obsolete. It must have been such a specimen that served as type of Sclater's
description. Birds from western Ecuador agree in every respect with the
Colombian onesÓ. Isler and colleagues (2012) found this to be incorrect, a
mistake stemming from ÒBogot‡Ó trade skins in different museums from different
regions in Colombia, where the diversity of this group of antbirds is
concentrated.
Chapman
added to the confusion when he wrote (1917, p. 378): Òin the absence of topotypical specimens I was
led to believe, both by Sclater's original description and plate, as well as by
his description in the British Museum Catalogue, in which it is said the
"centre of the cap is black," that true caudata had the cap black
and, consequently, that Santa Marta males, in which the cap is black
represented this form. Hence the birds from western Colombia with a striped
crown were described under the name striaticeps. Hellmayr, however, writes me
that the type, as well as other Bogota specimens, which he has examined, have
the crown striped, and are not separable from Ecuadorian specimens. It follows,
therefore, that striaticeps becomes a synonym of caudata, from which the
black-crowned Santa Marta bird is separableÓ.
Other subspecies were described in
the 20Õs and 30Õs from the Andes of Ecuador Peru and Bolivia, all with males
with striped crowns. Carriker (1935, p. 324) when describing the subspecies boliviana argued against HellmayrÕs
interpretation by stressing that: ÒContrary to the views of Dr. Hellmayr, I
think that striaticeps Chapman, is a perfectly good race [É].
The males differ from caudata in having the whole pileum heavily streaked with
white, while in caudata the median portion of the pileum and occiput is pure
black [Éand by having] much heavier
streaking on the throat and chest.Ó Nonetheless, striaticeps
continued to be treated as a junior synonym of caudata, the newer more southern forms were also synonymized with caudata (see Peters 1951, p. 210),
leading to the taxonomy of three subspecies recognized until today: caudata, hellmayri and klagesi (Zimmer
and Isler, 2003) in addition to the more recently introduced aristeguietana from Serran’a de Perij‡
(Aveledo H. and PŽrez C., 1994). None of the subspecies of Drymophila caudata has ever been treated as separate species.
New published information: Isler et al. (2012)
conducted a study combining data on phylogeography, vocalizations, geographic
plumage variation, including the syntypes of D. caudata caudata, and environmental and elevational distributions
to attempt to resolve this taxonomic conundrum, to assess species limits, and
to study the biogeography of differentiation of these montane antbirds. These
authors uncovered the confusion outlined above and concluded that the description
by Sclater is indeed accurate and that the syntypes are clearly distinct from
all other subsequently named forms in this group, including the other two black
capped taxa klagesi and hellmayri, and even more so from the
streaked capped striaticeps (contra
Hellmayr). The authors found support for recognizing four valid species-level
taxa.
Male
specimens of the four species recommended by Isler et al. (2012). Photos
courtesy H. V. Grouw and J. P. L—pez.
The four major lineages recovered
in the molecular analysis corresponded to four major, divergent, vocal and
plumage groups to the level that these were recommended for recognition as
separate species. Some of these species are also divergent in their ecological
and elevational ranges Ð with hellmayri and klagesi found at more foothill
elevations than the upper montane species caudata
and striaticeps. All the details
of the analyses and rationale behind the taxonomic recommendations can be found
in the paper whereas the map in Fig. 1 depicts the occurrence records of the
four species:
- Drymophila klagesi (Hellmayr and Seilern, 1912) - KlagesÕs Antbird.
Venezuela and NE Colombia in Serran’a de Perij‡ and the northern Eastern Andes
in depto. Norte de Santander.
- Drymophila hellmayri (Todd, 1915) - Santa Marta Antbird. Colombia, endemic
to the Sierra Nevada de Santa Marta.
- Drymophila caudata (Sclater, 1854) - Long-tailed Antbird. Colombia,
endemic to the western slope of the Eastern Andes and the Upper Magdalena
valley in Caquet‡ and Huila.
- Drymophila striaticeps (Chapman,
1912) - Streak-headed Antbird. Colombia, Ecuador, Peru, and Bolivia along the
main Andean cordillera.
The region of provenance of the
syntypes is discussed by Isler et al (2012, p. 580). Given all the information
available to the authors they deduced that the syntypes corresponded to one of
the four proposed species recovered in their analysis, the one that is
distributed in the western slope of the Eastern Andes south to the Upper Magdalena
valley in Caquet‡ and Huila, Colombia. The authors did not declare a particular
locality for the syntypes in the strict sense nor they designated new types
either. The map (Fig. 1) is explicit in their take on the provenance of the
syntypes, and it parallels their conclusion: "...and it appears likely
that the types of caudata came from
somewhere in this area,
probably Santander". ÒBogot‡Ó skins were collected in various regions
of Colombia (hence, the presence of streaked and unstreaked-headed Drymophila specimens). Chapman's account
on the history of ÒBogot‡Ó collections is compelling and continues to be the
most important study of these collections (1917, p. 13-15); he explained that
among the areas of origin of ÒBogot‡Ó skins included southern Santander and the
upper Magdalena Valley in San Agustin Ð areas were Isler et al. (2012) had
modern specimens and vocal samples indicating a species-level divergent
lineage, i.e. D. caudata sensu
stricto. Given all available information, I think that there is no other region
in South America where the syntypes of
caudata could have come from other than that stretch of the western slope
of the Eastern Andes where the sampling gaps still remain large. Hopefully,
modern specimens and data from this region are made available sometime soon and
confirm this conclusion.
Recommendation: I recommend a YES vote to
recognize these species limits and English names.
Literature cited
Isler, M. L., A. M. Cuervo, G. A. Bravo, & R. T.
Brumfield. 2012. An integrative approach to species-level systematics reveals
the depth of diversification in an Andean thamnophilid, the Long-tailed
Antbird. Condor 114: 571Ð583
Other references therein and in the SACC bibliography.
(PDFs of the
original description papers and monographs can be freely accessed on BHL and other
such sites, or are also available upon request, including a translation to
English of the description of D. c.
klagesi).
AndrŽs
Cuervo, September 2012
Comments
from Stiles: ÒYES. A really interesting and
thoughtful piece of work!Ó
Comments
from Remsen: ÒYES. Good vocal evidence for 4 species-level
taxa.Ó
Comments
from Zimmer:
ÒYES. Nice
concordance between vocal, morphological, molecular, and ecological data
sets. The extent of the vocal
differences alone between the four groups provides sufficient evidence for
splitting along the lines proposed by the authors.Ó
Comments from Thomas Donegan: ÒWe recently assessed these splits for the Colombian checklist and accepted all of them. Some comments on sampling issues and gaps which affect some of the newly split species and photographs in life of most of them are set out in the paper linked below and may be of interest.
ÒReference: Donegan,
T.M., Quevedo, A., Salaman, P. & McMullan, M. 2012. Revision of the status
of bird species occurring or reported in Colombia 2012. Conservaci—n
Colombiana 17: 4-14. http://www.proaves.org/proaves/images/RCC/Con_Col_17_1-14_Actualizacion_Listado.pdfÓ
Comments from Pacheco: ÒYES. A consistent suggestion. A minor correction about the indication of name and authorship: the authorship must remain in parentheses only in Drymophila caudata (Sclater, 1854) because it was originally described in different genus. That is not the case in other three.Ó
Comments from Nores: ÒYES. Good concordance between molecular, vocal and morphological evidence.Ó