Proposal (650) to South American Classification Committee
A. Resurrect Mustelirallus for Porzana albicollis
B. Transfer Neocrex to Mustelirallus
Porzana albicollis (Ash-throated Crake) has remained in the Porzana for most of its history,
starting in 1868 with Sclater and Salvin, although Bonaparte in 1858 had
described a new monotypic genus, Mustelirallus,
for what was then Rallus albicollis. It basically “looks like” a Sora, so no
surprise (to me) that its placement has been uncontroversial. The only contrary opinion that I can find is
that of Benson and Winterbottom (1968), who proposed that it was the sister to
African Crecopsis egregia.
Garcia-R.
et al. (2014) produced a phylogeny for the Rallidae based on a fairly large
analysis of DNA sequence data, both mitochondrial and nuclear, largely compiled
from GenBank etc. Their taxon sampling
was fairly good for a family that is cosmopolitan and difficult to collect: 70
species in 22 of 33 extant genera. They
found that Porzana albicollis was not
particularly closely related to true Porzana
(of which our P. carolina is a
member; type species = P. porzana)
but rather was the sister to Neocrex. A section of their tree is pasted in below –
see the original paper for other trees and the full data set; let me know if
you need a pdf.
Analysis: The genetic data require
removal of albicollis from Porzana.
That Porzana albicollis has an
antiphonal duet has been reported in the literature, and for is unlike anything
I associate with Porzana carolina or
can find for P. porzana. Check out
this amazing recording by Roger Ahlman on xeno-canto. Also, true Porzana also have greenish or yellowish legs, whereas those of albicollis are a purplish brown. Mustelirallus
Bonaparte, 1856, is available; as noted above, Bonaparte described this genus
to remove the species from Rallus,
which at that time was broadly defined.
However,
as pointed out to me by Mark Robbins, a better solution would be to merge Mustelirallus albicollis with Neocrex. From the figure above, as Mark pointed
out, based just on branch lengths, this would be consistent with the genetic
data. The two species of Neocrex share with albicollis a Neotropical distribution, general similarity in size
and bill shape, and a tendency to occur in habitats besides marshes, such as
grassy areas. Obviously, this is not
evidence for congener status, but the point is that treating albicollis and the two Neocrex as congeners does not violate
any important morphological or habitat themes.
The two Neocrex have red legs,
matching their red bill bases.
(Tangentially, red-legged Cyanolimnas
of Cuba with its red bill base is almost certainly a Neocrex-derivative, and I see no reason to maintain that monotypic
genus … but that’s a NACC issue.)
Mustelirallus Bonaparte1858 has priority over Neocrex Sclater & Salvin 1868.
This causes some unfortunate taxonomic instability. Neocrex
is feminine whereas I assume Mustelirallus
is masculine (because Rallus
is). Neocrex
colombiana would thus become Mustelirallus
colombianus, but erythrops in
invariable.
This
proposal is separated into two parts:
A.
Resurrect Mustelirallus for albicollis.
B. Merge
Neocrex into Mustelirallus.
Recommendation: I recommend a YES to both because (1) unless the sample is
badly misidentified or the analyses totally botched, albicollis cannot be maintained in Porzana, and (2) treating albicollis
and the two Neocrex as congeners is
preferable, in my opinion, to resurrecting a monotypic genus. Reasons to vote NO would be (1) to wait for
additional corroborating samples or data, or (2) to prefer monotypic Mustelirallus.
Literature
Cited:
BENSON, C. W., AND J. M. WINTERBOTTOM. 1968. The relationship of the Striped Crake Crecopsis egregia (Peters) and the
White-throated Crake Porzana albicollis
(Vieillot). Ostrich 39: 177-179.
GARCIA-R, J. C., G. C. GIBB, AND S. A. TREWICK. 2014.
Deep global evolutionary radiation in birds: diversification and trait
evolution in the cosmopolitan bird family Rallidae. Molecular Phylogenetics and Evolution 81:
96–108.
Van Remsen, October 2014
_________________________________________________________________
Comments
from Stiles: “YES to
treating albicollis as congeneric
with the two “Neocrex”, and to using Mustirallus as the genus name due to
priority.”
Comments
from Nores: “YES. The
two species are sister taxa and Mustelirallus
(Bonaparte 1858) has priority over
Neocrex (Sclater & Salvin 1868).”
Comments
from Zimmer: “YES. Genetic data look solid, and the antiphonal dueting
of albicollis was the first thing
that came to my mind when hearing that genetic data places it someplace other
than with Porzana. Hearing a recording of that antiphonal duet
is one thing – you should see and hear it at close range – very impressive
indeed, and not completely unlike anything you would ever hear out of P. carolina.”
Comments from Robbins: “YES, for moving albicollis out of Porzana
based on the genetic data. It is
unfortunate that an esoteric name like Mustelirallus
has to be resurrected to deal to include it with Neocrex. Given that Mustelirallus hasn’t been used for >
150 years, one could argue for using the well-established Neocrex. Regardless of the avenue taken, it is better to unite albicollis and Neocrex into the same genus instead of yet another monotypic genus.”
Comments
from Areta: “A. YES
to placing albicollis in Mustelirallus, B. NO to merging it with Neocrex. Vocally and in plumage and
shape albicollis is very different
from Neocrex erythrops, and we know
nothing about vocalizations of N.
colombiana. I think in this case a conservative change is better than one
that goes too far. Crecopsis egregia
is now considered Crex egregia, and
vocally it doesn't seem very similar to albicollis.
Even if egregia is sister to albicollis, Mustelirallus antedates Crecopsis,
so the use of Mustelirallus albicollis
is a good, solid, taxonomic move.”
Additional comments from Robbins:
“Given Nacho’s comments, I vote NO on B.”
Comments
from Jaramillo: “YES to
both. A – Ash-throated Crake cannot remain in Porzana, due to voice, molecular data, and in my mind morphology.
Other than having a short bill, I see very little to unite it with true Porzana.
“B – YES. Although the red on bill
and legs is a clear difference between Neocrex
and albicollis it is a minor one it
seems. Red legs pop in and out in some
South American Rails (Red-and-white Crake is one that comes to mind) yet it
seems to be closely related to green legged species. At least in coloration and voice. So the coloration does not make me all that
concerned. I do think that
morphologically Neocrex and Mustelirallus albicollis are not that far off, they share the short bill, the
somewhat stout body shape, and they also have curiously barred undertail
coverts which are not common in our rails. Agree that the Zapata Rail should be looked
at, and it may be in this group. However, few living people have seen it, no
vocal data exists, and we only have a handful of specimens so good luck on that
one.”
Comments
solicited from Dan Lane: “The
two parts of Proposal 650 seem to have been passed by SACC a bit too easily
without really considering the second part. I agree that Part 1 is a required move given
the molecular data, and not a surprising one considering aspects of the life
history of M. albicollis. But
Part 2 is rather a leap! I don't
understand what problem there is with resurrecting a monotypic genus for albicollis
(or for any bird that shares no distinct unifying characters with its closest
relatives)! I see no SACC proposals to
lump Amaurolimnas or Micropygia and abolish those (rightfully
maintained, in my opinion) monotypic genera, so what would be so terrible about
having yet another?”
“In plumage characters and voice, I would say that there is
relatively little to unite Mustelirallus albicollis and Neocrex. I don't have experience with N. colombiana
in life, but my experience with Neocrex erythrops is probably about as
much as most field ornithologists have had, and I have a bit of experience with
Mustelirallus albicollis as well. The two species may share similar habitats
(fields and drier marsh, much like most rails), and have short bills (as do all
crakes), but the similarities end there, and none seem distinct from other rail
lineages to me. On the contrary, there
are several aspects that distinguish M. albicollis and N. erythrops.
For example, there is mounting evidence
that Neocrex erythrops is a long-distance migrant (e.g., the type
locality is Lima, Peru, but there seems to be no evidence of resident
populations there; I have made several efforts to find them in the only likely
habitat I know around the city--coastal wetlands--using playback, and have had
no success. To my knowledge, the only modern records from the city are birds
found in town parks, city streets, and other unlikely habitats that suggest
they are on the move, and there are North American records of the species also
supporting long-distance migration). I
know of no suggestion of migration with Mustelirallus albicollis.
“As far as I'm aware, the vocalizations of N. erythrops
were only discovered with any certainty in the past decade or so, and the
repertoire of the species is still being sorted -- factors that belie the
inconspicuousness of the sounds; their structure is not like that of Mustelirallus
(see http://www.xeno-canto.org/species/Neocrex-erythrops).
Mustelirallus albicollis,
by comparison, is easily detected by voice, but its primary vocalizations seem
to be typically given as a duet (as Kevin mentions above) with the two sexes
(presumably) giving rather different sounds in an overlapping way (see http://www.xeno-canto.org/species/Porzana-albicollis).
Other (mostly not closely related)
Neotropical rails have similar duets using unlike, sex-specific components
(e.g., Aramides cajanea, Anurolimnas castaneiceps, Pardirallus nigricans
and P. sanguinolentus, and some members of the Rallus
crepitans/longirostris group), but this dueting format seems to have no
homologous version in Neocrex.
“Given no obvious uniting morphological or vocal characters,
I think it is best to take the conservative route suggested by Nacho and
maintain Neocrex separate from Mustelirallus until and unless
unifying characters are uncovered ... otherwise, what sense does it make to treat
them as congeners? What value is a genus
if there are no unifying characters among its members?”