Proposal (1053) to South American Classification Committee
Treat Diglossa
cyanea as two species
Effect
on SACC:
This would split widespread Diglossa cyanea into two species separated
by the Marañon/North Peruvian Low.
Background: Diglossa cyanea
(Masked Flowerpiercer) as traditionally treated consists of five subspecies
from the montane northern Venezuela through the Andes to central Bolivia. Four of the five occur northern of the
Marañon and are distinguished by minor, qualitative differences in
plumage. The subspecies south of the
Marañon (melanopis) is somewhat more distinctive in being larger, duller
in plumage, and having a paler forehead and other minor plumage differences. To the best of my knowledge, no one has ever
proposed that any of these taxa be treated in any way other than subspecies.
New
information:
Martínez-Gómez et al. (2023) analyzed vocalizations (N=88), mtDNA (N=122), and
wing length (N=364) of all taxa from throughout the range.
The
songs showed strong differences between the northern taxa and melanopis
in spectral frequency and structure, with melanopis having up to 5
whistles at the end of the song not detected in samples from any of the
northern taxa. Here are two sonograms
from the paper:
Here
is a graphical depiction of mean standardized differences in song parameters
for melanopis vs. northern populations:
The
northern populations showed strong differences in mtDNA sequence divergence
(6.7%) from melanopis; in fact, the mtDNA gene tree showed paraphyly
with respect to Diglossa caerulescens, which was dismissed as a likely
gene tree vs. species tree problem. That
degree of difference (6.7%) in mtDNA is greater than that between most
currently recognized species of Diglossa (see Mauck & Burns 2009)
Discussion. Here is what we wrote in the paper:
“Taxonomic Implications
“Based on our analysis of
vocal divergence combined with in- sights on their behavioral isolation
consequences from play- back experiments (see Freeman et al. 2022), we
recommend that the 2 primary lineages be treated as separate species under the
Biological Species Concept (Mayr 1942), specific- ally D. melanopis and D.
cyanea (sensu stricto). The depth of genetic divergence in ND2 (6.7%) is
even higher than differences between most other currently recognized species in
Diglossa (Mauck and Burns 2009). These 2 species have been evolving in
isolation for at least 2.7 million years and exhibit song differences that
indicate behavioral isolation (Uy et al. 2018).”
There’s
not much more to add to that. Obviously,
I recommend a YES on this, with the attitude that I think we shifted
burden-of-proof to the single-species treatment. One could vote NO because of insufficient
number of true playback experiments or lack of comparative analysis with other Diglossa
taxa that are considered species or subspecies.
Some will be impressed with the genetic distance, but I personally don’t
think that adds anything one way or another when looking at allopatric,
sedentary tropical taxa. Also, samples
near the northern boundary of melanopis distribution are missing (in
contrast to samples from near the southern extreme of nominate group
distribution), so one could use that as a reason to vote NO..
Note
on English names:
We recommended “Warbling Masked-Flowerpiercer” and “Whistling
Masked-Flowerpiercer”. The rationale was
to emphasize that vocal differences were the way to distinguish them while
continuing the connection to the parental name “Masked Flowerpiercer”. My inclination is to do a separate proposal
on the names, but if you are happy with these and don’t want to go through the
work of a separate proposal, please say so.
Lit
Cit:
MARTÍNEZ-GÓMEZ, S. C., C. E. LARA, J. V. REMSEN, JR., AND R. T.
BRUMFIELD. 2023. Unmasking hidden genetic, vocal, and size
variation in the Masked Flowerpiercer along the Andes supports two species
separated by Northern Peruvian Low.
Ornithology 140: 1–14.
Van Remsen, May 2025
Voting Chart: https://www.museum.lsu.edu/~Remsen/SACCPropChart1044+.htm
Comments
from Stiles:
“This split seems quite clear-cut, based upon definite differences in plumages
and vocalizations , the depth of the split in time (2.5 mya, as deep as the
splits of several other species in the genus, and the well-known geographic
barrier separating them, so YES to the recognition of two species. With regard
to E-names, the suggested vocalization-based ones of Van are certainly
accurate, but to use them one would have to hear them sing! I might suggest two
plumage-based ones: Bright-blue vs. Dusky (Masked) Flower-piercers.”
Comments
from Lane:
“YES. The study and results seem pretty straightforward. Not sure I think
“whistling” quite describes the song of the melanopis group as well as
“screeching” but that’s a conversation to have at a later time.”
Comments
from Areta:
“YES to splitting a
monotypic D. melanopis from a
polytypic D. cyanea. The
vocalizations, wing length, and genetics all support the split across the dry
Marañón Valley. The plumage distinctions are subtle, but that is why they had
different names in the first place. It seems that obscura (whose diagnosability was questioned by Martínez-Gómez et
al. 2023) and tovarensis
(with its somewhat different song, which I´ve recently recorded) do not differ
to an extent that we should worry about them being split in the future. So, I
am happy to consider obscura and tovarensis as subspecies of D.
cyanea.”
Comments
from Naka:
“YES, I fully agree in splitting the two allopatric populations across the
Marañon into D. melanopis and D. cyanea. This study is as good as
it gets, with morphological, vocal and deep genetic variation associated with a
very known geographical barrier. Vocal differences are stunning, and I do like
the English names proposed by Silvia and co-authors.”
Comments
from Robbins:
“YES for recognizing two species. The distinct songs alone support species
recognition. The limited genetic data and subtle plumage differences are
consistent with the genetic break at the Marañon/North Peruvian Low.”
Comments
from Stiles:
“YES.”