Proposal (412) to South
American Classification Committee
Split Momotus momota into five
species
This proposal
would reverse the decision of Proposal no. 117 which favored lumping the highland form aequatorialis (considered a separate
species in the baseline list) into a broad M.
momota due to the lack of published evidence supporting the split, and in
view of the fact that other taxa currently included in M. momota would probably deserve species rank were a comprehensive
analysis to be performed. I have
attempted such an analysis (Stiles 2009), now published in Ornitología
Colombiana, the online journal of the Asociación Colombiana de
Ornitología. Hopefully by now the
members of SACC have received from Van a pdf of this study; if not, it can be
downloaded from the web page of the journal Ornitología Colombiana: www.ornitologiacolombiana.org/revista/htm.
Basically, I drew my data from three
sources: plumage patterns, biometrics and vocalizations, supplemented by
information on geographic distributions and ecology. I examined a total of 512 specimens of ten
“focal” taxa occurring in the area between southern Central America, northern
and western South America from Colombia east to the Guianas and south to
northern Peru, and Trinidad-Tobago. I
also examined ca. 30 specimens from areas slightly to the south and east to
further check for intraspecific variation.
I defined 14 characters of plumage pattern and took six 6 measurements
of bill, wing and tail. For
vocalizations, I restricted the main analysis to the ‘hooting’ “primary song”;
motmots have a much broader vocal repertoire but other vocalizations had not
been recorded consistently for all taxa. From sonograms, I measured five
parameters of frequency and duration for those taxa in which this song
consisted of a single note, and six additional parameters for taxa in which the
song consisted of two notes. Data were
analyzed with t-tests, ANOVA, discriminant analysis and principal components
analysis. I defined species limits in
this complex on the basis of two general criteria: diagnosability and the
probability that the differences observed would assure maintenance of
reproductive isolation should currently allopatric groups enter into contact.
My results support recognition of five species-level taxa in this complex: lessonii Lesson 1842 (including 2-3
additional subspecies in Mexico beyond the scope of this study), momota Linnaeus 1766 (including the
nominate, microstephanus Sclater 1855
and several other subspecies of eastern and southern South America beyond the
scope of this study); M. aequatorialis Gould
1857 (including the subspecies chlorolaemus
Berlepsch and Stolzmann 1902); bahamensis
Swainson 1837 and subrufescens Sclater
1853. In the latter species, I recognize
as subspecies osgoodi Cory 1913, argenticinctus Sharpe 1892 and spatha Wetmore 1946, but find the
following taxa not adequately diagnosable and recommend lumping them into
nominate subrufescens: conexus Thayer & Bangs 1906, reconditus Nelson 1912 and olivaresi Hernandez & Romero 1978.
For the purposes of SACC, my
analysis would recognize four species in our area (lessonii being restricted to Central America): cis-Andean momota, Andean aequatorialis, northwestern, trans-Andean subrufescens and Trinidad-Tobago bahamensis. My conclusions are congruent with a
phylogeographic analysis of the Momotidae (as yet unpublished) by Chris Witt,
save that bahamensis is nested within
the subrufescens clade; I present
arguments, mainly from plumage and biometrics, in support of species status for
bahamensis. Regarding English names, I propose Amazonian
Motmot for momota since the Amazon
basin includes the vast majority of its distribution (and because of the great
variation among the named subspecies, I could devise no adequately descriptive
name suitable for all of them); Whooping Motmot for subrufescens because its rather long-drawn-out single-note song
does indeed sound like a whoop; Andean Motmot for aequatorialis because it is indeed restricted to the Andes and
because other species of motmot are also “highland” birds; and Trinidad Motmot
for bahamensis.
The important references for this
study are given in Proposal 117
and the pdf of this study. I recommend a
YES on this proposal (obviously!).
F. Gary Stiles, August 2009
Comments from Robbins:
“YES. Gary has thoroughly documented
species level differences among these taxa.”
Comments
from Zimmer:
“YES. Gary has done a nice job of
providing the analysis that we all wanted when we voted on Proposal 117. Biometrics, plumage patterns, and vocal data
all point toward the proposed splits, and I would further add my support for
Gary’s proposed English names for the various resulting species.”
Comments
from Cadena:
“YES. Gary has done an admirable job describing
geographic variation in this group. Because many of the populations are
allopatric, several difficulties remain regarding where does one draw species
limits, but I think it is likely that these difficulties will persist
regardless of how much additional data we throw at problems like this (a
similar situation occurs in Arremon
torquatus, on which I will submit a proposal shortly). Gary's proposed
classification, which considers likelihood of reproductive isolation and also
the distinctiveness of evolutionary lineages, is a substantial improvement in
comparison to what we had before.”
Comments
from Remsen: “YES.
Gary has taken all available phenotypic data and partitioned the
geographic variation into the units that are most defensible from the standpoint
of known or likely reproductive isolation … a big step forward.”
Comments from Pacheco:
“YES. im para a proposição em considerar momota,
aequatorialis, subrufescens e bahamensis como espécies distintas.
Gary fez um excelente trabalho elucidando as interrelações dos vários táxons de
Momota presentes na região selecionada.”
Comments from Jaramillo:
“YES. It
is fantastic when a new classification is also a clarification. Traveling
around it is clear that members of this group are certainly similar to each
other, but at the same time the differences are notable. My first trip to
Trinidad and Tobago had me staring at this strange thing, thinking…surely this
is not the same creature as in Mexico, or Ecuador…or…. I particularly like that
this is a new classification based on traditional methods, and it is tight and
well done. It does scream out that while molecular methodology is an
indispensable tool, you can attack these problems carefully with traditional
datasets and come up with something very strong. I look forward to the eventual
publication of molecular datasets on this, which will surely strengthen much of
what is put forward here.”
Comments from Nores: “YES, pero con
reservas. Aunque considero que el análisis hecho por Gary es excelente y tiene
un detalle asombroso, hubiera sido perfecto 10 o 15 años atrás cuando no
existían o estaban poco desarrollados los estudios meoleculares. En este
momento, yo hubiera deseado ver algún análisis molecular antes de realizar la
separación en cinco especies. Además, yo soy muy partidario del “biogeographic species concept”
developed by Hellmayr: allopatric representatives of a common stock should be
considered subspecies. A pesar de esto, considero que hasta tanto haya estudios
moleculares está bien en aceptar la propuesta de separar las especies.”