My dissections demonstrated that, in relation to the size of the doves,
the jaw musculature of all the specimens investigated was so nearly
alike that only one major difference was detected. _M. pseudotemporalis
profundus_ appeared to be enlarged in the White-winged Dove. This might
have been predicted, since the white-wing was also shown to possess an
elongated beak, presumably an adaptation for nectar-feeding, which
would necessitate additional muscle development in order to compensate
for the added length. Measurements recorded from several skulls
indicated that the heads of the birds (excluding the beak) are nearly
proportional.
Perhaps plumage patterns are the most widely used characters for
determining generic relationships of birds. Ridgway (1916:339-385)
followed the columbid classification of Salvadori (1893) using plumage
patterns and body proportions to distinguish between the genera. In the
genus _Zenaidura_ he included the unique specimen _Zenaidura
yucatanensis_, and he placed _auriculata_ in _Zenaida_. The
White-winged Dove was referred to a separate genus, _Melopelia_. He
described the genus _Zenaidura_ in the following manner:
"Plumage of head, neck and under parts soft and blended;
bare orbital space moderate, broadest beneath eyes.
Coloration plain, the proximal secondaries (sometimes
adjacent wing-coverts and scapulars also) spotted with
black; rectrices (except middle pair) with a black band
across postmedian portion, the apical portion paler gray
than basal portion, sometimes white; a small black
subauricular spot; adult males with head, neck and anterior
under parts more or less vinaceous and sides of neck glossed
with metallic purple."
He noted that the plumage of _Zenaida_ was almost precisely as
described for _Zenaidura_. Also, although all members of _Zenaida_
reputedly possessed twelve rectrices, a characteristic of the genus, it
was later found that _auriculata_ possessed fourteen rectrices. The
species was promptly placed in the genus _Zenaidura_ by Peters
(1934:213-215). In plumage and coloration, _Melopia_ was described as
similar to _Zenaida_ and _Zenaidura_ but without black spots on the
wings.
The White-winged Dove also has twelve rectrices, but Bond (1940:53) and
Goodwin (1958:330-334) considered the number and shape of rectrices to
be of minor importance when compared to the homologous markings of the
plumage. Goodwin stated that his conclusion was emphasized by the fact
that the tail of _auriculata_ is intermediate in length and shape
between those of _macroura_ and _aurita_. In summary Goodwin "lumped"
the genera _Zenaida_ and _Zenaidura_ under the genus _Zenaida_.