Miller (Proc. Acad. Nat. Sci. Philadelphia, 1902, p. 390, September
3,1902) based the name _Pipistrellus cinnamomeus_ on a skin and skull of
a vespertilionid bat obtained on May 4, 1900, at Montecristo, Tabasco,
Mexico, by E. W. Nelson and E. A. Goldman. A single specimen was
available to Miller when he proposed the name _P. cinnamomeus_. Dalquest
and Hall (Jour. Mamm., 29:180, May 14, 1948) reported three additional
specimens collected in 1946 by W. W. Dalquest on the Rio Blanco, twenty
kilometers west-northwest of Piedras Negras, Veracruz, Mexico. No other
published information concerning this species is known to us, although
the name has, of course, appeared in regional lists, for example in the
"List of North American Recent Mammals, 1923" (Bull. U. S. National
Museum, 128:75, April 29, 1924) by Gerrit S. Miller, Jr.
Additional specimens, nevertheless, are known. Two collected on April 18
and 20, 1903, at Papayo, Guerrero, by Nelson and Goldman, are in the
Biological Surveys Collection in the United States National Museum. A
skin, probably of this species, for which the skull cannot now be found,
was taken on October 27, 1904, at Esquinapa, Sinaloa, by J. H. Batty and
is in the American Museum of Natural History. This is the skin referred
by Miller and Allen (Bull. U. S. Nat. Mus., 144:100, May 25, 1928) to
_Myotis occultus_. Three additional specimens, each a skin with skull,
were collected twenty kilometers east-northeast of Jesus Carranza, at
200 feet elevation, Veracruz, by Walter W. Dalquest, two on April 13,
1949, and one on May 16 of the same year. These are in the Museum of
Natural History of the University of Kansas, as also are the three
previously reported by Dalquest and Hall (_loc. cit._). A total of ten
specimens, from five localities, all in Mexico, thus is accounted for.
On page 392 of the original description--which our study of the holotype
shows to be accurate--Miller wrote: "This bat differs so widely from the
other known American species of _Pipistrellus_ as to need no special
comparisons. Superficially it has much the appearance of an unusually
red _Myotis lucifugus_, and only on examination of the teeth do the
animal's true relationships become apparent." In referring to the teeth
Miller almost certainly was thinking of the premolars of which there are
only two on each side of the upper jaw and on each side of the lower jaw
in _Pipistrellus_, including his _Pipistrellus cinnamomeus_, whereas
_Myotis_ at that time was thought always to have three premolars on each
side of both the upper and lower jaw, except in rare instances where one
premolar might be lacking on one side of one jaw or even more rarely on
both sides of the upper jaw. In his original description of _P.
cinnamomeus_, Miller mentioned also that it had the "Inner upper incisor
distinctly smaller than the outer, not approximately equal to it as is
the case in _P. subflavus_."
At this point it is well to make clear that each of the genera
_Pipistrellus_ and _Myotis_ contains a large number of species and that
the differences between the two genera are few. Our examination of
American specimens reveals only one differential character: In _Myotis_
the outer upper incisor is distinctly larger than the inner, whereas the
two incisors are of approximately equal size in _Pipistrellus_. It may
be noted that the outer upper incisor of several, but not all, species
of _Myotis_ has a well-developed concave surface directed toward the
canine whereas this surface is flat or convex in _Pipistrellus_. In both
features, the type of _Pipistrellus cinnamomeus_ Miller agrees with
_Myotis_ and differs from _Pipistrellus_.
Five years after naming and describing _Pipistrellus cinnamomeus_,
Miller published his monumental work entitled "The families and genera
of bats" (Bull. U. S. Nat. Mus., 57, June 29, 1907) wherein he points
out the differences in the upper incisors between _Pipistrellus_ and
_Myotis_ (by a _lapsus plumae_ ascribes subequal incisors to _Myotis_
and unequal incisors to _Pipistrellus_) but seemingly failed to
reexamine _P. cinnamomeus_ in the light of this better understanding of
the two genera, or if he did examine _P. cinnamomeus_ he possibly was
misled still by the absence of the third premolar on each side of both
the upper and lower jaw.
In 1928 when Miller and Allen published their account of "The American
bats of the Genera _Myotis_ and _Pizonyx_" (Bull. U. S. Nat. Mus., 144,
May 25, 1928) they examined specimens of _Myotis occultus_ which they
implied (_op. cit._: 99-100) had only two instead of three premolars on
each side of both the upper and lower jaws. In preparing this taxonomic
account of bats of the genus _Myotis_, the specimens (type and two from
Papayo) of _Pipistrellus cinnamomeus_ seem not to have been examined.
Indeed, it is almost certain that they were not examined for the species
was renamed; the new name, _Myotis lucifugus fortidens_ Miller and
Allen (Bull. U. S. Nat. Mus., 144:54, May 25, 1928), was based on a
skull with the corresponding body in alcohol. The characters of this
specimen are almost exactly those of _Pipistrellus cinnamomeus_, named
and described by Miller 26 years earlier. The type locality (Teapa) of
_M. l. fortidens_ is 80 miles westerly from the type locality of _P.
cinnamomeus_; both are in the state of Tabasco, and in the same
life-zone, at equivalent elevations (neither higher than 50 meters).
Since there are no characters of taxonomic worth to distinguish the two
named specimens, _Myotis lucifugus fortidens_ Miller and Allen 1928
falls as a synonym of _Pipistrellus cinnamomeus_ Miller 1902. But,
according to Miller and Allen (Bull. U. S. Nat. Mus., 144:19, 197),
_Vespertilio cinnamomeus_ Wagner 1855 is a name based on _Myotis ruber_
(E. Geoffroy, 1806) from Paraguay and hence _Myotis cinnamomeus_
(Miller) 1902 is a homonym of _Myotis cinnamomeus_ (Wagner) 1855 and is
unavailable for the animal from Montecristo when it is transferred to
the genus _Myotis_; the species of animal concerned will take the next
available name, which seems to be _Myotis lucifugus fortidens_ Miller
and Allen 1928.
It may reasonably be asked if _Myotis_ and _Pipistrellus_ should be
retained as separate genera if the only constant difference between the
two is subequal versus unequal upper incisors. In our opinion it would
be worth-while for someone who had access to adequate material from both
the Old World and the New World to investigate this question. We lack
adequate material from the Old World.
When Miller and Allen named _M. l. fortidens_ they had only two
specimens, the holotype from Teapa, Tabasco, and a referred specimen
from Fort Hancock, El Paso County, Texas, approximately 1,200 miles
north-northwest of Teapa. We have examined this specimen from Texas (U.
S. Nat. Mus., 21083/36121, skin and skull) and regard it as _Myotis
lucifugus carissima_ Thomas. Furthermore, we regard the holotype of
_Myotis lucifugus fortidens_ Miller and Allen 1928 as specifically
distinct from _Myotis lucifugus_ of Miller and Allen 1928. The Cinnamon
Myotis, described below, therefore may stand as:
~Myotis fortidens~ Miller and Allen