Pipistrellus cinnamomeus Miller 1902 Referred to the Genus Myotis

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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....