Taxonomic Notes on Mexican Bats of the Genus Rhogeessa by Eugene Raymond Hall

Five skins with skulls of _Rhogeessa_, collected by J. R. Alcorn in the states of Sonora and Nayarit of western Mexico, were recently received at the Museum of Natural History of the University of Kansas. Two other specimens of the same genus, collected by Walter W. Dalquest in the state of Veracruz of eastern Mexico, also are in the Museum of Natural History. With the aim of applying names to these bats they were compared with materials in the United States National Museum (including the Biological Surveys collection) where there are approximately the same number of Mexican specimens of _Rhogeessa_ as are in the Museum of Natural History.

The three kinds of _Rhogeessa_ named from Mexico are as follows: _R. parvula_ from the Tres Marias Islands off the west coast of Nayarit; _R. tumida_ from Mirador, Veracruz, on the eastern slope of the Republic; and _R. gracilis_ from Piaxtla, Puebla, on the southern end of the Mexican Plateau.

Of _Rhogeessa gracilis_ Miller (N. Amer. Fauna, 13: 126, October 16, 1897) only three specimens are known; two are from Piaxtla, Puebla, and the third is from the Isthmus of Tehuantepec. Only the specimen from the Isthmus has a complete skull. The broken skull of the holotype is partly separated from the skin of the head and in such a manner as to reveal the teeth. The skull of the holotype seems to be broader (relative to its length) across the mastoids and posterior parts of the zygomata than in _R. tumida_ or than in _R. parvula_. My comparisons indicate that _Rhogeessa gracilis_ has larger (longer and wider) ears than _R. parvula_ and _R. tumida_ and that it is specifically distinct from the two last mentioned kinds.

The two other nominal species from Mexico, _R. parvula_ and _R. tumida_, were named and described by Harrison Allen (Proc. Acad. Nat. Sci. Philadelphia, 1866: 285 and 286, respectively) on the basis of three specimens in the United States National Museum. Two were from the Tres Marias Islands and were the basis of the name _R. parvula_; the third was from Mirador, Veracruz, and was the basis of the name _R. tumida_. These specimens seem to have been preserved in alcohol. I have examined the skulls of two of these. One (U. S. N. M., new number 37329, old number 7842) is alleged to be the paratype of _R. parvula_ and the other (U. S. N. M., 84021) is alleged to be the holotype of _R. tumida_. In the glass vial containing skull No. 84021, there is a label in the handwriting of Gerrit S. Miller, Jr., bearing the following information: "In the orig. descr. the number of this sp. is said to be 8195. This is an error.

Specimen catalogued 3.1.98 G. S. M. Jr. " On the back of a second label in the skull vial there is written, "There is no doubt that this is the type skull. It was returned by H. A. with no. given in orig. descr. G. S. M. Jr. " In the catalogue of the U. S. National Museum there is the statement that the type of _Rhogeessa tumida_ was collected by H. A. Grayson.

The name _Rhogeessa parvula_ was based on two specimens (Smithsonian Institution Nos. 7841 the type and 7842, in alcohol, collected by Col. Grayson in the Tres Marias Islands off the west coast of Mexico.) The type seems never to have been returned from the Academy of Sciences of Philadelphia to the U. S. National Museum in Washington, D. C., and cannot (in 1951) be found in Philadelphia or anywhere else. The skull, but no other part, of the second specimen is in the United States National Museum under the catalogue number 37329 (old No. 7842). The skull has been broken in two through the interorbital region but is glued together.

Of _R. tumida_, no additional specimen has been saved, so far as I know, from the type locality, Mirador, Veracruz.

Of _R. parvula_, Nelson and Goldman, on May 19, 1897, on Maria Madre Island, saved in alcohol an additional specimen (92413 U. S. N. M.) from which J. Biggs, Preparator at the National Museum, in 1951, removed and cleaned the skull. In small size and in all other features, the skull of 92413 closely resembles those of specimens saved by Alcorn from the adjoining mainland of Mexico in Sonora and Nayarit. The pelage of the upper parts of 92413 could be described as "of a light greyish-brown at basal third, fawn-chestnut-brown at apical two-thirds" which are the words that H. Allen (_op. cit._: 285) used to describe the pelage of his _R. parvula_. The external measurements of 92413 are: total length, 60; length of tail, 25; length of hind foot, 5.5; and ear from notch, 11.0. The first two measurements are slightly smaller than the corresponding measurements of any other specimen seen. Nevertheless, the measurements (tail, 30.5; hind foot, 5.3 [after H. Allen, orig. descr.])

of the holotype of _R. parvula_, also from the Tres Marias Islands, show that it was as large as no. 39724 from the adjoining mainland (see table 1).

According to the original descriptions, _R. parvula_ and _R. tumida_ differ in size, _R. parvula_ being the smaller. As may be seen from table 1, the alleged type of _R. tumida_ and the alleged paratype of _R. parvula_ indicate the opposite! All specimens obtained since the time of the original descriptions, as may be seen by inspecting table 1, support the correctness of the original descriptions. Therefore, and also because of the other information presented above, I am inclined to the opinion that the holotype of _R. tumida_ and the paratype of _R. parvula_ have been switched; each now is associated with the name and data, at least for locality, of the other.

Other opinions are that _Rhogeessa_ from the Tres Marias Islands average smaller than _Rhogeessa_ of the adjoining mainland of western Mexico but not enough smaller to warrant subspecific separation of the two. Specimens from places geographically intermediate between the geographic ranges, as now known, of _R. parvula_ and _R. tumida_ probably will reveal intergradation between the two kinds, which, therefore, should stand as subspecies of a single species.