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UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY

Volume 14, No. 7, pp. 111-120, 1 fig.

December 29, 1961

Taxonomic Status of Some Mice of The Peromyscus boylii Group in Eastern Mexico, With Description of a New Subspecies

TICUL ALVAREZ

UNIVERSITY OF KANSAS LAWRENCE 1961

UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Theodore H. Eaton, Jr.

Volume 14, No. 7, pp. 111-120, 1 fig. Published December 29, 1961

UNIVERSITY OF KANSAS Lawrence, Kansas

PRINTED BY JEAN M. NEIBARGER, STATE PRINTER TOPEKA, KANSAS 1961

29-393

Taxonomic Status of Some Mice of The Peromyscus boylii Group in Eastern Mexico, With Description of a New Subspecies

TICUL ALVAREZ

Saussure (1860) described Peromyscus aztecus from southern Mexico. Osgood (1909) by comparison of one of Saussure's specimens with some from Mirador, Veracruz, concluded that aztecus was a subspecies of P. boylii. Dalquest (1953) incorrectly reported specimens of P. boylii from San Luis Potosi as P. b. aztecus. Merriam (1898) named Peromyscus levipes from Mt. Malinche, Tlaxcala. Thomas (1903) described from Orizaba, Veracruz, P. beatae, which Osgood (1909) mistakenly thought was indistinguishable from P. boylii levipes. Therefore, Osgood in 1909 in his revision of the genus Peromyscus reported only two subspecies of P. boylii from eastern Mexico: P. b. levipes, and P. b. aztecus. Study of Osgood's and Thomas' material, along with recently collected specimens from the states of eastern Mexico, leads me to conclude that P. aztecus and P. boylii are different species; that P. beatae is a valid subspecies different from P. b. levipes; and finally that specimens of P. boylii from Nuevo Leon and northwestern Tamaulipas pertain to an hitherto unnamed subspecies.

#Peromyscus aztecus# Saussure

1860. H[esperomys]. aztecus Saussure, Revue et Mag. Zool., Paris, ser. 2, 12:105, type from southern Mexico, probably from the vicinity of Mirador, Veracruz, according to Osgood (N. Amer. Fauna, 28:156-157, April 17, 1909).

1909. Peromyscus boylei aztecus, Osgood, N. Amer. Fauna, 28:156, April 17.

Geographic distribution.--Known only from Mirador and Jalapa in Veracruz, and Huachinango in Puebla.

Diagnosis.--Size medium for the genus (see measurements); tail about as long as head and body; dorsal coloration near Sayal Brown (capitalized color terms after Ridgway, 1912); sides reddish; underparts Light Buff; tail bicolored but not distinctly so; supraorbital border of skull angular, and bullae pointed anteriorly; anterior half of braincase nearly straight (not rounded) as viewed from above; upper molar series long (4.7-5.0); incisive foramina short in relation to length of skull.

Comparisons.--From Peromyscus boylii, P. aztecus differs as follows: Larger in most parts measured; maxillary tooth-row 4.7-5.0 instead of 4.0-4.6; color brighter on sides (reddish instead of ochraceous); supraorbital border angular instead of rounded; anterior border of zygomatic plate convex in upper half and almost straight in lower half as opposed to nearly straight throughout in boylii; pterygoid fossa broader; bullae more pointed anteriorly and less inflated; mesostyles of upper molars larger; surface between orbital region and nasals convex in lateral view instead of flat.

Remarks.--When Saussure (1860:105) described P. aztecus he did not designate a type or type locality. Osgood (1909:157) designated as lectotype the mounted specimen, in the Geneva Museum, which has the skull inside and of which Saussure figured the molar teeth. Osgood (loc. cit.) examined one of the three specimens (No. 3926 USNM) that Saussure used in describing P. aztecus and found that it agreed "in every respect with recently collected specimens from Mirador, Veracruz, which, in the lack of exact knowledge, may be assumed to be the type locality, as it is certain that some at least of Saussure's specimens were taken near there."

Osgood regarded P. aztecus as a subspecies of P. boylii because of the resemblance between aztecus and P. b. evides, but evides is far removed geographically (occurring only in western Mexico) from aztecus, and is smaller. P. aztecus is larger than any known subspecies of P. boylii, and is not known to intergrade with P. b. levipes or P. b. beatae (with which aztecus occurs sympatrically at Jalapa, Veracruz), the two subspecies of boylii that are found nearest the geographic range of P. aztecus. Also, as mentioned previously, aztecus possesses distinctive characters that distinguish it from all subspecies of boylii. For these reasons I regard aztecus as a distinct species.

According to Hall and Kelson (1959:634), P. aztecus occurs in San Luis Potosi, Hidalgo, and west-central Veracruz, but their map 364 is based on the records of Osgood (1909:158) and Dalquest (1953:143). I have examined all the specimens reported by the two authors last named and find that those from San Luis Potosi are P. boylii levipes.

The diagnosis and comparisons here presented of aztecus were based on specimens from Mirador in comparison with all the specimens of P. boylii from eastern Mexico listed beyond. The largest specimens of P. boylii that I have examined are from Las Vigas, Veracruz, and localities within a radius of five kilometers thereof. Some measurements of these large specimens of P. boylii overlap those of P. aztecus but the two kinds of mice differ greatly in characters of the skull, in color, and in length of tail.

The specimens (three adults and three juveniles) from Huachinango, Puebla, are slightly darker than specimens from Mirador but do not differ otherwise. Of two specimens reported from Jalapa, Veracruz, by Osgood (1909:158), one (108547 USNM) agrees with specimens from Mirador in color and cranial characteristics and is P. aztecus, whereas the other (108548 USNM) is P. b. beatae.

Specimens examined.--Total 16 (all USNM) as follows: PUEBLA: Huachinango, 6. VERACRUZ: Mirador, 9; Jalapa, 1.