A New Long-eared Myotis (Myotis Evotis) From Northeastern Mexico
by Rollin H. Baker
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A New Long-eared Myotis (Myotis evotis) from Northeastern Mexico



University of Kansas Lawrence 1955

University of Kansas Publications Museum of Natural History

Vol. 9, No. 3, pp. 81-84

December 10, 1955

Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Robert W. Wilson




A New Long-eared Myotis (Myotis Evotis) From Northeastern Mexico



Long-eared bats obtained by field parties from the University of Kansas in the Mexican states of Coahuila, Nuevo Leon, and Tamaulipas, are found to belong to the species, Myotis evotis, but are not referable to any named subspecies. They are named and described as follows:

Myotis evotis auriculus new subspecies

Type.—Female, adult, skin and skull; No. 55110, Univ. Kansas Mus. Nat. Hist.; 10 mi. W and 2 mi. S Piedra, 1200 ft., Sierra de Tamaulipas, Tamaulipas; 9 June 1953; obtained by Gerd H. Heinrich, original number 7061.

Distribution.—Coastal foothills and adjacent mountains of northeastern Mexico from central Coahuila south and east to central Veracruz.

Diagnosis.—Size medium (see measurements), ears small for the species; color dark, upper parts (j14) Ochraceous-Tawny (color terms are after Ridgway, Color Standards and Color Nomenclature, Washington, D. C., 1912), underparts Warm Buff, ears pale; skull large, teeth large, mandible long.

Comparison.—From Myotis evotis evotis (H. Allen), from Colorado, Wyoming, and Montana, M. e. auriculus differs in: Ears averaging shorter; color darker and richer; ears paler and contrasting less, in color, with pelage; skull larger in all measurements taken except that of least interorbital constriction; forehead, when viewed laterally, rising more abruptly, because frontal region is more inflated; teeth larger.

Remarks.Myotis evotis auriculus, although no larger externally than M. e. evotis, has a larger skull, which in lateral view has a more abruptly rising forehead. The teeth, especially the first upper premolars, of auriculus are noticeably larger than those of evotis. The first two lower premolars are sub-equal in auriculus whereas in evotis the first lower premolar usually is larger. The mandible, in relation to the greatest length of the skull, is longer in auriculus (ratio, 71-74) than in evotis (ratio, 67-71).

Coahuilan specimens, although assigned to auriculus, are slightly paler (upper parts (16) Ochraceous-Tawny; underparts (e) Light Buff) and have less abruptly rising foreheads than do the bats from Tamaulipas. In these features, the Coahuilan animals are somewhat intermediate between typical auriculus and evotis. The bat from Nuevo Leon, in both color and degree of slope of forehead, is intermediate between those from Coahuila and those from Tamaulipas.

A bat from Perote, Veracruz, identified as Myotis evotis chrysonotus (J. A. Allen) [=M. e. evotis] by Miller and Allen (U. S. Nat. Mus., Bull. 144:118 and 120-121, May 25, 1928) is here assigned to M. e. auriculus. Measurements given by these authors indicate that this bat has a large skull, which is characteristic of this subspecies. Another specimen, similarly assigned by these authors and from the San Luis Mountains in northwestern Chihuahua, seems to be M. e. evotis, although the published measurements (loc. cit.) show that this bat tends toward auriculus in size of skull and mandible.

All specimens were taken in mist nets stretched over water. Those from Coahuila were snared over a concrete water tank situated near the base of low hills in mixed mesquite and chaparral. In Nuevo Leon, one bat was netted over a small pond around which grew some low trees in an intermontane valley in the Sierra Madre Oriental. In Tamaulipas two bats were caught in a mist net stretched across a narrow, brush-bordered arroyo in the Sierra de Tamaulipas. One adult male weighed 7.0 grams; average and extreme weights of 7 adult, non-pregnant females were 6.8 (5.2-8.0). Females taken on March 25 and 26 were not pregnant; one obtained on June 20 was lactating. Funds for financing field work were made available by the Kansas University Endowment Association and the National Science Foundation.

Measurements.—Measurements, in millimeters, of the holotype and another female (No. 55111 KU) from the type locality and 3 females (Nos. 44726, 44729-30 KU) from Coahuila, respectively, are: total length, 94, 93, 97, 86, 96; length of tail vertebrae, 43, 42, 41, 39, 45; length of hind foot, 9.5, 9, 10, 10, 8; height of ear from notch, 20, 20, 20, 18, 20; length of forearm, 37.9, 38.4, 40.2, 37.3, 38.5; greatest length of skull, 16.1, 16.4, 16.2, 15.8, 16.1; condylobasal length, 15.4, 15.4, 15.6, 15.0, 15.4; zygomatic breadth, 9.7, 9.9, 10.1, 9.4, 9.9; least interorbital constriction, 3.9, 3.8, 3.9, 3.7, 3.7; breadth of braincase, 7.5, 7.6, 7.5, 7.5, 7.6; occipital depth, 5.9, 5.9, 5.5, 5.7, 5.6; palatal length, 8.5, 8.7, 8.7, 8.7, 8.9; mastoid breadth, 8.2, 8.4, 8.3, 8.2, 8.3; breadth across third upper molars, 6.1, 6.2, 6.3, 6.1, 6.1; length of maxillary tooth-row, 6.5, 6.5, 6.7, 6.6, 6.6; length of mandible, 11.5, 11.8, 11.9, 11.2, 11.7; length of mandibular tooth-row, 8.0, 8.0, 8.1, 8.1, 8.1.

Specimens examined.—Total, 8, all in the University of Kansas Museum of Natural History. Coahuila: 4 mi. W Hacienda La Mariposa, 2300 ft., 5 (2 alcoholics). Nuevo Leon: Iturbide, 5000 ft., Sierra Madre Oriental, 1. Tamaulipas: 10 mi. W and 2 mi. S Piedra, 1200 ft., Sierra de Tamaulipas, 2.

Transmitted April 16, 1955.


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