Chapter I

[Transcriber's Note: The following typographical errors are noted,
but not corrected in the text:
page 116: "typotypes" should be "topotypes"
page 116: "Potosi" should be "Potosi"
page 116: "San Miguel" should be "San Miguel"
page 116: "San Isidro" should be "San Isidro"
page 117: "pleateau" should be "plateau"
page 120: "Nuevo Leon" should be "Nuevo Leon"]

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

BY

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

BY

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.

#Peromyscus boylii levipes# Merriam

1898. _Peromyscus levipes_ Merriam, Proc. Biol. Soc.
Washington, 12:123, April 30, type from Mt. Malinche, 8400
ft., Tlaxcala.

1909. _Peromyscus boylei levipes_, Osgood, N. Amer. Fauna,
28:153, April 17.

_Geographic distribution._--Southeastern Tamaulipas and eastern
San Luis Potosi, south through the central states of Mexico to
Guatemala.

_Diagnosis._--Size medium for the species; tail shorter or
longer than head and body (83-112.3%); color variable according
to locality but in general ochraceous, having some dusky on
upper parts; supraorbital border not angular, almost rounded;
auditory bullae large.

_Comparisons._--For comparisons see accounts of the subspecies
discussed beyond and Osgood (1909:145).

_Remarks._--A precise diagnosis for _P. b. levipes_ is difficult to prepare because some geographic variation in color and in the cranial characters is present within the range of the subspecies as here understood. For instance there is a gradual cline of decreasing size to the northward in nearly all measurements, but the ratio of length of tail to length of head and body does not present such a cline; mice from several localities in San Luis Potosi have a relatively shorter tail than do mice from farther north and from farther south. Also, specimens labeled in reference to Zacualpilla, Jacales, Jacala, Tulancingo, and San Miguel Regla average slightly darker dorsally than do typotypes. Some of these specimens are reddish on the cheek and lateral line. Specimens from San Luis Potosi resemble topotypes, but some specimens from northeastern localities in that state have cinnamon or brownish upper parts and are intermediate in coloration between populations of _levipes_ to the south and populations of the same subspecies to the north from the Sierra Madre Oriental and the Sierra de Tamaulipas. Specimens from these two sierras have a cinnamon-reddish color that is more intense in specimens from the Sierra de Tamaulipas.

Osgood (1909:153) recorded _P. b. levipes_ as occurring from central Nuevo Leon south through San Luis Potosi, Hidalgo, and Veracruz to southern Oaxaca. Actually specimens from Nuevo Leon and from most parts of Veracruz differ subspecifically from _levipes_ and also from each other. In Veracruz, _P. b. levipes_ is known only from the northwestern part.

_Specimens examined._--Total 179 as follows: TAMAULIPAS: Sierra
Madre Oriental, 5 mi. S, 3 mi. W Victoria, 1900 ft., 2; _8 mi.
S, 6 mi. W Victoria, 4000 ft._, 37; Sierra de Tamaulipas, 2000
ft., 8 mi. S, 11 mi. W Piedra, 13. SAN LUIS POTOSI: Villar, 11
(USNM); 10 km. E Platanito, 19 (LSU); _8 mi. E (by road) Santa
Barbarita_, 12 (LSU); _Agua Zarca_, 3 (LSU); 6 km. NE Cd. Maiz,
13 (LSU); _Pendencia Region (Puerto Lobos)_, 1 (LSU);
_Pendencia, 2-1/2 mi. N Puerto Lobos_, 5 (LSU); 3 km. SW San
Isidro, 15 (LSU); Cerro Coneja Region, Llano Coneja, 6100 ft., 2
(LSU); Xilitla, 4 (LSU). HIDALGO: 10 mi. NE Jacala, 5050 ft., 7;
Regla (San Miguel), 2250 m., 4; Arroyo de las Tinajas, 2370 m.,
9.5 km. SSW Tulancingo, 1; 10 mi. NW Apam, 7750 ft., 1.
VERACRUZ: 3 km. N Zacualpan, 6000 ft., 1; _3 km. W Zacualpan,
6000 ft._, 12; _2 km. N Los Jacales, 7500 ft._, 8; _6 km. WSW
Zacualpilla, 6500 ft._, 5. TLAXCALA: Mt. Malinche, 3 (USNM).

#Peromyscus boylii beatae# Thomas

1903. _Peromyscus beatae_ Thomas, Ann. Mag. Nat. Hist., ser. 7,
11:485, May, type from Xometla Camp, Mt. Orizaba, Veracruz.

_Geographic distribution._--East side of the Sierra Madre
Oriental in Veracruz, from Jalancingo south to Xuchil.

_Diagnosis._--Size large for the species; tail no shorter than
head and body (100-114.8%); dorsum dark (near Prout's Brown or
Mummy Brown middorsally, Clay Color on sides); supraorbital
border rounded; anterior palatine foramina long.

_Comparisons._--_P. b. beatae_ differs from other subspecies of
_P. boylii_ by the combination of large size, long tail, and
dark color.

_Remarks._--Thomas (1903:485) described _P. beatae_ on the basis of five specimens from Xometla Camp (lat. 18 deg. 59' N, long. 97 deg. 10' W) and one juvenile from Santa Barbara Camp, both on the Volcan de Orizaba, Veracruz. Thomas thought that _beatae_ was related to _aztecus_, but the differences relied on by him to distinguish the two are the same as those that distinguish _aztecus_ from _boylii_. Osgood (1909:153) placed _beatae_ in synonymy under _P. b. levipes_ because Mount Orizaba (type locality of _beatae_) is "relatively very near" Mount Malinche (type locality of _levipes_), and Thomas had not compared _beatae_ with _levipes_. Xometla, on the east side of the Volcan de Orizaba, is approximately 56 miles east of the Tlaxcalan part of Mount Malinche and is situated where the Tropical Life-zone begins, whereas Mount Malinche is in the Austral Life-zone on the Mexican Plateau; the difference in habitat between the two places is great. Topotypes of _levipes_ differ from two topotypes of _beatae_ in the same fashion as do other specimens of _levipes_ (from San Luis Potosi) from other specimens of _beatae_ (from Veracruz). Unfortunately, the topotypes of _beatae_ lack external measurements and are subadults, but their coloration agrees with that of other specimens that are here referred to _beatae_.

Hall and Kelson (1959:634, map 364) incorrectly mapped the distribution of _levipes_ in Veracruz. There are at least two places named Xuchil in the state of Veracruz and Hall and Kelson (_loc. cit._) unfortunately plotted the one at lat. 20 deg. 42' N, long. 97 deg. 42' W whereas the specimens actually were collected at the Xuchil on the pleateau south of the Volcan de Orizaba (18 deg. 53' N, 97 deg. 14' W) in the west-central part of Veracruz. The specimens from Xuchil are _P. b. beatae_.

Intergradation in color between the two subspecies _levipes_ and _beatae_ is seen in specimens from Jalapa and Zacualpan (3 km. N, also others from 3 km. W), Veracruz. Intergradation between these two subspecies possibly will be found elsewhere along the Sierra Madre Oriental.

_Specimens examined._--Total 60 as follows: VERACRUZ: 1 km. E
Jalancingo, 6500 ft., 2; _2 km. S Jalancingo_, 2; 6 km. SSE
Altotonga, 8000 ft., 8; _1 km. W Las Vigas, 8500 ft._, 2; Las
Vigas, 8500 ft., 13; _2 km. E Las Vigas, 8000 ft._, 5; _3 km. E
Las Vigas, 8000 ft._, 8; _5 km. E Las Vigas_, 7 (TAM); _5 km. N
Jalapa, 4500 ft._, 2; _Jalapa_, 1 (USNM); 10 km. SE Perote, N
slope Cofre de Perote, 10,500 ft., 1 (TAM); Xometla Camp, Mt.
Orizaba, 8500 ft., 2 (BM); _Sta. Barbara, Mt. Orizaba, 12,000
ft._, 1 (BM); Xuchil, 6 (CM).

#Peromyscus boylii ambiguus# new subspecies

_Type._--Male, adult, skin and skull, No. 33092, United States
National Museum, from Monterrey, Nuevo Leon; obtained on
February 17, 1891, by Wm. Lloyd, original number 377.

_Geographic distribution._--Eastern Coahuila, central Nuevo
Leon, and the Sierra San Carlos, Tamaulipas.

_Diagnosis._--Size small for the species; tail averaging longer
than head and body (90-114%); dorsal coloration ochraceous,
slightly darker middorsally; cheeks and lateral line Capucine
Orange; skull small; supraorbital border rounded; anterior
palatine foramina short.

_Comparisons._--_P. b. ambiguus_ differs from _P. b. levipes_ in
smaller size, longer tail relative to length of head and body,
smaller incisive foramina, brighter and paler color, and
relatively broader interorbital region. From _P. b. beatae_, _P.
b. ambiguus_ differs in being smaller in all parts measured and
paler.

_Remarks._--Osgood (1909:155) reported as _P. b. levipes_ 37 specimens from Monterrey and 18 from Cerro de la Silla, Nuevo Leon, but noted that they were "aberrant." I have examined those same specimens and can hardly decide to which species, _P. boylii_ or _P. pectoralis_, they belong. Everything considered I, as did Osgood, opine that the specimens are _P. boylii_. However, I do not rule out the possibility that in this area there is an unnamed species, because I find an unusually wide range of variation in such cranial characters as size of the bullae, width and form of the pterygoid fossa, and shape of the braincase. Extremes of these characters are not constantly associated except in one specimen (33124 USNM), which is the smallest of all the adults examined. It has small bullae, a short rostrum, widely spreading zygomatic arches anteriorly, and a narrow pterygoid fossa, but does not differ externally from the other specimens. Additional material from this area is needed in order to make out the systematic position of these mice.

Because of the wide range of variation in some of its characters, _P. b. ambiguus_ is difficult to diagnose. Nevertheless, its small external and cranial size, short anterior palatine foramina, and bright color seem to separate it from other subspecies of _P. boylii_ in the eastern part of the range of the species. These differences are most conspicuous when specimens from the northernmost part of the range of _levipes_ are compared with specimens of _ambiguus_.

The specimens from the Sierra San Carlos, Tamaulipas, closely resemble _levipes_ in color, but are referred to _ambiguus_ on the basis of small size, as also are the two specimens from 12 km. E San Antonio de las Alazanas, Coahuila.

TABLE 1. MEASUREMENTS (IN MILLIMETERS) OF PEROMYSCUS

A: Number of specimens B: Total length C: Length of tail-vertebrae D: Length of hind foot E: Per cent length of tail to head and body F: Greatest length of skull G: Zygomatic breadth H: Interorbital constriction I: Length of nasals J: Palatine slits K: Maxillary tooth-row

=======+======+======+=====+======+=====+=====+====+=====+====+====
A | B | C | D | E | F | G | H | I | J | K
-------+------+------+-----+------+-----+-----+----+-----+----+----
_P. aztecus_
Mirador, Veracruz
-------+------+------+-----+------+-----+-----+----+-----+----+----
7 mean| 229 | 113 | 24.5| ... | 30.1| 15.3| 4.7| 12.5| 6.4| 4.8
max.| 238 | 121 | 26 | ... | 30.9| 15.8| 5.0| 13.5| 6.8| 5.0
min.| 215 | 107 | 24 | ... | 29.2| 14.9| 4.6| 11.2| 5.7| 4.7
-------+------+------+-----+------+-----+-----+----+-----+----+----
_P. boylii beatae_
Las Vigas to 3 km. E thereof, Veracruz
-------+------+------+-----+------+-----+-----+----+-----+----+----
14 mean| 219.3| 116.7| 23.8| 113.7| 28.9| 14.4| 4.5| 11.5| 6.3| 4.5
max.| 235 | 130 | 25 | 128.9| 29.8| 15.1| 4.7| 12.5| 6.8| 4.8
min.| 204 | 107 | 22 | 100.0| 27.9| 13.8| 4.2| 10.7| 5.9| 4.4
-------+------+------+-----+------+-----+-----+----+-----+----+----
6 km. SSE Altotonga, Veracruz
-------+------+------+-----+------+-----+-----+----+-----+----+----
5 mean| 224.4| 116.1| 24.1| 109.4| 29.1| 14.5| 4.5| 11.6| 6.4| 4.5
max.| 241 | 126 | 25 | 114.8| 30.1| 15.2| 4.6| 12.0| 6.7| 4.7
min.| 221 | 110 | 24 | 100.0| 28.6| 14.0| 4.4| 11.2| 6.0| 4.3
-------+------+------+-----+------+-----+-----+----+-----+----+----
_P. boylii levipes_
3 km. SW San Isidro, San Luis Potosi
-------+------+------+-----+------+-----+-----+----+-----+----+----
11 mean| 205.6| 99.5| 22.4| 93.8| 28.5| 14.2| 4.4| 11.3| 5.9| 4.4
max.| 219 | 114 | 23 | 108.6| 30.5| 14.5| 4.6| 12.2| 6.4| 4.6
min.| 193 | 90 | 21 | 87.4| 27.2| 13.8| 4.2| 10.8| 5.6| 4.1
-------+------+------+-----+------+-----+-----+----+-----+----+----
6 km. NE Cd. del Maiz, San Luis Potosi
-------+------+------+-----+------+-----+-----+----+-----+----+----
9 mean| 198.7| 96 | 22 | 93.4| 28.1| 14.0| 4.4| 11.2| 6.0| 4.5
max.| 205 | 105 | 22 | 105.0| 28.7| 14.2| 4.6| 11.7| 6.4| 4.6
min.| 187 | 90 | 22 | 85.7| 27.3| 13.4| 4.3| 10.6| 5.7| 4.3
-------+------+------+-----+------+-----+-----+----+-----+----+----
11 mi. W, 8 mi. S Piedra, Tamaulipas
-------+------+------+-----+------+-----+-----+----+-----+----+----
5 mean| 201.8| 101.8| 22.6| 101.8| 28.5| 14.0| 4.4| 11.3| 6.1| 4.3
max.| 214 | 110 | 23 | 109.3| 29.0| 14.1| 4.6| 11.5| 6.2| 4.7
min.| 193 | 94 | 22 | 94.9| 28.2| 13.9| 4.2| 11.0| 6.0| 4.1
-------+------+------+-----+------+-----+-----+----+-----+----+----
_P. boylii ambiguus_
La Vegonia, Tamaulipas
-------+------+------+-----+------+-----+-----+----+-----+----+----
7 mean| 199.1| 101.6| 21.3| 104.3| 26.9| 13.4| 4.3| 10.5| 5.6| 4.3
max.| 213 | 109 | 22.4| 108.9| 28.6| 13.7| 4.5| 11.8| 5.9| 4.7
min.| 188 | 97 | 20 | 98.0| 26.4| 13.2| 4.2| 9.5| 5.3| 4.1
-------+------+------+-----+------+-----+-----+----+-----+----+----
Monterrey, Nuevo Leon
-------+------+------+-----+------+-----+-----+----+-----+----+----
16 mean| 199.7| 103.2| 21.3| 106.9| 27.6| 13.9| 4.4| 10.7| 5.6| 4.2
max.| 216 | 114 | 22 | 125.6| 28.2| 14.9| 4.6| 11.5| 5.8| 4.5
min.| 176 | 92 | 19 | 88.0| 26.8| 13.2| 4.1| 10.2| 5.0| 4.0
-------+------+------+-----+------+-----+-----+----+-----+----+----

_Specimens examined._--Total 64 as follows: NUEVO LEON (USNM):
Monterrey, 37; _Cerro de la Silla_, 18. COAHUILA: 12 km. E San
Antonio de las Alazanas, 9000 ft., 2. TAMAULIPAS: La Vegonia,
Sierra San Carlos, 7 (UMMZ).

I am grateful to the following persons for the loan of specimens: G. B. Corbet, British Museum, Natural History (BM); David H. Johnson, United States National Museum (USNM); George H. Lowery, Jr., Louisiana State University (LSU); Philip Hershkovitz, Chicago Natural History Museum (CM); William B. Davis, Texas Agricultural and Mechanical College (TAM); W. H. Burt and Emmet T. Hooper, University of Michigan Museum of Zoology (UMMZ). Specimens lacking designation as to collection are housed in the Museum of Natural History of The University of Kansas. I am indebted to Professor E. Raymond Hall and Mr. J. Knox Jones, Jr. for the use of these specimens and for other assistance. It is appropriate to record also that the findings reported above are an outgrowth of related work done as a Research Assistant under Grant No. 56 G 103 from the National Science Foundation.

LITERATURE CITED

DALQUEST, W. W.

1953. Mammals of the Mexican state of San Luis Potosi. Louisiana
State Univ. Biol. Sci. Ser., 1:1-233, December 28.

HALL, E. R., and KELSON, K. R.

1959. The mammals of North America. The Ronald Press, New York,
vol. 2:ix + 547-1083 + 79, illustrated, March 31.

OSGOOD, W. H.

1909. Revision of the mice of the American genus Peromyscus. N.
Amer. Fauna, 28:1-285, 8 pls., April 17.

RIDGWAY, R.

1912. Color standards and color nomenclature. Washington, D. C.,
iv + 43 pp., 53 pls.

SAUSSURE, M. H. de

1860. Note sur quelques mammiferes du Mexique. Revue et Mag.
Zool., Paris, ser. 2, 12:97-110, March.

THOMAS, O.

1903. _On three new forms of _Peromyscus_ obtained by Dr. Hans
Gadow, F. R. S., and Mrs. Gadow in Mexico._ Ann. Mag. Nat.
Hist., ser. 7, 11:484-487, May.

_Transmitted June 30, 1961._

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