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[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 "Potosí"
    page 116: "Sán Miguel" should be "San Miguel"
    page 116: "Sán Isidro" should be "San Isidro"
    page 117: "pleateau" should be "plateau"
    page 120: "Nuevo Leon" should be "Nuevo León"]


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

[Illustration]

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 México.
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 Potosí 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 México: _P. b.
levipes_, and _P. b. aztecus_. Study of Osgood's and Thomas' material,
along with recently collected specimens from the states of eastern
México, 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
León 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 México, 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."

[Illustration: FIG. 1. Two species of _Peromyscus_.
    1. _P. boylii ambiguus_
    2. _P. boylii beatae_
    3. _P. boylii levipes_
    4. _P. aztecus_ (triangles)]

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 México) 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
Potosí, 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 Potosí 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 México 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 Potosí, south through the central states of México 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 Potosí 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 Potosí 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 León south through San Luis Potosí, Hidalgo, and Veracruz to
southern Oaxaca. Actually specimens from Nuevo León 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. Maíz,
    13 (LSU); _Pendencia Region (Puerto Lobos)_, 1 (LSU);
    _Pendencia, 2-1/2 mi. N Puerto Lobos_, 5 (LSU); 3 km. SW Sán
    Isidro, 15 (LSU); Cerro Coneja Region, Llano Coneja, 6100 ft., 2
    (LSU); Xilitla, 4 (LSU). HIDALGO: 10 mi. NE Jacala, 5050 ft., 7;
    Regla (Sán 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° 59' N, long. 97° 10' W) and one
juvenile from Santa Barbara Camp, both on the Volcán 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 Volcán 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 Potosí) 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° 42' N, long. 97° 42' W whereas the specimens
actually were collected at the Xuchil on the pleateau south of the
Volcán de Orizaba (18° 53' N, 97° 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 León; obtained on
    February 17, 1891, by Wm. Lloyd, original number 377.

    _Geographic distribution._--Eastern Coahuila, central Nuevo
    León, 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 León, 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 Potosí
-------+------+------+-----+------+-----+-----+----+-----+----+----
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 Maíz, San Luis Potosí
-------+------+------+-----+------+-----+-----+----+-----+----+----
 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 León
-------+------+------+-----+------+-----+-----+----+-----+----+----
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 Potosí. 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 mammifères 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._


29-393