Title: A New Snake of the Genus Geophis From Chihuahua, Mexico
Author: Legler, John M.
Language: English
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UNIVERSITY OF KANSAS PUBLICATIONS
MUSEUM OF NATURAL HISTORY


Volume 11, No. 4, pp. 327-334, 2 figs.
January 28, 1959



A New Snake of the Genus Geophis
From Chihuahua, Mexico


BY

JOHN M. LEGLER



UNIVERSITY OF KANSAS
LAWRENCE
1959



UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch, Robert W. Wilson


Volume 11, No. 4, pp. 327-334
Published January 28, 1959

University of Kansas
Lawrence, Kansas

PRINTED IN
THE STATE PRINTING PLANT
TOPEKA, KANSAS
1959



A New Snake of the Genus Geophis From Chihuahua, Mexico

BY

JOHN M. LEGLER


In July, 1957, members of a field party from the University of Kansas
Museum of Natural History, under the direction of Mr. Sydney Anderson,
spent 12 days collecting vertebrates in the vicinity of Creel in
southwestern Chihuahua. Among the specimens are two snakes representing
an undescribed species of the genus _Geophis_. A description and
illustrations of these two specimens were prepared and submitted for
publication in the spring of 1958. At that time it came to my attention
that Dr. Norman Hartweg, Museum of Zoology, University of Michigan, was
also preparing a report on four specimens of the same species from two
additional localities in southwestern Chihuahua. Upon learning of my
work on the species, Dr. Hartweg generously loaned me his specimens and
notes and allowed me to incorporate them in the present report. The
snakes may be known and described as:


_Geophis aquilonaris_ new species

    _Holotype._--Adult female, KU 44265, alcoholic; 23 mi. S and 1-1/2
    mi. E Creel, Chihuahua, Mexico; 23 July 1957; original number 198,
    Ronald H. Pine.

    _Paratypes._--(Total of five alcoholic specimens, all from
    Chihuahua) Male (probably subadult), KU 44266, same data as
    holotype; male, UMMZ 117770, Mojarachic, 23 July 1957, Irving W.
    Knobloch; females, UMMZ 111501-2, Maguarachic, August 1954, and UMMZ
    117771, Maguarachic, August 1957, Irving W. Knobloch.

    _Diagnosis._--Size small; 15 rows of smooth scales; a high number of
    ventral (173 to 183) and subcaudal (55 to 64) scales; alternating
    dark and pale rings on body and tail; dark rings, and often pale
    rings, complete.

    _Description of Holotype._--Snout-vent length 327 mm.; length
    of tail 93 mm.; anal scale entire; ventral scales 181 + anal;
    subcaudal scales 63 + tip; dorsal scales in 15 rows on all parts of
    body; six supralabials (fifth and sixth fused on left side), third
    and fourth entering orbit; fifth supralabial largest and in broad
    contact with parietal, posterior temporal, and postocular; six
    infralabials on each side, first pair in contact behind mental;
    enlarged chin shields in two pairs, anterior pair longer than
    posterior pair; anterior chin shields in contact for half their
    length with fourth infralabials; rostral nearly as high as broad;
    internasal and prefrontal scales paired and distinct; anterior and
    posterior segments of nasals distinct and nearly equal in size;
    loreal twice as long as high, in contact with eye; preocular lacking
    (represented by minute scale on left side); vertical diameter of eye
    equal to distance from lower rim of orbit to free edge of upper lip;
    temporal formula 0 + 1, the single temporal scale separating sixth
    supralabial and parietal; one postocular and one supraocular on each
    side; all scales perfectly smooth; no scale-pits evident; dentary
    bone bearing eight teeth; maxillary bone bearing seven teeth;
    posterior tooth longest, thinnest, and separated from other teeth by
    slight diastema (maxillary teeth in UMMZ 111502, 6/7, dentary teeth
    8/8, no diastema in maxillary series).

  [Illustration: FIG. 1. _Geophis aquilonaris_ new species, KU 44265,
  Holotype; lateral, dorsal, and ventral views of head and neck
  (approximately × 6).]

  [Illustration: FIG. 2. _Geophis aquilonaris_ new species, KU 44265,
  Holotype; scalation and coloration at mid-body showing 19th and 20th
  white rings (approximately × 7).]

    Head slate-black above, having dim pale mark on anterior part of
    each prefrontal and another on interparietal seam; an indistinct
    pale gray crescent on posterior border of nostril; narrow cream band
    covering posterior edges of parietal and half of first dorsal scale
    row, widening laterally to include temporal and posterior two or
    three supralabials; throat cream (except for dark markings on
    mental, on first three infralabials, and on anterior chin shields),
    its pale area continuous with pale band on head; body and tail
    marked with alternating white and black rings; white rings
    (excluding band on head) 38 on body, 17 on tail; each white ring
    alternately one and two scales wide dorsally (producing wavy or
    zigzag effect), widened laterally, and three to four scales wide on
    belly; black rings three to four and one half scales wide on
    middorsal line, and two to three scales wide on belly; black and
    white rings (excepting first black ring behind head) continuous
    around body and tail. Colors described above nearly same as in
    living specimens.

    _Range._--The species is known only from three localities on the
    Pacific drainage of southwestern Chihuahua; the geographic range
    probably includes parts of southern Sonora and northern Sinaloa. The
    discovery of _Geophis_ in southern Chihuahua increases to 21 the
    number of species of the genus known to occur in Mexico and extends
    the known range of the genus approximately 560 miles northwestward
    from the type locality of _G. latifrontalis_, a point 50 miles south
    (in Guanajuato?) of San Luis Potosí, or, a slightly lesser number of
    miles north-northwestward from an indefinite locality for _G.
    bicolor_ in western Jalisco (La Cumbre de los Arrastrados)
    (Boulenger, Catalogue of the snakes in the British Museum, Vol. 2,
    1894, p. 298).

    _Variation._--Standard counts of scales are given for the paratypes
    as well as the holotype in table 1. The fifth and sixth supralabial
    scales are fused on both sides of one specimen (UMMZ 117771) as is
    the case on the left side of the holotype. Except for one specimen
    (UMMZ 117770) that has a small anterior temporal separating the
    posterior two-thirds of the fifth supralabial from the parietal on
    each side, the temporal formula in the type series is uniformly 0 +
    1.

TABLE 1.--COUNTS OF SCALES, MEASUREMENTS, AND OTHER DATA
PERTAINING TO HOLOTYPE AND PARATYPES OF _Geophis aquilonaris_
NEW SPECIES.

====+======+========+======+========+==========+==========+==========+======
    |      |  Sex   |Dorsal|Ventrals|Subcaudals|Pale rings|Snout-vent|Length
    |      |        |scale |        |          +----+-----+  length  |  of
    |      |        |rows  |        |          |Body|Tail |          | tail
----+------+--------+------+--------+----------+----+-----+----------+------
UMMZ|111501|[Female]|  15  |  173   |   55     | 29 | 12  |  237     |  60
UMMZ|111502|[Female]|  15  |  181   |   58     | 34 | 14  |  355     |  88
UMMZ|117771|[Female]|  15  |  182   |   55     | 39 | 16  |  371     |  90
KU  |44265 |[Female]|  15  |  183   |   63     | 38 | 17  |  327     |  93
KU  |44266 |[Male]  |  15  |  175   |   60     | 30 | 13  |  160     |  43
UMMZ|117770|[Male]  |  15  |  174   |   64     | 34 | 15  |  245     |  74
----+------+--------+------+--------+----------+----+-----+----------+------

    Considerably more variation occurs in color and in the arrangement
    of markings than in squamation. The ground color of the two
    specimens from Creel is black with little or no trace of brown, and
    the rings are white. Ground color in the remaining paratypes ranges
    from grayish black, with some brownishness on the belly, to dark
    brown, the colors in one specimen approximating the range from Mummy
    brown to Dresden brown, becoming paler posteriorly and ventrally.
    The head is slate gray to blackish brown in all the specimens. Those
    having a suggestion of brown on the head tend also to have more
    brown on the body.

    The dark band on the neck is complete in four of the paratypes and
    incomplete (as in holotype) in one. Pale marks on the prefrontals
    are lacking in three of the paratypes and the pale mark between the
    parietals is lacking in two specimens (fused with white band on neck
    of one specimen). Pale postnarial crescents are evident in three
    paratypes.

    As stated above, the rings on the holotype are mostly complete.
    Exceptions occur between the 13th and 15th white rings where two
    black rings are fused on the left side, rendering one black and one
    white ring (the 14th) incomplete. Also, where the ninth and tenth
    white rings fuse on the left side, they enclose a black ring and
    render it incomplete. The markings of the three smaller paratypes
    are substantially the same as those of the holotype--complete rings
    with a small number of variations in each specimen. In the two
    largest paratypes nearly all the white rings are incomplete
    ventrally, appearing to have been encroached upon by the darker
    ground color. In the larger speicmens there is a tendency also for
    the white rings to be one scale wide (rather than alternately one
    and two scales wide) and to lack a zigzag appearance; this appears
    to be due to the darkening of entire scales and to the darkening of
    the edges of other scales.

_Relationships._--_Geophis aquilonaris_ is distinct from all other
Mexican representatives of the genus in having, on the body and tail,
numerous, alternating pale and dark bands. Both sets of bands are in the
form of complete rings or the dark bands are joined ventrally rendering
the belly dark.

Of the seven other Mexican _Geophis_ having 15 rows of scales, four
species (_cancellatus_, _dugesii_, _chalybeus_, and _semidoliatus_)
have alternating pale and dark transverse markings and therefore
superficially resemble _aquilonaris_. Of the latter two species, the
poorly known _G. chalybeus_ (Veracruz) has a much lower (137 to 142)
number of ventrals than _aquilonaris_, and _G. semidoliatus_
(southeastern Mexico--Veracruz, Hidalgo, and Oaxaca) has a narrower
head, fewer supralabials (four to five with only the third entering the
orbit), and fewer ventrals (136 to 169) than _aquilonaris_. _Geophis
aquilonaris_ seems to be most closely allied to _G. cancellatus_
(Chicharras, Chiapas) and _G. dugesii_ (known from two localities in
northern Michoacán); all three species resemble one another in the
number and arrangement of the scales of the head, in general coloration,
and in having relatively high numbers of ventral scales (171 in
_cancellatus_, 150 to 164 in _dugesii_). _G. cancellatus_ differs from
the other two species in lacking internasal scales. _Geophis
aquilonaris_ differs from both species in having a higher number of
ventral and subcaudal scales, a longer tail (tail contained in
snout-vent length three to four times in _aquilonaris_, four and one
half to six times in _dugesii_, 11 to 12 times in _cancellatus_), and in
having more bands on the body (28 to 32 in _cancel latus_, two to seven
in _dugesii_). The belly in _dugesii_ and _cancellatus_ is pale but in
_aquilonaris_ it is ringed or of a solid dark color.

As more specimens of _Geophis_ become available from intermediate
localities in Mexico, it will perhaps be demonstrated that many of the
kinds now thought of as full species (including those discussed above)
are subspecies of a few wide-ranging species.

_Remarks._--The type locality of _G. aquilonaris_ is the small village
of Barranca at the bottom of the valley of the Río Urique, several miles
south and west of the continental divide. The Urique Valley, known as
the Barranca del Cobre in the region south of Creel, is a deep canyon,
the walls of which slope abruptly from approximately 7300 to 3000 feet
and are dissected by deep side-canyons. Coniferous forest on the upper
rim of the canyon is replaced by scrub vegetation on the rocky walls and
by an arid tropical flora on the bottom.

Maguarachic (elevation approximately 5400 feet, longitude and latitude
respectively, 108 degrees, 03 minutes W and 27 degrees, 50 minutes N)
and Mojarachic (elevation approximately 7000 feet, longitude and
latitude respectively, 108 degrees W and 27 degrees, 52 minutes N) are
situated approximately three miles from each other and approximately 27
miles northwest of Creel. Maguarachic is given as "Mafuarachic" on the
American Geographical Society map (NG 12, Baja California-Mexico, Prov.
Ed., 1924). Mojarachic is not on any map of Chihuahua that I have
examined.

The type and topotypic paratype were given to a member of the K.U. field
party by a Mexican youth who had obtained them the previous night on the
lower rocky slopes of the canyon. Both specimens were damaged by the
collector piercing their heads with thorns, presumably to kill them. The
type contained three oviducal eggs, each about four millimeters long.
The stomachs of both specimens from Creel contained earthworms.

The presence of _Geophis_ in this area suggests that the distribution of
the genus is more or less continuous, on the western slope of the Sierra
Madre Occidental, from Jalisco to southern Sonora.

    I am grateful to Mr. Sydney Anderson and Mr. Ronald Pine for
    permission to use their field notes, to Dr. Hobart M. Smith for his
    examination of the specimens from Creel, to Mrs. Lorna Cordonnier
    for the drawings of the type, to Dr. Norman Hartweg for permitting
    me to study materials in his care and upon which he was making an
    independent study, and to Mr. Thomas M. Uzzell for locality data
    pertaining to the UMMZ paratypes.


_Transmitted November 10, 1958._





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