Title: A New Tortoise, Genus Gopherus, From North-central Mexico
Author: Legler, John M.
Language: English
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UNIVERSITY OF KANSAS PUBLICATIONS
MUSEUM OF NATURAL HISTORY


Volume 11, No. 5, pp. 335-343, pls. 7 and 8
April 24, 1959



A New Tortoise, Genus Gopherus,
From North-central 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. 5, pp. 335-343
Published April 24, 1959

UNIVERSITY OF KANSAS
Lawrence, Kansas

PRINTED IN
THE STATE PRINTING PLANT
TOPEKA, KANSAS
1959



A New Tortoise, Genus Gopherus,
From North-central Mexico

BY

JOHN M. LEGLER


In the course of taxonomic studies of the genus _Gopherus_ it was
found that specimens from north-central Mexico belong to an hitherto
unrecognized species, which is named and described below.


Gopherus flavomarginatus new species

    _Holotype._--U.S. National Museum 61253, adult; stuffed specimen
    with disassociated skull; 30 to 40 miles from Lerdo, Durango,
    Mexico; obtained by Dr. Elswood Chaffee, 1918.

    _Paratypes._--USNM 61254, adult, stuffed specimen with skull in
    place, other data the same as those for holotype; USNM 60976,
    adult, stuffed specimen with disassociated skull, Lerdo, Durango,
    Dr. Elswood Chaffee, May 1918; University of Illinois 42953-4,
    adults, two carapaces, Carrillo, Chihuahua, Pete S. Chrapliwy and
    Kenneth L. Williams, 1 August 1958; University of Kansas 39415,
    adult, carapace only, 8 mi. E and 2 mi. S Americanos, Coahuila,
    Robert W. Dickerman, 19 May 1954.

    _Diagnosis._--A large tortoise of the genus _Gopherus_, having a
    flat-topped, posteriorly-flared shell, carapacal laminae that are
    pale with contrasting dark centers (at least on the lateral margins
    of the carapace), intergular seam longer than interhumeral, obtuse
    gular projections, and a relatively wider skull than other Mexican
    representatives of the genus.

    _Description of species._--Ground color of carapace pale yellow to
    straw in smaller specimens, pale brown in larger specimens; in some
    specimens a slight indication of darker radial markings on
    carapace; epidermal areolae of carapace (if present) and first two
    or three zones of growth (around areolae) dark brown to black,
    their contrast with the ground color greater in smaller specimens;
    ground color of lateral marginals yellowish, much paler than
    remainder of carapace; black areolae of marginals contrasting
    sharply with ground color even in old individuals; plastron pale,
    approximately the same shade of yellow as lateral marginals, marked
    with sharply contrasting blotches of black or dark brown in younger
    specimens, becoming immaculate with age.

    Carapace low, evenly arched or slightly flat-topped in cross
    section, its height slightly more than 50 per cent of its length;
    top of carapace, between highest parts of first and fourth central
    laminae, more or less flat in profile; carapace flared, wider
    posteriorly than anteriorly; central laminae all broader than long,
    the first not (or but slightly) narrower posteriorly than
    anteriorly; plastron deeply notched behind, the inner margins of
    the notch straight, neither convex nor concave; gular projections
    truncate (not pronglike) having no notch or but a shallow notch
    between them; greatest combined width of gular laminae much greater
    than greatest length; interlaminal length of gular greater than
    that of humeral; one large axillary scute on each side,
    approximately rectangular but slightly wider below than above; one
    or two inguinal scutes on each side, the anterior roughly
    triangular and much larger than posterior.

    Anterior surface of antebrachium having enlarged, juxtaposed (or
    slightly imbricated), osteodermal scales arranged in seven to eight
    longitudinal rows, each scale yellowish with a black or dark brown
    center; scales on lateral edge of antebrachium, from fifth claw to
    elbow, ten in number and darker than other antebrachial scales; two
    enlarged black-tipped, yellow spurs on posterior surface of thigh,
    inner spur approximately half the size of outer. Head relatively
    wide, greatest width of skull slightly more than 80 per cent of
    condylobasilar length; width of head 1.3 to 1.7 times diameter of
    hind foot; scales on top of head large but irregularly arranged
    (see table 1 for measurements of type and paratypes).

  TABLE 1. Measurements, in Millimeters, of the Holotype and Paratypes
  of Gopherus Flavomarginatus New Species

  ----------------+--------+--------+--------+------+---------+------
  Catalogue Number|Length  |Width   |Length  |      |Diameter |Width
  and Collection  |of      |of      |of      |Height|of       |of
                  |carapace|carapace|plastron|      |hind foot|head
  ----------------+--------+--------+--------+------+---------+------
  USNM 60976      |  246   |  212   |  252   | 108  |   31    | 41
  ----------------+--------+--------+--------+------+---------+------
  USNM 61253      |  222   |  166   |  212   |  96  |   21    | 36
  ----------------+--------+--------+--------+------+---------+------
  USNM 61254      |  371   |  292   |  358   | 157  |   43    | 55
  ----------------+--------+--------+--------+------+---------+------
  IU 42953        |  281   |  220   |        |      |         |
  ----------------+--------+--------+--------+------+---------+------
  IU 42954        |  278   |  214   |        |      |         |
  ----------------+--------+--------+--------+------+---------+------
  KU 39415        |  303   |  232   |        |      |         |
  ----------------+--------+--------+--------+------+---------+------

    Duges (1888:146-147, and 1896:479) twice reported specimens of
    _Gopherus polyphemus_ from Chihuahua (see discussion of distribution);
    his description of two living examples (1888) agrees generally with
    the above description of _G. flavomarginatus_. He stated that the
    iris of his smaller specimen was yellow and the iris of a larger
    specimen brown.

    It will be most interesting to learn the color of juveniles of _G.
    flavomarginatus_. Considering the dark color of the epidermal
    areolae of adults, I would expect the color of hatchlings to be
    dark brown to nearly black, with each lamina acquiring paler
    borders as it grew, rather than acquiring darker borders as is
    usually the case in _G. berlandieri_ (personal observation),
    _agassizii_ (Miller, 1932:194, pl. 2; Woodbury and Hardy, 1948:165,
    figs. 9 and 10), and _polyphemus_ (personal observation).

[Illustration: PLATE 7

PLATE 7. _Gopherus flavomarginatus_ new species: _Top_--Dorsal and
ventral views of holotype (× 1/3); _Middle_--Lateral view of holotype
(× 1/3); _Bottom_--Head of paratype (USNM 61254) (× 1/2) and
antebrachium of holotype (× 5/6). Dark outline on plastron of holotype
indicates where portion of shell was removed (and then replaced) in
course of preparation.]

[Illustration: PLATE 8

PLATE 8. _Gopherus flavomarginatus_ new species: Dorsal views of
paratypes (from top to bottom, IU 42953, IU 42954, and KU 39415),
approximately 1/5 natural size.]

[Illustration: FIG. 1. _Gopherus flavomarginatus_ new species: 1a and
1b--Lateral and ventral views of skull of holotype (× 1); 1c--Cross
section of paratype (USNM 60976) taken through middle of third central
lamina (× 2/5).]

    _Anomalies._--There is a high incidence of anomaly in the type
    series. Three of the specimens (USNM 60976, IU 42954, and KU 39415)
    have a supernumerary central lamina. All of the specimens from
    Durango are anomalous in regard to the marginal laminae. In the
    holotype the first marginals are small, approximately as wide as
    the small precentral. In the largest paratype (USNM 61254) the
    first and second marginals are fused to form a single large scute
    on each side. In the remaining Durangan paratype (USNM 60976) there
    are eleven normal marginals on each side but a supernumerary lamina
    occurs between the first and second marginal on the left and
    between the precentral and first marginal on the right side. The
    remaining three paratypes have the number of marginals that is
    normal for the genus.

    _Relationships._--_Gopherus flavomarginatus_ differs from all other
    species of the genus by its larger size and by having an intergular
    seam that is longer than the interhumeral seam. The possession of
    a single, rectangular axillary scale, wider below than above,
    also tends to distinguish _flavomarginatus_ from other living
    _Gopherus_; in the other species this scute (frequently paired in
    _berlandieri_) is generally triangular or at least pointed below.
    Femoral spurs are developed to varying degrees in the other species
    of _Gopherus_; they are usually lacking in individuals of small to
    medium size. In large specimens of _agassizii_ and _polyphemus_
    that I have examined, there is but one enlarged spur, although
    several pointed osteodermal scales may be present on the back of
    the thigh.

    _Gopherus berlandieri_, the closest relative of _G. flavomarginatus_
    in a geographic sense, has a highly arched shell and pronglike gular
    projections, between which there is nearly always a deep notch.
    _Gopherus agassizii_, morphologically the closest Mexican relative
    of _flavomarginatus_, differs from it in having a narrower head and
    in lacking the contrasting pale and dark coloration of the plastron
    and lateral marginal area. _Gopherus polyphemus_ seems to be the
    closest relative of _flavomarginatus_ and differs from it in having
    an unflared shell (anterior and posterior widths of carapace
    subequal or carapace narrower behind) and in the characteristics of
    color mentioned above. Certain proportional differences between the
    living species of _Gopherus_ are summarized in table 2.

    _Distribution._--The discovery of a new _Gopherus_ from
    north-central Mexico increases to four the recognized forms of the
    genus and extends the known range of the genus onto the Mexican
    highlands, approximately 410 miles eastward from Alamos, Sonora
    (_G. agassizii_), approximately 100 miles westward from a point 2
    mi. W of Monclova, Coahuila (_G. berlandieri_), and approximately
    200 miles westward from Monterrey, Nuevo León (_G. berlandieri_).

  TABLE 2. Bodily Proportions in the Known Species of Gopherus. Two
  Specimens of G. polyphemus from Harmon, Mississippi (USNM 53166-7),
  Are Considered Separately Because of Their Notably Narrower Heads.
  The Size of Each Sample Is Given in Parentheses Above the Average;
  Extremes Are in Parentheses Following the Averages.

  ---------------------+-----------+-------------+-------------+--------
  Species              |Greatest   |Height     | Height     |Diameter
  and                  |width of   |of         | of         |of
  General Locality     |skull as a |shell as a | shell as a |hind foot
                       |percentage |percentage | percentage |as a
                       |of         |of width   | of length  |percentage
                       |condy-     |of         | of         |of width
                       |lobasilar  |carapace   | carapace   |of head
                       |length     |           |            |
  ---------------------+-----------+-----------+------------+----------
  _G. polyphemus_      | (6)       |(13)       |(13)        |
  (Florida)            |.94        |.53        |.39         |
                       |(.92-.97)  |(.48-.58)  |(.36-.42)   |
  ---------------------+-----------+-----------+------------+----------
  _G. polyphemus_      |(2)        |(2)        |(2)         |
  (Mississippi)        |.87        |.53        |.43         |
                       |(.84-.89)  |(.52-.54)  |(.40-.45)   |
  ---------------------+-----------+-----------+------------+----------
  _G. berlandieri_     |(21)       |(22)       |(21)        |
  (Texas and NE Mexico)|.78        |.56        |.46         |
                       |(.70-.83)  |(.48-.62)  |(.43-.51)   |
  ---------------------+-----------+-----------+------------+----------
  _G. agassizii_       |(6)        |(8)        |(8)         |
  (U.S. and N. Sonora) |.77        |.53 |.41   |(.38-.44)   |
                       |(.70-.83)  |(.49-.58)  |            |
  ---------------------+-----------+-----------+------------+----------
  _G. agassizii_       |           |(4)        |(4)         |(4)
  (Alamos, Sonora)     |           |.56        |.39         |.92
                       |           |(.52-.59)  |(.37-.41)   |(.87-1.00)
  ---------------------+-----------+-----------+------------+----------
  _G. flavomarginatus_ |(2)        |(3)        |(3)         |(3)
  (North-central       |           |           |            |
  Mexico)              |.83        |.54        |.43         |.71
                       |(.82-.83)  |(.51-.58)  |(.42-.44)   |(.58-.78)
  ---------------------+-----------+-----------+------------+----------

    Thus far, _G. flavomarginatus_ is known only from the three
    localities represented in the type series and from the indefinite
    locality, "Bolson de Mapimí", Chihuahua, given by Duges
    (1888:146-7, and 1896:479). These long-doubted references of
    Duges to _Gopherus polyphemus_ seem clearly to represent _G.
    flavomarginatus_, which probably occurs in several or all of the
    internally drained basins in northeastern Chihuahua, western
    Coahuila, and northern Durango. This region is within the Basin and
    Range physiographic province of Fenneman (1931:326-8) and the
    Mapimí biotic province of Smith (1949:231). Duges (_supra cit._)
    seems to have used "Bolson de Mapimí" in a restricted sense, as it
    is shown on some recent maps (Nat. Geog. Soc., Map of Mexico and
    Central America, 1953) (American Geog. Soc., Culican Map, NG 13,
    1935). Other maps show this bolson to include internally drained
    portions of the Mexican highlands from northeastern Chihuahua to
    the region near Lerdo and Torreon. Thayer (1916:73) pointed out
    that the Bolson de Mapimí, in its larger sense, consists of a
    series of basins separated by mountains of considerable elevation.

    The range of _G. flavomarginatus_ appears to be limited ultimately
    by the higher elevations of the Sierra Madre Occidental and the
    Sierra Madre Oriental to the west and east, respectively, and to
    the south by the Mexican plateau. The northern limits of the range
    are less clear; possibly the range extends as far as the portions
    of the United States adjacent to northeastern Chihuahua, but this
    is doubtful. The range seems not to overlap that of any other
    species of _Gopherus_, although the ranges of _G. flavomarginatus_
    and _G. berlandieri_ closely approximate each other in central
    Coahuila.

    In September, 1958, when I was collecting turtles near Cuatro
    Cienegas, Coahuila, I took the opportunity to query natives, as
    well as an American rancher, about the possible occurrence of
    tortoises in the area. Most persons had seen no tortoises in the
    area or said they had seen them only rarely. Several older men who
    had herded goats in the area all their lives said that tortoises
    (referred to as "Tortuga del Monte") were common on the other side
    of the Sierra de La Madera and Sierra de La Fragua ranges west of
    Cuatro Cienegas. These men referred probably to _G.
    flavomarginatus_. Americanos lies approximately 75 miles
    west-northwest of Cuatro Cienegas.

    It is indeed remarkable that a population of large tortoises in
    northern Mexico has so long escaped the notice of naturalists. Also
    remarkable is the fact that the late Dr. Leonhard Stejneger, in
    view of his intense interest in North American chelonians and his
    familiarity with the genus _Gopherus_, did not remark on the
    specimens from Durango when he saw them; a thorough search of
    Stejneger's notes revealed no clue that he had ever studied the
    specimens. Perhaps his first reaction to the specimens, like mine
    when I first examined the two disassociated skulls, was to consider
    "Lerdo" a misspelling of "Laredo." However, a check of old
    correspondence and accession records at the National Museum
    confirmed, beyond doubt, the validity of the locality data for
    these specimens. Dr. Chaffee, the collector, frequently sent
    specimens of plants and animals to the Museum from Durango and
    Zacatecas; his home was in Lerdo.

    _Size._--The largest specimen of _Gopherus flavomarginatus_ (USNM
    61254) exceeds by more than 50 millimeters the length of the
    largest known specimens of _G. agassizii_, and slightly exceeds the
    length of the largest specimen of _G. polyphemus_ that I have
    examined (USNM 51357, length of carapace 360 millimeters, a
    specimen formerly kept at the National Zoological Park). _G.
    polyphemus_ is the largest tortoise inhabiting the United States;
    the maximum length of 343 millimeters given for the species by Carr
    (1952:334) probably more closely approaches the true maximum in
    free-living populations. _G. agassizii_ rarely attains a length
    greater than 300 millimeters (Woodbury and Hardy, 1948:152-5). The
    fact that representatives of the genus do not attain a larger size
    in the United States may be due to the decimation of natural
    populations by man for food and souvenirs.

    There have been several indications that a large species of
    tortoise existed in north-central Mexico. The Chihuahuan specimens
    reported by Duges (248 and 202 millimeters long, respectively) rank
    in size with the smaller paratypes of _G. flavomarginatus_; Duges
    stated, however, that the species was said to attain a length of
    one meter but that he thought such large size surely to apply to
    another species.

    Mr. Charles M. Bogert recently related to me two stories that are
    here worthy of note. One of them, which Bogert learned from the
    late Dr. Karl P. Schmidt, concerns a collector who was sent by the
    Chicago Natural History Museum (then Field Museum) to Coahuila in
    the early part of the century to obtain materials for a desert
    exhibit. When the exhibit had been completed several decades later,
    the collector, visiting the museum, inquired as to where the large
    tortoises were that he had collected in Coahuila. Dr. Schmidt could
    find no record of such tortoises and suggested that possibly they
    had been confused with Galapagos tortoises (_Geochelone_). Dr.
    Robert F. Inger is unable to locate the specimens or add anything
    to the story. The collector stated that the large tortoises had
    been found in only one bolson in Coahuila.

    Mr. Bogert further related that, in 1946 when he was camped at Las
    Delicias, Coahuila, a Mexican mule herder told him of seeing a
    large tortoise "three bolsons north" of the bolson in which Las
    Delicias is located (the general area referred to would be near
    Americanos). The man awoke one morning to find his saddle missing;
    following tracks from the place where the saddle had been left, the
    man eventually found it on the back of a large tortoise. The
    tortoise had apparently sought shelter beneath the saddle and,
    finding it unsatisfactory, had walked away with the saddle on his
    back.

    Either of the incidents related above, or the reference of Duges
    (_loc. cit._) to large size, since they are based on second or
    third-hand accounts, would seem to be unrealistic and of little
    scientific value when considered alone and at face value. However,
    in the light of the discovery of _Gopherus flavomarginatus_, these
    accounts have new meaning and tend to support my proposal that the
    species is the largest tortoise in North America.

    _Remarks._--The paratypes at the University of Illinois were found
    in a trash-dump in Carrillo. According to what the collectors
    learned from local inhabitants, the species is used for food and
    the shells are sometimes used for poultry dishes or even for eating
    utensils. Although the species is found on the flat, sandy desert
    near Carrillo, it is more common on the nearby mountain slopes and
    is seen there most frequently after rains. Dickerman (field notes,
    1954) likewise noted that the species was eaten near Americanos;
    the K.U. paratype represents the best (and only specimen saved) of
    several broken shells found in that area. Judging by the habits of
    other members of the genus and by the notes of Duges (1888:147),
    _G. flavomarginatus_ is probably herbivorous.

    _Acknowledgments._--A portion of this study was completed in the
    summer of 1958, while I was an internee at the United States
    National Museum. I am grateful to Dr. Doris M. Cochran of that
    institution for helpful information regarding the origin of the
    type and for permission to study other specimens in her care.
    Thanks are due also to Messrs. Pete S. Chrapliwy and Kenneth L.
    Williams who collected two of the paratypes and who generously
    provided their notes on the specimens when learning of my study, to
    Dr. Hobart M. Smith and Mr. Charles M. Bogert for offering helpful
    suggestions and for the loan of specimens, and to Mr. Jebb Taylor
    for assistance with taking data. The drawings are the work of Mrs.
    Connie Spitz; the photographs are by the author.



LITERATURE CITED


CARR, A.

    1952. Handbook of turtles; the turtles of the United States,
    Canada, and Baja California. Cornell Univ. Press, xv + 542 pp., 37
    figs., 82 pls., 15 tables, 23 maps.

DUGES, A.

    1888. La Tortuga Polifemo. La Naturaleza, 1(ser. 2):146-147.

    1896. Reptiles y Batracios de los E. U. Mexicanos. La Naturaleza,
    2(ser. 2):479-485.

FENNEMAN, N. M.

    1931. Physiography of western United States. McGraw-Hill, New York,
    1st. ed., v-xii + 534 pp., 173 figs.

MILLER, L.

    1932. Notes on the desert tortoise (_Testudo agassizii_).
    Trans. San Diego Soc. Nat. Hist., 7:187-208.

SMITH, H. M.

    1949. Herpetogeny in Mexico and Guatemala. Ann. Assn. American
    Geographers, 34(3):219-238, 1 fig.

THAYER, W. N.

    1916. The physiography of Mexico. Journ. Geol., 24:61-94, 2 figs.

WOODBURY, A. M., and HARDY, R.

    1948. Studies of the desert tortoise, _Gopherus agassizii_.
    Ecol. Monogr., 18:145-200, 25 figs., 4 tables.


_Transmitted November 18, 1958._





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