and arid habitats from the upper Balsas Basin in Puebla westward to the
lower slopes of the Sierra de Coalcoman, whereas _S. m. mutabilis_
lives in foothills of the Sierra Madre Occidental from southern Jalisco
to Nayarit. Zweifel (1959b:6) presented evidence to show that specimens
of _S. m. mutabilis_ supposedly from "Distrito Federal" probably bear
erroneous locality data.
~Tantilla bocourti~ (Guenther)
_Homalocranium bocourti_ Guenther, Biologia
Centrali-Americana, Reptilia, p. 149, 1895.--Guanajuato,
Guanajuato, Mexico.
_Tantilla bocourti_, Cope, Amer. Nat., 30:1021, December,
1896.
Carapan; Patzcuaro (2); between Zitacuaro and Rio Tuxpan
(11).
This small snake is an inhabitant of the coniferous forests and the
pine-oak forests on the Cordillera Volcanica. Data on the series from
between Zitacuaro and the Rio Tuxpan were given by Taylor (1940c:481).
~Tantilla calamarina~ Cope
_Tantilla calamarina_ Cope, Proc. Acad. Nat. Sci.
Philadelphia, 18:320, February 13, 1867.--Guadalajara,
Jalisco, Mexico.
Apatzingan; La Placita.
Although this snake has been collected at high elevations along the rim
of the Mexican Plateau in Nayarit, Jalisco, Mexico, and Puebla, the
specimens from Michoacan are from arid scrub forest at elevations of
less than 400 meters. The species has been found in similar habitats in
Colima (Oliver, 1937:24) and in Sinaloa and the Tres Marias Islands
(Zweifel, 1960:110).
~Toluca lineata lineata~ Kennicott
_Toluca lineata_ Kennicott, _in_ Baird, Report on the United
States and Mexican boundary survey, 2, Reptiles, p. 23,
1859.--Valley of Mexico.
_Toluca lineata lineata_, Taylor and Smith, Univ. Kansas
Sci. Bull., 28:343, May 15, 1942.
Capacuaro; Carapan (12); Cheran (23); Cojumatlan; Los Reyes;
Morelia (2); Nahuatzen; Paracho (10); Patzcuaro (17);
Uruapan (2).
This small snake is an inhabitant of the coniferous forests between
elevations of about 1550 and 2800 meters. Not infrequently, individuals
have been found in pine-oak forest within these elevations.
The generic status of _Toluca_ is unsettled. Taylor and Smith (1942b)
separated _Toluca_ from _Conopsis_ by the presence of enlarged and
grooved posterior maxillary teeth in _Toluca_ and their absence in
_Conopsis_. Bogert and Oliver (1945:378) suggested synonymizing _Toluca_
with _Conopsis_. Smith and Laufe (1945:12) defined the generic position
of _Toluca_. Actually, in deciding the generic position of these snakes,
five genera (_Ficimia_, _Gyalopion_, _Pseudoficimia_, _Conopsis_, and
_Toluca_) must be considered. Of these _Ficimia_ and _Gyalopion_ are
closely related; they have been placed in one genus by some workers.
_Pseudoficimia_ is intermediate between _Ficimia-Gyalopion_ and
_Toluca-Conopsis_. A workable definition of the supraspecific
classification of these snakes must await a thorough review of the
species.
~Trimorphodon biscutatus biscutatus~ (Dumeril, Bibron, and Dumeril)
_Dipsas biscutata_ Dumeril, Bibron, and Dumeril, Erpetologie
generale, 7 (pt. 2):1153, 1854.--Mexico. Type locality
restricted to Tehuantepec, Oaxaca, Mexico, by Smith and
Taylor (1950a:340).
_Trimorphodon biscutatus biscutatus_, Smith, Proc. U. S.
Natl. Mus., 91:159, November 10, 1941.
Apatzingan (11); Cofradia; Cuatro Caminos; El Sabino (2); La
Placita; La Playa (2); Lombardia (2); Nueva Italia (2); Rio
Tepalcatepec, 27 km. S of Apatzingan; Tafetan.
In the arid lowlands of the Tepalcatepec Valley and presumably also in
the scrub forest of the coastal lowlands, this is an abundant snake,
which is active only at night. Usually snakes of this species are found
on the ground, but one large individual was observed at night in a low
tree. That individual defied capture by widely opening its mouth and
striking repeatedly at the collector. The excreta of one specimen
contained feathers of an unidentified species of bird.
~Trimorphodon latifascia~ Peters
_Trimorphodon biscutata latifascia_ Peters, Monats. Akad.
Wiss. Berlin, p. 877, 1869.--Puebla, Mexico. Type locality
restricted to Izucar de Matamoros, Puebla, Mexico, by Smith
and Taylor (1950a:341).
_Trimorphodon latifascia_. Taylor, Univ. Kansas Sci. Bull.,
25:364, July 10, 1939.
Apatzingan (5); Casada Tzararacua; Coalcoman (2); Lombardia;
14 km. S of Lombardia; Nueva Italia; San Salvador.
In Michoacan this species has been collected in semi-arid habitats at
elevations from 300 to 1430 meters in the Tepalcatepec Valley and lower
slopes of the Cordillera Volcanica. In this area it occurs sympatrically
with _Trimorphodon biscutatus biscutatus_.
In life, adults have a pale tan dorsal ground color and rich chocolate
brown cross-bands; the eye is pale grayish tan. A juvenile from
Coalcoman has black cross-bands on a pale grayish tan ground color. As
stated by Schmidt and Shannon (1947:83) and Peters (1954:32), the type
specimen of _Trimorphodon fasciolata_ Smith from Cascada Tzararacua is
indistinguishable from specimens of _Trimorphodon latifascia_.
Seven males have 209 to 223 (216.5) ventrals; one female has 227
ventrals. The number of dark cross-bands on the body varies from 12 to
16 (13.5). The relationships of this species are with _Trimorphodon
tau_ on the Mexican Plateau. In fact, additional specimens from the
headwaters of the Tepalcatepec Valley and the lower slopes of the
Mexican Plateau in eastern Michoacan and adjacent Jalisco may show that
the two are conspecific. _Trimorphodon latifascia_ differs from _tau_ in
having fewer dark cross-bands on the body and in lacking an interocular
bar.
~Trimorphodon tau~ Cope
_Trimorphodon tau_ Cope, Proc. Amer. Philos. Soc., 11:151,
1869.--Quiotepec, Oaxaca, Mexico.
Emiliano Zapata (2); between Morelia and Ciudad Hidalgo;
Tacicuaro; Tangamandapio.
Two of the specimens from Michoacan (UMMZ 118948 from Tangamandapio and
UIMNH 19138 from Tacicuaro) have cream-colored, Y-shaped marks on the
head. These markings supposedly are characteristic of _Trimorphodon
upsilon_. One specimen from Emiliano Zapata (UMMZ 118950) and one from
between Morelia and Ciudad Hidalgo (EHT-HMS 21402) have a cream-colored
line on the parietal suture; in another specimen from Emiliano Zapata
(UMMZ 118949) the anterior end of this line is expanded, giving the
appearance of an incipient "Y". Thus, the nature of the markings on the
head in specimens from Michoacan is intermediate between the typical
condition in _Trimorphodon tau_ and the usual condition in _T. upsilon_.
Smith and Taylor (1945:148) gave the range of _Trimorphodon tau_ as:
"Central Guerrero, in the Sierra Madre del Sur; central Oaxaca; and the
edge of the plateau in central Michoacan." They gave the range of
_Trimorphodon upsilon_ as: "Southern Chihuahua south to central
Michoacan, east to central Hidalgo." Specimens referable to _T. tau_
have been found at La Joya de Salas, near Ciudad Victoria, and near
Llera, Tamaulipas (see Smith and Darling, 1952:85, and Martin, 1958:74).
Some of these specimens also show combinations of characteristics of _T.
tau_ and _T. upsilon_. Smith and Darling (_loc. cit._) suggested that
_T. tau_ and _T. upsilon_ be considered as subspecies. However, if _T.
tau_ and _T. upsilon_ are subspecies, intergrades would be expected
between the ranges of the two populations and not on the northeastern
and southwestern periphery of their combined ranges. Instead, the
limited evidence now available suggests that _T. tau_ and _T. upsilon_
are names based on a highly variable character of color pattern of the
head, and that only one species is involved.
In Michoacan this species inhabits the mesquite grassland on the Mexican
Plateau.
~Tropidodipsas occidentala~ Oliver
_Tropidodipsas occidentala_ Oliver, Occ. Pap. Mus. Zool.
Univ. Michigan, 360:20, November 20, 1937.--Comala, Colima,
Mexico.
Coalcoman.
This specimen was reported by Peters (1954:34), who found it beneath a
rock at the mouth of a heavily wooded ravine near Coalcoman at an
elevation of 950 meters. The only other known specimen is from Comala,
Colima, a village, like Coalcoman, that is located near the upper limits
of the arid scrub forest.
~Natrix valida isabelleae~ Conant
_Natrix valida isabelleae_ Conant, Nat. Hist. Misc., 126:7,
September 15, 1953.--Pie de la Cuesta, Laguna Coyuca,
Guerrero, Mexico.
Coahuayana; Playa Azul (2); Punto San Juan de Lima.
Three females and one male have, respectively, 133, 135, 135, and 131
ventrals, and 68, 68, 73, and 75 caudals. The grayish stippling on the
posterior ventral surfaces mentioned by Conant (1953:9) is not visible
on these specimens. In the small individuals from Punto San Juan de Lima
and from Coahuayana there are four longitudinal rows of dark spots on
the dorsum; in two large females from Playa Azul the spots are barely
discernible.
All of the specimens from Michoacan were found in the coastal lowlands;
those from Playa Azul were collected from a small brackish,
mangrove-lined lagoon.
~Storeria storerioides~ (Cope)
_Tropidoclonium storerioides_ Cope, Proc. Acad. Nat. Sci.
Philadelphia, 17:190, December 26, 1865.--Mexican Plateau.
Type locality restricted to Tres Cumbres, Morelos, Mexico,
by Smith and Taylor (1950a:336).
_Storeria storerioides_, Garman, Mem. Mus. Comp. Zool.,
8(3):29, June, 1883.
Dos Aguas (11); Puerto de Garnica; Tancitaro (11); Tzitzio;
Uruapan; 16 km. NW of Zacapu.
Three males and six females from the Sierra de Coalcoman have,
respectively, 122-128 (125.3) and 126-136 (130.0) ventrals, and 46-47
(46.7) and 38-42 (39.1) caudals. Four males and eleven females from the
Cordillera Volcanica have, respectively, 124-132 (128.5) and 127-139
(136.4) ventrals, and 43-48 (44.7) and 38-44 (40.2) caudals. These data
show that, although there is little difference in the number of caudals,
specimens from the Sierra de Coalcoman have fewer ventrals than do
specimens from the Cordillera Volcanica. Of eleven specimens from the
Sierra de Coalcoman, two have black bellies. Five others from the Sierra
de Coalcoman and one from Puerto de Garnica in the Cordillera Volcanica
have the bellies heavily stippled with black, giving a gray appearance.
Melanistic tendencies in this species have been discussed by Anderson
(1960:64), who examined the specimen from Tzitzio. In life, one specimen
from Dos Aguas (UMMZ 119451) had a cream-colored belly; the edges of the
ventrals were dark brick-red.
In Michoacan this snake inhabits pine-oak, pine, and fir forests at
elevations between 1550 and 2800 meters in the Cordillera Volcanica and
the Sierra de Coalcoman. Most specimens were found beneath rocks; the
one from Tzitzio was removed from the stomach of a Mexican Motmot
(Anderson, 1960:66).
~Thamnophis dorsalis cyclides~ Cope
_Thamnophis cyrtopsis cyclides_ Cope, Proc. Acad. Nat. Sci.
Philadelphia, 13:299, December 28, 1861.--Cape San Lucas,
Baja California (in error). Type locality restricted to
Guanajuato, Guanajuato, Mexico, by Smith and Taylor
(1950a:330). Smith, Copeia, no. 2:140, June 8, 1951.
Milstead, Texas Jour. Sci., 5:368, September, 1953.
_Thamnophis eques eques_ (_nec._ Reuss), Smith, Zoologica,
27:106, October 23, 1942. Bogert and Oliver, Bull. Amer.
Mus. Nat. Hist., 83:356, March 30, 1945.
_Thamnophis vicinus_ Smith, Zoologica, 27:104, October 23,
1942.--Temazcal, Michoacan, Mexico.
_Thamnophis dorsalis cyclides_, Fitch and Milstead, Copeia,
no. 1:112, March 17, 1961.
Barolosa; Coalcoman; Dos Aguas (3); Los Reyes; Morelia (16);
Opopeo; Pino Gordo; Tacicuaro (16); Tancitaro (14);
Tangamandapio (2); Temazcal (2); Tzintzuntzan; Uruapan.
The snakes comprising the former _Thamnophis eques_-group have undergone
extensive taxonomic and nomenclatural shuffling by Smith (1942 and
1951), Bogert and Oliver (1945), Milstead (1953), and Fitch and Milstead
(1961). Smith recognized in Michoacan three members of the _T. eques_ (=
_dorsalis_) complex: _eques eques_, _eques postremus_, and _vicinus_.
Later, Smith (1951) showed that the specific name _eques_ had been
misapplied, so that _T. eques eques_ became _T. cyrtopsis cyclides_, and
_T. eques postremus_ became _T. cyrtopsis postremus_; under this
arrangement _T. vicinus_ stood unchanged. In the meantime, Bogert and
Oliver (1945:359) presented a reinterpretation of Smith's data and
suggested that _T. vicinus_, which differs from _T. dorsalis cyclides_
only in lacking a middorsal stripe, "... is not a species, but only a
pattern phase, possibly a simple mutant of _T. e. eques_" (= _T.
dorsalis cyclides_, by present arrangement). Milstead (1953) agreed with
Bogert and Oliver on the status of _T. vicinus_; furthermore, on the
basis of only a few specimens, Milstead concluded that _T. cyrtopsis
postremus_ was not subspecifically distinct from _T. cyrtopsis
cyclides_. Recently, Fitch and Milstead (1961) showed that _Thamnophis
dorsalis_ Baird and Girard (1853) was the correct name for the snakes
that had been recognized as _Thamnophis cyrtopsis_ Kennicott (1860).
Consequently, the snakes referred to _T. eques eques_ by Smith (1942)
and to _T. cyrtopsis cyclides_ by Smith (1951) and Milstead (1953) are
now _T. dorsalis cyclides_.
Aside from one specimen from Temazcal and nine from Morelia (paratypes
of _T. vicinus_), only two other specimens completely lacking the
middorsal stripe have been seen; one is a male (UMMZ 102510) having 161
ventrals and an incomplete tail from Pino Gordo, and the other is a male
(CNHM 39060) from Tancitaro having 158 ventrals and an incomplete tail.
A female from Tancitaro (CNHM 39061) having 153 ventrals and 77 caudals
has no lateral stripes and only a narrow middorsal stripe on the
anterior part of the body. Throughout the region where _T. vicinus_-like
snakes have been found, typical _T. dorsalis cyclides_ occurs in much
greater numbers. I concur with Bogert and Oliver in placing _T. vicinus_
as a synonym of _T. dorsalis cyclides_.
[Illustration: FIG. 10. Dorsal color pattern of _Thamnophis dorsalis
cyclides_ (A) and _Thamnophis dorsalis postremus_ (B).]
Milstead (1953) had available few specimens of _Thamnophis dorsalis_
from the Tepalcatepec Valley. The large series now in existence shows
that the population in the Tepalcatepec Valley differs distinctly from
that inhabiting the Mexican Plateau, Cordillera Volcanica, and Sierra de
Coalcoman. Therefore the name _T. dorsalis postremus_ Smith (1942) is
resurrected for the population in the Tepalcatepec Valley. _T. dorsalis
cyclides_ and _T. dorsalis postremus_ differ in color pattern (Fig. 10)
and in scutellation (Table 6). Specimens from the Mexican Plateau and
mountain ranges have a distinct light stripe on the second and third
scale rows, a dark brown dorsum having squarish black spots, and a row
of dark spots on the first row of dorsal scales. Specimens from the
Tepalcatepec Valley have a grayish brown dorsum having smaller and less
distinct dark spots and no light stripe on the second and third scale
rows; the first, second, and third rows of scales are colored like the
venter. In some specimens there are small dark flecks on the first row
of dorsal scales.
TABLE 6.--VARIATION IN SCUTELLATION IN THAMNOPHIS DORSALIS.
+---------------------------------+-------+---------+------------+
| Character |Mexican|Sierra de|Tepalcatepec|
| |Plateau|Coalcoman| Valley |
+------------------+--------------+-------+---------+------------+
| Ventrals | Female N | 31 | 2 | 32 |
| | Mean | 164.0 | 156.5 | 144.6 |
| | Range|153-171| 154-159 | 138-151 |
| +--------------+-------+---------+------------+
| | Male N | 19 | 2 | 32 |
| | Mean | 153.5 | 154.7 | 138.3 |
| | Range|149-159| 149-159 | 131-141 |
+------------------+--------------+-------+---------+------------+
| Caudals | Female N | 28 | 2 | 29 |
| | Mean | 83.8 | 81.0 | 73.4 |
| | Range|80-100 | 79-83 | 70-79 |
| +--------------+-------+---------+------------+
| | Male N | 14 | 2 | 28 |
| | Mean | 78.0 | 72.0 | 68.5 |
| | Range| 71-87 | 72 | 63-73 |
+------------------+--------------+-------+---------+------------+
One specimen from Uruapan (1550 meters) and one from Coalcoman (950
meters) are intermediate in color pattern between _T. dorsalis cyclides_
and _T. dorsalis postremus_. Both have indistinct lateral stripes and
only small dark spots below the stripes. In scutellation these specimens
are like _T. dorsalis cyclides_.
In Michoacan _Thamnophis dorsalis cyclides_ has been collected in a
variety of habitats on the Mexican Plateau: pine-oak forest, fir forest,
marshes, and cleared land from 1550 to 2800 meters. In the Sierra de
Coalcoman one was taken in broad-leafed forest at 950 meters, three in
pine-oak forest at 2100 meters, and one in pine forest at 2300 meters.
~Thamnophis dorsalis postremus~ Smith
_Thamnophis eques postremus_ Smith, Zoologica, 27:109,
October 23, 1942.--El Sabino, Michoacan, Mexico.
_Thamnophis cyrtopsis postremus_ Smith, Copeia, no. 2:140,
June 8, 1951.
_Thamnophis cyrtopsis cyclides_ (part), Milstead, Texas
Jour. Sci., 5:368, September, 1953.
_Thamnophis dorsalis postremus_, Fitch and Milstead, Copeia,
no. 1:112, March 17, 1961.
Apatzingan (31); Capirio (2); Charapendo; Cuatro Caminos
(22); El Sabino; Lombardia (9); Nueva Italia (8); Uruapan
(3).
The reasons for recognizing the population of _Thamnophis dorsalis_ in
the Tepalcatepec Valley as distinct from that on the surrounding
highlands are presented in the discussion of _Thamnophis dorsalis
cyclides_. In certain features of coloration and in the low numbers of
ventrals and caudals, _T. dorsalis postremus_ shows more resemblance to
_T. dorsalis sumichrasti_ than to _T. dorsalis cyclides_. According to
Milstead (1953:367), _T. dorsalis cyclides_ ranges southward from the
Rio Balsas in southwestern Mexico. If specimens could be obtained from
the upper Balsas Basin they might show that _T. dorsalis postremus_
inhabits that extensive basin.
In the Tepalcatepec Valley _T. dorsalis postremus_ is most frequently
found at night in the rainy season, at which time the snakes are
abundant near temporary pools where frogs are breeding. The absence of
specimens from the coastal lowlands of Guerrero, Michoacan, and Colima
indicate that, although the species inhabits the lowlands of the
Tepalcatepec Valley, its range does not include the coastal lowlands.
A female (UMMZ 119402 from Cuatro Caminos) having 139 ventrals and a
body length of 576 mm., on June 20, 1958, gave birth to 25 young, of
which 18 (9 males and 9 females) were preserved. In body length the
males varied from 132 to 141 (137.3) mm.; the females, 125 to 137
(133.1) mm. In tail length the males varied from 38 to 44 (42.4) mm.;
females, 35 to 42 (39.7) mm. The males have 138 to 147 (142.2) ventrals
and 70 to 75 (72.9) caudals; females have 131 to 140 (135.8) ventrals
and 63 to 71 (67.0) caudals.
~Thamnophis eques eques~ (Reuss)
_Coluber eques_ Reuss, Zool. Misc., p. 152, 1834.--Mexico.
Type locality restricted to Guadalajara, Jalisco, Mexico, by
Smith and Taylor (1950a:334).
_Thamnophis macrostemma macrostemma_, Smith and Taylor,
Bull. U. S. Natl. Mus., 187:163, October 5, 1945.
_Thamnophis subcarinata subcarinata_, Smith, Herpetologica,
5:63, May 31, 1949.
_Thamnophis eques eques_, Smith, Copeia, no. 2:139, June 8,
1951.
Jiquilpan; Lago de Cuitzeo; Lago de Patzcuaro (17);
Patzcuaro (5); Tangancicuaro; Tupataro (2); Undameo; Zacapu.
Although this snake has been collected in open pine-oak forest and in
oak-bunch grass associations, it seems to reach its greatest abundance
in marshes on the Mexican Plateau at elevations of 1550 to 2300 meters.
~Thamnophis melanogaster canescens~ Smith
_Thamnophis melanogaster canescens_ Smith, Zoologica,
27:117, October 23, 1942.--Chapala, Jalisco, Mexico.
Lago de Cuitzeo (5); Lago de Patzcuaro; Patzcuaro;
Tacicuaro; Tangamandapio (2).
This species of garter snake seems to be most abundant in the marshes
adjacent to the lakes on the Mexican Plateau in Michoacan and Jalisco.
At these elevations (1550 to 2200 meters) it often is found in
association with _Thamnophis eques eques_ and sometimes with _Thamnophis
dorsalis cyclides_. On June 11, 1958, individuals of this species were
found in a hyacinth-choked marsh at Tangamandapio at night.
One specimen from Tangamandapio (UMMZ 119414) had, in life, a dark
chocolate brown dorsum, reddish brown sides, and cream-colored belly,
chin, and labials. There were no longitudinal dorsal stripes.
~Thamnophis scalaris scaliger~ (Jan)
_Tropidonotus scaliger_ Jan, Elenco sistematico degli Ofidi,
p. 70, 1863.--No type locality designated. Type locality
restricted to Mexico City, Distrito Federal, by Smith and
Taylor (1950a:329).
_Thamnophis scalaris scaliger_, Smith, Zoologica, 27:103,
October 23, 1942.
Cerro Tancitaro (2); Nahuatzen; Opopeo; 26 km. S of
Patzcuaro.
The few specimens of this species from Michoacan have been collected at
elevations from 1800 to 3400 meters in pine or fir forest in the
Cordillera Volcanica.
~Micrurus distans michoacanensis~ (Duges)
_Elaps diastema michoacanensis_ Duges, La Naturaleza, ser.
2, 1:487, 1891.--Michoacan. Type locality restricted to
Apatzingan, Michoacan, Mexico, by Smith and Taylor
(1950a:335).
_Micrurus distans michoacanensis_, Zweifel, Amer. Mus.
Novitates, 1953:11, June 26, 1959.
Apatzingan (6).
All specimens were collected in the arid scrub forest of the
Tepalcatepec Valley. The number of black rings on the body varies from
six to eleven. In this respect they agree with the diagnosis of this
subspecies presented by Zweifel (1959b:9).
~Micrurus laticollaris~ (Peters)
_Elaps marcgravii laticollaris_ Peters, Monats. Akad. Wiss.
Berlin, p. 877, 1869.--Izucar de Matamoros, Puebla, Mexico.
_Micrurus laticollaris_, Schmidt, Publ. Field Mus. Nat.
Hist., zool. ser., 20:39, December 11, 1933.
El Sabino (2); Lombardia.
This species ranges throughout the Balsas-Tepalcatepec Basin westward
into Colima; specimens from Michoacan were collected in arid scrub
forest at elevations from 500 to 1050 meters. The limited observations
on _Micrurus distans michoacanensis_ and _M. laticollaris_ indicate
that, at least in the Tepalcatepec Valley, _M. laticollaris_ seems to
inhabit slightly more mesic areas than does _M. distans michoacanensis_.
~Pelamis platurus~ (Linnaeus)
_Anguis platura_ Linnaeus, Systema naturae, ed. 12, 1:391,
1766.--Pine Island, Pacific Ocean.
_Pelamis platurus_, Gray, Ann. Philos., p. 15, 1825.
Boca de Apiza.