The opossum occurs throughout Tamaulipas but is commonest in the south,
especially in the areas of tropical forest and along water courses.
Most of the specimens examined were caught in steel traps baited with
remains of small animals (mostly mammals and birds, but one trap was
baited with the head of a black bass). At Villa Mainero five
individuals were caught in one night in five of seven traps scented
with spilogale musk. These traps were set in runways along a thick
thorn-brush fence, which separated a cornfield from thorn-brush desert.
Along the Rio Purificacion 36 kilometers north and 10 kilometers west
of Victoria an opossum was eaten in a trap by a small carnivore,
probably a felid judging from tracks around the trap.
A female with 14 pouch young was taken in June in the Sierra de
Tamaulipas and weighed 1350 grams; a March-taken female with nine small
young in her pouch, from Soto la Marina, weighed 1800 grams. A male
from the Sierra de Tamaulipas also weighed 1800 grams.
=Didelphis marsupialis californica= Bennett
1833. _Didelphis Californica_ Bennett, Proc. Zool. Soc.
London, p. 40, May 17, type locality restricted to Sonora by
Hershkovitz (_infra_).
1951. _Didelphis marsupialis californica_, Hershkovitz
Fieldiana-Zool., Chicago Nat. Hist. Mus., 31(47):548, July
10.
_Distribution in Tamaulipas._--Southeastern part of state,
north at least to Soto la Marina.
In studying Tamaulipan specimens, I was mindful that Hershkovitz
(1951:550) regarded all opossums of this species in Mexico as a single
subspecies, even though J. A. Allen (1901) recognized two subspecies in
the northeastern part of the Republic. According to Allen (p. 172), _D.
m. texensis_ (to which he ascribed a distribution in Texas and
adjoining Tamaulipas) was described as: "Similar in coloration to _D.
marsupialis_ (_typica_) [_D. m. californica_], but with a relatively
longer tail, longer nasals, usually terminating posteriorly in an acute
angle, instead of being rounded or more or less abruptly truncated on
the posterior border." The available material from Tamaulipas can be
divided into two groups on the basis of shape and proportion of the
nasals. In opossums from the southeast the nasals are truncate
posteriorly and average 47.0 (45.1-48.4) per cent of the condylobasal
length, whereas in specimens from elsewhere the nasals are acute
posteriorly and average 50.7 (49.7-51.8) per cent of the condylobasal
length. Tentatively, therefore, I follow Allen in recognizing two
subspecies in northeastern Mexico.
I note no especial difference in length of tail between _texensis_ and
_californica_. Hooper (1951:3) followed Hershkovitz in reporting as
_californica_ a specimen from Rancho del Cielo; to me, specimens from
this area are referable to _texensis_.
One of the specimens from two miles south and 10 miles west of Piedra
(54917) has a supernumerary tooth lingual and anterior to the last
upper molar. The tooth is small (2.7 mm. long) and peglike.
_Records of occurrence._--Specimens examined, 8: 3 mi. N
Soto la Marina, 1; 2 mi. S, 10 mi. W Piedra, 12,000 ft., 7.
Additional records: Matamoros (Baird, 1858:234); Altamira
(J. A. Allen, 1901:167).
=Didelphis marsupialis texensis= J. A. Allen
1901. _Didelphis marsupialis texensis_ J. A. Allen, Bull.
Amer. Mus. Hist., 14:172, June 15, type from Brownsville,
Cameron County, Texas.
_Distribution in Tamaulipas._--Northern, central and
southwestern parts of state.
_Records of occurrence._--Specimens examined, 7: San
Fernando, 180 ft., 1; Villa Mainero, 1700 ft., 2; 36 km. N,
10 km. W Cd. Victoria (1 km. E El Barretal), on Rio
Purificacion, 1; 12 km. N, 4 km. W Cd. Victoria, 1; Ejido
Santa Isabel (12 km. S Llera), 2 km. W Pan-American Highway,
2000 ft., 1; 4 mi. N Jaumave, 2500 ft., 1.
Additional records: Matamoros (J. A. Allen, 1901:173); El
Mulato, San Carlos Mts. (Dice, 1937:249); Rancho del Cielo
(Hooper, 1953:3).
=Philander opossum pallidus= (J. A. Allen)