Part 3

Two of the eleven specimens of D. o. largus are of the light color phase (upper parts Cartridge Buff) whereas all but two of the eleven specimens of D. o. compactus are of the light color phase. Each of the cheek-teeth of the upper jaw of D. o. largus has a complete ring of enamel around the dentine of the occlusal surface, as described by Setzer (Univ. Kansas Publ., Mus. Nat. Hist., 1:517, December 27, 1949) for D. o. compactus. The upper dentitions of ten specimens of D. o. compactus examined by me in this respect reveal a total of only five teeth (in four individual animals) that have the enamel ring incomplete; one premolar and three molars are incomplete on the lingual side and one molar is incomplete on the labial side.

Two specimens from Bagdad, Tamaulipas, in the delta of the Río Grande (Nos. 116485 and 11487, U.S.N.M., Biol. Surv. Coll.), are referred to D. o. compactus on basis of long body and long tail. The specimens, both Light Ochraceous-Buff, are so young that not all of the enamel is worn off the crowns of the cheek-teeth. Specimens of D. o. compactus, D. o. parvabullatus and D. o. sennetti of comparable age are not available, and it, therefore, is impossible to know whether size and shape of the skull in the population at Bagdad are the same as they are in D. o. compactus of Padre Island.

Specimens examined.--Total, 11, all from Texas. Aransas County: Mustang Island, 14 mi. SW Port Aransas.

Sigmodon hispidus solus new subspecies

Hispid Cotton Rat

Type.--Male, adult, skull and skin; No. 35468, Mus. Nat. Hist., Univ. Kansas; from island, 88 mi. S and 10 mi. W Matamoros, Tamaulipas, Mexico; 22 March 1950; obtained by E.R. Hall and Curt von Wedel; original No. 6806 E.R. Hall.

Range.--Known from the type locality only but probably occurring on most of the chain of islands off the coast of Tamaulipas.

Diagnosis.--Small; hind foot short; rostrum broad.

Comparison.--From its nearest relative, geographically and morphologically, Sigmodon hispidus berlandieri Baird of the adjacent mainland, S. h. solus differs in smaller size, and a rostrum that is broader in relation to the length of the skull.

Remarks.--On the last night of our stay on the island, traps set in grass approximately 20 inches high, yielded one pair of Sigmodon. The color is lighter than in the average of specimens from the mainland (for instance those from Victoria and Soto la Marina) but can be matched by selected specimens. In animals of equal age, the hind foot and basilar length are shorter in S. h. solus than in berlandieri. The broadening of the rostrum, which occurs with advanced age, is attained in solus when the skull is yet short; the maximum breadth of the rostrum in the adults is more, instead of less, than a fourth of the basilar length.

Measurements.--The following measurements are of specimens in which the occlusal face of each molar tooth is worn flat. The first measurement is of the holotype followed by the corresponding measurement of a male of T. b. berlandieri, No. 116466 from Camargo, Tamaulipas, in parentheses. The third measurement is that of the female from the type locality of S. h. solus and it is followed by the corresponding measurement of a female of T. b. berlandieri, No. 116462 from Camargo, Tamaulipas. Total length, 266 (298),--(293); length of tail, 113 (135),--(137); length of head and body, 153 (163), 155 (156); length of hind foot, 30 (35), 30 (33); basilar length of Hensel, 28.2 (28.9); 27.9 (29.0); zygomatic breadth, 19.5 (--), 19.0 (20.8); mastoidal breadth, 13.9 (14.4), 13.9 (14.8); greatest breadth of rostrum, 7.2 (7.3), 7.8 (7.2); length of nasals, 14.6 (14.1), 13.4 (14.2); crown length of upper molar teeth, 6.3 (6.1), 6.3 (5.9).

Specimens examined.--Two from the type locality.

Lepus californicus curti new subspecies

Black-tailed Jack Rabbit

Type.--Female, adult, skull and skin, No. 35470, Mus. Nat. Hist., Univ. Kansas; from island, 88 miles south and 10 miles west of Matamoros, Tamaulipas, Mexico; obtained 19 March 1950 by E.R. Hall; original No. 6783.

Range.--Islands along coast of Tamaulipas, Mexico.

Diagnosis.--Color pale; size small; ears short; tympanic bullae small.

Comparisons.--From Lepus californicus merriami Mearns (specimens from Fort Clark, Brownsville and intermediate localities), L. c. curti differs in paler color, lesser size except ear that is of almost same length and except interorbital breadth that is approximately same in the two subspecies; tympanic bullae notably smaller. From Lepus californicus altamirae Nelson, L. c. curti differs in having the black patch on the nape less definitely divided by a median, longitudinal band of buffy color, and lesser size. Exception is to be made for the ear and tympanic bullae, which are of approximately the same size in the two subspecies.

Remarks.--The subspecific part of the name Lepus californicus curti is proposed in honor of Dr. Curt von Wedel who shared the pleasure of collecting on the islands where this handsome hare lives.

The specimens of L. c. curti are all females, which, in the genus Lepus, average larger than the males. Comparison of the measurements recorded below with those in the account by Nelson (N. Amer. Fauna, 29:129, 1909) may not reveal the full measure of difference in size between L. c. curti and other subspecies because Nelson (op. cit.) pooled males and females in obtaining the average measurements that he records. For example, he used three males and two females of Lepus altamirae in obtaining an average (op. cit.:117). The specimens of L. c. curti here recorded are thought to be of full size inasmuch as the degree of fusion of bones in the skull, and the density of the cranial bones indicate full adulthood for each specimen. Reproductive-wise, there is no question as to adulthood; each of the four females was pregnant. One specimen had two embryos (each 30 millimeters long in crown-rump measurement) and each of the other specimens contained one embryo. These three embryos were 55, 60, and 105 mm. long.

Three of our specimens, including the holotype, were obtained north of the eighth pass and the other specimen, No. 35473, was obtained a few hundred yards south of the pass. Because the part of the barrier beach south of the pass was connected to the mainland, it is likely that the newly named subspecies occurs also on the adjacent mainland; however, we have examined no specimens of Lepus californicus from the opposite mainland except from Matamoros, ninety miles to the north, and from Altamira, approximately one hundred and fifty miles south of our collecting locality. A specimen from Matamoros, Tamaulipas, and several from Brownsville, Texas, in size of auditory bullae, larger overall size and darker color clearly are L. c. merriami and not L. c. curti.

The small tympanic bullae of the specimens from Padre Island were commented upon by Nelson (op. cit.:149) who found smallness of bullae to characterize many of the specimens from the eastern part of the geographic range of L. c. merriami. In the northeastern part of the geographic range of L. c. merriami, as Nelson pointed out, the small size of the tympanic bullae was one of several evidences of intergradation there with Lepus californicus melanotis, the subspecies next adjacent to the north. In the light of present information, it seems that the smallness of the tympanic bullae in the specimens (3) from Padre Island may be an independent development--an adaptation to environmental conditions that reaches its fullest development on the same chain of islands eighty-odd miles southward of Matamoros. The specimens from Padre Island, although possessing small bullae, in other features, for example, larger size of other parts, are merriami.

The four specimens of L. c. curti are in worn winter pelage and the new pelage is coming in on the thighs. Most of the specimens (6) of the L. c. altamirae are in the same condition of pelage. In color and color pattern, the two subspecies are, to me, indistinguishable except that the black patch on the nape is less widely and less definitely separated into two parts by a median, longitudinal, band of buffy color.

Lepus californicus altamirae was named by Nelson (Proc. Biol. Soc. Washington, 17:109, May 18, 1904) as a black-tailed jack rabbit, Lepus merriami altamirae, but was later transferred by Nelson (N. Amer. Fauna, 29:124, 1909) to the white-sided section of the genus and arranged as a full species, Lepus altamirae. In making this transfer, Nelson (op. cit.:125) wrote that in "This well marked species ... the lack of a black patch on the posterior half of the ear at the tip and the white flanks (somewhat obscured in some of the original specimens) are strong characters which place it in the callotis group." "Posterior half of ears white without any trace of black at tip", was the way Nelson (op. cit.:124) described the ears in L. altamirae. My examination of the original series including the type, reveals that the ears do have some black at the tip of the posterior half in three of the specimens, some brown in one other specimen, and only a dusky tinge in two others. In the four specimens of L. c. curti the tip of the ear is faintly brownish in one animal and dusky in three. The extent of the white flanks seems to be identical in the two series. Fortunately they are in the same pelage and same stage of molt on the hind legs. The one difference that I can detect is in the coloration of the nape. In each of the specimens of L. altamirae the coloration is as described by Nelson (op. cit.:124): "nape with two lateral black bands extending back from base of ears, and separated by a median band of buffy." In L. c. curti the nape is all black in one specimen and the median band of buffy is present in the other three but is narrower and more dusky than in L. altamirae. Since the characters (color of tip of ear and extent of white on the flank) relied upon by Nelson for placing L. altamirae in the callotis group are duplicated in the californicus group, in L. c. curti, there is reason for questioning whether altamirae is correctly placed, taxonomically, in the L. callotis group.

Cursory examination of skulls of the callotis group and the californicus group indicates that the prepalatal spine (the part of the palate which extends anteriorly toward the vomer) is longer in L. californicus than in L. callotis, L. gaillardi and L. alleni. In this feature, L. altamirae agrees with Lepus californicus and differs from members of the Lepus callotis group. Furthermore, the newly named L. c. curti, in color of ear and color of nape, is intermediate between L. altamirae and L. c. merriami. Consequently, Lepus merriami altamirae Nelson, it seems, should stand as Lepus californicus altamirae.

Mention should be made here of the view of Shamel (Proc. Biol. Soc. Washington, 55:25-26, May 12, 1942) that the californicus group should be divided into two groups (each group possibly amounting to something more than a species and something less than a subgenus) on the basis of a white rump and complex infolding of the enamel layer of the front of the first upper incisor versus a dark rump and simple infolding of the mentioned layer of enamel. He placed Lepus californicus merriami Mearns, among other subspecies, in a group different from the one in which he placed several other subspecies of Lepus californicus.

Specimens (skulls with accompanying skins) of the species Lepus californicus in the Biological Surveys Collection of the United States National Museum, representative of a gradual transition from the dark rump and simple fold in the enamel to the white rump and complex fold in the enamel are as follows: L. c. deserticola, No. 29733/41808, Paharanagat Valley, Nevada; Nos. 117463 and 156744, Beals Spring, Arizona. L. c. texianus, No. 24635/32031, Springerville, Arizona; No. 97453, Roswell, New Mexico; No. 118751, Toyah, Texas; No. 118749, Valentine, Texas; and No. 108700, Terlingua Creek, Texas. In the continuously distributed species Lepus californicus, along the northwest to southeast line provided by the localities of occurrence listed immediately above, there is a gradual transition from one kind of fold to the other kind and from one color of rump to the other color. It is clear that Shamel (op. cit.) was in error in his conclusions; the kinds of black-tailed jack rabbits to which Shamel (op. cit.) applied the name Macrotolagus should stand as given below.

Correct names: