Sylvilagus floridanus similis Nelson
1907. Sylvilagus floridanus similis Nelson, Proc. Biol. Soc. Washington, 20:82, July 22.
Some confusion has existed concerning the subspecific identity of the Florida cottontail in Nebraska because of the way in which Nelson recorded specimens in his "The Rabbits of North America" (N. Amer. Fauna, 29:fig. 11, and pp. 169–174, August 31, 1909). He (op. cit.:174) listed the following specimens under the western subspecies, S. f. similis: Two topotypes (Nos. 87784 and 18738/25532) and of course the type; the specimen (No. 116288) from the Snake River [= Snake Creek of maps], 11 mi. NW Kennedy; two from Neligh (126074 and 151438); and one (probably 18680/25410) from Kennedy. But, he listed (op. cit.:172) under S. f. mearnsi, the eastern subspecies, a specimen (10721) from Brownlee, and two from Kennedy. One of the two from Kennedy probably was the one that is recorded in the files of the U.S. Fish and Wildlife Service as "identified by Cary. spec. in Univ. Nebraska". The other, or third, specimen from Kennedy, we judge, did not exist at all but was recorded by Nelson because a card in the reference file, under Kennedy, Nebraska, in addition to No. 18680/25410, carried a second entry, a number 3471X. The latter is the X-catalogue number of specimen No. 116288 from the Snake River! The X-catalogue is used in place of a field catalogue for specimens sent to the mammal collection of the United States Fish and Wildlife Service, by persons who do not keep regular field numbers of their own. It seems that Nelson prepared (or had prepared) his lists of specimens, at least in part, from cards rather than from the labels on the specimens themselves. Some further confusion as to names that Nelson intended to apply to cottontails in Nebraska resulted from the fact that his map (op. cit.:fig. 11) indicated that the localities mentioned above for S. f. mearnsi were within the geographic range of S. f. similis.
Our comparison of each of the Nebraskan specimens with specimens of S. f. mearnsi in comparable pelage from Iowa and with the type and topotypes of S. f. similis reveals that each of the specimens of which catalogue numbers are given above is clearly referable to Sylvilagus floridanus similis.
Because some mammalogists have suspected that intergradation between Sylvilagus floridanus similis and Sylvilagus nuttallii grangeri occurs along the eastern base of the Rocky Mountains, we have examined specimens which may throw light on this matter.
From S. f. similis (holotype and three topotypes), S. n. grangeri (eight practical topotypes from Redfern, South Dakota) differ as follows: Throat patch darker; hind foot shorter; ear (dry) from notch longer; rostrum narrower; posterior extension of supraorbital process enclosing a longer and wider space between it and the braincase; superior border of premaxilla straight in profile instead of convex dorsally; tympanic bullae more inflated; external auditory meatus larger (diameter of the meatus more, instead of less, than crown length of upper molars); posterior border of palate without, instead of with, spine.
Specimens of the two species from places as near each other as extreme southeastern Montana (S. f. similis from Boxelder Creek, Capitol and the Little Missouri River) and Devils Tower, Wyoming (S. n. grangeri), seem not to differ in the length of the hind foot and the ear and in the color of the spot on the chest. Also, the presence or absence of the spine on the posterior margin of the palate is subject to individual variation in these specimens but the other cranial differences, mentioned above, still are apparent. These same cranial differences are readily apparent between specimens of the two species taken only five miles apart in eastern Wyoming (for the precise localities, see the following paragraph). It is concluded, therefore, that S. f. similis and S. n. grangeri do not inter-grade along the eastern base of the Rocky Mountains.
Data on specimens from Laramie County in eastern Wyoming show that S. f. similis is a heavier animal than S. n. grangeri and also that similis molts earlier. For example, an adult female (K.U. No. 15936) taken on July 13, 1945, three miles east of Horse Creek P.O., 6400 ft., weighed 1374 grams and is in fresh pelage, whereas an adult female of S. n. grangeri (K.U. No. 15935), taken on July 17, 1945, two miles west of Horse Creek P.O., 6600 ft., weighed only 1149 grams, and still has some of the worn winter pelage on the upper parts.
Sylvilagus floridanus holzneri (Mearns)
1896. Lepus sylvaticus holzneri Mearns, Proc. U.S. Nat. Mus., 18:554, June 24.