Characters of the species.—Size small (extremes in external measurements of adults: total length, 87-123; length of tail vertebrae, 34-53; length of hind foot, 12-15; length of ear, 9-12). Upper parts pale drab or reddish-brown to almost black; underparts grayish to cream-buff.
Geographic variation.—Eight subspecies are here recognized (see [Figure 11]). Features that vary geographically are mostly the same as those that do so in B. musculus (see [page 609]).
External and cranial size is less in B. t. allex, the southernmost subspecies, and progressively more in B. t. paulus, B. t. taylori, B. t. ater, B. t. subater, B. t. fuliginatus, B. t. canutus, and B. t. analogous. Size is largest in subspecies that occur at higher altitudes. Those subspecies are B. t. analogous and B. t. fuliginatus. The correlation with Bergman's Rule is less exact in B. taylori than in B. musculus. It is noteworthy that the smallest subspecies, B. t. allex, occurs in the area where the two species are sympatric.
There is close correlation in B. taylori, as also in B. musculus, of darker pelages with zones of high relative humidity. The subspecies having dark pelages are: analogous, fuliginatus, and subater. The two first-mentioned subspecies occur at high altitudes, and the other, subater, occurs in the humid coastal region of Texas. The paler subspecies, taylori, canutus, and allex, occur at lower altitudes. Two subspecies that occur at relatively high altitudes, ater and paulus, are reddish-brown. The color of pelage in these subspecies resembles the color of soil upon which they live. Blair and Blossom (1948:5) demonstrated close correlation of color of soil with color of pelage in B. t. ater by use of an Ives tint photometer.
Fig. 11. Distribution of Baiomys taylori. Known localities of occurrence are represented by circles and black dots; the former denote localities that are peripheral (marginal) for the subspecies concerned.
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1. B. t. allex 2. B. t. analogous 3. B. t. ater 4. B. t. canutus |
5. B. t. fuliginatus 6. B. t. paulus 7. B. t. subater 8. B. t. taylori |
Natural History