PALEOECOLOGICAL SIGNIFICANCE OF SHORT-TAILED SHREW (BLARINA), WITH A SYSTEMATIC DISCUSSION OF BLARINA-OZARKENSIS

The parapatric distributions of Recent Blarina brevicauda brevicauda, B. b. kirtlandi and B. b. carolinensis correspond to the subhumit microthermal, humid microthermal and humid mesothermal climatic regions. Three late Pleistocene populations of Blarina can be equated with the extant subspecies B. b. brevicauda, B. b. birtlandi and B. b. carolinensis by means of statistical analysis of mandibular parameters. All 3 ecotypes are found together, distinct and sympatric, in the Pleistocene deposits of Cumberland, New Paris No. 4 and Peccary Caves; Meyer Cave, Crankshaft Pit, Natural Chimneys and Welsh Cave [USA] local faunas contain 2 distinct phena. Coexistence of these phena in the same deposit without apparent interbreeding suggests a specific rather than subspecific relationship. Sympatry of these phena during the Pleistocene suggests that a more equable climate existed during glacial time than at present and that sympatric phena of Blarina coexisted in partitioned niches that presently are not defined. Post-glacial continental climates subsequently divided the 3 phena into their existing parapatric distributions. B. b. fossilis is synonymized with B. b. brevicauda. B. ozarkensis, an extinct species from the Conard Fissure, is distinguished from other species of Blarina by the absence of the lingual accessory cone posterior to the protoconid on the 1st lower unicuspid of extant species; the proportionally larger and more bulbous cingula of the 3rd and 4th upper unicuspids, the 2nd lower unicuspid and the lower molars; its reduced 5th upper unicuspid; and its reduced talonid of M3. The Conard Fissure population of B. ozarkensis is more variable than any modern population of Blarina examined.