Cryptotis merriami Choate in Costa Rica: Syntopy with Cryptotis nigrescens (Allen) and Possible Character Displacement (Mammalia: Insectivora)

•A recent review of small-eared shrews, genus Cryptotis (Mammalia: Insectivora: Soricidae), in the collection of the Museo Nacional de Costa Rica, revealed a previously unidentified specimen of Cryptotis merriami Choate from the Monteverde Cloud Forest Reserve. This specimen is only the second record of C. merriami from Costa Rica, it represents the southernmost record for the species, and it documents the first case of syntopy between C. merriami and Cryptotis nigrescens (Allen). The co-occurence of C. merriami and C. nigrescens provides conclusive support for the hypothesis they are distinct species within the C. nigrescensgroup (sensu Woodman and Timm, 1993). The soricid community at Monteverde is comprised of three species in three evenly-spaced size classes: the numerically-dominant C. nigrescens, C. merriami, and an undescribed, endemic species the size of typical C. merriami. Morphometrical analysis indicated that C. merriami exhibits no apparent geographic trends in size throughout most of its range, yet the Monteverde specimen is significantly larger than all other C. merriami. Its large size at Monteverde apparently represents character displacement in response to the presence of a more abundant sister species, C. nigrescens; the presence of a second, unrelated shrew the size of more typical C. merriami; or interactions with both.