Taxonomy and evolutionary relationships of Phillips' small-eared shrew, Cryptotis phillipsii (Schaldach, 1966), from Oaxaca, Mexico (Mammalia: Insectivora: Soricidae)

•The name Cryptotis peregrina (Merriam, 1895) previously encompassed two separate populations of a small-eared shrew of the Cryptotis mexicana-group inhabiting the Sierra de Cuatro Venados and the Sierra de Miahuatlan in Oaxaca, Mexico. Analysis of museum specimens from these two populations, including the type series of C. peregrina, indicates that they are neither conspecific nor even sister taxa. We taxonomically restrict the name C. peregrina to populations in the Sierra de Cuatro Venados and adjoining Sierra Yucuyacua, whereas the name Cryptotis phillipsii (Schaldach, 1966) is available for the population in the Sierra de Miahuatlan. Moreover, we demonstrate that C. phillipsii is the most primitive member of the C. mexicana-group, whereas, C. peregrina is one of the more derived members of the group. Choate's (1970) comprehensive revision of the small-eared shrews of the genus Cryptotis divided the Mexican and Central American species into three informal groupings: the "Cryptotis mexicanagroup," the "Cryptotis parva-group," and a group of three "relict species." At that time, C. mexicana (with four subspecies), Cryptotis goldmani (with two subspecies), and the monotypic Cryptotis goodwini comprised the C. mexicana-group. Based on cranial and postcranial morphology (in particular, unique modifications of the forelimb) and biogeographic patterns, we (Woodman & Timm 1999) recently revised the C mexicana-group, providing evidence that it may represent a natural grouping distinct from other members of the genus. Our revision recognized eight species in the C. mexicana-group, many of which were treated previously as subspecies (Choate 1970, Hall 1981): C. alticola, C. goldmani, C. goodwini, C. griseoventris, C. mexicana, C. nelsoni, C. obscura, and C. peregrina. Cryptotis peregrina, which is endemic to Oaxaca, Mexico, was first described by Merriam (1895) as a subspecies of C. mexicana based on a series of 24 specimens collected by E. W Nelson and E. A. Goldman in 1894 "from mountains 15 miles [south] west of city of Oaxaca" (Merriam 1895:24). Binford (1989) identified this range of mountains as the Sierra de Cuatro Venados. In addition to the type series, Choate (1970) referred specimens from the Sierra de Miahuatlan in southern Oaxaca, including the holotype and two paratypes of Notiosorex phillipsii, to C. mexicana peregrina. We initially agreed with Choate's assessment, referring material from the Sierra de Cuatro Venados and the Sierra de Miahuatlan to the species Cryptotis peregrina (Woodman & Timm 1999). Cranially, the shrews previously considered by Choate (1970) and subsequent authors (e.g., Hall 340 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 1981) to be subspecies of C. mexicana (C. mexicana, C. nelsoni, C. obscura, C. peregrind) are quite similar and can be difficult to distinguish. However, the foreclaws vary noticably in length and breadth among members of the C. mexicana-group (Choate 1970, Woodman & Timm 1999), and we showed that other aspects of the forelimb, in particular the morphology of the humerus, are distinct as well (Woodman & Timm 1999). Our phylogenetic analysis indicated that C. peregrina was the most plesiomorphic member of the C. mexicana-group. Our study (Woodman & Timm 1999) focused mainly on the larger, broad-clawed shrews that we termed the Cryptotis goldmani-group, which are a subset of the C. mexicana-group. Initially, we were interested in the former subspecies of C. mexicana primarily as outgroups to aid in polarizing characters for phylogenetic analysis. In studying Cryptotis peregrina, we depended heavily on specimens from the Sierra de Miahuatlan in the University of Kansas Natural History Museum collection, because they were readily available to us and included the only postcranial material then known for the species. One inconsistency we noted between our study and Choate's revision was that he referred to C. [m.] mexicana as "having less highly developed front feet and claws" (Choate 1970:232) than C. [m.] peregrina. However, the specimens from the Sierra de Miahuatlan had distinctly shorter and narrower claws than C. mexicana. We also observed that their humeri were less modified that those of C. mexicana, adding to our view of their being more plesiomorphic. Recently, we re-studied the holotype and type series of Cryptotis peregrina at the National Museum of Natural History and discovered that Choate's (1970) observations were correct•specimens in the type series from Sierra de Cuatro Venados all possess longer, broader claws than C. mexicana. In addition, we were graciously granted permission by the American Museum of Natural History to remove the humerus from the only known fluid-preserved specimen of C. peregrina from the Sierra Yucuyacua, a mountain range in western Oaxaca that adjoins the Sierra de Cuatro Venados. Study of these specimens indicates that the two populations of Cryptotis inhabiting the Sierra de Cuatro VenadosXSierra Yucuyacua complex and the Sierra de Miahuatlan, respectively, are not conspecific. Herein, we taxonomically restrict the name Cryptotis peregrina to shrews inhabiting the former region. The name Cryptotis phillipsii (Schaldach, 1966) is available for the population in the Sierra de Miahuatlan. Much of what we reported earlier in regard to C. peregrina (Woodman & Timm 1999) actually refers to a combination of C. peregrina and C. phillipsii. It is our purpose here to redescribe C. peregrina and C. phillipsii in light of this new information and to clarify the distinctions among the species in the Cryptotis mexicana-group. In addition, we present a refined hypothesis of phylogenetic relationships among the species in this group of shrews.