Protomyobia panamensis n. sp. is described from Cryptotis parva orophila from Panama. It is the only known Protomyobia with ovoid ventromedian setae on the tibia and genua of legs I in males. Protomyobia americana McDaniel, 1967, is redescribed from its typical host, Cryptotis parva, but mites of the genus Protomyobia from Blarina brevicauda, formerly also classed as P. americana, are here described as Protomyobia blarinae. In males of P. americana, ic 1 is short and thin while cx 12 is much heavier and longer. In P. blarinae, ic 1 is longer than cx I2. These 3 species comprise the P. americana host group which are separable in males from all other Protomyobia in having setae sc i behind level of sc e, seta d 1 short and setiform, cx 12 heavy with a blunt end, and second claw of legs II without a ventral notch. Derived characters of all known Protomyobia species are summarized, and a cladogram of the genus was produced which was similar to the cladogram for the host groups. Ewing (1938) erected the genus Protomyobia based on the species Myobia claparedei Poppe, 1896, from the type host Sorex vulgaris (now araneus) with the type locality as Central Europe. Ewing's description is based on specimens from Blarina brevicauda from near Washington, from Sorex fumeus from New Hampshire, and from an unidentified small short-tailed shrew from North Carolina. Jameson (1948) described Protomyobia claparedei (Poppe, 1896) from Blarina brevicauda from Ontario and New York, and from Sorex cinereus from New York. He mentioned slight differences from the original description of Poppe (1896) and from European specimens borrowed from Radford. He suggested that description of a separate subspecies would be necessary when more data became available. McDaniel (1967) erected the subspecies Protomyobia claparedei americana based on the position of sc i in the male, a character previously mentioned by Jameson. McDaniel stated that Cryptotis parva from Texas was the type host but he also included in the subspecies Protomyobia from Blarina brevicauda, Sorexfontinalis, Sorex cinereus, Sorexfumeus, and Cryptotis parva. Fain et al. (1982) elevated americana from the subReceived 22 August 1986; revised 9 March 1987; accepted 11 September 1987. * Deceased. t Department of Life Sciences, Indiana State University, Terre Haute, Indiana 47809. species to the species level, but included only specimens from Cryptotis parva and Blarina brevicauda. In none of these studies was the ventral side of the male described, and the characters of the mites from the 2 American Blarini genera, Blarina and Cryptotis, had not been compared. Previous studies indicated that one parasite species was present on a number of different hosts, which in turn led to statements concerning transmission between hosts (Jameson, 1948; Jameson and Dusbabek, 1971; Fain et al., 1982). We have now examined characters of Protomyobia from a number of host species. Our analysis indicates more host specificity than formerly recognized and that specimens from Blarina brevicauda and Cryptotis parva from North America, both of which had been known as P. americana, were different. In addition, we found that Protomyobia from Cryptotis parva orophila from Panama constituted a new species, although comparison with related species proved to be difficult because previous descriptions lacked detail. The purpose of this paper is to describe the Protomyobia from Cryptotis parva orophila, to divide P. americana into separate species, and to present the results of our study of the cladistics of Protomyobia. MATERIALS AND METHODS We examined Protomyobia from a number of hosts. Mites from Cryptotisparva orophila from Panama were