Microtus pennsylvanicus (Ord, 1815) . In Guthrie, New Geogr., Hist., Commi., Grammar, Philadelphia, 2nd ed., 2:292.

TYPE LOCALITY: USA, Pennsylvania, "meadows below Philadelphia."

DISTRIBUTION: Meadowlands interspersed across boreal and mixed coniferous-deciduous biomes of North America: C Alaska to Labrador, including Newfoundland and Prince Edwards Island, Canada; south in Rocky Mountains to N New Mexico, in Great Plains to N Kansas, and in Appalachians to N Georgia, USA; isolated populations in W New Mexico and Florida, USA, and in N Chihuahua, Mexico.

STATUS: U.S. ESA - Endangered as M. p. dukecampbelli; IUCN - Endangered as M. p. chihuahuensis and M. p. dukecampbelli.

SYNONYMS: acadicus, admiraltiae, alborufescens, alcorni, aphorodemus, arcticus, aztecus, chihuahuensis, copelandi, dekayi, drummondii, dukecampbelli, enixus, finitus, fontigenus, fulva, funebris, hirsutus, insperatus, kincaidi, labradorius, longipilis, magdalenensis, microcephalus, modestus, nasuta, nesophilus, nigrans, noveboracensis, oneida, palustris, pratensis, provectus, pullatus, rubidus, rufescens, rufidorsum, shattucki, stonei, tananaensis, terraenovae, uligocola, wahema.

COMMENTS: Subgenus Mynomes, pennsylvanicus species group sensu Zagorodnyuk (1990) . Proposed as conspecific with Old World M. agrestis by Klimkiewicz (1970), but Gbanded chromosomal differences support their recognition as distinct species (Modi, 1987; Vorontsov and Lyapunova, 1986). Aside from the probable insular derivative M. breweri (see above account), pennsylvanicus may be closely related to M. montanus and M. townsendii among New World species (see Hooper and Hart, 1962; Modi, 1987; Moore and Janecek, 1990). Regional studies of variation undertaken (e.g., Anderson, 1956; Anderson and Hubbard, 1971; Weddle and Choate, 1983), but comprehensive review of entire species warranted. Insular form provectus relegated to subspecific status by Chamberlain (1954) and Moyer et al. (1988) and nesophilus by Jones et al. (1986). See Reich (1981, Mammalian Species, 159).