Rattus norvegicus (Berkenhout, 1769) . Outlines of the Natural History of Great Britain and Ireland, 1:5.

TYPE LOCALITY: Great Britain .

DISTRIBUTION: Original distribution assumed to be SE Siberia and N China (Heilongjiang), but introduced worldwide where it is more common in colder climates of high latitudes (Kucheruk, 1990); in warmer regions and tropics restricted to habitats highly modified by humans—sewers, buildings, wharves, and breakwaters, for example (Johnson, 1962a).

SYNONYMS: norvegicus var. albus, caraco, caspius, cauquenensis, decaryi, decumanoides (nomen nudum), decumanus, discolor, griseipectus, hibernicus, hoffmanni (Trouessart, 1904, not Matschie, 1901), humiliatus, hybridus, insolatus, javanus, leucosternum, lutescens, magnirostris, decumanus var. major, maniculatus, norvegicus var. orii, norvegicus var. otomoi, plumbeus, praestans, primarius, simpsoni (Philippi, 1900, not Ellerman, 1949), socer, sowerbyi, surmulottus, tamarensis (see Ellerman and Morrison-Scott, 1951; Jones and Johnson, 1965; Laurie and Hill, 1954; Mahoney and Richardson, 1988; Musser, 1977a; Musser and Newcomb, 1985; Sody, 1941; and Osgood, 1943).

COMMENTS: Geographic variation among presumably native Chinese populations reported by Wu (1982). Samples from native Asian, free-living introduced, and laboratory populations were the subjects of numerous morphological (e.g., Bugge, 1970; Greene, 1935), physiological, chromosomal and molecular (many are summarized in Yosida, 1980, and Levan et al., 1990) studies, which have produced among the mass of data a gene map of R. norvegicus (Levan et al., 1990), and results of attempted hybridizations between R. norvegicus and different forms of R. rattus (summarized by Yosida, 1980). Review of European populations provided by Becker (1978b); overall review of systematics reported by Milyutin (1990). Phylogenetic relationships to other members of subgenus Rattus equivocal (e.g., contrast Chan et al., 1979, with Pasteur et al., 1982), but morphological and biochemical data indicate significant phylogenetic divergence between R. norvegicus and R. rattus (Baverstock et al., 1983 a, b, 1986; Chan, 1977). Phallic morphology of Chinese samples described by Yang and Fang (1988) in context of assessing phylogenetic relationships among Chinese murines.