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SPECIES Rattus tanezumi

Author:Temminck, 1844.
Citation:In Siebold, Temminck, and Schlegel. Fauna Japonica, Arnz et Socii, Lugduni Batavorum: 51.
Common Name:Oriental House Rat
Type Locality:Japan, possibly from near Nagasaki on Kyushu Isl (see Jones and Johnson, 1965).
Distribution:Apparently indigenous to SE Asia, from E Afghanistan (Niethammer and Martens, 1975) through C and S Nepal (below about 2000 m), Bhutan, N India, N Bangladesh and NE India into S and C China (including Hainan Isl), Korea, and mainland Indochina (including offshore islands) south to Isthmus of Kra; also probably native to Mergui Arch.; not found in the Andaman Isls and most of the Nicobar Isls. Whether native or introduced to Taiwan and Japan is unknown (but see Yosida and Harada, 1985; Japanese distribution reviewed by Kaneko, 1994). Most likely introduced to the Malay Peninsula and islands on the Sunda Shelf (Medway and Yong, 1976) and nearby archipelagos just off of the Shelf, including the Mentawais (Musser and Califia, 1982; Musser and Newcomb, 1983) and Nicobar Isls (the only museum records are the holotype of pulliventer from Great Nicobar Isl described by Miller, 1902, and BMNH 20.3.1907 from Little Nicobar Isl; Musserís identifications). Certainly introduced to the Philippines (Musser, 1977a; Heaney et al., 1998, summarized records), Sulawesi (Musser and Holden, 1991), and numerous islands east through the Moluccas and Nusa Tenggara (Flannery, 1995b; Musser, 1970a, 1972, 1981c) to W New Guinea (Flannery, 1995a; Sody, 1941), and farther east through Micronesia to islands of Eniwetok and Fiji (Johnson, 1962a, b), but not to the Samoas where R. rattus occurs (Yosida et al., 1985).
Status:IUCN Ė Lower Risk (lc).

Rattus rattus species group. The authority is usually cited as 1845, but was published in 1844 (Holthuis and Sakai, 1970). The name tanezumi is the oldest for the 2n = 42 group of Asian houserats that is distinguished from the 2n = 38/40 R. rattus not only by chromosomal characters but also morphological and biochemical traits (see account of R. rattus). The probable indigenous range is generally north and east of peninsular India (judged by Musserís study of material in AMNH, BMNH, FMNH, MZB, RMNH, USNM, and geographic distribution of karyotypes with 2n = 42; Duncan and Van Peenen, 1971; Gadi and Sharma, 1983; Markvong et al., 1973; Niethammer, 1975; Niethammer and Martens, 1975; Ray-Chaudhuri and Pathak, 1970; Raman and Sharma, 1974, 1977; Gill and Gupta, 1989; Tripathy et al., 1985; Yong, 1969; Yosida et al., 1971). In the southern portion of the Western Ghats (along SW peninsula in Karnataka and Maharashtra States) at Sagar, three individuals trapped in forest exhibited 2n = 42, and three from a nearby "domestic site" had 2n = 38. The former diploid number was attributed to R. r. wroughtoni and the latter to R. r. rufescens (Lakhotia et al., 1973; Pradhan et al., 1991), but holotypes and paratypes of wroughtoni represent R. rattus (which includes rufescens as a synonym), and the 2n = 42 sample is R. satarae (see that account). Dark-bellied populations identified as R. rattus rufescens are found occurring together with white-bellied rats in India, which prompted Tiwari et al. (1972) to recognize rufescens as a separate species, but it is simply a phenotypic morph of R. rattus found in the same populations containing the white-bellied morph (see account of R. rattus). Distributional and ecological relationships between R. rattus and R. tanezumi along the N portion of the Indian subcontinent where indigenous ranges are either parapatric or overlap still requires resolution (see discussion in Corbet and Hill, 1992).

More than one species may be present in our concept of R. tanezumi, but careful taxonomic revision using morphological, chromosomal and molecular characters will have to test such an hypothesis. Verneau et al. (1997), for example, split Vietnamese R. flavipectus from R. tanezumi because of a difference in Fundamental Numbers of karyotypes. Wang (2003) recognized yunnanensis as a separate species, but no data substantiates that treatment (see G. M. Allen, 1940, and Osgood, 1932). He also listed brunneusculus as a species with sladeni, molliculus, canna, tistae, and hainanicus as subspecies. We associate the first four taxa with R. tanezumi and hainanicus with R. andamanensis (see that account). An extensive taxonomic survey of these populations, based on a combination of DNA sequencing and morphological studies, is currently underway by K. Aplin, H. Suzuki and their various collaborators (Aplin et al., 2003b; K. Aplin, in litt., 2004). Their preliminary analysis, using the mitochondrial cytochrome b gene, suggests that the 2n = 42 Asian group includes two distinct taxa, with a level of divergence equal to or greater that characterizes the 2n = 38 cluster. Aplin et al. (2003b:489) summarized the fundamental division as between ". . . an endemic Southeast Asian taxon (recorded from Vietnam, Cambodia and southern Laos) and a northern and South Asian taxon (recorded thus far from Japan, Hong Kong, northern Vietnam, northern Laos and Bangladesh). These taxa are probably regionally sympatric in parts of Vietnam and Laos." Their work also suggests that island populations off the Sunda Shelf contain a complex admixture of both major haplotype groups, suggestive of prehistoric introductions from multiple areas with subsequent hybridization (K. Aplin, in litt., 2004). Aplin et all. (2003c:489) suggested that ". . . it would be premature to speculate on the appropriate names for each of the two Asian taxa," and caution that ". . .the apparent extension of the north Asian taxon (which probably includes Japanese tanezumi) through to the Indian subcontinent raises the possibility that tanezumi may not be the earliest available name for this group."

Females in most populations of R. tanezumi have five pairs of mammae (one pectoral, one postaxillary, one abdominal, and two inguinal), but in some populations the postaxillary pair is twinned with the teats close together (less than 1 cm apart, usually 5 mm). This configuration is different from the six pairs of teats characterizing certain species of Rattus in the R. rattus species group (e. g., R. andamanensis) in which there are two distinct pairs of postaxillary teats, usually 1 cm or more apart. We have not seen such variation in R. rattus.

Phallic morphology of Chinese flavipectus described by Yang and Fang (1988) in context of assessing phylogenetic relationships among Chinese murines. Standard karyotype of Philippine samples described by Rickart and Musser (1993). Taxonomic, chromosomal, and ecological aspects of Chinese populations (under flavipectus) described by Zhang et al. (2000). Md Nor (1996) documented its distribution and ecology on the small islands off the northern tip of Sabah. The species does not occur on Christmas Isl or Madagascar (R. rattus was introduced on those islands), or in the Andaman and Nicobar Isls except for Greater Nicobar Isl (see above); R. rattus from Barren Isl is the only recorded introduction of a commensal Rattus in the Andaman Isls (see account of R. andamanensis).




    alangensis Chasen, 1937
    amboinensis Laurie and Hill, 1954
    argyraceus Sody, 1941
    auroreus Sody, 1941
    barussanoides Sody, 1941
    benguetensis Hollister, 1913
    bhotia Hinton, 1918
    brevicaudus Kuroda, 1952
    brevicaudus Chakraborty, 1975
    brunneus (Hodgson, 1845)
    brunneusculus (Hodgson, 1845)
    bullocki Roonwal, 1948
    canna (Swinhoe, 1871)
    coloratus (Hollister, 1913)
    dammermani Thomas, 1921
    dentatus (Miller, 1913)
    diardii (Jentink, 1880)
    exsul (Miller, 1913)
    flavipectus (Milne-Edwards, 1872)
    fortunatus (Miller, 1913)
    gangutrianus Hinton, 1919
    germaini (Milne-Edwards, 1872)
    griseiventer (Bonhote, 1903)
    insulanus (Miller, 1913)
    kadanus Chasen, 1937
    kelleri (Mearns, 1905)
    khyensis Hinton, 1919
    kurokuma Kuroda, 1953
    kramensis Kloss, 1919
    lalolis Tate and Archbold, 1935
    lanensis Kloss, 1919
    lontaris Chasen, 1937
    macmillani Hinton, 1919
    makassarius Sody, 1941
    makensis Kloss, 1916
    mansorius Johnson, 1962
    masaretes Sody, 1937
    mesanis Kloss, 1919
    mindanensis (Mearns, 1905)
    moheius Chasen, 1937
    molliculus Robinson and Kloss, 1922
    moluccarius Sody, 1933
    neglectus (Jentink, 1880)
    nemoralis (Blyth, 1851)
    obiensis Sody, 1941
    ouangthomae (Milne-Edwards, 1872)
    palelae Miller and Hollister, 1921
    palembang Tate and Archbold, 1935
    panjius Chasen, 1937
    pannellus (Miller, 1913)
    pannosus (Miller, 1900)
    pelengensis Sody, 1941
    pipidonis Chasen, 1937
    poenitentiarii (Kloss, 1915)
    portus (Kloss, 1915)
    povolny Niethammer and Martens, 1975
    pulliventer (Miller, 1902)
    rangensis (Kloss, 1916)
    robiginosus (Hollister, 1913)
    robinsoni Chasen, 1940
    robustulus (Blyth, 1859)
    sakisimana Tokuda, 1939
    samati Sody, 1932
    santalum Sody, 1932
    sapoensis Sody, 1941
    satarae Hinton, 1918
    septicus Sody, 1933
    shirokuma Kuroda, 1953
    sladeni (Anderson, 1879)
    sumbae Sody, 1930
    tablasi Taylor, 1934
    talaudensis Sody, 1941
    tatkonensis Hinton, 1910
    thai Kloss, 1917
    tikos Hinton, 1919
    tistae Hinton, 1918
    toxi Sody, 1941
    turbidus (Miller, 1913)
    yeni Dao, 1960
    yunnanensis (Anderson, 1879)
    zamboangae (Mearns, 1905)

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