Okinawa Island Spiny Rat

discussion

Discussion: Originally described as a subspecies of T. osimensis (Johnson, 1946 a), but chromosomal evidence (2 n = 44 for muenninki, 2 n = 25 for osimensis), as well as external and cranial morphology distinguish muenninki as a separate species (Kaneko, 2001; Tsuchiya, 1981, Tsuchiya et al., 1989). Based upon molar measurements, Kaneko (2001) suggested that the late Pleistocene specimens identified as T. osimensis by Kowalski and Hasegawa (1976) and Kawamura (1989, 1991, 1994) actually represent T. muenninki and T. osimensis, indicating that both species occurred on Okinawa during late Pleistocene. Kaneko cautioned, however, that the fossils must be reexamined to confirm these possible identifications. A population of Tokudaia also occurs on Tokuno-shima Isl, south of Amami-oshima and north of Okinawa. Chromosomal distinctions between osimensis (2 n = 25) from Amami-oshima, muenninki (2 n = 44) from Okinawa, and the population from Tokuno-shima Isl (2 n = 45) were documented by Honda et al. (1978), Tsuchiya (1981) and Tsuchiya et al. (1989). While that data suggested the Tokuno-Shima Isl sample to represent a third species, Kaneko unfortunately could not include the population in

Order Rodentia - Family Muridae

distribution

Distribution: Known by modern specimens from N Okinawa, and late Pleistocene and Holocene samples from Okinawa and adjacent island of Le-jima (Kawamura, 1989; Kowalski and Hasegawa, 1976).

Order Rodentia - Family Muridae

materials_examined

Type Locality: Japan, Ryukyu Isls (= Nansei Isls), N Okinawa Isl, Hentona (western coast).

Order Rodentia - Family Muridae

discussion

COMMENTS: Originally described as a subspecies of T. osimensis (Johnson, 1946), chromosomal evidence, as well as external and cranial morphology, clearly distinguished muenninki as a separate species (Tsuchiya, 1981).

Order Rodentia - Family Muridae