O. Gy. Dely szerk.: Vertebrata Hungarica 23. (Budapest, 1989)

Cao, van Sung: On the problem of zoogeographical division of the rodent fauna of Vietnam (Mammalia, Rodentia) 57-66. o.

VERTEBRATA HUNGARICA TOM. XXIII. 1989 p. 57.56 On the problem of zoogeographical division of the rodent fauna of Vietnam (Mammalia, Rodentia) By CAO van Sung (Received 30 November, 1986) "On the problem of zoogeographical division of the rodent fauna of Vietnam (Mammalia, Rodentia)" - CAO van Sung - Vertebr. hung., 23: 57-66. 1989. Abstract: Having analysed the rodent fauna of Vietnam author proposes to divide Vietnam into two zoogeographical provinces; a northern one consisting of the north-western, north-eastern and North Truong-son district and a southern one with two districts - South Truong-son and Nam Bo. The boundary between the two provinces is the range of Hái Van. An analysis of the rodent fauna of Vietnam and that of the surrounding countries may assist us in the zoogeographical division of these countries into regions. The boundary between the subtropical and tropical regions crosses the territory of Vietnam, a fact that focusses interest on the zoogeography of this country. In this paper I attempt to discuss on the basis of distribution data of rodents the problem concerning the zoogeographical division of Vietnam. MATERIAL AND METHODS Distribution data were studied of rodent collections deposited in the following institutions: Institute of Ecology and Bioresources, National Center for Scientific Research of Vietnam (Hanoi), University of Hanoi, Institute Pasteur (Ho-Shi-Minh City), Musée Nationale Histoire-naturelle Paris, Hungarian Natural History Museum, Budapest, and Zoological Institute of the Soviet Academy of Sciences, Leningrad. JACCARD's (1902) formula was used for calculating the similarity coefficients between the rodent faunas inhabiting Vietnam's different areas: n 100 . Co = 'n. + n 1 2 where C = number of species common to the two compared areas, n^ and n^ = number of the species exclusive to each areas, respectively RESULTS Before discussing the zoogeographical division of the rodent fauna of Vietnam it is necessary to briefly summarize the physico-geographical characteristics of the country.