The Current Geographic Faunal Pattern of Reptiles and Amphibians of the Ryukyu Archipelago and Adjacent Regions.

The Ryukyu Archipelago accomrhodates 52 native species/subspecies (26 genera belonging to ten families) of tenestrial reptiles and 22native species/subspecies (ten genera belonging to six families) of amphibians.This paper reviews the geographic similarity and diversity pattemJoflhe current herpetofauna of the Ryukyus and adjacent regions, and discusses factors influencing the formation of it in this archipelago.Cluster analyses of similarity indices for both reptiles and amphibians indicate that the Ryukyu herpetofauna is strongly influenced by geohistory ofthis archipelago involving long isolation especially in its north-cenhal part (i.e., southem Tokara, Amami, anA Oiinawa Groupsf Correlation analyses suggest that the faunal diversity on each island is significantly influenced by iis habitat diversity as reflected by the island area (for reptiles) or height (amphibians). Key words: herpetofauna / isolation / paleogeography / habitat diversityThe Ryukyu Archipelago is an assemblage of old continental islands located in the humid subtropical area of the western Pacific (Takara, 1962l' Kizaki, 1985: Fig. 1).This archipelago accommodates a diverse biota including various reptiles and amphibians (e.g., Ikehara & Kato, 1997).Several previous authors have analysed the Ryukyu herpetofauna (e.g., Inger, L947; Koba, 1962; Kuramoto, 1979) and argued the predominaace of Oriental elements (i.e., taxa having closest relatives in southeastern China and Southeast Asia) over Palearctic elements (i.e., those most closely related to taxa in the main-islands of Japan and eastern China).Since then, a number of taxonomic changes have been made for the Ryukyu herpetofauna as a result of discoveries of new taxa, as well as of philosophical and methodological improvements of biological systematics [see Ota (2000) for example].In this paper, I briefly review the geographic similarity and diversity patterns of the current herpetofauna of the Ryukyu Archipelago and adjacent regions by incorporating information recently added to our knowledge.I then discuss factors influencing the formation of that herpetofauna in this region.