Recent cryptic extinction of squamate reptiles on Yoronjima Island of the Ryukyu Archipelago, Japan, inferred from garbage dump remains

Abstract

We report recent skeletal remains of squamate reptiles screened from an old garbage dump deposit found on Yoronjima Island, a small island of the Ryukyu Archipelago, in the subtropical northwestern Pacific. Identified remains include at least three species of terrestrial snakes, one sea snake, and seven species of lizards. Among these, the Ryukyu Short-legged Skink, Ateuchosaurus pellopleurus; Kuroiwa’s Leopard Gecko, Goniurosaurus kuroiwae; and one unidentified Gekko species constitute entirely new findings. For a further two snake species and one lizard species, the evidence presented here is the first specimen-based documentation that these species existed on this island, where they are now evidently absent. The present absence of these species on Yoronjima is mainly attributable to predation by the Japanese Weasel, Mustela itatsi, introduced in the mid-1950s. Our results demonstrate a prominent case of recent, sizable deterioration of insular herpetofaunal diversity, which has never been documented with certainty in the Ryukyu Archipelago, and suggest that human influence should be taken into account in biodiversity research in this area.