Species information
Scientific name: Geothelphusa grandiovata
Japanese name: オキナワオオサワガニ
Chinese name: 巨圓澤蟹
English name: Okinawa Geothelphusa Freshwater Crab
Origin: Endemic to Okinawajima
Ecology and description
This species is one of the largest in the genus Geothelphusa found in Japan. Its surface is smooth and glossy, with a wide range of colors including reddish-brown, yellowish-brown, and purplish-brown. The species name grandiovata is derived from the combination of the words “grandis” (large) and “ovatus” (oval), indicating its large size and the prominent arch of its carapace. It was once thought that populations from Tokashikijima, Kumejima, and Iheyajima belonged to the same species, but detailed studies have shown that each island has evolved its own distinct species. This species is endemic to Okinawajima.
Okinawa Geothelphusa Freshwater Crab completes its life cycle in streams, with the female protecting eggs on her abdomen until the young crabs undergo their first molt. The species has a broad diet, having been observed consuming frogs, Fabaceae seeds, and snails.
Field photographs taken during our tours, with observation dates
During our 【Herping】 tour in the summer season, there is an opportunity to see this species.
