Abstract / Introduction / Summary:
The deep-sea spider crab Cyrtomaia suhmii Miers, 1886 (Oregoniidae) is distributed throughout the Indo– West Pacific region, but in Japan it has previously been recorded only from Tosa Bay (Kochi Prefecture) and Sagami Bay (Kanagawa Prefecture). In January 2020, an ovigerous female was captured at a depth of 360– 400 m off Inatori, Higashi-Izu Town, Shizuoka Prefecture. This represents the first record of C. suhmii from Shizuoka Prefecture and the first confirmed ovigerous specimen of this species in Japan. The female measured 63.5 mm in carapace length and 78.7 mm in carapace width and carried approximately 7,500 eggs. Egg diameter ranged from 0.63 to 0.92 mm and increased gradually during rearing. Embryonic development was described following the stages of Pillay and Ono (1978). Egg mortality occurred during late development, likely due to fungal contamination after filter backwashing in the aquarium system. These observations provide new information on the reproductive biology of C. suhmii and contribute to understanding the life history of deep-sea spider crabs in Japanese waters.
