The parasitic barnacle Sacculina lata Boschma, 1933 (Cirripedia, Rhizocephala, Sacculinidae) infecting the commercial swimming crab Charybdis miles (De Haan, 1835) (Decapoda, Portunidae) in the Beibu Gulf, South China Sea

Abstract

Abstract A sacculinid rhizocephalan parasite, Sacculina lata Boschma, 1933, was discovered in the Beibu Gulf (= Gulf of Tonkin) west of Hainan Island, China, occurring in 7.4% of 363 Charybdis miles (De Haan, 1835) collected by 30 trawls in July 2017. This is the first time that S. lata has been recorded in Beibu Gulf and in the Chinese Exclusive Economic Zones (EEZs). Of the sampled crabs from 9 stations, 8 males and 19 females were found bearing externae of S. lata on the abdomen, a prevalence of 4.1 and 11.2% in male and female crabs, respectively. The dominant size group of infected males was larger than that of females. There was no significant relationship between water depth and infection rate of the parasite. A positive correlation was found both between volume and weight of externae, and between surface area of externae and abdomen width of the host crabs. Carapace width and wet weight of infected crabs were significantly less than those of uninfected crabs. In male crabs, the first pleopods of infected individuals were shorter than normal, but their pleons were wider. The propodus of the chela of a parasitized crab was significantly larger than that of normal crabs, both in males and females. No rhizocephalan-infected female crab was found bearing eggs.