Reproductive biology of the bopyrid isopod Robinione overstreeti, a branchial parasite of the ghost shrimp Callichirus islagrande (Decapoda: Callichiridae) in the Gulf of Mexico

Abstract

ABSTRACT Robinione overstreeti is a bopyrid isopod endemic to the Gulf of Mexico that inhabits the branchial chamber of the ghost shrimp Callichirus islagrande. Information on this host–parasite association is scant. This study describes population and reproductive features of R. overstreeti and its host. A total of 90 (9.97%) out of 903 individuals of C. islagrande collected from Tamiahua lagoon, Veracruz, Mexico, between April 2012 and October 2013, were parasitized by R. overstreeti. Parasite prevalence in male and female ghost shrimps was similar. However, no parasitized ovigerous females of C. islagrande were recorded, suggesting that R. overstreeti is a parasitic castrator. Host and parasite body sizes were positively correlated suggesting early host infestation by parasites and simultaneous growth of the host and parasite. Parasitic isopods frequently inhabited the same branchial chamber (n = 77) of ghost shrimps as adult male-female pairs. Females were occasionally found with supernumerary juveniles and cryptoniscus larvae in the same host individual, and rarely solitarily. Furthermore, the body size of paired adult male and female parasites was tightly correlated suggesting long-term ‘social’ monogamy in R. overstreeti. Fecundity in R. overstreeti varied between 1668 and 9884 embryos female−1 and increased with female body size.