BAUER, R.T.*; NEWMAN, W.A.; Univ. of Louisiana, Lafayette; Scripps Inst. Oceanography: Protandric simultaneous hermaphroditism in the marine shrimp Lysmata californica (Caridea: Hippolytidae)

Until recently, the only hermaphroditism documented in decapod crustaceans was protandry, in which individuals first develop and function as males (male phase = MP) before changing to females (female phase = FP). However, studies on Lysmata wurdemanni (Gulf of Mexico) and L. amboinensis (Indo-Pacific) have shown that their FPs, externally female in morphology, mate successfully both as male and female. To determine the extent of this sexual system, protandric simultaneous hermaphroditism (PSH), in the genus Lysmata, observations were made on L. californica, a warm temperate eastern Pacific species. FPs paired with other FPs went through successive cycles of vitellogenesis, molting, spawning, and embryo incubation. Time-lapse video observations confirmed that FPs copulate as males and inseminate postmolt, prespawning FPs. Such FPs maintained alone did not self-fertilize. Thus, FPs of L. californica are outcrossing simultaneous hermaphrodites. Size-frequency distributions showed that individuals develop first as MPs before changing to FPs. Individuals apparently change from MP to FP in a single molt, as shown by (a) “transitional” individuals that were fully MP externally but whose ovotestes were full of vitellogenic oocytes and (b) a distinct change in pleopod morphology from MP to FP. FPs retain male gonopores, and relative growth of male ejaculatory ducts is similar in MPs and FPs. Pleopod flanges related to embryo incubation are somewhat masculinized in FPs. PSH is probably widespread in the genus Lysmata. However, given the intrageneric variability of sexual systems of other carideans, simple protandry or even gonochory are possible in other Lysmata spp.