Effects of cheliped autotomy on female reproductive performance in the porcellanid crab <i>Petrolisthes japonicus</i> (De Haan, 1849) (Decapoda: Anomura: Porcellanidae) under laboratory conditions

Abstract Limb autotomy is a common phenomenon among decapod crustaceans, with chelipeds being the appendages most frequently lost. The loss of chelipeds can reduce mating success in males, as they play a crucial role in mate competition. Little is known, however, about the effects of cheliped autotomy on the reproductive performance of female decapods. This laboratory study investigated the number of spawns, as well as the number and body size of newly hatched larvae, in females subjected to different cheliped autotomy conditions in the porcellanid crab Petrolisthes japonicus (De Haan, 1849). Porcellanids are primarily suspension feeders that use their maxillipeds; thus, the effects of cheliped loss can be evaluated in terms of energy expenditure related solely to the regeneration of lost appendages. Females were reared throughout the breeding season under three different autotomy conditions: both chelipeds intact (control), one cheliped autotomized (OCA), and both chelipeds autotomized (BCA). Females produced eggs and molted in all the groups. The incidence of molting prior to the first spawning differed between the groups, with females in the BCA group molting rather than spawning following the autotomy treatment. Larval body size was unaffected by the autotomy condition, whereas both the number of spawns and the number of larvae were significantly reduced in the BCA group compared to the control group. These findings underscore the negative impact of cheliped autotomy on reproductive performance and demonstrate the trade-off between energy allocation for reproduction and molting (i.e., regeneration) in P. japonicus females, depending on the number of chelipeds lost.