Reproductive traits of Pagurus lanuginosus are described and compared with three sympatric, congener species. Female P. lanuginosus mature at about 5 mm shield length, spawn clutches in autumn and spring, and are considered to have two or more clutches per year. Among the four sympatric Pagurus species (P. lanuginosus, P. middendorffii, P. filholi, P. nigrofascia), spawning season, hatch-out season, annual spawning times, maturity size, and incubation period differed. Specific differences in annual spawning times and some related traits may be explained by differences between species in maximizing the fitness component. Species with several clutches each year and a short incubation may segregate settlement timing to reduce intra- and interspecific competition for unpredictably supplied small shells among settling and newly settled crabs and, thus, maximize the number of clutches per annum. Alternatively, species with single annual clutch, early spring hatch out, and long incubation may be selected to maximize larval survival and/or settlement success if early spring is the optimal season for larval settlement success.