EPIBIOSIS AND RHIZOCEPHALAN INFESTATION PATTERNS IN RELATION TO THE REPRODUCTIVE BIOLOGY OF LITHODES FEROX (FILHOL, 1885) (ANOMURA: LITHODIDAE)

Abstract

ABSTRACT Aspects of the reproductive biology of Lithodes ferox, namely, size dimorphism, rhizocephalan infestation, occurrence of ovigerous females, morphometrics of chelae, and incidence of epibionts, were studied in individuals collected from fishery research cruises off southern Namibia between 1983 and 1989. All these aspects appeared closely related to each other. A small proportion of the population was infested by the rhizocephalan cirripede Briarosaccus callosus. We found no strong evidence of seasonality in reproduction. Two discontinuities in male chela allometry were identified: juvenile-immature, and immature-adult. Relative chela growth in females was closer to isometry. Size at maturity was estimated at 108-mm CL for males, based on chela allometry, and 83-mm CL for females, based on the presence of eggs on the pleopod setae. Fecundity increased with female size. Females carried up to 8,000 eggs each. Epibiosis by the thoracican cirripede Poecilasma kaempferi was more prevalent in females than in males, and in ovigerous rather than in nonovigerous females. The pattern shown by the proportion of crabs with epibionts within each host size class varied between the sexes. There is a good fit between maturity and epibiosis patterns with size in females. The high levels of epibiosis in mature females are probably due to a reduction in molt frequency on maturation.