Relative growth of Eurynolambrus australis H. Milne Edwards & Lucas, 1841 (Decapoda: Brachyura: Majidae): use of epibionts to interpret moulting patterns and maturation

Abstract

Abstract Males of the brachyuran crab Eurynolambrus australisH. Milne Edwards & Lucas, 1841 have three phases of growth recognizable by breaks in relative growth in the chelipeds in relation to carapace width. Females have two growth phases marked by increased abdomen width and pleopod length at sexual maturity. The difference between the maximum size of E. australis and the maximum size of the preceding phase in both sexes is large and may not be achieved in a single moult, suggesting that post-pubertal moulting could occur. Relative growth could involve both growth- and size-allometry. This is supported to some extent by the distribution of spirorbid tube worms. The lack of correlation between number and size of tube worms and crab carapace width suggests that epibionts do not accumulate over time. Crabs without attached tube worms (suggesting recent moulting) occur in all growth phases, but some of these may have recently moulted. Some large specimens, however, do carry a load of epibionts large enough to suggest terminal moulting. The possibility of post-pubertal moulting remains an open question.