A new ctenostome bryozoan ectosymbiotic with terminal‐moult paddle crabs (Portunidae) in New Zealand

Abstract

Triticella capsularis sp. nov. (Bryozoa, Ctenostomata) is newly described as an ectosymbiont of paddle crabs (Ovalipes catharus) in central New Zealand (Bay of Plenty to northern South Island). The bryozoan produces the longest zooids known in the genus Triticella, with colonies forming a “fur” up to almost 10 mm thick on large crabs, mostly males. The densest area of colonisation is the ventral anterior half of the crab. The bryozoan lives only on O. catharus and probably benefits from its “messy” and voracious feeding habits, opportunities for gene exchange during crab swarming behaviour, and dispersal. There is no synchrony between reproduction of the bryozoan and moulting cycles of the crab, as the bryozoan achieves reproductive colony size only on old terminal‐moult crabs. Although visually striking when dense, the bryozoan growth is only superficial and affects neither the behaviour of the crab nor the quality of its meat.