ASSOCIATION OF THE COMMENSAL SCALEWORM GASTROLEPIDIA-CLAVIGERA (POLYCHAETA, POLYNOIDAE) WITH HOLOTHURIANS NEAR THE COAST OF SOUTH-VIETNAM

The Indo-West Pacific commensal scaleworm Gastrolepidia clavigera Schm arda, 1861 is here recorded for the first time from the waters of Viet nam. It was associated with the sea cucumbers Stichopus chloronotus Br andt, S. variegatus Semper, Holothuria atra Jaeger, H. leucospilota Br andt and Actinopyga echinites (Jaeger). The last two species are repor ted as hosts for the first time. Each host harboured 1-3 worms. About half of the infested hosts (51.4%) harboured a pair of worms, one male and one female. The frequency of occurrence of G. clavigera on hosts varied from 31.9% on A. echinites to 80.0% on S. variegatus. Infested hosts were larger than non-infested ones. A sexual size dimorphism is characteristic of G. clavigera with females larger than males. A posit ive correlation between size of males and females from every pair was found; a correlation between size of holothurian hosts and size of the ir commensals was not observed. Commensal worms show two main types of trauma, which are described and discussed.