[Demography of the snail Plicopurpura pansa (Neotaenioglossa: Muricidae) and constitution of the associated mollusk community, in Guerrero, Mexico].

We quarterly sampled the molluskan community of Playa Ventura, Guerrero, Mexico. Sample size (20 m2 in lm2 units) was determined by the spatial distribution pattern of Plicopurpura pansa using a negative binomial distribution. The density of the P. pansa was 5.19 snails/m2 and the sex ratio near 1:1. The average size was 20.10 mm (most females were 10.5 to 27.0 mm; most males 12.0 to 27.0 mm). Density was high and small sized dominated. Mean size varied with time. General mean weight was 1.79 g. Females weight varied more, maybe because of the reproductive cycle. Recruits were collected in five samplings. Most copulation activity was in March of 2001. The associated community includes 26 species of Gastropoda, five ofBivalvia and one of Polyplacophora, Brachidontes semilaevis being dominant.