Coral reef ecosystem–associated echinoderms (Echinodermata) at the Southern Mexican Pacific: species richness, distribution, and composition

Despite the high relevance of echinoderms in the Southern Mexican Pacific coral reef systems, there is no detailed analysis of their regional diversity. Based on records from field surveys and literature, this work analyzed for the first time the echinoderm species composition in coral reef systems in the Southern Mexican Pacific, evaluating their richness and distribution patterns. Fifty-two species represent the region (six Asteroidea, eight Echinoidea, 15 Ophiuroidea, and 23 Holothuroidea), a more significant number than other coral reef systems in the Mexican Pacific and Central America. New records are presented at the region, zone, and site level. At the zone level, the highest species richness occurred in Huatulco (52 species), followed by Ixtapa (45), Acapulco and Puerto Ángel (33), and Puerto Escondido (23). At the site level, La Entrega had the highest number of species (32), while various sites in Acapulco had <10 species. The species richness in the region showed considerably high representativeness since the non-parametric estimators suggested a potential increase of ~10% more species; a more significant percentage is expected in the Acapulco zone (47.5%). All echinoderms had 100% representativeness at the class level, except for Holothuroidea. It is recommended to use as many sampling methods and as many substrates as possible during different seasons and time days to contribute to increasing representativeness. Acapulco had an average taxonomic distinctness different from that predicted by regional models and an echinoderm assemblage more dissimilar from the other areas. The latter may be the product of the scarce sampling effort carried out in Acapulco and probably because it has one of the most degraded coral reef systems within the study area.