Marine Priority Region No. 33 (MPR 33) lies
in the State of Guerrero, where the National Commission for Knowledge and Use
of Biodiversity has declared a lack of information on marine species, Class
POLYPLACOPHORA among others. This program was carried out on the rocky
intertidal zone of MPR 33 with the objectives to: 1) determine species
richness, 2) community composition based on families represented, 3) estimate
the density, 4) index of diversity, 5) analyze body proportions and 6)
geographic distribution of species. Three surveys on five sites were conducted
during 2009 and 2012, using one mt2 quadrant for systematic sampling
procedure; collecting all POLYPLACOPHORA specimens found within the quadrants,
then proceeding with their preservation. 441 organisms were analyzed where 17
species were identified, on nine genera within six families. Fifteen new
species were recorded for the MPR 33. Family ISCHNOCHITONIDAE Dall, 1889 was
the best represented in species richness and CHITONIDAE Rafinesque, 1815 in
abundance. Density of 8.82 organisms/m2, the H′ index was 2.38
bits/individuals and J′ = 0.57. The species Chiton (Chiton) articulatus Sowerby, 1832 showed the highest density, greater size
and was found in all five collection sites. Three species, (Chiton (C.) articulatus, Ischnochiton (Ischnochiton) muscarius (Reeve,
1847) and Chiton (Chiton) alboli-neatus Broderip & Sowerby, 1829), were considered wide. Intertidal species
richness was associated with habitat stability and wave intensity; the more
unstable sites had greater richness while most stable sites lower. Species
inventory and understanding the communities’ interactions of the marine fauna
of the State of Guerrero are important; therefore these efforts must be
continued.