Fishing of marine mollusks in Acapulco de Juarez, Guerrero, is intense and diverse and there is little knowledge about this resource. Therefore, for most of species subject to fishing there is no regulation. Due to this, the aims of this study were update inventory of mollusks that are fished for human consumption, determine species that are most important and analyze composition of catch sizes. Biological samples were taken from 2011 to 2014, directly from catches of fishermen. 72 interviews were conducted. 48 species were identified and 16 were the most important. In most species, organisms that did not reach size that would allow them to participate in renewal of reproductive stock were captured. Fishery biological studies are necessary to contribute to regulation of coastal fishing of mollusks.

Chitons from southern México have been poorly documented hitherto and little is known about the species present in this region. Here we report 12 intertidal to shallow subtidal species in six families and nine genera. Chiton articulatus, Chiton albolineatus, and Ischnochiton muscarius were numerically the most common species, accounting for 29%, 27%, and 26% of individuals found, followed by Chaetopleura lurida (7%) and Stenoplax limaciformis (3%). The remainder of the species obtained were present with between 0.5 and 2% of the total sample. Eight species are distributed along the Tropical Eastern Pacific, and four species (I. muscarius, C. albolineatus, C. articulatus, and Lepidochitona acapulcoensis sp. nov.) are endemic to the Mexican subprovince, distributed from Mazatlán to Oaxaca. A morphological comparison of Guerrero chitons with those from several points along the Mexican Tropical Pacific and La Paz Baja California Sur, revealed important variations. Specimens of Chaetopleura lurida from Guerrero contrasts in the valve sculpturing density and arrangement when compared to those from Mazatlán and Oaxaca. Callistochiton elenensis from Guerrero exhibits fewer ribs on the head valve and postmucronal area of the tail valve than specimens from La Paz, Baja California Sur. Color pattern differences were identified for Mazatlán and Oaxaca specimens of I. muscarius, C. articulatus, and C. albolineatus. Details are presented for the valve tegmentum, girdle elements, and radula for each species. In addition, we herein describe Lepidochitona acapulcoensis sp. nov. as a new species using barcode (cox1) and morphological data.

The state of Guerrero, Mexico, has approximately 470 km of seashore but the marine fauna is not well known. The coastline has three marine areas for priority conservation of coastal and oceanic biodiversity, for which Comisión Nacional para la Conservación y Uso de la Biodiversidad (CONABIO) notes a distinct lack of knowledge in these areas. This study was carried out in a rocky intertidal middle zone from Playa ‘Majahua’, Acapulco, located south of Bahia de Puerto Marques. The objectives were to study: the species richness for classes Gastropoda, Bivalvia and Polyplacophora; the community structure from the representation of classes, families and genera; estimate density and species composition within a community; analyse size and structure of populations in the mollusc community; and estimate the diversity index. Three samplings were made in the intertidal middle zone in 2009. Ten square metres were sampled at each visit. Ninety-nine mollusc species were found to be represented, corresponding to 36 families. From all of these species, no record in Acapulco was found for 21 Gastropoda, 5 Bivalvia and 8 Polyplacophora species recorded. Gastropoda was the best represented; 1737 organisms were analysed with an estimated density of 86.8 organisms/m² and 31 species were dominant. Crucibullum umbrella was the largest sized species. The diversity and equity index estimate in Majahua was the highest found for the rocky coast of Guerrero, indicating a mega-diverse area with great uniformity.

The present study contributes to the knowledge of epibionts recorded on sea turtles that nested on a beach in the South Pacific of Mexico. A total of 125 Lepidochelys olivacea turtles nested on Llano Real beach, Guerrero, Mexico, were examined. We collected 450 conspicuous organisms from 8 species from 43 turtles. The corresponding data analysis was carried out to obtain the relative abundance, the relationship between turtle sizes and the presence of organisms, the similarity of species between the sampling months, and the interspecific relationships between the epibionts and the turtles observed. Chelonibia testudinaria was the most abundant species, while Remora remora was the least abundant species. The turtles were divided into six body sections, with the greatest abundance of these organisms located in the head–neck section of turtles, and there was a significant difference in the size of the turtles that presented epibionts and those that did not. C. testudinaria showed greater similarity between sampling months, and the interspecific relationships recorded were commensalism, parasitism, amensalism, and protocooperation. This research contributes the first record of epibionts in L. olivacea nesting in Guerrero, Mexico.