Large-scale project ‘Chiton of the Mexican Tropical Pacific’: Chiton articulatus (Mollusca: Polyplacophora)

The marine mollusc, commonly called sea cockroach or chiton Chiton articulatus, is a mollusc belonging to the group known as Polyplacophora because its shell is composed of eight individual plates. This mollusc inhabits the rocky intertidal shore of the Mexican Tropical Pacific, where it is endemic. It has ecological, but also economic, importance. Ecologically, it is the preferred food of the snail Plicopurpura pansa, a protected species, in the cultural heritage of the country. Additionally, it is a basibiont (generates substrate for other individuals) that maintains the biodiversity of the Region. Economically, it has changed from artisanal consumption to become a culinary tourist attraction, offered at restaurants as an exotic and aphrodisiac dish, in tourist places like Huatulco or Acapulco. Despite being an exploited resource for decades, little is known about its life history. The Mexican Authorities have not yet recognised this mollusc as a fishing resource, so that it does not have any law that controls its extraction, sale and consumption, putting at risk the recruitment, survival and permanence of this species. The goal of this project is the preservation and support for the management of the species. The Project "Quiton del Pacifico Tropical Mexicano" seeks to provide the biological, ecological, reproductive, genetic, anatomical and morphometric bases of the populations of Chiton articulatus. The project was structured in four stages: 1) field sampling and obtaining samples, 2) disclosure and presentation of the project, 3) inclusion of students at the undergraduate and graduate level, 4) application of results. The inclusion and recognition of C. articulatus as a fishing resource will achieve impact at the national and regional level through the implementation of laws that regulate its fishing, as well as its inclusion in management and food security policies. Additionally, this Mexican Chiton Project is currently replicating with chiton species in Galapagos, Ecuador.

Larval digenean preferences in two sympatric snail species at differing tidal levels off the Atlantic coast of Patagonia

Larval stages of the trematodesMaritrema madrynenseand Hemiuroidea fam. gen. et sp. differentially parasitizedSiphonaria lessoniiandS. lateralis, two sympatric pulmonate snail species on the rocky intertidal shore at Puerto Deseado, south-western Atlantic coast of Patagonia, Argentina. Snail specimens were collected at two sampling sites with contrasting physical–chemical characteristics. One site, in the upper intertidal, was exposed to sewage from fish-processing plants, greater hydrodynamic forcing and desiccation, a wider temperature range, longer exposure to ultraviolet radiation and higher abundance of birds. The second site, in the lower intertidal, was generally characterized by less stressful environmental conditions. At both sites,S. lateralisshowed a markedly higher density thanS. lessonii(55.13 vs. 5.87 snails/m2, respectively). Despite this, the prevalence of both digeneans was higher inS. lessonii(17.37% and 3.52% forM. madrynenseand Hemiuroidea, respectively) than inS. lateralis(0.09% and 0% forM. madrynenseand Hemiuroidea, respectively). This study demonstrates high parasite specificity for the host. Low densities ofS. lessoniiare attributed to castration of parasitized hosts and reduction of their physiological condition. The prevalence and intensity of infection of both digenean parasites were higher at the more stressful, upper intertidal site, thus suggesting that a higher abundance of birds and exposure to sewage pollution may promote the transmission of trematodes.

Leslibetaeus coibita, n. gen., n. sp., a new alpheid shrimp from the Pacific coast of Panama (Crustacea: Decapoda)

A new alpheid shrimp, Leslibetaeus coibita, n. gen., n. sp., is described on the basis of two specimens extracted from crevices in a shale rock on the rocky intertidal shore in the Isla Coiba National Park, Pacific coast of Panama. Leslibetaeus is characterized by absence of rostrum and orbital teeth; eyes being only partially covered by carapace; sixth abdominal somite without articulated plate; first segment of the antennular peduncle without tooth on ventromesial carina; short scaphocerite; tip of third maxilliped with stout spines; and strap-like epipods present on third maxilliped and first to fifth pereiopod; stout symmetrical chelipeds, with carpus distally strongly lobed and bearing two rows of setae mesially, and chela without snapping mechanism; carpus of second pereiopod five-segmented, with second segment distinctly longer than first; ischium and merus of third pereiopod unarmed. The new genus appears to be relatively basal and not closely related to any of the currently described alpheid genera. The finding of this new taxon in a relatively accessible habitat indicates a yet unexplored biological potential of the Isla Coiba National Park.