Reproducción y limitaciones de pesca recomendadas para el caracol marino Hexaplex princeps (Neogastropoda: Muricidae) en Guerrero, México / Reproduction and recommended fishing limitations for the marine snail Hexaplex princeps (Neogastropoda: Muricidae) in Guerrero, Mexico

Abstract Introduction: The snail Hexaplex princeps is the most important gastropod in the fishery of Guerrero, but capture is not legally regulated for lack of enough studies about its reproduction, growth and other fishing aspects. Objective: To assess fishery data for H. princeps in Guerrero. Methods: From October 2016 to December 2017, we analyzed histological samples of the gonads from 6 to 13 individuals per month. We also collected data on pre-reproductive organisms captured in Costa Chica (2013 and 2014), Costa Grande (2017) and Acapulco (2019 and 2020). Results: Both sexes have five stages of gonadal development; most reproductive activity was from December to July, related to sea surface temperatures of 26 to 28 °C. The LC M in females was 94.1 mm (males: 86.1 mm). There was a high percentage of juvenile organisms in the catches (88.6 %). Conclusions: To let these snails reproduce at least once, we recommend a fishing ban from December to July, and that the minimum size of commercial capture be set at 94.1 mm.

Resumen Introducción: El caracol Hexaplex princeps es el gasterópodo más importante en la pesquería de Guerrero, pero su captura no está regulada legalmente por falta de suficientes estudios sobre su reproducción, crecimiento y otros aspectos de la pesca. Objetivo: Evaluar los datos de pesca de H. princeps en Guerrero. Métodos: De octubre 2016 a diciembre 2017, analizamos muestras histológicas de las gónadas de 6 a 13 individuos por mes. También recolectamos datos sobre organismos pre-reproductivos capturados en Costa Chica (2013 y 2014), Costa Grande (2017) y Acapulco (2019 y 2020). Resultados: Ambos sexos tienen cinco etapas de desarrollo gonadal; la mayor actividad reproductiva fue de diciembre a julio, relacionada con las temperaturas superficiales del mar, que se encuentran entre 26 y 28 °C. El LC M en hembras fue de 94.1 mm (machos: 86.1 mm). Hubo un alto porcentaje de organismos juveniles en las capturas (88.6 %). Conclusiones: Para que estos caracoles se reproduzcan al menos una vez, se recomienda una veda de diciembre a julio y que la talla mínima de captura comercial se fije en 94.1 mm.

Intertidal chitons (Mollusca: Polyplacophora) from the rocky coastline of Guerrero, Mxico, with the description of a new species.

Chitons from southern Mxico 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 Mazatln 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 Mazatln 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 Mazatln 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.

Efecto de la reubicación de nidos en el éxito reproductivo de la tortuga marina Lepidochelys olivacea (Testudinata: Cheloniidae) / Effect of nest relocation on the reproductive success of the marine turtle Lepidochelys olivacea (Testudinata: Cheloniidae)

Resumen Introducción: Para incrementar el número de crías de tortugas marinas, es necesario mejorar estrategias de conservación, como incubación de nidos, en condiciones de vivero que contrarresten los efectos de las condiciones climáticas extremas. Objetivo: Comparar cinco parámetros de éxito reproductivo (éxito de eclosión, huevos sin desarrollo aparente, crías muertas, mortalidad embrionaria y período de incubación) de la tortuga marina Lepidochelys olivacea. Métodos: Se evaluó la incubación de nidos bajo dos períodos de reubicación de nidos (P1 ~28.8 °C agosto-septiembre y P2 ~27.1 °C octubre-noviembre, temperatura ambiental promedio, bajo condiciones de vivero, en el 2018 en Guerrero, México. Resultados: Se encontraron diferencias significativas en el éxito de eclosión y la mortalidad embrionaria entre los períodos de reubicación de nidos (P < 0.001). En P1, se observaron valores más bajos de éxito de eclosión (77.0 % P1 vs 88.6 % P2) y valores más altos de mortalidad embrionaria (13.7 % P1 vs 3.3 % P2) comparados con los de P2. Es importante señalar que, en el presente estudio la mortalidad embrionaria se presentó en una etapa tardía de desarrollo, es decir, en embriones casi completamente desarrollados. No se encontraron diferencias entre periodos respecto a los parámetros de huevos sin desarrollo aparente, crías muertas y período de incubación. Conclusiones: Las diferencias entre las condiciones ambientales durante el primer período de reubicación de nidos en comparación con el segundo período parecen afectar el éxito de eclosión y mortalidad embrionaria de L. olivacea. Por lo tanto, es importante tomar medidas al respecto durante esta etapa de incubación para tratar de mejorar la incubación de nidos bajo condiciones de vivero.

Abstract Introduction: In order to increase the number of sea turtle hatchlings, it is necessary to improve conservation strategies, such as nest incubation in hatchery conditions that counteract the effects of extreme climatic conditions. Objective: To compare five reproductive success parameters (hatching success, eggs with no apparent embryonic development, dead hatchlings, embryonic mortality, and incubation period) of the sea turtle Lepidochelys olivacea. Methods: The incubation of nests was evaluated under two periods of nest relocation, P1 ~28.8 °C (August and September) and P2 ~27.1 °C (October and November), average ambient temperature, under hatchery condition, in 2018 in Guerrero, Mexico. Results: Significant differences were found in hatching success and embryonic mortality between nest relocation periods (P < 0.001). In P1, lower values of hatching success (77.0 % P1 vs 88.6 % P2) and higher values of embryonic mortality (13.7 % P1 vs 3.3 % P2) were observed compared to those of P2. It's important pointing that, in the present study, embryonic mortality occurred at a late stage of development, that is, in almost fully developed embryos. No differences were found between periods regarding the parameters eggs with no apparent embryonic development, dead hatchlings and incubation period. Conclusions: The differences between the environmental conditions during the first period of nest relocation compared to the second period, respectively, seem to affect the hatching success and embryonic mortality of L. olivacea. Therefore, it is important to take action on this issue during this incubation stage to try to improve the incubation of nests under hatchery conditions.

Diversity of Epibionts Associated with Lepidochelys olivacea (Eschscholtz 1829) Sea Turtles Nesting in the Mexican South Pacific.

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.

Composición de la familia Fissurellidae (Mollusca: Gastropoda) en el intermareal rocoso de las regiones marinas prioritarias en Guerrero, México / Composition of the family Fissurellidae (Mollusca: Gastropoda) in the rocky intertidal zone of priority marine regions in Guerrero, Mexico

Resumen La información sobre los diversos aspectos ecológicos de interés de los moluscos gasterópodos en México es insuficiente, sobre todo en las regiones marinas prioritarias (RMPs), que la Comisión Nacional para el Conocimiento y Uso de la Biodiversidad ha decretado. En el estado de Guerrero existen cuatro RMPs. El objetivo de esta investigación fue determinar la riqueza, abundancia, distribución, composición de tallas y la relación de la abundancia y longitud de las especies dominantes de la familia Fissurellidae (Mollusca: Gastropoda), con el tipo de sustrato y la intensidad del oleaje, que ha sido reportada como familia representativa del intermareal rocoso de Guerrero. Se trabajó en la zona intermareal rocosa de 23 sitios; las colectas se realizaron durante la marea baja; la unidad de muestreo fue de 1 m2; el área muestreada por sitio y por colecta fue de 10 m2. Los especímenes encontrados dentro de la unidad de muestreo se colectaron y preservaron en alcohol al 96 %. Se analizaron 1 669 especímenes, de los cuales, se identificaron 14 especies. Se reporta a Fissurella morrisoni como una nueva adhesión al listado de especies de esta familia en Guerrero. Fissurella nigrocincta registró la mayor abundancia con 1 043 organismos. Se determinó a Fissurella nigrocincta y Fissurella gemmata como de amplia distribución, al estar presentes en más del 90 % de los sitios. Fissurella gemmata registró la mayor longitud en concha. Las especies de mayor abundancia y longitud presentaron preferencias por un sustrato compuesto por macizos rocosos y grandes bloques, en donde la intensidad del oleaje es alta.

Abstract Information dealing with different ecological aspects of gastropod mollusks in Mexico is insufficient, especially in marine priority regions (MPRs) that have been determined by the National Commission for Knowledge and Use of Biodiversity. In the state of Guerrero there are four MPRs. The aim of this research was to determine the richness, abundance, distribution, size composition and abundance and length relationship of the dominant species of the Fissurellidae family with the type of substrate and wave intensity (Mollusca: Gastropoda), which has been reported as representative family in the rocky intertidal zone in Guerrero. The work was carried out at 23 sites in the rocky intertidal zone. The specimens were collected at low tide and the sampling unit was 1 m2. The sampled area by site and collection was 10 m2. The specimens found within the sampling unit, were collected and preserved in 96 % alcohol. 1 669 specimens were analyzed; 14 species were identified. Fissurella morrisoni is reported as a new adhesion to the list of species of this family in Guerrero. Fissurella nigrocincta has the highest abundance with 1 043 agencies. It was determined that Fissurella. nigrocincta and Fissurella gemmata as species with wide distribution to be present in 90 % of sites. Fissurella gemmata has the greatest length in shell. The species with the greatest abundance and lengths have preferences for a substrate composed of rock masses and large blocks, where wave intensity is high.

Parasite communities of the neotropical cormorant Phalacrocorax brasilianus (Gmelin) (Aves, Phalacrocoracidae) from two coastal lagoons in Guerrero state, Mexico.

The parasite community structure of the neotropical cormorant, Phalacrocorax brasilianus, from two lagoons (Coyuca and Tres Palos) from Guerrero state, México, was examined. Fourteen species of adult helminths (6,391 individuals) from 48 cormorants were identified: 9 digeneans, 1 acanthocephalan, 1 cestode, and 3 nematodes. A total of 11 species were collected in Coyuca Lagoon and 12 in Tres Palos Lagoon. Nine species co-occurred in cormorants of both lagoons but, with the exception of Contracaecum multipapillatum and Drepanocephalus olivaceus, species were not equally common in both lagoons. The prevalence values of six species of helminth and the mean abundance of four species varied significantly between lagoons, and C. multipapillatum was numerically dominant in both lagoons. The qualitative similarity between the two communities at the component level was 64%. All cormorants examined were infected, and parasite species richness was 3-5 in Coyuca and 4-9 in Tres Palos lagoon. The results indicate that both communities presented a similar structure at the component level, probably because the cormorants of both lagoons feed on the same species of fish and thus acquire almost the same species of parasites. Differences observed at the infracommunity level were attributed to variations in the degree of dominance of the particular species.

Demografía del caracol Plicopurpura pansa (Neotaenioglossa: Muricidae) y constitución de la comunidad malacológica asociada en Guerrero, México

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 1m² 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 of Bivalvia and one of Polyplacophora, Brachidontes semilaevis being dominant. Rev. Biol. Trop. 55 (3-4): 867-878. Epub 2007 December, 28.

Estudiamos la demografía de Plicopurpura pansa en Playa Ventura, Guerrero, México, con base en muestreos trimestrales. Su densidad fue de 5.19 caracoles/m². La proporción sexual fue cercana al 1:1. La talla promedio fue de 20.10 mm. Las tallas mejor representadas en hembras fueron de 10.5 a 27.0 mm y en machos de 12.0 a 27.0 mm. La población es de alta densidad y mayor frecuencia de tallas pequeñas. Hubo diferencias entre las tallas promedio de cada muestreo, formándose dos grupos de medias para cada sexo. El peso promedio fue 1.79 g. Las hembras presentaron mayor variación en peso, lo cual podría estar relacionado con el ciclo reproductivo. Hubo reclutamiento en cinco fechas de recolección. El mayor número de cópulas se observaron en marzo de 2001. Se identificaron 26 especies de gasterópodos, siete de bivalvos y una de poliplacóforos. La especie con mayor dominancia fue Brachidontes semilaevis.

[Demography of the snail Plicopurpura pansa (Neotaenioglossa: Muricidae) and constitution of the associated mollusk community, in Guerrero, Mexico]. / Demografia del caracol Plicopurpura pansa (Neotaenioglossa: Muricidae) y constitución de la comunidad malacológica asociada en Guerrero, México.

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.