\u3ci\u3eNeonchocotyle violantei\u3c/i\u3e n. sp. (Monogenea, Hexabothriidae) from \u3ci\u3ePseudobatos lentiginosus\u3c/i\u3e (Rhinopristiformes, Rhinobatidae) of Yucatán, Gulf of Mexico = \u3ci\u3eNeonchocotyle violantei\u3c/i\u3e n. sp. (Monogenea, Hexabothriidae) do \u3ci\u3ePseudobatos lentiginosus\u3c/i\u3e (Rhinopristiformes, Rhinobatidae) de Yucatán, Golfo do México

Abstract Neonchocotyle violantei n. sp. (Monogenea: Hexabothriidae) infects the gill of the Atlantic guitarfish, Pseudobatos lentiginosus (Rhinopristiformes, Rhinobatidae) from littoral waters of Celestún, Yucatán, Mexico. It is assigned to Neonchocotyle because it has, among other features, an asymmetrical haptor, a seminal receptacle, a smooth oötype, and an egg with two elongate filaments. It differs from Neonchocotyle pastinacae, the only congener, by having a small body (821 long by 315 wide, length to width = 2.6:1), two pairs of microhooks between the haptoral appendix suckers, extracaecal (submarginal) vaginal pores, and 5-9 testes. This is the first record of a species of Neonchocotyle in the Gulf of Mexico, the first monogenean reported from P. lentiginosus in Mexico and the second species of Hexabothriidae reported from Mexico. Resumo Neonchocotyle violantei n. sp. (Monogenea: Hexabothriidae) infecta brânquia de Pseudobatos lentiginosus, (Rhinopristiformes, Rhinobatidae) de águas litorâneas ao largo da costa de Celestún, Yucatán, México. É atribuído a Neonchocotyle porque tem, entre outras características, um haptor assimétrico, um receptáculo seminal, um tipo oótipo liso e um ovo com dois filamentos alongados. Difere de Neonchocotyle pastinacae, o único congênere, por ter um corpo pequeno (821 de comprimento por 315 de largura, comprimento a largura = 2,6: 1), dois pares de microganchos entre as ventosas do apêndice haptoral, poros vaginais extracaecais (submarginal) e 5-9 testículos. Este é o primeiro registro de uma espécie de Neonchocotyle no Golfo do México, o primeiro monogenético registrado em P. lentiginosus no México e a segunda espécie de Hexabothriidae relatada no México

Neonchocotyle violantei n. sp. (Monogenea, Hexabothriidae) from Pseudobatos lentiginosus (Rhinopristiformes, Rhinobatidae) of Yucatán, Gulf of Mexico

Abstract Neonchocotyle violantei n. sp. (Monogenea: Hexabothriidae) infects the gill of the Atlantic guitarfish, Pseudobatos lentiginosus (Rhinopristiformes, Rhinobatidae) from littoral waters of Celestún, Yucatán, Mexico. It is assigned to Neonchocotyle because it has, among other features, an asymmetrical haptor, a seminal receptacle, a smooth oötype, and an egg with two elongate filaments. It differs from Neonchocotyle pastinacae, the only congener, by having a small body (821 long by 315 wide, length to width = 2.6:1), two pairs of microhooks between the haptoral appendix suckers, extracaecal (submarginal) vaginal pores, and 5-9 testes. This is the first record of a species of Neonchocotyle in the Gulf of Mexico, the first monogenean reported from P. lentiginosus in Mexico and the second species of Hexabothriidae reported from Mexico

Life on the beach for a sand crab (Emerita rathbunae) (Decapoda, Hippidae): parasite-induced mortality of females in populations of the Pacific sand crab caused by Microphallus nicolli (Microphallidae)

Parasites, by definition, can affect mortality of their host, making parasitism an important biotic determinant of animal population dynamics and community structure. Reduction in the number of larger, reproductive age females in populations of the Pacific sand crab, Emerita rathbunae (Decapoda, Hippidae), was observed in studies of the helminth community of this host. The aim of this study was to determine if high abundance of the metacercaria of the trematode, Microphallus nicolli (Microphallidae), causes mortality in this host. Females of E. rathbunae were collected from four sandy beaches in Guerrero State, Mexico, and helminths were collected from each crab. An analysis of variance (Anova) was applied to these data in order to identify differences in abundance between sizes of crabs, and an analysis of covariance (Ancova) was applied to identify differences in the abundance of metacercariae between locations. Parasite-related mortality was inferred by a decrease in abundance in older hosts. Linear and polynomial regressions of mean abundance of helminths (log x+1 transformed data) vs. cephalothorax length of crabs were significant for the four populations of E. rathbunae, indicating increased mortality of older, more heavily infected female crabs and resultant removal from the population. Encapsulation and melanization of cysts by crabs was observed, indicating that an immune response by crabs also killed a portion of the cysts from subsequent exposures. Mortality of hosts through behavioral modification favoring transmission of highly infected crabs was suggested as the driving force behind this process