ABSTRACT There are few studies about parasitic infections in Crotalus triseriatus (Wagler, 1830), an endemic rattlesnake from the highlands of central Mexico. This species occupies several habitats, from conserved forested regions to heavily impacted landscapes. To increase the parasitological knowledge of this reptile species without impacting populations, we obtained fecal samples of 16 rattlesnakes between 2012 and 2014 from Toluca Valley, Mexico. By using flotation technique, we found oocysts of Eimeria sp. and eggs of Capillariidae sp. The most frequent parasite was Eimeria sp. (62.5%). This study provides the first records of occurrence of parasites in reptilian feces from Mexico. Our results may be important for wildlife conservation purposes, for example, they could indicate of the population health of this species during processes of translocation.

Abstract: As a part of the revision of unidentified specimens harbored by the Colección Nacional de Helmintos of the Instituto de Biología, Universidad Nacional Autónoma de México, we studied several specimens of trematodes collected and processed between 1950 and 1980 in marine fishes from several localities along the Pacific coast of Mexico. Among these specimens, we found 1 undescribed species of the genus Pseudopecoelus von Wicklen, 1946 (Pseudopecoelus ibunami n. sp.) of the intestine of the spotted grouper Epinephelus analogus Gill, 1863 (Actinopterygii: Serranidae) from Bahía de La Paz, Baja California Sur. This species is the number 40 known for this genus worldwide and the fifth registered parasitizing fishes from Mexico. The new species differs from the 17 species of Pseudopecoelus with vitelline follicles distributed anteriorly to ventral sucker by having a combination of the following traits: 1) body elongate, narrow, with irregular posterior end, 2) testes and ovary deeply-lobed, and 3) external seminal vesicle reaching only the anterior margin of ventral sucker. In addition, in this study we present new host and geographical records for 6 species of trematodes in marine fishes from Mexico and Pachycreadium gastrocotylum (Manter, 1940) Manter, 1954 is recorded for the first time in this country.

Resumen: Como parte del proceso de revisión de ejemplares no identificados del acervo de material depositado en la Colección Nacional de Helmintos del Instituto de Biología de la Universidad Nacional Autónoma de México, estudiamos un lote de tremátodos recolectados y procesados entre 1950 y 1980 en varias localidades de la costa del Pacífico mexicano. Entre dicho material, encontramos 1 especie no descrita del género Pseudopecoelus von Wicklen, 1946 (Pseudopecoelus ibunami n. sp.) en el intestino de la cabrilla pinta Epinephelus analogus Gill, 1863 (Actinopterygii: Serranidae) de la bahía de La Paz, Baja California Sur. Esta especie es la número 40 para el género en todo el mundo y la quinta registrada parasitando peces de México. La nueva especie difiere de las 17 especies de Pseudopecoelus que presentan los folículos vitelinos distribuidos anteriormente a la ventosa ventral, por la combinación de las siguientes características: 1) cuerpo alargado, estrecho, con el extremo posterior irregular, 2) testículos y ovario profundamente lobulados y 3) vesícula seminal externa alcanzando solamente el borde anterior del acetábulo. Adicionalmente, en este trabajo se amplía la distribución geográfica y el registro de hospederos para 6 especies de tremátodos de peces marinos del país y Pachycreadium gastrocotylum (Manter, 1940) Manter, 1954 se registra por primera vez en México.

A total of 11 parasitic endohelminth taxa were found in 7 freshwater fish species of the subfamily Goodeinae in Zacapu Lake, Michoacan, Mexico. Six were adults (Margotrema cf. bravoae, Phyllodistomum sp., Saccocoelioides sogandaresi, Rhabdochona lichtenfelsi, Bothriocephalus acheilognathi and Caryophillidae gen. sp.), while the remaining 5 taxa (Clinostomum complanatum, Posthodiplostomum minimum, Tylodelphis sp., Eustrongylides sp. and Polymorphus brevis) were larvae. The taxa S. sogandaresi, Tylodelphis sp., and R. lichtenfelsi reached the highest levels of prevalence and mean abundance among all hosts, while the cestodes B. acheilognathi and Caryophillidae gen. sp. showed the lowest values. This study contributes with the inventory of the freshwater fish helminth fauna in Central Mexico Plateau, and particularly with the previous work that has been done with Goodeinae, a subfamily of freshwater fishes endemic to that part of the country.

En este trabajo se registran 11 taxa de helmintos endoparásitos de 7 especies de peces de la subfamilia Goodeinae del lago de Zacapu, Michoacán, en la mesa central de México. Seis taxa se registraron en estado adulto (Margotrema cf. bravoae, Phyllodistomum sp., Saccocoelioides sogandaresi, Rhabdochona lichtenfelsi, Bothriocephalus acheilognathi y Caryophillidae gen. sp.), en tanto que los 5 restantes correspondieron a larvas (Clinostomum complanatum, Posthodiplostomum minimum, Tylodelphys sp. y Eustrongylides sp. y Polymorphus brevis). Los taxa S. sogandaresi, Tylodelphis sp. y R. lichtenfelsi presentaron los valores más altos de prevalencia y abundancia en los peces estudiados, mientras que los céstodos B. acheilognathi y Caryophillidae gen. sp. presentaron los valores más bajos. Este estudio contribuye al inventario de la fauna helmintológica de peces de agua dulce de la mesa central de México y en particular al que ha sido realizado con Goodeinae, una subfamilia de peces dulceacuícolas endémica de esa parte del territorio nacional.