Morphological and Molecular Data Reveal Two New Species of Viannaia (Nematoda: Viannaiidae), Parasitizing Opossums (Mammalia: Didelphidae) in Mexico.

Two new species of Viannaia from the intestine of the North American opossums, Didelphis virginiana (Virginia opossum), and Philander opossum (gray four-eyed opossum), are described based on morphological and molecular data, through an integrative taxonomic approach. Maximum likelihood and Bayesian inference analyses for each dataset and the concatenated dataset were performed using a mitochondrial cytochrome c oxidase subunit 1 (COI) gene, and the nuclear ribosomal internal transcribed spacer region (ITS1-5.8S-ITS2).

A New Species of (Nematoda: Coronostomatoidea) Parasite of (Coleoptera: Passalidae) from Mexico, and the Position of the Family in the Oxyuridomorpha.

A new species of the nematode Kloss, 1962 (Oxyuridomorpha), is described from the wood beetle Truqui from the mountain mesophilic forest in Hidalgo State, Mexico. n. sp.

Helminth Community Structure of the Gray Four-Eyed Opossum (Mammalia: Didelphidae) in the Neotropical Portion of Mexico.

Studies on helminth communities associated with didelphids are scarce; the majority of works have focused at taxonomic level. To increase the ecological knowledge of these host-parasite associations, during March (dry season) of 3 consecutive years (2013-2015) a total of 49 adults of the gray four-eyed opossum () was collected in the Neotropical portion of Mexico (Agua Fría, Chiapas State) and examined for helminths. The main objectives of this study were to describe the infra- and component communities of helminths associated with and to compare the helminth fauna of the Mexican population of this host species with those studied in French Guiana and in other Mexican terrestrial didelphids.