Molecular Phylogeny of Thelastomatoidea (Nematoda) with the Description of a New Genus and Two New Species of Hystrignathidae Associated with Bess Beetles (Coleoptera: Passalidae) from Oaxaca, Mexico.

Bess beetles (Passalidae) display important roles in forestall ecosystems, particularly in energy extraction from dead wood. These organisms maintain complex biological interactions with their gut symbiotic communities, including bacteria, protists, and metazoans. Very little is known about symbionts since most of the species of Passalidae haven't been studied from a parasitological point of view. Here we describe a new genus and 2 new species of nematodes of the family Hystrignathidae associated with 2 beetle species of the tribe Proculini collected in the State of Oaxaca, Mexico. Tuhmai garciaprietoi n. gen., n. sp., found in Vindex agnoscendus is characterized by the presence of an unarmed cervical cuticle, a subcylindrical procorpus and a conspicuous isthmus, a monodelphic-prodelphic reproductive system, and a short subulate tail. Urbanonema osorioi n. sp., found in Verres hageni mainly differs from other species of Urbanonema by the number and disposition of cervical spines, as well as by a subulate tail. For each new taxon, we describe the external and internal morphology, and we generated molecular data (nuclear ribosomal DNA) to place the new taxa in a phylogenetic context.

Pseudacanthus alani, a New Species of Mesoamerican Bess Beetles (Coleoptera: Passalidae) of Oaxaca, Mexico and Nomenclatural Notes for the Genus.

A new species, Pseudacanthus alani n. sp., is described from cloud forest in Oaxaca, Mexico. This species is similar to Pseudacanthus junctistriatus Kuwert 1891 in size, shape of antennal lamella, and the absence of pubescence on abdominal terga, but has larger internal tubercles, an apex of central tubercle that is not free, glabrous elytral humerus, pubescent mesepisternum and mesepimeron and mesosternal scar, and male sexual characters. Photographs are provided of the head, male and female genitalia, and plectrum. Additionally, a taxonomic key to species of Pseudacanthus Kaup 1869 is provided, complemented with photographs of diagnostic characters. Finally, we propose two junior synonyms: Pseudacanthus solidus (Arrow 1907) n. syn. of Pseudacanthus junctistriatus and Pseudacanthus truquii Kuwert 1891 n. syn. of Pseudacanthus mexicanus (Truqui 1857).

Passalidae (Coleoptera: Scarabaeoidea) of the Biogeographical Province of Chocó and the West Andean Region of Colombia, with the Description of Two New Species.

We present a synopsis of the Passalidae of the Chocó biogeographical province and the western slopes of the Western Andean range of Colombia as a result of field collections, examination of entomological collections, and review of the literature. We record a total of 41 species, provide an identification key, and, for the 39 species for which we were able to examine specimens, include a diagnosis and collecting data. Two new species of Passalus (Pertinax) are described and illustrated. The species of this region compose 42% of the passalid species known for Colombia. The richness of species and the high degree of endemism (34%) indicate the faunistic importance of this area, which is closely related to the fauna of lowland Central America.