Redescription and Molecular Characterization of Pachysentis canicola Meyer, 1931 (Acanthocephala: Oligacanthorhynchidae) from the Maned Wolf, Chrysocyon brachyurus (Illiger, 1815) in Texas.

Background: The original description of Pachysentis canicola Meyer, 1931 was based on an unknown number of specimens from an undetermined species of Canis in Brazil from the Berlin Museum. It has since been reported from other carnivores in South and North America. Our specimens from the maned wolf, Chrysocyon brachyurus (Illiger, 1815), in Texas, represent a new host record, and has shed more light on morphometric characteristics missing from the original description, and expanded the range of variations in characters that remained fixed since 1931 and that have been repeated in other taxonomic accounts. We have found additional specimens in striped skunk, Mephitis mephitis Schreber, also in Texas.

Methods: We have performed metal analysis on hooks using EDXA (energy dispersive X-ray analysis). Sequences for the 18S gene and ITS1-5.8-ITS2 region of rDNA were generated to molecularly characterize the species for the first time.

Results: Worms with a massive trunk and a globular proboscis with prominent dome-like apical organ and 12 irregular spiral rows of 4-5 hooks deeply embedded in cuticular folds each, totaling 48-60 hooks. We have included line drawings of the male and female reproductive systems, among other structures, also missing from the original and subsequent descriptions. We describe a new population of P. canicola from Texas and report on the metal analysis of its hooks using EDXA. We also assess the phylogenetic position of P. canicola supporting its independent status in the family Oligacanthorhynchidae, inferred from the two molecular markers.

Conclusions: This is the foremost molecular characterization of any species of Pachysentis and will provide significant insights and reference for future molecular study of species of Pachysentis, especially from this newly described Texas population.