Pachysentis species attach themselves to the inner lining of the gastrointestinal tract of their hosts using their hook-covered proboscis.

This genus appears identical to the closely related Oncicola apart from a greater number of hooks on the proboscis.

[3] Phylogenetic analyses have also been conducted on Oncicola, a genus morphologically nearly identical to Pachysentis apart from the number of hooks on the proboscis, and have also placed it in the family Oligacanthorhynchidae.

Gigantorhynchus echinodiscus Pachysentis looks identical to the closely related Oncicola apart from the number of hooks on the proboscis.

There are eight cement glands compactly arranged each with a single giant nucleus used to temporarily close the posterior end of the female after copulation.

[2] The genus Pachysentis Meyer, 1931 contains eleven species, although P. septemserialis is of uncertain taxonomic status.

[11] P. canicola was found infesting the red fox (Vulpes vulpes) in Bushehr, Bushehr Province, Iran,[12] the golden jackal (Canis aureus) also in Iran,[13] captive maned wolves (Chrysocyon brachyurus) in a zoo in Texas, and the striped skunk (Mephitis mephitis) found nearby.

[1] P. dollfusi was found infesting the intestines of the common brown lemur (Eulemur fulvus) in a Brazilian zoo but originally from the island of Madagascar.

[2] P. ehrenbergi was reported infesting the body cavity of 5.4% of a sample of African five-lined skinks (Trachylepis quinquetaeniata) in the Qena Governorate of Egypt, however the measurements and morphological description do not match either the original description by Meyer in 1931[1] or the reexamination of original specimens by Gomes and colleagues in 2019.

[2] Juvenile P. ehrenbergi have been reported infesting the long-eared hedgehog (Hemiechinus auritus) in the Faran Oasis, South Sinai, Egypt.

[18] P. gethi was originally described in 1950 by Machado-Filho infesting tayra (Eira barbara) in Pará and Rio de Janeiro, Brazil but this remained the only record until it was rediscovered in 2016 infesting the wild lesser grison (Galictis cuja), also in Rio de Janeiro, with different measurements.

[2] P. lenti has been found infesting the white-headed marmoset (Callithrix geoffroyi) in Espírito Santo, Brazil.

[20] P. procyonis was found infesting the intestines of a crab-eating raccoon (Procyon cancrivorus) in Rio de Janeiro, Brazil.

Distinguishing features include eight clustered cement glands and very short lemnisci that do not reach the anterior testis.

This species can be identified by its clustered cement glands and long leminisci that reach the anterior testis.

P. septemserialis is considered by Gomes et al. in 2019 to have an uncertain taxonomic status due to differences between the paratypes morphological characteristics and the original description, the similarity in hosts (primates of the family Callitrichidae including the black tamarin (Saguinus niger),[24] and the absence of samples or measurements of adult males.

[2] Paratenic hosts (hosts where parasites infest but do not undergo larval development or sexual reproduction) for Pachysentis have been found for P. ehrenbergi (Egyptian cobra, Naja haje)[18] and P. canicola (western diamondback rattlesnake, Crotalus atrox).

[15] There are no reported cases of any Pachysentis species infesting humans in the English language medical literature.