The thorny-headed worm family Polymorphidae contains endoparasites which as adults feed mainly in fish and aquatic birds. When this taxon was erected by Meyer in 1931, a subfamily Polymorphinae was established in it. As the Polymorphidae as presently understood would then be monotypic, with no basal genera outside the Polymorphinae, the proposed subfamily is redundant for the time being and therefore most modern treatments simply omit it. Polymorphus minutus is an economically significant parasite in goose and duck farming.
Gigantorhynchida is an order containing a single family, Gigantorhynchidae of Acanthocephala that parasitize vertebrates by attaching themselves to the intestinal wall of their host. There are over 60 species classified into three genera in GigantorhynchidaGigantorhynchus, Intraproboscis, and Mediorhynchus.
Gigantorhynchus is a genus of Acanthocephala that parasitize marsupials, anteaters, and possibly baboons by attaching themselves to the intestines using their hook-covered proboscis. Their life cycle includes an egg stage found in host feces, a cystacanth (larval) stage in an intermediate host such as termites, and an adult stage where cystacanths mature in the intestines of the host. This genus is characterized by a cylindrical proboscis with a crown of robust hooks at the apex followed by numerous small hooks on the rest of the proboscis, a long body with pseudosegmentation, filiform lemnisci, and ellipsoid testes. The largest known specimen is the female G. ortizi with a length of around 240 millimetres (9.4 in) and a width of 2 millimetres (0.08 in). Genetic analysis on one species of Gigantorhynchus places it with the related genus Mediorhynchus in the family Gigantorhynchidae. Six species in this genus are distributed across Central and South America and possibly Zimbabwe. Infestation by a Gigantorhynchus species may cause partial obstructions of the intestines, severe lesions of the intestinal wall, and may lead to death.
Mediorhynchus is a genus of small parasitic spiny-headed worms. Phylogenetic analysis has been conducted on two known species of Mediorhynchus and confirmed the placement along with the related genus Gigantorhynchus in the family Gigantorhynchida. The distinguishing features of this order among archiacanthocephalans is a divided proboscis. This genus contains fifty-eight species that are distributed globally. These worms exclusively parasitize birds by attaching themselves around the cloaca using their hook-covered proboscis. The bird hosts are of different orders.
Moniliformidae is a family of parasitic spiny-headed worms. It is the only family in the Moniliformida order and contains three genera: Australiformis containing a single species, Moniliformis containing eighteen species and Promoniliformis containing a single species. Genetic analysis have determined that the clade is monophyletic despite being distributed globally. These worms primarily parasitize mammals, including humans in the case of Moniliformis moniliformis, and occasionally birds by attaching themselves into the intestinal wall using their hook-covered proboscis. The intermediate hosts are mostly cockroaches. The distinguishing features of this order among archiacanthocephalans is the presence of a cylindrical proboscis with long rows of hooks with posteriorly directed roots and proboscis retractor muscles that pierce both the posterior and ventral end or just posterior end of the receptacle. Infestation with Monoliformida species can cause moniliformiasis, an intestinal condition characterized as causing lesions, intestinal distension, perforated ulcers, enteritis, gastritis, crypt hypertrophy, goblet cell hyperplasia, and blockages.
Moniliformis is a genus of parasitic worms in the Acanthocephala phylum.
Arhythmacanthidae is a family of parasitic worms from the order Echinorhynchida.
Neoechinorhynchidae is a family of parasitic worms from the order Neoechinorhynchida.
Neoandracantha is a genus of parasitic worms from the phylum Acanthocephala. The genus was created in 2017 by Amin & Heckmann for the single species Neoandracantha peruensis.
Australiformis is a monotypic genus of acanthocephalans containing a single species, Australiformis semoni, that infests marsupials in Australia and New Guinea. Its body consists of a proboscis armed with hooks which it uses to pierce and hold the gut wall of its host, and a long trunk. This genus resembles species in the genus Moniliformis but is characterized by a lack of spiral muscles in the outer wall of the proboscis receptacle. The proboscis is armed with 12 rows of 13 to 15 hooks which are used to attach themselves to the small or large intestines of the host. The female worms range from 95 to 197 millimetres long, virtually all of which is the trunk, and 1.75 to 3.5 millimetres wide. There is pronounced sexual dimorphism in this species as females are around twice the size of the males whose trunks range from 46 to 80 millimetres long and 2 millimetres (0.079 in) wide. Infestation by A. semoni may cause debilitating inflammation of the stomach (gastritis) with granulomatous ulcers.
Heptamegacanthus is a monotypic genus of acanthocephalans. It contains a single species, Heptamegacanthus niekerki, parasite of the endangered giant golden mole found in South Africa. Its body consists of a proboscis armed with hooks which it uses to pierce and hold the rectal wall of its host, and a short, wide trunk. The proboscis is armed with 40 to 45 hooks arranged in rings that are not radially symmetrical, with seven large anterior hooks. The hooks in the anterior ring are twice as large as those in second ring and the remaining hooks decrease progressively in size posteriorly. The worms are about 4 millimetres (0.2 in) long and 2 millimetres (0.08 in) wide. The life cycle of H. niekerki remains unknown; however, like other acanthocephalans, it likely involves complex life cycles with at least two hosts. Although the intermediate host for Heptamegacanthus is not definitively identified, it is presumed to be an arthropod. In this host, the larvae develop into an infectious stage known as a cystacanth. These are then ingested by the definitive host, where they mature and reproduce sexually within the intestines. The resulting eggs are expelled and hatch into new larvae.
Prosthenorchis is a genus of parasitic worms belonging to the family Oligacanthorhynchidae. Prosthenorchis have a trunk up to 50 mm long, a proboscis that is not ornate with three barbed hooks in each of 12 rows. They have complex hook roots with large manubria, and a small discoid posterior hook base. There are up to 23 festoons. Gonopore is subterminal. The primary host are primates in South America and Felidae in Africa with cockroaches and beetles as intermediate hosts.
Paraprosthenorchis is a monotypic genus of acanthocephalans. It contains a single species, Paraprosthenorchis ornatus, which infests the Chinese pangolin in Vietnam.
Pachysentis is a genus in Acanthocephala that parasitize primates and carnivorans. They are distributed across Africa, the Middle East, and the Americas. Pachysentis species attach themselves to the inner lining of the gastrointestinal tract of their hosts using their hook-covered proboscis. Their life cycle includes an egg stage found in host feces, a cystacanth (larval) stage in an intermediate host such as the Egyptian cobra, and an adult stage where cystacanths mature in the intestines of the host. This genus appears identical to the closely related Oncicola apart from a greater number of hooks on the proboscis. There are eleven species assigned to this genus, although P. septemserialis is of uncertain taxonomic status. The female worms range from 12 millimetres (0.47 in) long and 1.6 millimetres (0.063 in) wide in P. lauroi to 50 millimetres (2.0 in) long and 4 millimetres (0.16 in) wide in P. dollfusi. Virtually all of the length is the trunk, with a short proboscis. There is pronounced sexual dimorphism in this species as females are around twice the size of the males.
Oncicola is a genus of parasitic worms belonging to the family Oligacanthorhynchidae. Oncicola belongs to the phylum Acanthocephalans that include many thorny-headed worms. This family contains 12 genera including the genus Oncicola. Oncicola is a part of the phylum Acanthocephalans that include many thorny-headed worms. The name comes from the prefix onc- meaning “barbed” and -cola meaning “to inhabit” in Latin. It was named and discovered in 1916 by Travassos. These worms are defined by their parasitic nature which involves hook structures found at their front end.
Macracanthorhynchus, also known as the giant thorny-headed worm of swine, is a member of the Oligacanthorhynchidae which contains four species.
Neoncicola is a genus of parasitic worms containing nine species and belongs to the family Oligacanthorhynchidae.
Oligacanthorhynchus is a genus of parasitic worms belonging to the family Oligacanthorhynchidae.
Nephridiacanthus is a genus of parasitic worms belonging to the family Oligacanthorhynchidae.
Intraproboscis is a monotypic genus of acanthocephalans that infest African black-bellied pangolin in the Central African Republic. Its body consists of a proboscis armed with hooks which it uses to pierce and hold the gut wall of its host, and a long trunk. It contains a single species, Intraproboscis sanghae. This genus resembles species in the genus Mediorhynchus but is characterized by infesting a mammal instead of birds, and having a simple proboscis receptacle that is completely suspended within the proboscis, the passage of the retractor muscles through the receptacle into the body cavity posteriorly, absence of neck, presence of a parareceptacle structure, and a uterine vesicle. The proboscis is armed with 34–36 rows of 6 to 7 hooks anteriorly and 15–17 spinelike hooks posteriorly which are used to attach themselves to the intestines of the host. The female worms are up to 180 millimetres long, virtually all of which is the trunk, and 2 millimetres wide.
