| Cathayacanthus | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Acanthocephala |
| Class: | Palaeacanthocephala |
| Order: | Echinorhynchida |
| Family: | Rhadinorhynchidae |
| Genus: | Cathayacanthus Golvan, 1969 |
Cathayacanthus is a genus in Acanthocephala (thorny-headed worms, also known as spiny-headed worms). [1]
The genus was described by Golvan in 1969 when he moved Rhadinorhynchus exilisVan Cleave, 1928 to a new genus he called Cathayacanthus as it did not have large specialized basal proboscis hooks that are a distinguishing feature of the species in Rhadinorhynchus. [2] The National Center for Biotechnology Information does not indicate that any phylogenetic analysis has been published on any Cathayacanthus species that would confirm its position as a unique order in the class Rhadinorhynchidae. [3] The species Cathayacanthus bagariiMoravec & Sey, 1989 was removed from the genus due to the presence of four tubular cement glands. [2]
The genus Cathayacanthus contains two species: [1]
C. spinitruncatus was found infesting the Common ponyfish (Leiognathus equulus) in Hai Phong and Nha Trang in Vietnam and from the Yellowspotted ponyfish (Nuchequula flavaxilla) in Quang Ninh in the Pacific Ocean off the coast of Vietnam. Females are larger and have more and larger proboscis hooks and trunk spines than males. In the female, the proboscis receptacle is only about one fifth the length of the trunk whereas in the male, the proboscis receptacle is more than half the length of the trunk and contains a cephalic ganglion at its anterior end. The male reproductive structures are in the posterior fifth of the trunk and with six club-shaped cement glands (used to temporarily close the posterior end of the female after copulation) gradually merging into six separate cement gland ducts. [2]
The distribution of Cathayacanthus is determined by that of its hosts.
The life cycle of an acanthocephalan consists of three stages, beginning when an infective acanthor (development of an egg) is released from the intestines of the definitive host and then ingested by an arthropod, the intermediate host. Although the intermediate hosts of Cathayacanthus are arthropods. When the acanthor molts, the second stage called the acanthella begins. This stage involves penetrating the wall of the mesenteron or the intestine of the intermediate host and growing. The final stage is the infective cystacanth which is the larval or juvenile state of an Acanthocephalan, differing from the adult only in size and stage of sexual development. The cystacanths within the intermediate hosts are consumed by the definitive host, usually attaching to the walls of the intestines, and as adults they reproduce sexually in the intestines. The acanthor is passed in the feces of the definitive host and the cycle repeats. There may be paratenic hosts (hosts where parasites infest but do not undergo larval development or sexual reproduction) for Cathayacanthus. [7]
Cathayacanthus parasitizes fish. There are no reported cases of Cathayacanthus infesting humans in the English language medical literature. [6]
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.
Promoniliformis is a monotypic genus of acanthocephalans containing a single species, Promoniliformis ovocristatus, that infests tenrecs in Madagascar. The genus PromoniliformisDollfus and Golvan, 1963 is characterized by possessing two distinct kinds of proboscis hooks. There is only one species in this genus.
Rhadinorhynchidae is a family of parasitic worms from the order Echinorhynchida.
Acanthocephaloides is a genus of parasitic worms belonging to the family Arhythmacanthidae.
Cucullanorhynchus is a monotypic genus of acanthocephalans. It contains a single species, Cucullanorhynchus constrictruncatus, which infests leopards in Vietnam.
Breizacanthus is a genus in Acanthocephala.
Euzetacanthus is a genus in Acanthocephala.
Paracanthocephaloides is a genus in Acanthocephala.
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.
Floridosentis is a genus in Acanthocephala.
Pararaosentis is a monotypic genus of acanthocephalans containing a single species, Pararaosentis golvani.
Southwellina is a genus in Acanthocephala.
Cavisoma is a monotypic genus of acanthocephalans containing a single species, Cavisoma magnum, that infests animals.
Filisoma is a genus in Acanthocephala.
Pallisentis is a genus in Acanthocephala.
Nephridiacanthus is a genus of parasitic worms belonging to the family Oligacanthorhynchidae.
Hexaspiron is a genus in Acanthocephala belonging to the family Neoechinorhynchidae.
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.
Paraechinorhynchus is a monotypic genus of acanthocephalans containing a single species, Paraechinorhynchus kalriai, that infests the rohu.