''Ardeirhynchus'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus of

parasitic worms Parasitic worms, also known as helminths, are a polyphyletic group of large macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. Other par ...

belonging to the family

Polymorphidae The thorny-headed worm family (biology), 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 Poly ...

. Its sole described species is '' Ardeirhynchus spiralis'' , which is found in Northern America.

Taxonomy

The genus was described by Dimitrova & Georgiev in 1994. The original description of '' Ardeirhynchus spiralis'' was done by Rudolphi in 1809. The

National Center for Biotechnology Information The National Center for Biotechnology Information (NCBI) is part of the National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The NCBI is lo ...

does not indicate that any

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis has been published on ''Ardeirhynchus'' that would confirm its position as a unique genus in the family

. A phylogenetic tree was created.

Description

''A. spiralis'' consists of a proboscis covered in hooks and a long trunk. The genus is distinguished from Arhythmorhynchus, which is the most morphologically similar genus, in three ways: a considerably shorter neck, minute trunk spines, the distribution of groups of hypodermal nuclei in the anterior part of the trunk and in lateral rows along the length of the posterior part of the trunk, the position of the male genital system (which in this genus occupies the posterior 1/8-1/6 part of the trunk), and a terminal genital pore.

Distribution

The distribution of ''A. spiralis'' is determined by that of its hosts. It is found in Bulgaria (host: Squacco heron).

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 In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include ...

and then ingested by an arthropod, the

intermediate host In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include ...

. Although the intermediate hosts of ''Ardeirhynchus'' are arthropods. When the acanthor

molt In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...

s, the second stage called the acanthella begins. This stage involves penetrating the wall of the

mesenteron The midgut is the portion of the human embryo from which almost all of the small intestine and approximately half of the large intestine develop. After it bends around the superior mesenteric artery, it is called the "midgut loop". It comprises t ...

or the intestine of the intermediate host and growing. The final stage is the infective cystacanth which is the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

l 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 Feces (also known as faeces American and British English spelling differences#ae and oe, or fæces; : faex) are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the ...

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 ''Ardeirhynchus''. ''A. spiralis'' parasitizes the herons Little bittern (''Botaurus minutus'') and

squacco heron The squacco heron (''Ardeola ralloides'') is a small heron, long, of which the body is , with wingspan. It is of Old World origins, breeding in southern Europe and the Greater Middle East. Behaviour The squacco heron is a migrant, wintering ...

(''Ardeola ralloides''). The prevalence in the first host is 1.9% and usually only 1 worm is found.Santoro, M., D'Alessio, N., Di Prisco, F., Veneziano, V., Galiero, G., Cerrone, A., ... & Aznar, F. J. (2016). Helminth communities of herons (Aves: Ardeidae) in southern Italy. Parasitology international, 65(4), 340-346. There are no reported cases of ''A. spiralis'' infesting humans in the English language medical literature. Zwergdommel.jpg, Little bittern File:Crabier chevelu.jpg,

Notes

References

Polymorphidae Acanthocephala genera {{acanthocephalan-stub Monotypic protostome genera