''Promoniliformis'' 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

acanthocephala Acanthocephala ( Greek , ' 'thorn' + , ' 'head') is a group of parasitic worms known as acanthocephalans, thorny-headed worms, or spiny-headed worms, characterized by the presence of an eversible proboscis, armed with spines, which it uses t ...

ns (thorny-headed or spiny-headed

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

worms) containing a single species, ''Promoniliformis ovocristatus'', that infests

tenrecs A tenrec () is a mammal belonging to any species within the afrotherian family Tenrecidae, which is endemic to Madagascar. Tenrecs are a very diverse group, as a result of adaptive radiation, and exhibit convergent evolution, some resemble hedge ...

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

. The genus ''Promoniliformis'' Dollfus and Golvan, 1963 is characterized by possessing two distinct kinds of proboscis hooks. There is only one species in this genus.

Taxonomy

''Promoniliformis ovocristatus'' was originally named ''Echinorhynchus ovocristatus'' by von Linstow in 1897 and renamed ''Moniliformis ovocristatus'' by Petrotschenko in 1958 and later ''Heteracanthorhynchus echinopsi'' by Hörchner in 1962. In 1963 Dollfus and Golvan introduced the present genus and species. ''P. ovocristatus'' is the type species. 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 ''Promoniliformis'' that would confirm its position as a unique genus in the family

Moniliformidae Moniliformidae is a family of parasitic spiny-headed (or thorny-headed) worms. It is the only family in the Moniliformida order and contains three genera: ''Australiformis'' containing a single species, ''Moniliformis'' containing eighteen specie ...

Description

The largest female was 222 mm long and 1.1 to 1.5 mm wide whereas the largest male was much smaller at 65 mm long and 0.85 to 1 mm wide. There is no pseudosegmentation as seen in ''Moniliformis'' species. The proboscis is 0.550 mm long and 0.250 to 0.300 mm wide at the widest point. The proboscis contains 20 to 24 longitudinal rows of 8 to 10 hooks each with the 4 or 5 superior hooks being large and possessing well-developed roots whereas the 4 or 5 inferior hooks are small and have reduced roots. The receptacle measures 0.550 to 0.650 mm long with a maximum width of 0.125 mm. It is the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

Distribution

The distribution of ''P. ovocristatus'' is determined by that of its hosts. ''P. ovocristatus'' has been found in

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 ''Promoniliformis'' are not known, without exception for the order

Moniliformida Moniliformidae is a family of parasitic spiny-headed (or thorny-headed) worms. It is the only family in the Moniliformida order and contains three genera: ''Australiformis'' containing a single species, ''Moniliformis'' containing eighteen specie ...

, this intermediate host is an insect. 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 are 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 are no known paratenic hosts (hosts where parasites infest but do not undergo larval development or sexual reproduction) for ''Promoniliformis''. ''Promoniliformis ovocristatus'' has been found parasitizing

including the

tailless tenrec The tailless tenrec (''Tenrec ecaudatus''), also known as the common tenrec, is a species of mammal in the family Tenrecidae. It is the only member of the genus ''Tenrec''. Native to Madagascar, it is also found on the Comoros, Mauritius, Réun ...

(''Tenrec ecaudatus'') and the

lesser hedgehog tenrec The lesser hedgehog tenrec (''Echinops telfairi'') is a species of mammal in the family Tenrecidae. It is the only species in the genus ''Echinops'' and is named in honour of Charles Telfair. It is endemic to Madagascar. Its natural habitats ...

(''Echinops telfairi''). There are no reported cases of ''P. ovocristatus'' infesting humans in the English language medical literature. File:Kleiner-igeltanrek-a.jpg, alt=Lesser hedgehog tenrec in profile on sand, The

is a host of ''P. ovocristatus'' File:Tanrek.jpg, alt=Tailless tenrec on the forest floor,

Tailless tenrec The tailless tenrec (''Tenrec ecaudatus''), also known as the common tenrec, is a species of mammal in the family Tenrecidae. It is the only member of the genus ''Tenrec''. Native to Madagascar, it is also found on the Comoros, Mauritius, Réun ...

is a host of ''P. ovocristatus''

Notes

References

{{Taxonbar, from1=Q18519264, from2=Q2783013 Archiacanthocephala Monotypic protostome genera Acanthocephala genera