Apororhynchus | |
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Drawing of Apororhynchus hemignathi by Arthur Shipley in 1896. This is the original sketch of the first species in the genus Apororhynchus to be described. | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Acanthocephala |
Class: | Archiacanthocephala |
Order: | Apororhynchida Thapar, 1927 [1] |
Family: | Apororhynchidae Shipley, 1899 [2] |
Genus: | Apororhynchus Shipley, 1899 |
Type species | |
Apororhynchus hemignathi (Shipley, 1896) | |
Other species | |
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Apororhynchus is a genus of small parasitic spiny-headed (or thorny-headed) worms. It is the only genus in the family Apororhynchidae, which in turn is the only member of the order Apororhynchida. [3] A lack of features commonly found in the phylum Acanthocephala (primarily musculature) suggests an evolutionary branching from the other three orders of class Archiacanthocephala; however no genetic analysis has been completed to determine the evolutionary relationship between species. The distinguishing features of this order among archiacanthocephalans is a highly enlarged proboscis which contain small hooks. The musculature around the proboscis (the proboscis receptacle and receptacle protrusor) is also structured differently in this order. This genus contains six species that are distributed globally, being collected sporadically in Hawaii, Europe, North America, South America, and Asia. These worms exclusively parasitize birds by attaching themselves around the cloaca using their hook-covered proboscis. The bird hosts are of different orders, including owls, waders, and passerines. Infestation by an Apororhynchus species may cause enteritis and anemia.
The first species in this order to be described was Apororhynchus hemignathi which was originally named Arhynchus hemignathi by Arthur Shipley in 1896. The name Arhynchus [a] was chosen based on the characteristic absence of a proboscis in this species of Acanthocephala. [2] It was later renamed Apororhynchus (along with the family name Apororhynchidae) by Shipley in 1899 due to the name Arhynchus having been used by Dujean in 1834 for a beetle. [4]
The National Center for Biotechnology Information does not indicate that any phylogenetic analysis has been published on Apororhynchida that would confirm its position as a unique order in the class Archiacanthocephala. [5] The lack of morphological features such as an absence of a muscle plate, a midventral longitudinal muscle, lateral receptacle flexors, and an apical sensory organ when compared to the other three orders of class Archiacanthocephala indicate it is an early offshoot (basal). [6]
The genus Apororhynchus consists of ectoparasitic worms that attach themselves beneath the skin and around the anus of birds. [6] [7] The distinguishing features of this order among acanthocephalans are a highly enlarged proboscis with limited motility and a reduced size of the hooks (or spines). [6] Apororhynchus species have short conical trunks and a reduced or absent neck. [8] The proboscis is large and globular with numerous deeply set spirally arranged rootless hooks usually not reaching the surface, or with no hooks. [8] They contain sets of muscles that are common to all Acanthocephala including a proboscis receptacle, a receptacle-surrounding muscle called a receptacle protrusor, retinacula (connective tissue that stabilizes tendons), a neck retractor, proboscis and receptacle retractors, [8] circular and longitudinal musculature under the metasomal (trunk) tegument, and a single muscular layer beneath the proboscis wall. [6]
Two regions of musculature are considerably different in Apororhynchus compared to the other acanthocephalan orders: the proboscis receptacle and receptacle protrusor are both reorganized in Apororhynchus with the muscles subdivided into strands extending from the cerebral ganglion, or nerve bundle, to the proboscis wall. These two muscles suspend the cerebral ganglion but are not involved in the eversion of the proboscis. [6] Additional anatomical features that can be used to distinguish this genus among other acanthocephalans include a cerebral ganglion located under the anterior wall of the proboscis, long and tubular lemnisci (bundles of sensory nerve fibers) that run along a central canal, the lack of any protonephridia (an organ which functions as a kidney), and the presence of eight pear-shaped cement glands used to temporarily close the posterior end of the female after copulation. [9] [10]
There are six species in the genus Apororhynchus. [11] [12] A seventh species, Apororhynchus bivolucrusDas, 1950 [13] [14] (also called A. bivolucrus) from an Egyptian vulture (Neophron percnopterus) from India was considered to be a strigeid trematode by Yamaguti (1963). [15]
A. aculeatus has been found in Santos, Brazil, parasitizing a New World oriole. [17] The parasite was discovered in 1931, in the Berlin Museum, taken from the digestive tube of a bird named at that time as "Oriolus cristatus", which was likely a crested oropendola (Psarocolius decumanus). [b] A. aculeatus was the second parasite to be discovered in its genus, and the specimen used to describe the species was female. [17] Numerous fine hooks on the bulb-shaped proboscis, as well as the different host and location, distinguish it from A. hemignathi. [17]
The parasite was discovered in the summer of 1947 infesting a Canada warbler (Cardellina canadensis formerly Wilsonia canadensis) in Mountain Lake, Virginia, and a Northern parula (Setophaga americana formerly Compsothlyphis americana) in Augusta, Georgia, thus making it the third species in its genus to be discovered, and the first species in its genus to be discovered in North America. [17] It was found in the digestive tract, just inside the vent. The species name amphistomi derives from a superficial resemblance to the amphistomate trematodes (flukes with stoma on opposite sides). [17] On the proboscis, there are approximately 20 very fine hooks found on each of 40 rows. The two lemnisci are longer than the body length and are folded in the body cavity. Females are 2.13 mm long by 0.83 mm in maximum width and the proboscis is 0.36 mm long by 0.44 mm in maximum width. The male is smaller being 1.43 mm long by 0.53 mm in maximum width and the proboscis is 0.44 mm long by 0.74 mm in maximum width. [17]
A. chauhani is the only Apororhynchus species described from India. It was discovered in Srisailam, Andhra Pradesh, in 1975. [23] A. chauhani was named after Birendra Singh Chauhan, a member of the Zoological Society of India. [23] [24] It parasitizes the spotted owlet (Athene brama) and has been found in the intestine. The body is 4.70 mm by 1.70 mm long with a proboscis that is 1.11 mm by 1.68 mm in length and immature eggs are around 0.015 mm to 0.035 mm in diameter. The hooks on the proboscis are finger shaped and numerous, especially in the posterior. The rest of the hooks on the anterior side are irregularly directed and sparse. The proboscis sheath is absent. The nerve ganglion is large and located near the anterior proboscis. The lemnisci are very long and unequal. [15]
A. hemignathi was the first species of Apororhynchus to be described with the creation of the genus and family by Arthur Shipley in 1896 due to its uniqueness among already described Acanthocephala. [17] It has been found in Kaua'i, Hawaii, parasitizing the now extinct Kauaʻi ʻakialoa (Akialoa stejnegeri). [17] A. hemignathi was named after the genus of the Kauaʻi ʻakialoa, which was Hemignathus at the time of the description. Specimens range from 2.5 mm to 3.5 mm long, distended 1 mm to 1.5 mm longer. [4] It has two to four nuclei in the lemnisci. [25] It is the type species for the genus. [11]
This parasite has been found in the black-winged pratincole (Glareola nordmanni) at Malye Chany Lake, in Russia, [26] and in the colon and cloaca of the Eastern yellow wagtail (Motacilla tschutschensis) in Chukotka and Kamchatka (including the Karaginsky Island), also in Russia. [25] It was described in 1966. [11] [25] The proboscis is large compared to the body and spherical. It is armed with 10–12 spiral rows of hooks with 14–15 hooks in each row. The hook has a thin blade with a curved tip and root thickened with broadened base. In the body, there are 10–16 giant nuclei with a diameter of 0.050–0.077 mm. There is a very short neck (0.153 mm long) between the proboscis and the body with attached ribbon-like lemnisci longer than their own body length. Females are 3.7 mm long by 0.92 mm in maximum width and the proboscis is 1.30 mm long by 1.53 mm in maximum width. The male is smaller being 3.21 mm long by 0.766 mm in maximum width and the proboscis is 0.796 mm long by 0.995 mm in maximum width. The eggs were oval shaped with three concentric shells around 0.074–0.080 mm long and 0.040–0.043 mm wide. [25]
A. silesiacus was found in the cloaca of the European robin (Erithacus rubecula), the thrush nightingale (Luscinia luscinia) and the common nightingale (Luscinia megarhynchos) in Wroclaw, Poland, [27] and of the European robin in Alsóperepuszta, Hungary. [28] Described in 1980, it is the most recently classified species of the Apororhynchus. A. silesiacus is named after Silesia, a region in Poland where the parasite was found. [27] Specimens were between 3.21 and 3.51 mm in total length, with a maximum width of 0.80 to 1.05 mm at middle and the eggs were around 0.07 mm long and 0.035 mm wide. [28] It has a proboscis wider than the anterior part of the trunk, with about 40 spiral rows of hooks, each row bearing 14 to 16 hooks. There are 28 to 31 giant nuclei in the body wall and 9 to 12 in the lemnisci. The testes are almost parallel. The parasite has been found infesting juvenile European robins, indicating that the infestation occurred in the nesting area. [27]
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. The intermediate hosts of Apororhynchus are not known. 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 are passed in the feces 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 Apororhynchus. [31]
Apororhynchus species exclusively parasitize avian hosts of different orders including owls, waders, and passerines. [7] The parasite attaches to the cloaca and in some cases the intestinal wall using a hook-covered proboscis. [6] [10] Infestation can cause enteritis and anemia in Hawaiian honeycreepers. [32] There are no reported cases of any Apororhynchus species infesting humans in the English language medical literature. [30]
Archiacanthocephala is a class within the phylum of Acanthocephala. They are parasitic worms that attach themselves to the intestinal wall of terrestrial vertebrates, including humans. They are characterised by the body wall and the lemnisci, which have nuclei that divide without spindle formation, or the appearance of chromosomes, or it has a few amoebae-like giant nuclei. Typically, there are eight separate cement glands in the male, which is one of the few ways to distinguish the dorsal and ventral sides of these organisms.
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.
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.
Oligacanthorhynchida is an order containing a single parasitic worm family, Oligacanthorhynchidae, that attach themselves to the intestinal wall of terrestrial vertebrates.
Fessisentis is a genus of parasitic spiny-headed worms. It is the only genus in the family Fessisentidae. This genus contains six species that are distributed across the Eastern continental United States as far west as Oklahoma and Wisconsin. These worms parasitize salamanders and fish.
Dendronucleata is a genus of small parasitic spiny-headed worms. It is the only genus in the family Dendronucleatidae. This genus contains three species that are distributed globally, being collected in North America and Asia. The distinguishing features of this genus among Archiacanthocephalans is the presence of randomly distributed dendritically branched giant hypodermic nuclei. Dendronucleata parasitize freshwater fish and a salamander by attaching themselves in the intestines using their hook covered proboscis and adhesives secreted from cement glands.
Breizacanthus is a genus in Acanthocephala.
Euzetacanthus is a genus in Acanthocephala.
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 genus of acanthocephalans containing a single species, Heptamegacanthus niekerki, that is a parasite of the endangered giant golden mole. It is found only in isolated forests in the Transkei and near East London, both in South Africa. The worms are about 4 mm long and 2 mm wide with minimal sexual dimorphism. An individual's body consists of a short, wide trunk and a tubular feeding and sucking organ called the proboscis which is covered with hooks. The hooks are used to pierce and hold the rectal wall of its host. There are 40 to 45 of these hooks arranged in rings surrounding the proboscis. They are not radially symmetrical. There are seven large anterior hooks; the hooks in the anterior ring are twice as large as those in the second ring and the remaining hooks decrease progressively in size posteriorly.
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.
Oligacanthorhynchus is a genus of parasitic worms belonging to the family Oligacanthorhynchidae.
Atactorhynchus is a genus in Acanthocephala which contains two species, A. verecundus and A. duranguensis.
Cathayacanthus is a genus in Acanthocephala.
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.
Mayarhynchus is a monotypic genus of acanthocephalans containing a single species, Mayarhynchus karlae, that infests animals.
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