Pachysentis | |
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Proboscis of P. lenti [1] | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Acanthocephala |
Class: | Archiacanthocephala |
Order: | Oligacanthorhynchida |
Family: | Oligacanthorhynchidae |
Genus: | Pachysentis Meyer, 1931 [2] |
Type species | |
Pachysentis canicola Meyer, 1931 | |
Other species | |
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Pachysentis is a genus in Acanthocephala (thorny-headed worms, also known as spiny-headed worms) 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.
Phylogenetic analysis has been conducted on one of the eleven species in the genus, P. canicola. [3] Sequences of the molecular marker 18S rDNA gene were compared to the same sequences in related species and it was concluded that P. canicola samples formed a well-supported group with other species in the family Oligacanthorhynchidae. [3] Phylogenetic analyses have also been conducted on Oncicola, a genus morphologically nearly identical to Pachysentis apart from the number of hooks on the proboscis, and have also placed it in the family Oligacanthorhynchidae. [4] The type species for Pachysentis is P. canicola. [5] [1] In 1972, Schmidt reclassified six species from the Prosthenorchis genus and one species from the Oncicola genus into the genus Pachysentis. [6]
Archiacanthocephala |
Phylogenetic reconstruction for select species in the class Archiacanthocephala based on a 28S rRNA gene comparison from Gomes et. al (2019) and a 18S rDNA gene comparison from Amin and colleagues (2020). [1] [7] Amin and colleagues (2022) used the 18S rDNA gene to add P. canicola phylogenetically to the family Oligacanthorhynchidae. [3] |
Number of proboscis hooks [1] | Barbs in hooks | |
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P. angolensis | 42 | No barbs |
P. canicola | 72 | No barbs |
P. dollfusi | 48 | Barbs |
P. ehrenbergi | 102 | Barbs [a] |
P. gethi | 42 | No barbs |
P. lauroi | 48 | Barbs |
P. lenti | 48 | No barbs |
P. procumbens | 90 | No barbs |
P. procyonis | 42 | No barbs |
P. rugosus | 42 | No barbs |
Pachysentis looks identical to the closely related Oncicola apart from the number of hooks on the proboscis. Species of Oncicola have 36 or fewer hooks whereas species of Pachysentis have more. The probosces of Pachysentis species are not quite spherical and contain 42 to 102 hooks arranged into 12 longitudinal rows of 3 to 12 hooks each. Depending on the species, the rows may be regularly or irregularly alternating and straight or crooked. Hooks have tips with or without barbs, and the larger hooks with complex heads (manubria) and roots with the remaining spines being rootless. The trunk is around twice as long as wide with the anterior half usually wider than the posterior half. The testes are in tandem with at least one located before the middle of the worm. There are eight cement glands compactly arranged each with a single giant nucleus used to temporarily close the posterior end of the female after copulation. [8] [9] The eggs have a sculptured outer membrane. Species can be distinguished based on the number and arrangements of proboscis hooks, whether these hooks are barbed, the arrangement of the cement glands, host, and the length of lemnisci (bundles of sensory nerve fibers). [1]
Female measurements (mm) [1] | |||||||||||
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Measurements [b] | P. angolensis | P. canicola | P. dollfusi | P. ehrenbergi | P. gethi | P. lauroi | P. lenti | P. procumbens [c] | P. procyonis | P. rugosus | |
Length of proboscis | 0.55-0.63 | 0.57-0.80 | ? | 0.8 | 0.583 | 0.68 | 0.63 | 0.55 | 0.697 | 0.564 | |
Width of proboscis | 0.70–0.82 | 0.57–0.85 | ? | 0.9 | 0.794 | 0.76 | 0.664 | 0.55 | 0.716 | 0.694 | |
Length of proboscis receptacle | 1.5 | 2 | ? | 1.3 | 1.07 | 1.16 | 1.32 | 1.2 | 1.37 | 1.24 | |
Width of proboscis receptacle | ? | ? | ? | ? | 0.498 | 0.47 | ? | ? | 0.531 | 0.481 | |
Length of trunk | 34–48 | 20–26 | 50 | 26–29 | 15–25 | 12.07 | 20–25 | 6 | 25-35 | 32 | |
Width of trunk | 4.8–5.5 | 5-11 | 4 | 6 | 1.5–3 | 1.62 | 2–2.5 | 1.25 | 2–3 | 3 | |
Length of lemnisci | 5.8–6 | 7 | 4.3–6.6 | 7 | 3.48 | 4.45 | 3.15 | ? | 3.64 | 4.64 | |
Width of lemnisci | ? | ? | ? | 0.8 | ? | ? | ? | ? | ? | ? | |
Uterine bell [d] | ? | 3.15–8.15 | ? | ? | 5.56 | 1.19 | 1.41 | ? | 4.64 | 5.86 | |
Size of eggs | 0.09 × 0.043 | 0.07 × 0.045 | 0.08 × 0.05 | 0.07 × 0.05 | 0.084 × 0.054 | 0.073 × 0.045 | ? | ? | 0.071 × 0.042 | ? | |
Male measurements (mm) [1] | |||||||||||
Length of proboscis | 0.55-0.63 | 0.57-0.80 | ? | 0.8 | 0.583 | 0.68 | 0.63 | 0.55 | 0.697 | 0.564 | |
Width of proboscis | 0.70–0.82 | 0.57–0.85 | ? | 0.9 | 0.794 | 0.76 | 0.664 | 0.55 | 0.716 | 0.694 | |
Length of proboscis receptacle | 1.5 | 2 | ? | 1.3 | 1.07 | 1.16 | 1.32 | 1.2 | 1.37 | 1.24 | |
Width of proboscis receptacle | ? | ? | ? | ? | 0.498 | 0.47 | ? | ? | 0.531 | 0.481 | |
Length of trunk | 17-23 | 15-28 | 50 | 25 | 10–15 × 1.0–2.5 | 9.63 | 15–20 | 6 | 20-30 | 25 | |
Width of trunk | 3.5–4 | 4-8 | 4 | 4 | 1.0–2.5 | 1.91 | 1.0–2.5 | 1.25 | 2–3 | 3.5 | |
Length of lemnisci | 5.8–6 | 7 | 4.3–6.6 | 7 | 3.48 | 4.45 | 3.15 | ? | 3.64 | 4.64 | |
Width of lemnisci | ? | ? | ? | 0.8 | ? | ? | ? | ? | ? | ? | |
Size of anterior testis | 2–3 × 0.9 | 2 | ? | 3 | 1.40 × 0.581 | 1.15 × 0.48 | 1.76 × 0.51 | ? | 3.01 × 1.24 | 1.57 × 0.697 | |
Size of posterior testis | 2–4.3 × 1.0 | 2 | ? | 3 | 1.40 × 0.581 | 1.27 × 0.55 | 1.82 × 0.547 | ? | 3.15 × 1.07 | 1.69 × 0.664 | |
Dimension of group of cement glands | 3 | 3 | ? | 7 | 1.54 | 0.86 × 0.56 | 2.98 | ? | 3.56 | 2.02 | |
Ejaculatory duct length | 2.3 | ? | ? | ? | 4.64 | 1.42 | ? | ? | 3.53 | 1.68 | |
The genus PachysentisMeyer, 1931 contains eleven species, although P. septemserialis is of uncertain taxonomic status. [1] [10] [e]
P. angolensis was found infesting the side-striped jackal (Canis adustus). The proboscis has a total of 42 hooks without barbs in 12 regularly alternating rows of three and four hooks (six rows of each). [11] The eight cement glands are organized in pairs. [1] This species is named after Angola, the country where it was first discovered. [11]
P. canicola was found infesting the red fox (Vulpes vulpes) in Bushehr, Bushehr Province, Iran, [12] the golden jackal (Canis aureus) also in Iran, [13] captive maned wolves (Chrysocyon brachyurus) in a zoo in Texas, and the striped skunk (Mephitis mephitis) found nearby. [3] It was also found infesting the western diamondback rattlesnake (Crotalus atrox). [14] [15] It is the type species of the genus Pachysentis. [2] The species name canicola is derived from the Latin word for canine which is the type of creature (family Canidae) that this species infests. [2]
P. dollfusi was found infesting the intestines of the common brown lemur (Eulemur fulvus) in a Brazilian zoo but originally from the island of Madagascar. [16] It is thus unknown if the worm originates from Brazil or Madagascar. [1] The proboscis has 48 barbed hooks arranged into six rows of four hooks each followed by another six rows of four hooks each. The cement glands are in uniform pairs. [1] It is synonymous with Prosthenorchis spirulaTravassos 1917. [17] It is named after the parasitologist Robert-Philippe Dollfus. [16]
P. ehrenbergi was found infesting the red fox (Vulpes vulpes) in Egypt and in an intermediate host, the Egyptian cobra (Naja haje). The proboscis is armed with 102 barbed hooks arranged into six rows of nine each followed by six rows of eight hooks each. [1] P. ehrenbergi was reported infesting the body cavity of 5.4% of a sample of African five-lined skinks (Trachylepis quinquetaeniata) in the Qena Governorate of Egypt, however the measurements and morphological description do not match either the original description by Meyer in 1931 [2] or the reexamination of original specimens by Gomes and colleagues in 2019. [1] Juvenile P. ehrenbergi have been reported infesting the long-eared hedgehog (Hemiechinus auritus) in the Faran Oasis, South Sinai, Egypt. Juvenile trunk length is reported to be 3.22–4.16 mm by 0.87–1.04 mm, the proboscis length to be 0.42–0.60 mm in length by 0.45–0.68 mm in width, the proboscis sheath to be 0.79–1.0 mm by 0.37–0.52 mm (whereas the measurements given by Meyer in the original 1931 description is larger, at 1.3 mm in length and the proboscis measuring 0.8 mm in length by 0.9 mm in width). The anterior proboscis hooks in the juveniles are reported to be large, from 0.078–0.086 mm long, and the posterior hooks smaller, from 0.052–0.062 mm. [18]
P. gethi was originally described in 1950 by Machado-Filho infesting tayra (Eira barbara) in Pará and Rio de Janeiro, Brazil but this remained the only record until it was rediscovered in 2016 infesting the wild lesser grison (Galictis cuja), also in Rio de Janeiro, with different measurements. [19] The proboscis has 42 hooks without barbs arranged into six rows of four hooks followed by six rows of three hooks. The eight cement glands occur in pairs. [1] The species is named after Dr. Geth Jansen. [16]
P. lauroi has been found infesting the South American coati (Nasua nasua) in Mato Grosso do Sul, Brazil. The proboscis has 48 barbed hooks arranged into six rows of four hooks followed by six rows of four hooks. The eight cement glands are clustered. It was found in the small intestine. [1] The species is named after Lauro Travassos , a parasitologist who studied Brazilian Acanthocephala. [1]
P. lenti has been found infesting the white-headed marmoset (Callithrix geoffroyi) in Espírito Santo, Brazil. The proboscis has 48 hooks without barbs arranged into six rows of four hooks followed by six rows of four hooks. [1] It is named after Herman Lent , a Brazilian parasitologist. [16]
P. procumbens has been found infesting the red fox (Vulpes vulpes) in Argo, Egypt. The proboscis has 90 hooks without barbs arranged into six rows of seven hooks followed by six rows of eight hooks. [1] The species name is from the Latin procumbent, meaning "lying prostrate". [20]
P. procyonis was found infesting the intestines of a crab-eating raccoon (Procyon cancrivorus) in Rio de Janeiro, Brazil. [21] The proboscis has 42 hooks without barbs arranged into six rows of four hooks followed by six rows of three hooks. Distinguishing features include eight clustered cement glands and very short lemnisci that do not reach the anterior testis. [1] The species is named after the genus of the host ( Procyon ) it was found infesting. [16] It is the only known parasite of the crab-eating racoon in Brazil. [22]
P. rugosus has been found to infest the large intestine of Azaras's capuchin (Sapajus cay) in Rio de Janeiro, Brazil, and the tufted capuchin (Sapajus apella), also in Brazil. [23] The proboscis is armed with 42 hooks without barbs arranged into six rows of four hooks each followed by six rows of three hooks each. This species can be identified by its clustered cement glands and long leminisci that reach the anterior testis. [1] The species name rugosus is Latin for 'wrinkled'.
P. septemserialis is considered by Gomes (2019) to have an uncertain taxonomic status due to differences between the paratypes morphological characteristics and the original description, the similarity in hosts (primates of the family Callitrichidae including the black tamarin (Saguinus niger), [24] and the absence of samples or measurements of adult males. Specifically, the original description of one paratype described the lack of a collar at the base of the proboscis whereas a collar was observed (suggesting affiliation with the genus Prosthenorchis ). A second discrepancy from another paratype is the number of hooks; 12 longitudinal rows of four hooks with total of 48 hooks were observed but contradicts the seven rows of seven hooks with a total of 49 hooks given in the original description. The name septemserialis refers to the seven rows in series. [16] Morphologically, new observations suggest it is synonymous with P. lenti. [1]
The distribution of Pachysentis species is determined by that of its hosts. Pachysentis species have been found in South America (Brazil), Africa (Egypt and Angola), Asia (Egypt and Iran). [1]
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 most Pachysentis species 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 is passed in the feces of the definitive host and the cycle repeats. [27]
Pachysentis species exclusively parasitize primates and carnivorans as their primary host. [1] Paratenic hosts (hosts where parasites infest but do not undergo larval development or sexual reproduction) for Pachysentis have been found for P. ehrenbergi (Egyptian cobra, Naja haje) [18] and P. canicola (western diamondback rattlesnake, Crotalus atrox). [15] There are no reported cases of any Pachysentis species infesting humans in the English language medical literature. [26]
Apororhynchus is a genus of small parasitic spiny-headed worms. It is the only genus in the family Apororhynchidae, which in turn is the only member of the order Apororhynchida. A lack of features commonly found in the phylum Acanthocephala 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 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.
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.
Oligacanthorhynchida is an order containing a single parasitic worm family, Oligacanthorhynchidae, that attach themselves to the intestinal wall of terrestrial vertebrates.
Neoechinorhynchidae is a family of parasitic worms from the order Neoechinorhynchida.
Paracanthocephaloides 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.
Paraprosthenorchis is a monotypic genus of acanthocephalans. It contains a single species, Paraprosthenorchis ornatus, which infests the Chinese pangolin in Vietnam.
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.
Floridosentis is a genus in Acanthocephala.
Cathayacanthus is a genus in Acanthocephala.
Palliolisentis is a genus in Acanthocephala.
Nephridiacanthus is a genus of parasitic worms belonging to the family Oligacanthorhynchidae.
Gorytocephalus 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.