Pachysentis

Pachysentis is a genus of parasitic spiny-headed (or thorny-headed) worms.

Pachysentis
Proboscis of P. lenti[1]
Scientific classification
Kingdom: Animalia
Phylum: Acanthocephala
Class: Archiacanthocephala
Order: Oligacanthorhynchida
Family: Oligacanthorhynchidae
Genus: Pachysentis
Meyer, 1931

Taxonomy

Pachysentis has not been included in phylogenetic analyses thus far,[2] and is categorized based on morphological features. Phylogenetic analyses have been conducted on Oncicola, a genus morphological nearly identical to Pachysentis apart from the number of hooks on the proboscis, and have placed it in the family Oligacanthorhynchidae.

Archiacanthocephala
Archiacanthocephala
Oligacanthorhynchidae
 

Macracanthorhynchus ingens

 
 

Oncicola venezuelensis

 
 

Oligacanthorhynchus tortuosa

 
 

Nephridiacanthus major

 
 
 
Moniliformidae

Moniliformis moniliformis

 
Gigantorhynchida
 

Mediorhynchus sp.

 
 

Gigantorhynchus echinodiscus

 
 
 
 
Phylogenetic reconstruction for select species in the class Archiacanthocephala[3][4]

Description
Diagram of a male P. lauroi showing the anterior and posterior testes, and eight cements glands in a clustered arrangement.

Pachysentis look identical to the closely related Oncicola apart from the number of hooks on the proboscis. Species of Oncicola have 36 or less hooks whereas species of Pachysentis have more. Specifically, the proboscis is not quite spherical and contains 42 to 102 hooks arranged into 12 longitudinal rows 3 to 12 hooks each. 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 manubria and roots with the remaining spines being rootless. The trunk is fairly wide relative to the length 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 single giant nucleus used to temporarily close the posterior end of the female after copulation.[5][6] The eggs have a sculptured outer membrane. Hosts include Brazilian or Egyptian carnivores. 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.[1]

Species
P. angolensis
Measurements[1]Female (mm)Male (mm)
Length of proboscis0.55-0.63
Width of proboscis0.70–0.82
Length of proboscis receptacle1.5
Length of trunk34-4817-23
Width of trunk4.8–5.53.5–4
Length of lemnisci5.8–6
Size of anterior testes2–3 × 0.9
Size of posterior testes2–4.3 × 1.0
Dimension of group of cement gland-3
Ejaculatory duct length-2.3
Size of eggs in mm0.09 × 0.043-
P. canicola
Measurements[1]Female (mm)Male (mm)
Length of proboscis0.57-0.80
Width of proboscis 0.57–0.85
Length of proboscis receptacle2
Length of trunk20–2615-28
Width of trunk5-114-8
Length of lemnisci7
Size of anterior testes2
Size of posterior testes2
Dimensions of cement glands3
Uterine bell3. 15–8.15
Size of eggs in mm0.07 × 0.045
P. dollfusi
Measurements[1]Female (mm)Male (mm)
Length of trunk5050 
Width of trunk44
Length of lemnisci4.3–6.6
Size of eggs in mm0.08 × 0.05
P. ehrenbergi
Measurements[1]Female (mm)Male (mm)
Length of proboscis0.8
Width of proboscis0.9
Length of proboscis receptacle1.3
Length of trunk26-2925
Width of trunk64
Length of lemnisci7
Width of lemnisci0.8
Size of anterior testes3
Size of posterior testes3
Dimension of group of cement gland7
Size of eggs in mm0.07 × 0.05
P. gethi
Measurements[1]Female (mm)Male (mm)
Length of proboscis0.583
Width of proboscis0.794
Length of proboscis receptacle1.07
Width of proboscis receptacle0.498
Length of trunk15–2510–15
Width of trunk1.5–31.0–2.5
Length of lemnisci3.48
Size of anterior testes1.40 × 0.581
Size of posterior testes1.40 × 0.581
Dimension of cement glands1.54
Ejaculatory duct length4.64
Uterine bell5.56
Size of eggs in mm0.084 × 0.054
P. lauroi
Measurements[1]Female (mm)Male (mm)
Length of proboscis0.68 × 0.76
Width of proboscis0.68 × 0.76
Length of proboscis receptacle1.16 × 0.47
Width of proboscis receptacle1.16 × 0.47
Length of trunk12.07 × 1.629.63 × 1.91
Width of trunk12.07 × 1.629.63 × 1.91
Length of lemnisci4.45
Size of anterior testis1.15 × 0.48
Size of posterior testis1.27 × 0.55
Dimension of group of cement gland0.86 × 0.56
Ejaculatory duct length1.42
Uterine bell1.19
Size of eggs0.073 × 0.045
P. lenti
Measurements[1]Female (mm)Male (mm)
Length of proboscis0.63
Width of proboscis0.664
Length of proboscis receptacle1.32
Length of trunk20–2515–20
Width of trunk2–2.5 1.0–2.5
Length of lemnisci3.15
Size of anterior testis1.76 × 0.51
Size of posterior testis1.82 × 0.547
Dimension of group of cement gland2.98
Uterine bell1.41
P. procumbens
Measurements[1]Juvenile (mm)
Length of proboscis0.55
Width of proboscis0.55
Length of proboscis receptacle1.2
Length of trunk6
Width of trunk1.25
P. procyonis
Measurements[1]Female (mm)Male (mm)
Length of proboscis0.697 
Width of proboscis0.716
Length of proboscis receptacle1.37
Width of proboscis receptacle0.531
Length of trunk25-3520-30 
Width of trunk2–32–3
Length of lemnisci3.64
Size of anterior testes3.01 × 1.24
Size of posterior testes3.15 × 1.07
Dimension of group of cement glands3.56
Ejaculatory duct length3.53
Uterine bell4.64
Size of eggs in mm0.071 × 0.042
P. rugosus
Measurements[1]Female (mm)Male (mm)
Length of proboscis|colspan="2"0.564
Width of proboscis0.694
Length of proboscis receptacle1.24
Width of proboscis receptacle0.481
Length of trunk3225
Width of trunk33.5
Dimension of group of cement glands2.02
Length of lemnisci4.64
Size of anterior testes1.57 × 0.697
Size of posterior testes1.69 × 0.664
Ejaculatory duct length2.02
Uterine bell5.86

The genus Pachysentis Meyer, 1931 contains eleven species, however P. septemserialis has an uncertain taxonomic status.[1][7][lower-alpha 1]

P. angolensis was found infesting the Side-striped jackal (Canis adustus) in Angola. The proboscis has a total of 42 hooks without barbs arranged in six rows of four hooks followed by six rows of three hooks.[1] The species name angolensis derives from the country, Angola, where it was discovered.[9]

  • Pachysentis canicola Meyer, 1931

P. canicola was found infesting the Red fox (Vulpes vulpes) in Bushehr, Bushehr Province, Iran,[10] a gray fox (Urocyon cinereoargenteus) in the United States, the Striped skunk (Mephitis mephitis), the American hog-nosed skunk (Conepatus leuconotus) and the Western spotted skunk (Spilogale gracilis) in North America, and a domestic dog (the type host) in Brazil. It is the type species. The proboscis contains 72 hooks without barbs arranged into six rows of four hooks followed by twelve rows of four hooks.[1] Intermediate hosts include Western diamondback rattlesnake (Crotalus atrox) found in Texas, United States.[11] P. canicola was also found infesting the golden jackal, (Canis aureus) in Iran.[12]

  • Pachysentis dollfusi (Machado-Filho, 1950)

P. dollfusi was found infesting the Common brown lemur (Eulemur fulvus) in a Brazilian zoo but originally from the island of Madagascar. It is thus unknown if the worm originates from Brazil or Madagascar. The proboscis has 48 barbed hooks arranged into six rows of four hooks each followed by six rows of four hooks each. The cement glands are in uniform pairs.[1]

  • Pachysentis ehrenbergi Meyer, 1931

P. ehrenbergi was found infesting the red fox (Vulpes vulpes) in Egypt. The proboscis is armed with 102 barbed hooks arranged into six rows of nine hooks each followed by six rows of eight hooks each. [1] The worm was also found inside the body cavity of 5.4% of the African five-lined skink (Trachylepis quinquetaeniata reported as Mabuya quinquetaeniata) sampled in the Qena Governorate, Egypt. The trunk is cylindrical and measures 2.6–3.7 mm in length and 0.78–0.83 mm in width in the female and measures 3–3.9 mm. in length and 0.81–0.84 mm in the much smaller male. The proboscis is relatively circular and is 0.40–0.46 mm long and 0.37–0.43 mm wide in the female and 0.46–0.49 mm long and 0.38–0.42 mm wide in the male. The proboscis contains longitudinal rows of 18 recurved hooks each. The proboscis receptacle is cylindrical, has two walls and measures 0.80–0.95 mm long and 0.36–0.39 mm wide in the female and 0.89–0.95 mm long and 0.36–0.40 mm wide in the male. The testes are oval and measures 0.20–0.26 mm by 0.10–0.14 mm. An intermediate host is the Egyptian cobra (Naja haje).[1]

  • Pachysentis gethi (Machado-Filho, 1950)[13]

P. gethi was found infesting the Tayra (Eira barbara) in Pará and Rio de Janeiro, Brazil. 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]

  • Pachysentis lauroi Gomes, Amin, Olifiers, Bianchi, Souza, Barbosa & Maldonado, 2019[1]

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. [1]

  • Pachysentis lenti (Machado-Filho, 1950)

P. lenti has been found infesting the White-headed marmoset (Callithrix geoffroyi) in Espirito Santo, Brazil. The proboscis has 48 hooks without barbs arranged into six rows of four hooks followed by six rows of four hooks.[1]

  • Pachysentis procumbens Meyer, 1931

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]

  • Pachysentis procyonis (Machado-Filho, 1950)

P. procyonis was found infesting the Crab-eating raccoon (Procyon cancrivorus) in Rio de Janeiro, Brazil. 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]

  • Pachysentis rugosus (Machado-Filho, 1950)

P. rugosus have been found infesting Azaras's capuchin (Sapajus cay) in Rio de Janeiro, Brazil. 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 their clustered cement glands and long leminisci that reach the anterior testis. [1]

  • Pachysentis septemserialis (Machado-Filho, 1950)

P. septemserialis is considered to have uncertain taxonomic status by Gomes (2019) due to the differences between the paratypes morphological characteristics and those of the original description, the similarity in hosts (primates of the family Callitrichidae), 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 incorrect 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. Morphologically, new observations suggests it is synonymous with P. lenti.[1]

Hosts

Pachysentis species exclusively parasitize carnivourous mammals as their primary host. Reptilian intermediate hosts have been found for P. ehrenbergi and P. canicola.

Notes
  1. A binomial authority in parentheses indicates that the species was originally described in a genus other than the present genus.
  2. P. angolensis was originally named Oncicola angolensis by Golvan in 1957 but was renamed by Schmidt in 1972 .[7][8]

References
  1. Gomes, Ana Paula N.; Amin, Omar M.; Olifiers, Natalie; Bianchi, Rita de Cassia; Souza, Joyce G. R.; Barbosa, Helene S.; Maldonado, Arnaldo (2019). "A New Species of Pachysentis Meyer, 1931 (Acanthocephala: Oligacanthorhynchidae) in the Brown-Nosed Coati Nasua nasua (Carnivora: Procyonidae) from Brazil, with Notes on the Genus and a Key to Species". Acta Parasitologica. 64 (3): 587–595. doi:10.2478/s11686-019-00080-6. PMC 6814649. PMID 31286360.
  2. "Search NCBI databases".
  3. Nascimento Gomes, Ana Paula; Cesário, Clarice Silva; Olifiers, Natalie; de Cassia Bianchi, Rita; Maldonado, Arnaldo; Vilela, Roberto do Val (December 2019). "New morphological and genetic data of Gigantorhynchus echinodiscus (Diesing, 1851) (Acanthocephala: Archiacanthocephala) in the giant anteater Myrmecophaga tridactyla Linnaeus, 1758 (Pilosa: Myrmecophagidae)". International Journal for Parasitology: Parasites and Wildlife. 10: 281–288. doi:10.1016/j.ijppaw.2019.09.008. PMC 6906829. PMID 31867208.
  4. Amin, O.M.; Sharifdini, M.; Heckmann, R.A.; Zarean, M. (2020). "New perspectives on Nephridiacanthus major (Acanthocephala: Oligacanthorhynchidae) collected from hedgehogs in Iran". Journal of Helminthology. 94: e133. doi:10.1017/S0022149X20000073. PMID 32114988.
  5. Bush, Albert O.; Fernández, Jacqueline C.; Esch, Gerald W.; Seed, J. Richard (2001). Parasitism : the diversity and ecology of animal parasites. Cambridge, UK New York, NY: Cambridge University Press. p. 203. ISBN 0-521-66278-8. OCLC 44131774.
  6. Kükenthal, W (2014). Gastrotricha and Gnathifera. Göttingen, Germany: Walter de Gruyter. p. 322. ISBN 978-3110274271.
  7. "Oligacanthorhynchidae Petrochenko, 1956". Integrated Taxonomic Information System (ITIS). 20 May 2020. Retrieved 20 May 2020.
  8. Amin, Omar M. (19 September 2013). "Classification of the Acanthocephala". Folia Parasitologica. 60 (4): 273–305. doi:10.14411/fp.2013.031. PMID 24261131.
  9. Golvan YJ (1957) Acanthocéphales de l’Angola. I. Oncicola angolensis n. sp. (Archiacanthocephala, Pachysentidae), parasite du chacal Canis adustus Sundevall. Publicacion Servicos Culturais de la Companhia de Diamantes de Angola, Museo do Dundo 34:39–50
  10. Tavakol, Sareh & Amin, Omar & Luus-Powell, Wilmien & Halajian, Ali. (2015). The acanthocephalan fauna of Iran, a check list. Zootaxa. 4033. 237-258. 10.11646/zootaxa.4033.2.3.|url=https://www.researchgate.net/publication/283153130_The_acanthocephalan_fauna_of_Iran_a_check_list
  11. Carbajal-Márquez, Rubén Alonso; González-Solís, David; Cedeño-Vázquez, J. Rogelio (2018). "Endoparasites of Crotalus tzabcan (Serpentes: Viperidae), with a checklist in rattlesnakes". Journal of Parasitic Diseases. 42 (2): 303–314. doi:10.1007/s12639-018-1001-3. PMC 5962485. PMID 29844637.
  12. Gherman, Călin Mircea; Mihalca, Andrei Daniel (2017). "A synoptic overview of golden jackal parasites reveals high diversity of species". Parasites & Vectors. 10 (1): 419. doi:10.1186/s13071-017-2329-8. PMC 5603039. PMID 28915831.
  13. Muniz-Pereira, Luís C.; Corrêa, Pilar; Bueno, Cecília; Vieira, Fabiano M. (2016). "Rediscovery of Pachysentis gethi (Acanthocephala: Oligacanthorhynchidae), a parasite of wild lesser grison Galictis cuja (Carnivora: Mustelidae) from Brazil". Revista Mexicana de Biodiversidad. 87 (4): 1356–1359. doi:10.1016/j.rmb.2016.10.010.
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