Phylum Nematoda
Class
Chromadorea
Subclass
Chromadoria
Order Rhabditida
Superfamily Cosmocercoidea
Atractidae (Railliet, 1917) Travassos, 1919
A family of nematodes that are mainly parasites of amphibians, reptiles and also of fish.
Members of the Atractidae are unusual in that eggs hatch and larvae develop to third stage in utero to autoinfect the current host (Anderson 2000, Bursey ey al., 2014).
Their transmission from host to host is not understood. The life cycles of Orientatractis and Rondonia have not been determined, however Costa (1962) believed that larvae of Rondonia (previously known only from fish) pass from the host to infect other fish directly. Petter (1966) claimed that tortoises became infected only after attaining sexual maturity and wondered if transmission occurred during mating.
Key to most of the Genera of the Family Atractidae (from Mondal and Manna, 2013)
| 1 | Didelphic | 2 |
| Monodelphic | 4 | |
| 2 | Oral opening elongated in lateral axis. Pharyngeal part of oesophagus forming small buccal cavity. Parasites of intestine of Hyracoidea | Nouvelnema |
| Oral opening not elongated . Pharyngeal part of oesophagus not forming buccal cavity. | 3 | |
| 3 | Tail of male rather short. Parasites of reptiles | Fitzsimmonsnema |
| Tail of male terminated by long filament. Parasites of intestine of Equidae and Primates | Probstmayria | |
| 4 | Parasites of mammals | 5 |
| Parasites of reptiles , fishes and amphibians | 9 | |
| 5 | Mouth simple | 6 |
| Mouth with cuticular formations | 7 | |
| Mouth with two rudimentary lips, with cup- shaped buccal capsule. Parasites of Rhinoceros | Diceronema | |
| Mouth with 6 lips , cup- shaped buccal cavity with a pair of sub ventral teeth | Rhinoceronema | |
| Mouth with more than 6 lips , without buccal capsule. Parasites of elephant | Leiperenia | |
| 7 | Pharynx without pectinated laminae. Parasites of intestine of Hyracoidea | Grassinema |
| Pharynx with pectinated laminae | 8 | |
| 8 | Mouth with 3 pairs of pectinated laminae. Parasites of equides and Rhinoceros | Crossocephalus |
| Mouth with two large lateral pointed elevations and no lamina. Parasites of intestine of Hippopotamus | Cobboldina | |
| 9 | Cuticle without spines | 10 |
| Cuticle with spines | 19 | |
| 10 | Vulva opening into rectum forming cloaca | Rondonia |
| Vulva separate from rectum and anus | 11 | |
| 11 | Mouth without lips. Parasites of fish and reptiles | Monhysterides |
| Mouth with 3 to 6 lips | 12 | |
| 12 | Oral opening apical in position | 13 |
| Oral opening ventrally displaced. Subventral lip with a fringe. Parasites of intestine of tortoise | Labiduris | |
| 13 | Mouth with cuticular formations | 14 |
| Mouth without cuticular formations | 15 | |
| 14 | Lips with small tongue-like cuticular expansions surrounding oral opening. Parasites of intestine of fish | Klossinemella |
| Lips without small tongue-like cuticular expansions surrounding oral opening. Parasites of intestine of tortoise | Orientatractis | |
| 15 | Mouth with three lips | 16 |
| Mouth with four lips | Paraorientatractis | |
| Mouth with six lips | 17 | |
| 16 | Vulva close to anus . Lung parasites of turtles | Pneumoatractis |
| Vulva pre or post-equatorial. Lung parasites of turtles | Pseudocyrtosomum | |
| 17 | Tail short. Parasites of turtle | Cyrtosomum |
| Tail long | 18 | |
| 18 | Buccal capsule present. Excretory-pore anterior to oesophageal bulb. Parasites of turtle | Rhinoclemmysnema |
| Buccal capsule absent. Excretory-pore posterior to oesophageal bulb. Parasites of reptiles, amphibians and fishes | Atractis | |
| 19 | Cuticle covered with many spines alternating in diagonal rows | 20 |
| Only posterior dorsal surface of the body with or without spines. Parasites of intestine of reptiles | Podocnematractis | |
| 20 | Spines extend along entire length of body. in diagonal rows. Parasites of intestine of turtle | Paratractis |
| Spines vary in arrangement and differing in shape and size. Parasites of intestine of reptiles | Buckleyatractis |
Anderson R.C. 2000. Nematode Parasites of Vertebrates: Their development and transmission. 2nd Ed. CABI Publishing, Wallingford, Oxon, UK, 650 pp
Bursey, C.R., Flanagan, J.P. 2002. Atractis marquezi n. sp. (Nematoda: Atractidae) and a Revision of Atractis Dujardin, 1845, Sensu Baker, 1987. J. Parasitol., 88:320-324.
Bursey, C.R., Goldberg, S.R., Kraus, F. 2014. New species of Rondonia (Nematoda: Atractidae), new species of Rondonia (Nematoda: Atractidae) and other helminths in Austrochaperina basipalmata (Anura: Microhylidae) from Papua New Guinea. Acta Parasitologica 59:115-121..
Bursey, C.R., Reavill, D., Greiner, E. 2009. Pneumoatractis podocnemis n.
gen., n. sp. (Nematoda: Atractidae) from the Yellow-Spotted Amazon River Turtle,
Podocnemis unifilis (Testudines: Pelomedusidae). Comp. Parasitol.
76(2):149-153
Mondal, S., Manna, B. 2013 Rhinoceronema unicornensis gen. n., sp. n. (Cosmocercoidea: Atractidae) from Indian one horned Rhinoceros (Rhinoceros unicornis Linnaeus, 1758) captivated at the Alipore Zoological Garden, Kolkata, India. J Parasit Dis 37134-141 https://doi.org/10.1007/s12639-012-0147-7.