Orientatractis bowseri

Orientatractis bowseri	Contents	Rev 01/07/2026
	Classification	Biology and Ecology
	Morphology and Anatomy	Life Cycle
Return to Orientatractis Menu		Ecosystem Functions and Services
	Distribution	Management
Return to Atractidae Menu	Feeding	References
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Cosmocercoidea

Atractidae

Orientatractis bowseri Jesus, Santos, Oliveira, Felix-Silva & Melo, 2024

Morphology and Anatomy:

Small and slender nematodes.
Cuticle with papilloid rounded ornamentations from mid region of esophagus to mid-body; lateral alae extending from first third of esophagus to anus/cloaca.
Cuticular projections of variable size, on dorsal side to anterior of vulva in females but absent or reduced in males.
Oral aperture irregular to circular, surrounded by eight submedian papillae in two circles, each with four papillae. Six lips: four submedian (two subdorsal and two subventral) each submedian lip with two well-sclerotized, recurved, pointed spines joined at base and a single median spine
Two lateral lips supporting large amphids with one pair lateral spines posterior to each amphidial pore.
Esophagus with anterior corpus and median isthmus and valved bulb. Nerve ring situated at beginning of isthmus. Deirids small, cone-shaped, somewhat posterior to nerve ring. Excretory pore slightly anterior to esophageal bulb
Tail slender, long, sharply pointed.



Males: Ten pairs of caudal papillae plus 1 unpaired papilla just anterior to cloaca Spicules unequal, proximal ends slightly expanded, distal ends sharply pointed; left spicule 292 um long, right spicule 92 um long; Gubernaculum well-sclerotized with proximal end expanded, deep medial depression and distal end pointed Tail 275 um long.	Female: Monodelphic-prodelphic Vulva around 70% of body length Viviparous, larvae often filling uterus ( Tail 624 um long Ref: Jesus et al., 2024
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

Distribution:

Nematodes recovered from the stomach of a freshwater turtle (Peltocephalus dumerilianus) in the Amazon River basin, Brazil.

Feeding:

Stomach parasite of a freshwater turtle.

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). 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.

Ecophysiological Parameters:

For Ecophysiological Parameters for this species, click	If species level data are not available, click for genus level parameters

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Ecosystem Functions and Services:

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Management:

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References:

Jesus, R.F., Santos, A.N., Oliveira, T.de A.P., Felix-Silva, D. & Melo, F.T.V., 2024. Orientatractis bowseri n. sp. (Nematoda: Cosmocercoidea: Atractidae) parasite of Peltocephalus dumerilianus (Schweigger) (Testudines: Podocnemididae) from the Brazilian Amazon. Syst. Parasitol. 101:5