Oncholaimus scanicus

Oncholaimus scanicus	Contents	Rev: 04/27/2024
	Classification	Hosts
	Morphology and Anatomy	Life Cycle
Return to Oncholaimus Menu	Economic Importance	Damage
	Distribution	Management
Return to Oncholaimidae Menu	Feeding	References
	Go to Nemaplex Main Menu	Go To Dictionary of Terminology

Classification:

Enoplida
Oncholaimoidea
Oncholaimidae

Oncholaimus scanicus (Allgen, 1935) Tchesunov, 2015

Synonyms:

Viscosia scanica Allgen, 1935

Morphology and Anatomy:

Large nematodes with long filiform body.
Cuticle with very fine transversal striation
Mouth opening wide, surrounded with six rounded triangular lips.
Six inner labial sensilla as papillae at the base of each lip.
Six outer labial setae and four cephalic setae joined in common circle posterior to the inner labial papillae.
Amphideal fovea cup-shaped thin-walled pockets with wide anterior aperture and posterior sclerotized short cylindrical amphideal duct
Short somatic setae distributed irregularly along the body, more numerous anterior to the nerve ring and sparsely on the postneural body.
Orthometanemes along the lateral fields.
Buccal cavity voluminous, cylindroid gymnostome with sclerotized walls (rhabdions) thickening posteriad steppedly. Buccal cavity armed with three onchia, the left lateroventral onch the largest . All three with subapical outlets of the pharyngeal glands.
Pharynx cylindroid, evenly muscular.
Ventral excretory/secretory pore a tiny transverse slit posterior to the buccal cavity.
Ventral gland cell body situated posterior to the cardia
Tail short, its basal part conoid, distal part cylindroid.
Caudal glands long, opening in one terminal outlet pore.

		Females: Monodelphic, prodelphic. Ovary antidromously reflexed Uterus may contain up to 15 fertilized eggs. Demanian system corresponding to the Oncholaimus type with a ductus uterinus extended from the uterus rearward and terminally swollen into a bunch of convex cells constituting an uvette. Copulatory pores present as transverse slits anteriorly to the anus. A short prominent main duct extending from each pore to the uvette, often filled with some sperm cells .
Oncholaimus scanicus: Male head. Bar = 20 um. From Tchesunov, 2015	Oncholaimus scanicus: a: Male (ant.t - anterior testis, post.t =posterior testis, b.s. - blind sac). b: Female. Bars = 1 mm From Tchesunov, 2015
Males: Diorchic, anterior testis outstretched, posterior exed; both on the same side of the intestine. Spicules short, strong, nearly straight, sword-shaped, proximally cephalated, distally pointed. Gubernaculum not developed. Cloacal opening flanked by a fringe of cuticular hair-like projections Ref: Tchesunov, 2015. Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

Distribution:

Free-living marine nematodes described from hydrothermal vents in the mid-Atlantic Ridge at depths of 700-865 meters..

Feeding:

Probably omnivore-predators with large stoma and sharp teeth (Heip et al., 1985; Tchesunov, 2015)

Life Cycle:

The following observations on sexual processes were made for Oncholaimus oxyuris. They may differ in other species.

The Demanian system features in "traumatic insemination" in which the male uses spicules and secretions to puncture the cuticle of the posterior of the female to form a copulatory pore. Sperm are released into the pore. The sperm injected into the female move through terminal ducts and reach the main duct of the Demanian system. The sperm move forward in the main duct to the uterus through the uvette and ductus uterinus. Eggs are fetrilized in the uterus. After withdrawal of the spicules a "wound plug" seals the pore (Coomans et al., 1988; Tchesunov, 2015).

Ecophysiological Parameters:

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

Tchesunov, A.V. 2015. Free-living nematode species (Nematoda) in hydrothermal sites of the North Mid-Atlantic Ridge. Helgoland Marine Research 69:343-384.