Phasmarhabditis circassica

Phasmarhabditis circassica	Contents	Rev 05/25/2021
	Classification	Biology and Ecology
	Morphology and Anatomy	Life Cycle
Return to Phasmarhabditis Menu		Ecosystem Functions and Services
	Distribution	Management
Return to Rhabditidae Menu	Feeding	References
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Rhabditoidea

Rhabditidae

Phasmarhabditis circassica Ivanova, Geraskina & Spiridonov. 2020.

Synonym:

Morphology and Anatomy:

Cuticle ca 1 um thick with transverse and longitudinal striations.
Lateral field ca 5 um wide a band with four ridges.
Deirids located at cardia level.
Head truncate, not offset. Six lips grouped in pairs, each lip bearing a small, short apical labial papilla. Each sublateral lip bearing small cephalic papilla located slightly posterior to labial papillae.
Pore-like amphids close to labial papillae on lateral lips.
Oral aperture triangular. Stoma tubular, wide and short (about as long as lip region diam.). Cheilostom not cuticularised. Gymnostom walls parallel, thickened. Stegostom with glottoid apparatus.
Pharyngeal collar narrow, enveloping two-thirds of stoma length. Pharynx muscular, corpus expanded posteriorly into a median bulb, follwed by a well-defined isthmus and small, pear-shaped terminal bulb with valve and haustrulum.
Excretory pore position variable, situated from just posterior to nerve ring to level with pharynx base, often obscure. Excretory duct short, weak. Cardia prominent, projecting into intestine.
Rectal glands present.

Female:

2.5 mm long.
Didelphic, amphidelphic, ovaries reflexed on dorsal side.
Oocytes rounded, large, arranged in two or three rows.
Oviduct short. Spermathecae filled with sperm cells. Uterus spacious containing 20-30 eggs with thin, smooth shells.
Vagina straight, muscular, less than half corresponding body diam. long.
Vulva median, a wide transverse slit. Vulval lips flat in mature specimens and inflated in younger examples. Copulatory plug covering vulva in fertilised specimens.
Rectum inflated, about corresponding body diam. long. Anus an arcuate slit.
Tail end initially widely conoid, followed by sturdy spike that is 55% of total tail length.
Phasmids thin, long, slightly projecting, located at spike base.

Male:

Shorter than female, 0.9 mm long
Monorchic, testis reflexed.
Spermatocytes rounded, arranged in two rows. Vas deferens wide, filled with large immature sperm cells . S
Bursa open, peloderan, narrow. Nine pairs of pedunculate genital papillae incorporated into bursa
Tail tip reaching edge of bursa.
Phasmids prominent,
Spicules nearly straight, uniformly thick for most of spicule length.
Gubernaculum boat-shaped, about half as long as spicules.

Ref: Ivanova et al (2020)

Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

Distribution:

Phasmarhabditis circassica is described from infected gastropod snails, Oxychilus difficilis collecetd in the Adygea Republic, North Caucuses of the Russian Federation (Ivanova et al., 2020).

Biology and Ecology:

Most of the biology of species of this genus is inferred from studies on P. hermaphrodita. other than that the species appears to be sexually reproducing with males common (Hooper et al (1999)

The infection rate of P. circassica on the snail Oxychilus difficilis was 83% (10 out of 12 snails infected) (Ivanova et al. (2020).

Life Cycle:

Ecophysiological Parameters:

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

Based on studies with P. hermaphrodita, dauer larvae are considered the infective stage.

Ecosystem Functions and Services:

Ivanova, E.S., A.P. Geraskina and S. E. Spiridonov. 2020. Two new species of Phasmarhabditis AndrÃ¡ssy, 1976 (Nematoda: Rhabditidae) associated with land snails in Northwest Caucasus, Russian Federation: description and molecular affiliation. Nematology 22:179-197.