Rhigonema

Rhigonema	Contents	Rev 02/21/2024
	Classification	Biology and Ecology
	Morphology and Anatomy	Life Cycle
Return to Rhigonema Menu		Ecosystem Functions and Services
	Distribution	Management
Return to Rhigonematidae Menu	Feeding	References
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Classification:

Enoplea

Rhabditida
Spirurina

Rhigonematomorpha

Rhigonematoidea

Rhigonematdae

Rhigonema Cobb, 1898

Morphology and Anatomy:

Based on description of general characetristics of Rhigonema sinense (Zhang et al., 2022).

Small-sized nematodes with a maximum width at about mid-body. \
Cephalic region heavily cuticularized, with well-developed cephalic cap and smooth cephalic collar. Cephalic cap bearing three lips, a dorsal lip with one pair of large cephalic papillae, two subventral lips each with a single large cephalic papilla.
Amphidial apertures located laterally at junction of cephalic cap and cephalic collar.
Oral aperture simple, somewhat triangular.
Cuticle posterior to cephalic region with dense, transverse rows of small spines (microtrichs); rows of spines gradually becoming distinctly sparser and smaller towards posterior region of body and disappearing at about the anterior 25% of body length.
Esophagus divided into short chitinized pharynx with three fabellate pharyngeal plates, muscular cylindrical corpus (posterior part slightly wider than anterior part), inconspicuous isthmus and ovoid or nearly rounded posterior bulb.
Nerve ring at about 50% of esophageal corpus.
Excretory pore close to junction of corpus and posterior esophageal bulb of esophagus.
Tail of both sexes conical, with polymorphic tip

Female:

Didelphic-amphidelphis, ovaries reflexed

Males:

Spicules unequal in length
No gubernaculum
Caudal papillae numerous

Body size range for the species of this genus in the database - Click:

The genus Rhigonema Cobb, 1898 is the largest group in the superfamily Rhigonematoidea. It includes approximately 90 nominal species that are mainly parasitic in millipedes in Africa, Asia, Australia and South and North America (Zhang et al., 2022)