Nematodirus helvetianus

Nematodirus helvetianus	Contents	Rev 10/20/2025
	Classification	Biology and Ecology
	Morphology and Anatomy	Life Cycle
Return to Nematodirus menu		Ecosystem Functions and Services
	Distribution	Management
Return to Molineidae Menu	Feeding	References
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Classification

Phylum: Nematoda
Class: Chromadorea
Order: Rhabditida

Superfamily: Molinieoidea

Family: Molineidae

Subfamily: Nematodirinae

Nematodirus helvetianus May, 1920

Morphology and Anatomy:

Slender,
Cuticle with about 18 longitudinal striations.
Mouth opening circular with a serrated, denticulate, circularized crown and a triangular dorsal tooth

Males:

Bursa large with large lobes
Length 11-17 mm,
Spicules 900-1250 um long sharp, symmetrical
No gubernaculum

Females:

18-25 mm long
Eggs large 84-110 x 184-233 um

Ref Snyder et al., 2020

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

Distribution:

Worldwide parasite of cattle, mainly in temperate zones, also sheep, goats and camels (Snyder et al., 2020).

Hosts:

Sheep, goats and cattle, camels (Snyder et al., 2020).

A simple, direct life-cycle without the need for an intermediate host. Infective third-stage larvae develop within the egg, Nematodirus helvetianus does not have the chilling temperature hatching requirement of N. battus. Hence, hatching is not seasonally synchronized and occurs year round under favorable conditions. More than one generation occurs per year (Snyder et al., 2020).

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