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Table 1 Morphological characteristics, pre-patent periods and locations in the host of key genera and species of gastrointestinal nematodes infecting sheep in Australia[6, 7, 10, 11]

From: Impact of gastrointestinal parasitic nematodes of sheep, and the role of advanced molecular tools for exploring epidemiology and drug resistance - an Australian perspective

Family Species Morphometrics/morphology Prepatent period Location in the host
Length (mm) Features (days)
Trichostrongylidae Haemonchus contortus ♂ 10-20 Red pseudocoelomic fluid and white coiled ovaries giving the appearance of a barber's pole. 18-21 Abomasum
♀ 18-30
Presence of vulvar flap depends on strain.
Teladorsagia circumcincta ♂ 7-8 Small head and buccal cavity. 15-21 Abomasum
♀ 10-12 In females, a vulvar flap can be present.
Trichostrongylus axei ♂ 2-6 Dissimilar spicules of unequal length. 15-23 Abomasum
♀ 3-8 or stomach
T. colubriformis ♂ 4-8 Equal length spicules with triangular tip. 15-23 Anterior small intestine
♀ 5-9  
T. vitrinus ♂ 4-7 Equal length spicules with sharp tips. 15-23 Anterior small intestine
♀ 5-8  
T. rugatus ♂ 4-7 Dissimilar spicules with foot-like appearance. 15-23 Small intestine
♀ 6-7  
Cooperia curticei ♂ 4-5 Transverse striation of cuticle in all species. 14-15 Small intestine
♀ 5-6 Watch-spring-like body posture and presence
a small cephalic vesicle are characteristic.
Molineidae Nematodirus spathiger ♂ 10-19 Small but distinct cephalic vesicle. 18 Small intestine
♀ 15-29 Very long spicules ending in a
spoon-shaped terminal piece.
N. filicollis ♂ 10-15 Small but distinct cephalic vesicle. 18 Small intestine
♀ 15-20 Long and slender spicules with a
narrow, lanceolate membrane.
Ancylostomatidae Bunostomum trigonocephalum ♂ 12-17 Anterior end is bend dorsally, 40-70 Small intestine
♀ 19-26 Buccal capsule with two cutting plates.
Chabertiidae Oesophagostomum columbianum ♂ 12-16 Have two leaf crowns and a shallow 40-45 Large Intestine
♀ 14-18 buccal capsule. Position of cervical papillae
used for species differentiation.
O. venulosum ♂ 11-16 Cervical papillae are situated 40-45 Large intestine
♀ 13-24 posterior to the oesophagus.
Chabertia ovina ♂ 13-14 Mouth is directed antero-ventrally. 42-50 Large intestine
♀ 17-20 Buccal capsule is subglobular
    without teeth.