Objective: To determine the characteristic features of the cuticle and its supplements in Trichostrongylidae in Iran.
Design: Descriptive study.
Material and Methods: The samples including Trichostrongylus probolurus, Nematodirus abnormalis, Nematodirella, Haemonchus contortus, Marshallagia marshalli and Comelostrongylus mentulatus were collected from digestive systems of the ruminants in Iran. Sections were prepared and studied by means of light microscope. Results: In this study cuticle and its supplements including cephalic inflation, the spine at the female's end, deirid, synlophe (its length, number and decoration of ridges) and thickness of the cuticle were compared in letween different species. - Cephalic inflation and the spine are present in Nabnormalis and Nematodirella. - Deirids are present in Hcontortus, Mmarshalli and Cmentulatus. In Hcontortus they are closer to the anterior end than two other species. - Synlophe is present in all species except T.probolurus. Synlophe begins from anterior part of the worm and ends just before the vulva in Nabnorma/is and Nematodirella. In Hcontortus it ends at midbody while it continues up to the posterior end of the body in Mmarshalli and Cmentulatus. The number of the ridges from the beginning to the end of the synlophe is decreased in Nabnormalis, while they are increased in Nematodirella. There are at most 29 ridges in both of them. In Hcontortus, Mmarshalli and Cmentulatus they are increased in anterior half of the synlophe, then decreased
in posterior half of the synlophe. The maximum number of ridges in Hcontortus, Mmarshalli and Cmentolatus are 36,46 and 42, respectively.
Conclusion: In general, presence of synlophe, its length, the number of ridges and their decoration on the cuticle are highly variable in Trichostrongylidae nematodes, so that they can be used as taxonomic criteria at the level of species. J. Fac. Vet. Med. Univ. Tehran. 58, 4:335-340,2003.