Differentiation of Fourth and Early Fifth Stages of Parascaris equorum (Goeze, 1782) Nematoda: Ascaridoidea

Authors

P. A. Pilitt, U.S. Department of Agriculture, Science and Education Administration, Agricultural Research, Beltsville, Maryland
J. R. Lichtenfels, Science and Education Administration, U.S. Department of Agriculture, Beltsville, Maryland
P. A. Madden, Science and Education Administration, U.S. Department of Agriculture, Beltsville, Maryland

Date of this Version

1979

Citation

Proceedings of the Helminthological Society of Washington, v. 46, no.1 (1979)

Comments

Used by permission

Abstract

The morphology of Parascaris equorum of horses was studied; light and scanning electron microscopy were used. Late fourth-stage larvae have narrow, rectangular lips bearing few, large . triangular, irregularly spaced denticles and the lips are not markedly set off from the body. The cuticle of the late fourth stage is completely transversely striated, with incomplete longitudinal ridges creating a brickwork pattern; longitudinal alae are present. Total body lengths of fourth-stage larvae range from 10 to 32 mm. A single molting fourth-stage male was found to be 33 mm long. Early fifthstage nematodes have wide, trilobate lips with a deep transverse groove on their medial surface; the lips bear many small regularly spaced denticles and are set off from the body by a deep postiabial constriction. The fifth-stage cuticle is finely striated, without markings; longitudinal alae are lacking. Early fifth stages are 33.3 to 85.0 mm long.