Description: Adult as described by Cram, 1927: Characterized by the sexual dimorphism of the species. Male with filiform body, white, unarmed or armed with spines. Cuticle more or less striated transversely. Caudal extremity pointed; usually two unequal spicules. Caudal papillae or spines may be present. Female red; body globular or spindle shaped, with two pointed extremities projecting and with 4 longitudinal furrows corresponding to the lateral and median lines. Digestive tract consists of mouth aperture with 3 small lips, followed by a chitinous mouth capsule, a muscular pharynx, a muscular esophagus and a thin-walled, wide, sac-like intestine which is usually filled with detritus and ends in a narrow tube opening at the anus. Genital system highly developed, the body cavity largely filled with numerous coils of the uteri, ovaries, and oviducts. Uteri contain an enormous number of eggs in various stages of development, the embryo being well formed when the egg is deposited. Vulva in posterior part of body, near anus. A saccualr diverticulum of the ovejector may be present, called by Seurat a “copulatory bursa” but preferably designated by some term not already used for male structure, such as “copulatory receptaculum.
Life Cycle: The life cycle of Tetrameres are indirect and use a variety of hosts as intermediate hosts (e. g. gammarids and grasshoppers) (Olsen, 1974).
Sources:Olsen, O.W. 1974. Animal parasites, their life cycles and ecology. 3rd Revd Edition, p. 472-474.