Discipline: Veterinary Medicine
The surface area of the terminal genitalium of five species of the genus Carmyerius namely C. gregarious, C Synethes, C mancupatus, C. cruciformis, and C. exoporus, were examined with a scanning electron microscope. In C. gregarius and C. synethes, the terminal genitalium is surrounded by a cavity (ventral atrium). The wall of the ventral fold surrounding the atrium is marked by cone-shaped and non-ciliated tegumental papiilae. The tegumental papillae in C. gregarius are larger than those of C. synethes. Some papillae of C. synethes are double peaked. The immediate outer surface of the genital fold is devoid of these papillae, The terminal genitalium of C. mancupatus does not have a ventral atrium and ventral fold. The genital fold of this species is an upraised triangular area with the apex directed anteriorly. Its surface is covered with randomly arranged tubercle-like tegumental papillae with smooth surface. The terminal genitalium of C. cruciformis is also devoid of a ventral fold and atrium. The genital fold of this species is a round elevated area surrounding the genital tube and is ornamented with nipple-like papillae with tufted apex. The terminal genitalium of C. exoporus is devoid of ventral fold and atrium. The genital fold and pillar are devoid of tegumental papillae. In cross section, the shape of the ventral pouch of Carmyerius gregarious, C. synethes and C. mancupatus is roughly triangular but the direction of their apices differs, bifid and dorsally directed in the former and simple and ventrally directed in the latter species. That of C. exoporus and C. crucifurmis is roughly hexagonal with unequal sides. A key to separate the five species using these characters is provided. The possible function of the tegumental papillae is discussed.