Discipline: Veterinary Medicine
Orthocoelium arambuloi n. sp. is described and illustrated from the rumen of cattle and water buffaloes in Indonesia and the Philippines, respectively. It is characterized by a small conical body, the presence of tegumental papillae around oral and genital openings, an acetabulum of the streptocoelium type, 1:4.9-8.8 ratio of acetabulum to body length, a pharynx of the dicranocoelium type (i.e. with anterior sphincter), 1:1.36-1.7 ratio of pharynx to acetabulum, a posterior muscular bulbous esophagus constituting about 62- 74% of its entire length, and a terminal genitalium of the leydeni type. It is differentiated from the valid species of the genus Orthocoelium (Stiles & Goldberger, 1910). Orthocoelium parastreptocoelium (Wang, 1959) and 0. sinuocoelium (Wang, 1959) are considered species inquirenda. A key to the species of the genus Orthocoelium is provided.