Aquatic Nematodes from Ethiopia VI. The Genera Chronogaster Cobb, 1913, Plectus Bastian, 1865 and Prismatolaimus de Man, 1880 with Descriptions of C. ethiopica n. sp. and C. getachewi n. sp. (Chromadorida: Nematoda) - Abebe, E.; Coomans, A. (Hydrobiologia, 1996)