Trematodes of Red Sea fishes: Hexangium brayi n. sp. (Angiodictyidae Looss, 1902) and Siphodera aegyptensis n. sp. (Cryptogonimidae Ward, 1917), with a review of their genera.

Specimens of the marine fishes Siganus luridus (Siganidae) and Caesio suevica (Lutjanidae) were caught in the Red Sea off the coast of Sharm El-Sheikh, South Sinai, Egypt. Twelve (30%) and eight (17%) fish, respectively, were found to harbour intestinal trematodes. S. luridus was parasitised by Hexangium brayi n. sp. (Angiodictyidae) and C. suevica by Siphodera aegyptensis n. sp. (Cryptogonimidae). H. brayi n. sp. is differentiated from the other two species of the genus by the vitelline follicles which are confined to the inter-caecal field, its body shape which is distinctly pyriform, the terminations of the intestinal caeca which are distinctly saccular, the eggs which are few in number, and by the excretory vesicle which gives off a lateral arm on each side that divides into two long collecting ducts. S. aegyptensis n. sp. is most similar to S. cirrhiti Yamaguti, 1970, but differs in having a definite number of testes (nine), seven arranged in a ring and the other two situated symmetrically or diagonally within this ring, and vitelline follicles extending posteriorly to the level of the anterior lobes of the ovary. Both genera Hexangium Goto & Ozaki, 1929 and Siphodera Linton, 1910 are reviewed in detail and redefined.