Records of two gonad-infecting species of Philometra (Nematoda: Philometridae) from marine fishes off Iraq, including the description of Philometra parabrevicollis n. sp. from the bigeye snapper Lutjanus lutjanus Bloch (Pisces, Lutjanidae)

Recent examinations of some marine fishes from off the southern coast of Iraq revealed the presence of two species of Philometra Costa, 1845 (Nematoda: Philometridae): P. parabrevicollis n. sp. (males and subgravid and nongravid females) from the ovary of the bigeye snapper Lutjanus lutjanus Bloch (Perciformes, Lutjanidae) and Philometra sp. (subgravid females) from the ovary of the bartail flathead Platycephalus indicus (Linnaeus) (Perciformes, Platycephalidae). Specimens of species are described and illustrated based on light and scanning electron microscopical examinations. Philometra parabrevicollis n. sp. is mainly characterised by the length of spicules (267–285 µm) and gubernaculum (159–168 µm), the gubernaculum/spicule length ratio (1:1.64–1.76), the structure of the gubernaculum distal tip and of the male caudal end, and the body length of males (4.03–4.90 mm). The description of this new species again confirms a high degree of host specificity of gonad-infecting species of Philometra in congeneric lutjanid hosts. Although Philometra sp. parasitising P. indicus in Iraqi waters was previously recorded, its subgravid females are described for the first time. A key to gonad-infecting species of Philometra parasitic in fishes of the family Lutjanidae is provided.