THE ACANTHOCOLPIDAE (DIGENEA) OF FISHES FROM THE NORTH-EAST ATLANTIC - THE STATUS OF NEOPHASIS STAFFORD, 1904 (DIGENEA) AND A STUDY OF NORTH-ATLANTIC FORMS

The genus Neophasis is defined. The taxonomic status of the genus is discussed in the light of its life-cycle, hosts and cercarial and adult morphology. It is considered to be closest to the family Acanthocolpidae due to the utilisation of a fish second intermediate host, the form of the cercarial excretory system and, in the adult, the presence of a uterine seminal receptacle and the absence of an external seminal vesicle. The taxonomic value of morphological features are discussed and a key to the north Atlantic species given. The following species are described: Neophasis oculatus (Levinsen) from Myoxocephalus scorpius off West Greenland (type-material), Norway and Denmark, Lycodes esmarkii off NW Scotland and the Faroes, and L. vahli off Newfoundland; N. burti n. sp. (distinguished from N. oculatus by sucker-ratio and testicular configuration) from Myoxocephalus octodecemspinosus off Nova Scotia (type-locality) and New Brunswick, also? immature in Gadus morhua from the Gulf of St. Lawrence; N. anarrhichae (Nicoll) from Anarhichas lupus in the North Sea and off the Faroes; and N. pusilla Stafford from A. lupus off 'eastern Canada' (type-material) and Nova Scotia. The only other species in the genus is N. symmetrorchis Machida from the NW Pacific Ocean.