The deep-sea fish digenean genus Tellervotrema Gibson & Bray, 1982 (Opecoelidae: Plagioporinae): Re-evaluation of the type species, T. armstrongi Gibson & Bray, 1982 and T. beringi (Mamaev, 1965)

Tellervotrema Gibson & Bray, 1982 (Digenea: Opecoelidae) was erected for Podocotyle-like species that possess a symmetrical pair of isolated groups of vitelline follicles in the posterior forebody, lack them dorsal to the caeca and parasitize archybenthal macrourid fishes. Tellervotrema armstrongi Gibson & Bray, 1982 is redescribed from the type host, the common Atlantic grenadier, Nezumia aequalis (Günther), N. cyrano Marshall & Iwamoto, and from an unidentified macrourid collected from the northern Gulf of Mexico. Tellervotrema beringi (Mamaev, 1965) is redescribed from the giant grenadier, Albatrossia pectoralis (Gilbert), and Coryphaenoides sp. obtained from off Oregon. The following six features are suggested to distinguish T. armstrongi and T. beringi: egg size; position of the genital pore; posterior extent of the cirrus-sac relative to the ventral sucker; testes volume relative to hindbody size; anterior extent of the paired vitelline groups in the forebody; and geographic locality. The generic diagnosis of Tellervotrema is amended o include circumcaecal vitelline follicles, and the presence of the vitelline gap itself was found to be a more consistent diagnostic generic character than the location of the resulting pair of distinct, isolated groups of vitelline follicles created by the gap. A neotype and paraneotypes are designated for T. beringi. The following new host and locality records are established: first original report of T. armstrongi from N. cyrano; first report of a member of Tellervotrema from the giant grenadier, A. pectoralis; and the waters off Oregon are a new locality record for Tellervotrema, a genus in the North Pacific Ocean known only from the Bering Sea and off Japan. A comprehensive listing of all parasites previously reported from the four macrourid species examined herein is given and intermediate hosts are postulated through which species of Tellervotrema may complete their life cycles in the deep.