New Data on the Morphology and Phylogenetic Connections of (Trematoda, Lepocreadioidea: Lepidapedidae), a Parasite of Antarctic and Sub-Antarctic Fishes.

The trematode (Zdzitowiecki, 1990) is a common intestinal parasite of the gadiform fishes of the Southern Ocean. In this work, we supplement the description of the species with the anatomy of the terminal part of the reproductive system and with molecular data. The male terminal genitalia are characterised by the presence of the external seminal vesicle and cirrus-sac. The external seminal vesicle is surrounded by aciniform groups of outer prostatic cells. Groups of outer prostatic cells and proximal parts of their ducts are associated with a thin-walled membrane that is connected to the proximal edge of the сirrus-sac. The cirrus-sac is claviform, with a long proximal part accommodating the tubular, thin-walled internal seminal vesicle and ducts of outer prostatic cells. The female terminal genitalia are represented by a thick-walled metraterm, which is surrounded by aciniform groups of glandular cells. Phylogenetic analysis based on 28S rDNA partial sequences data placed into the monophyletic group Lepidapedidae, including the species (Crowcroft, 1945), Durio et Manter, 1968, and Bray, Cribb et Barker, 1997. However, we were unable to detect direct phylogenetic connections between and .