New data on the morphology and phylogenetic connections of Postlepidapedon opisthobifurcatum (Trematoda, Lepocreadioidea: Lepidapedidae), a parasite of Antarctic and sub-Antarctic fishes

• Published in: Helminthologia
• Main Authors: Sokolov S. G., Khasanov F. K., Gordeev I. I.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Sciendo 2018
• Subjects: trematoda; postlepidapedon opisthobifurcatum; lepidapedidae; Microbiology; QR1-502; Antarctic; Southern Ocean; Antarc*
• Online Access: https://doi.org/10.2478/helm-2018-0002; https://doaj.org/article/4f3514aa3b9042b391e01d3b6c172833

The trematode Postlepidapedon opisthobifurcatum (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 cirrus-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 P. opisthobifurcatum into the monophyletic group Lepidapedidae, including the species Myzoxenus insolens (Crowcroft, 1945), Intusatrium robustum Durio et Manter, 1968, and Postlepidapedon uberisBray, Cribb et Barker, 1997. However, we were unable to detect direct phylogenetic connections between P. opisthobifurcatum and P. uberis.