Lissorchis macropharynx n. sp. (Digenea: Lissorchiidae) from the shorthead redhorse, Moxostoma macrolepidotum (LeSueur) (Osteichthyes: Catostomidae).

Lissorchis macropharynx (Digenea: Lissorchiidae) is described from the shorthead redhorse, Moxostoma macrolepidotum (LeSueur) (Catostomidae) from the Assiniboine River drainage of southern Manitoba. The species is morphologically similar to Lissorchis hypentelii in possessing a similar body shape (widest at the ovarian region and a relatively long hindbody), a distinctly trilobed and relatively posteriorly situated ovary, and in the distribution of the vitellaria. It differs from L. hypentelii and all other lissorchiids in possessing a massive pharynx that is generally equal in length to or longer than the oral sucker and almost as deep as the cervical region of the body it occupies, a protruding acetabular region with an aspinose ridged/folded and grooved anterior surface, and a massive cirrus sac that reaches the level of the ovary. Museum specimens of Lissorchis spp. from M. macrolepidotum from other drainages in Manitoba and Wisconsin were also identified as L. macropharynx.