RESURRECTION OF PLESIOCREADIUM WINFIELD, 1929 (DIGENEA: MACRODEROIDIDAE) WITH PHYLOGENETIC ANALYSES AND SUPPLEMENTAL...

We herein resurrect and emend PlesiocreadiumWinfield, 1929 (Digenea: Macroderoididae) and provide a supplemental description of its type species, Plesiocreadium typicumWinfield, 1929, based on adult specimens collected from the intestine of bowfins, Amia calva Linnaeus, 1766 (Amiiformes: Amiidae), captured in the L'Anguille River (Mississippi River Basin, Arkansas), Big Lake (Pascagoula River Basin, Mississippi), Chittenango Creek (Oneida Lake, New York), and Reelfoot Lake (Tennessee River Basin, Tennessee). Plesiocreadium spp. (Pl. typicum and Plesiocreadium flavum [Van Cleave and Mueller, 1932] n. comb.) differ from other macroderoidids by having a dorsoventrally flat forebody, ceca that extend posteriad beyond the testes and that do not form a cyclocoel, testes that are greater than one-half of maximum body width, a cirrus sac that is dorsal to the ventral sucker and arches dextrad or sinistrad, a uterine seminal receptacle, asymmetrical vitelline fields that remain separated anteriorly and posteriorly and that extend anteriad to the level of the ventral sucker, and an I-shaped excretory vesicle. Bayesian phylogenetic analyses (ITS2 and 28S) recovered monophyletic Plesiocreadium sensu stricto (as defined herein) sister to Macroderoides trilobatusTaylor, 1978 and that clade sister to the remaining macroderoidids, with sequences ascribed to species of Macroderoides Pearse, 1924 recovered as paraphyletic. We regard Macroderoides parvus (Hunter, 1932) Van Cleave and Mueller, 1934, M. trilobatus, and RauschiellaBabero, 1951 as incertae sedis. Arkansas, New York, and Tennessee comprise new locality records for Pl. typicum.