Molecular phylogeny supports invalidation of Didelphodiplostomum and Pharyngostomoides (Digenea: Diplostomidae) and reveals a Tylodelphys from mammals Author Achatz, Tyler J Author Chermak, Taylor P Author Martens, Jakson R Author Woodyard, Ethan T Author Rosser, Thomas G Author Pulis, Eric E Author Weinstein, Sara B Author Mcallister, Chris T Author Kinsella, John M Author Tkach, Vasyl V text Zoological Journal of the Linnean Society 2022 2022-09-01 196 1 124 136 https://academic.oup.com/zoolinnean/article/196/1/124/6517659 journal article 133186 10.1093/zoolinnean/zlab114 bd2fe3a4-83a4-4b80-aeba-39a775595da2 0024-4082 PMC9416008 36051981 7031477 STATUS OF DIDELPHODIPLOSTOMUM The analysis of 28S ( Fig. 1 ) places Did. variabile (shown as Tylodelphis variabilis comb. nov. in the figure) in the cluster of Tylodelphys and Austrodiplostomum species. The morphology of adult Didelphodiplostomum and Tylodelphys spp. is remarkably similar ( Fig. 4A ; Dubois, 1968). Furthermore, Didelphodiplostomum and Tylodelphys have identical flame-cell formulas, 2 [(2+2)+(2+[2])] = 16 ( Harris et al. , 1967 ; Dubois, 1968, 1970; Niewiadomska, 2002 ). Dubois (1968) emphasized the remarkable morphological similarity between Didelphodiplostomum and Tylodelphys species. However, the members of the two genera differ in the shape of anterior testis (asymmetrical in Didelphodiplostomum spp. vs. symmetrical in Tylodelphys spp. ) and the lack of a genital cone in Didelphodiplostomum spp. (present in Tylodelphys spp. , albeit weakly developed in some species). Our molecular phylogeny ( Fig. 1 ) clearly demonstrates that Did. variabile belongs to one of the two major clades of Tylodelphys . Taking into account the results of our phylogenetic analysis ( Fig. 1 ) and minor morphological differences between Didelphodiplostomum and Tylodelphys , we consider Didelphodiplostomum to be a junior synonym of Tylodelphys . As such, we transfer Did. variabile and Did. nunezae into Tylodelphys as T. variabilis ( Chandler, 1932 ) comb. nov. and Tylodelphys nunezae ( Dubois, 1976 ) comb. nov. , respectively. The partial 28S and cox1 sequences of T. variabilis and Tylodelphys sp. VVT1 of Achatz et al. (In press) are identical. It is clear that the larval specimens of Tylodelphys sp. VVT1 from the mole salamander Ambystoma talpoideum Holbrook, 1838 collected in Mississippi are conspecific with T. variabilis . An amended diagnosis of Tylodelphys is provided below.