REVISED CLASSIFICATION AND PHYLOGENETIC HYPOTHESIS FOR THE ACANTHOSTOMINAE LOOSS, 1899 (DIGENEA, OPISTHORCHIFORMES, CRYPTOGONIMIDAE)

Specimens of an acanthostome digenean originally identified as Acantho stomum scyphocephalum and later transferred to Timoniella are describe d and named as a distinct species of Timoniella. Acanthostomum scyphoc ephalum sensu strictu is included in an updated phylogenetic analysis of the acanthostome digeneans. The new analysis differs from an earlie r one by Brooks (1980) by allowing reversals (Wagner criterion vs. Cam in-Sokal criterion), producing a more parsimonious representation of c haracter data; no transformation series needed re-polarization. Acanth ostomum scyphocephalum is a member of the clade containing all other s pecies of Acanthostomum occurring in North, Central and South America. Acanthostomum is paraphyletic if Atrophecaecum is excluded from it, a ccordingly, the two genera are synonymized. No other changes from the hypothesis of Brooks (1980) resulted. The resulting annotated phylogen etic classification, with synapomorphic diagnoses, includes Acanthosto mum as the sister-group of Caimanicola, Proctocaecum as their sister-g roup, the monotypic Gymnatrema as their sister-group, and Timoniella a s the basal sister-group. Four new subgenera are proposed, one in Timo niella, one in Proctocaecum, and two in Acanthostomum.