Phylogenetic relationships of the genera of the Pronocephalidae Looss, 1902 (Digenea: Paramphistomiformes).

Quantitative phylogenetic analysis of 20 nominal genera of the Pronocephalidae based on 47 morphological transformation series produced 6 equally parsimonious trees, each with a consistency index of 77.8%. All trees agree that Adenogaster is the sister group to the rest of the pronocephalids, and a new subfamily is proposed for it. The Pronocephalinae comprises Pronocephalus, Ruicephalus, Neopronocephalus, Macravestibulum, Choanophorus, Cetiosaccus, and Metacetabulum. The Charaxicephalinae comprises Charaxicephalus, Desmogonius, Diaschistorchis, Pleurogonius, Iguanacola, Renigonius, Parapleurogonius, Himasomum, Pyelosomum, Cricocephalus, Barisomum, and Pseudobarisomum. An amended diagnosis for Himasomum is presented. The trees differ only in the placements of Pleurogonius, Renigonius + Parapleurogonius, Iguanacola, and Himasomum relative to each other. Parapronocephalum and Notocotyloides are members of the clade containing the Notocotylidae. The phylogenetic tree supports interpretations of 3-4 transitions from marine to freshwater turtles, 3 host switches from marine turtles to the Galapagos marine iguana and 3 from marine turtles to the French angelfish, and widespread host switching among marine chelonians. No switches to non-chelonian hosts coincide with transitions from marine to freshwater.