Taxonomy and systematics of freshwater turtle blood flukes (Digenea: Schistosomatoidea)

Abstract

Blood flukes (Platyhelminthes: Trematoda: Digenea: Schistosomatoidea) currently comprise three families: Schistosomatidae Stiles and Hassall, 1898 (species infecting mammals and birds and one crocodilian), Aporocotylidae Odhner, 1912 (species infecting elasmobranchs and fishes), and the paraphyletic "Spirorchiidae Stunkard, 1921" (species infecting marine and freshwater turtles; TBFs hereafter). Before this thesis, the turtle blood flukes comprised 84 species belonging to 19 genera, with much of the previous work focusing on TBFs infecting marine turtles (30 spp. [36%] of 10 genera described from three marine turtle species). Herein, I used morphology and molecular gene sequence data (large subunit rDNA [28S], small subunit rDNA [18S], internal transcribed region 2 [ITS2]) to explore alpha taxonomy and to revise the current systematics of freshwater turtle blood flukes domestic and abroad. Blood flukes examined herein were collected from turtles comprising 16 species of five families (Cryptodira: Chelydridae, Emydidae, Geoemydidae, Kinosternidae, Trionychidae) and from river drainages in Mississippi, Alabama, Florida (U.S.A.), Malaysia, and Vietnam. Collectively from these hosts, I identified 21 TBFs comprising six genera (Spirorchis MacCallum, 1918, Hapalorhynchus Stunkard, 1922, Vasotrema Stunkard, 1926, Coeuritrema Mehra, 1933 [resurrected herein], Baracktrema Roberts, Platt, and Bullard, 2016, and Platt Roberts and Bullard n. gen.). Newly collected specimens were compared to museum material of 22 TBF species comprising holotypes, paratypes, cotypes, syntypes, and vouchers (107 slides) from the United States National Museum, Smithsonian (USNM), American Museum of Natural History (AMNH), and the Harold W. Manter Laboratory Collection (HWML). From the newly collected 21 TBFs, I proposed two new genera (Baracktrema, Platt), resurrected one genus (Coeuritrema), revised one genus (Vasotrema), emended three genera (Spirorchis, Hapalorhynchus, Unicaecum), reassigned nine species, described eight new species, and reported 13 additional turtle blood fluke taxa (either previously described or innominate at this time). This thesis comprises the first records of any turtle blood fluke infecting turtles from Alabama river drainages.