ORIGINAL PAPER Phylogenetic relationships of the Gorgoderidae (Platyhelminthes: Trematoda), including the proposal of a new subfamily (Degeneriinae n. subfam.) Scott C. Cutmore & Terrence L. Miller & Stephen S. Curran & Michael B. Bennett & Thomas H. Cribb Received: 29 November 2012 / Accepted: 23 May 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Phylogenetic analyses of a range of gorgoderid trem- atodes based on ITS2 and partial 28S rDNA data lead us to propose the Degeneriinae n. subfam. for the genus Degeneria in recognition of its phylogenetic isolation and distinctive morphol- ogy and biology. The current concepts of the subfamilies Anaporrhutinae and Gorgoderinae were supported. Within the Gorgoderinae, the large genus Phyllodistomum is shown to be paraphyletic relative to Pseudophyllodistomum and Xystretrum. Notably, the clade of marine Phyllodistomum does not form a clade with the other marine genus, Xystretrum. Distinct clades within the Gorgoderinae correspond variously to identity of first intermediate host, form of cercaria and their marine or freshwa- ter habitat. We are not yet in a position to propose separate genera for these clades. Introduction The Gorgoderidae Looss, 1899 is a distinctive family of trematodes characterised by a broad range of characters, particularly the non-spinous tegument, simple male terminal genitalia, highly restricted vitellarium and extensive uterus. The family is relatively unusual among trematodes in being significantly radiated in chondrichthyans, actinopterygians and tetrapods. Infections in actinopterygians and tetrapods are typically in the urinary bladder, whereas those in chon- drichthyans are usually in the body cavity; a few species are reported from other sites (swim bladder, gall bladder and intestine; Campbell 2008). The molecular phylogenetic analysis of the Trematoda by Olson et al. (2003) incorporated species of four genera of Gorgoderidae which were recovered as monophyletic. Olson et al. ( 2003) recognised the Gorgoderidae within the Gorgoderoidea, one of four superfamilies within the crown sub- order Xiphidiata. Gorgoderoidea comprised the Callodistomidae, Dicrocoeliidae, Encyclometridae, Gorgoderidae, Haploporidae (with the Atractotrematidae nested within it), Orchipedidae, Paragonimidae and Troglotrematidae. Relationships within the Gorgoderidae were unresolved, except for the conclusion that the unusual deep-sea genus Degeneria Campbell, 1977 was indeed a gorgoderid, and that it was potentially basal within the family. Subsequent to Olson et al. (2003), Curran et al. (2006) expanded the range of relevant taxa analysed and concluded that another family, the Allocreadiidae, should be incorpo- rated in the Gorgoderoidea but that the Haploporidae and Atractotrematidae should be recognised in a separate super- family, the Haploporoidea. Choudhury et al. (2007), in work that partly paralleled some of that of Curran et al. (2006), also concluded that the Allocreadiidae was closely related to the Callodistomidae and Gorgoderidae. Bray and Blair (2008) based their conception of the Gorgoderoidea on the work of Olson et al. (2003), but added several families not included in that analysis for “convenience”. Although understanding of the overall phylogenetic posi- tion of the family appears to be relatively stable, little is known S. C. Cutmore (*) : T. H. Cribb School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia e-mail: scott.cutmore@uqconnect.edu.au T. L. Miller School of Marine and Tropical Biology, James Cook University, PO Box 6811, Cairns, QLD 4870, Australia S. S. Curran Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564, USA M. B. Bennett School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia Parasitol Res DOI 10.1007/s00436-013-3481-5