Cryptic species of Euryakaina n. g. (Digenea: Cryptogonimidae) from sympatric lutjanids in the Indo-West Pacific Terrence L. Miller • Robert D. Adlard • Rodney A. Bray • Jean-Lou Justine • Thomas H. Cribb Received: 6 April 2006 / Accepted: 27 June 2010 Ó Springer Science+Business Media B.V. 2010 Abstract A survey of the endohelminth fauna of Indo-West Pacific Lutjanidae (Perciformes) revealed the presence of the species Siphoderina manilensis (Velasquez, 1961) Miller & Cribb, 2008 and S. marina (Hafeezullah & Siddiqi, 1970) Miller & Cribb, 2008 in seven Lutjanus spp. from sites off the Great Barrier Reef, the Maldives, New Caledonia and Ningaloo Reef, Western Australia. A combination of morphological and ribosomal DNA analyses of these cryptogonimids prompted the transfer of these taxa to a new genus, Euryakaina n. g., as E. manilensis n. comb. and E. marina n. comb., based on comparative analysis with other cryptogonimid taxa. Euryakaina n. g. is distinguished from all other cryptogonimid genera by the combination of a fusiform body, the few relatively small, widely spaced oral spines (sometimes absent), a highly lobed ovary, opposite to slightly oblique testes, vitelline follicles that extend from the anterior margin of the testes to slightly posterior to the intestinal bifurcation, and an excretory vesicle that bifurcates dorsal to the ovary and reunites briefly slightly posterior to the intestinal bifurcation. Morphometric analysis of these taxa alone suggests they should be reduced to synonymy, but DNA sequence analyses and ecological niche partitioning provide evidence that they form a cryptic species complex in sympatric lutjanids in the Indo- West Pacific. The secondary structure of the ITS2 rDNA for species of Euryakaina was also modelled and analysed for the presences of compensatory base changes (CBCs) or hemi-CBCs in order to explore the usefulness of these changes as a tool to help elucidate the taxonomy of this complex system. We also report what we interpret here as intraspecific variation in the ITS2 rDNA between individuals of E. manilensis from Lutjanus vitta recovered off the Great Barrier Reef and New Caledonia. Introduction The Cryptogonimidae Ward, 1917 is a large family of digenetic trematodes with over 65 genera and 200 T. L. Miller (&) Á R. D. Adlard Biodiversity Program, Queensland Museum, PO Box 3300, South Brisbane, QLD 4101, Australia e-mail: terrence.miller@uqconnect.edu.au T. L. Miller Á T. H. Cribb School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia R. A. Bray Department of Zoology, Natural History Museum, Cromwell Road, London SW7 5BD, UK J.-L. Justine UMR 7138 Syste ´matique, Adaptation, E ´ volution, Muse ´um National d’Histoire Naturelle, Case Postale 52, 57, rue Cuvier, 75231 Paris Cedex 05, France J.-L. Justine Aquarium des Lagons, B.P. 8185, 98807 Noume ´a, New Caledonia 123 Syst Parasitol (2010) 77:185–204 DOI 10.1007/s11230-010-9266-7