Some Haliotrema (Monogenea: Dactylogyridae) from cultured grouper (Epinephelus Spp.) with emphasis on the phylogenetic position of Haliotrema cromileptis.

Three Haliotrema spp. are reported from the Vietnamese grouper. Morphological and morphometric characters show minor deviations from original descriptions of H. cromileptis Young, 1968 and H. epinepheli Young, 1968 . The third encountered species ( Haliotrema sp.) appears to be new to science. Genetically, H. cromileptis clusters with Bravohollisia , Pseudohaliotrema , and Haliotrema . The group is well supported by partial large subunit rDNA (LSU), complete small subunit rDNA (SSU), and partial SSU + ITS1 rDNA analyses. Ingroup phylogenetic relationships are not well resolved. Haliotrema cromileptis , H. fleti Young, 1968 , and Pseudohaliotrema sphincteroporus Yamaguti, 1953 are closely related to a monophyletic group of 5 Haliotrema spp. characterized by bell- or horn-shaped bases of the male copulatory organ (MCO), which contains an accessory piece. Based on SSU rDNA, H. cromileptis is a sister species to P. sphincteroporus and, together, they form a clade to 3 other Haliotrema spp. characterized by a bell-shape based MCO with an accessory piece. Data analysis conducted on partial SSU + ITS1 rDNA confirms the close phylogenetic relationship of H. cromileptis , H. fleti , H. chenhsintaoi Zhang, 2001 (possessing a horn-shaped base of the MCO), and Bravohollisia rosetta Lin, 1995. However, because major differences in diagnostic characters exist, this genetic relationship needs further elucidation.