Revision of Flagellotrema Ozaki, 1936 (Digenea, Gyliauchenidae Fukui, 1929), including the description of two species from acanthuroid fishes from the Great Barrier Reef, Queensland, Australia

Abstract

The taxonomy of the Gyliauchenidae Fukui, 1929 (Digenea) has been confounded historically by 2 main factors: difficulty in specimen preparation and varying opinion as to the consistency of morphological characters, such as the morphology of the oesophagus and the position of the ovary. Distinction between Flagellotrema Ozaki, 1936 and Gyliauchen Nicoll, 1915 has been blurred by overlap in the diagnoses of these genera. Here we provide a diagnosis for Flagellotrema, definitively separating it from Gyliauchen. We define Flagellotrema as possessing an oesophagus with at least 1 loop, an intertesticular ovary, and a cilia-like lining of the genital atrium, and also by the position of the genital pore definitely posterior to the intestinal bifurcation. We redescribe the type-species, Flagellotrema convolutum Ozaki, 1936 from Prionurus scalprum (Acanthuridae) from Japanese waters, based on our examination of type material and the literature, and describe 2 new cryptic species from acanthuroid fishes of the Great Barrier Reef, Australia. Flagellotrema amphitrite n. sp. is described from Prionurus maculatus from Heron Island, Great Barrier Reef, Australia and Flagellotrema reburrus is described from Siganus punctatus (Siganidae) from the same location. We also record F. reburrus from 3 other species of Siganus, S. corallinus, S. doliatus and S. vulpinus from Heron and Lizard Islands, Australia. Distinction between F. amphitrite and F. reburrus is difficult, and is based on the combination of morphometric data and sequence data from ITS2 and 28S (D1–D3) rDNA and ND1 mtDNA genes. We provide a taxonomic key to species of Flagellotrema and discuss the taxonomy and biogeography of the group. The description of 2 new species from acan-thuroid fishes on the Great Barrier Reef, Australia, expands the geographic range of Flagellotrema from Japan to the greater western Pacific Ocean.