A review of the Apocreadiidae Skrjabin, 1942 (Trematoda: Digenea) and description of Australian species

摘要

The Apocreadiidae is reviewed and is considered to include genera recognised previously within the families Apocreadiidae, Homalometridae, Schistorchiidae, Sphincterostomatidae and Trematobrienidae. Key features of the family are extensive vitellinefollicles, eye-spot pigment dispersed in forebody, I-shaped excretory vesicle, no cirrus-sac and genital pore opening immediately anterior to the ventral sucker (usually) or immediately posterior to it (Postporus). Three subfamilies and 18 genera are recognised within the Apocreadiidae. The Apocreadiinae comprises Homalometron (new syn. Barbulostomum), Callohelmis gen. nov., Choanodera, Crassicutis, Dactylotrema, Marsupiocetabulum, Microcreadium, Myzotus, Neoapocreadium, Neomegasolena, Pancreadium, Procaudotestis and Trematobrien. The Schistorchiinae comprises Schistorchis, Sphincterostoma, Sphincteristomum and Megacreadium. The Postporinae comprises only Postporus. A key to subfamilies and genera of the Apocreadiidae is provided. It is argued that there is no convincing basis for the recognition of the genus Apocreadium and all its constituent species are combined with Homalometron. The following new combinations are proposed for species previously recognised within Apocreadium: Homalometron balistis, H. caballeroi, H. cryptum, H. longisinosum, H. manteri, H. mexicanum and H. vinodae. Apocreadium uroproctoferum is found to lack a uroproct and is made a synonym of H. mexicanum, Homalometron verrunculi nom. nov. is proposed to replace the secondarilypre-occupied H. caballeroi. Barbulostomum is made a synonym of Homalometron and H. cupuloris comb. nov. is proposed. Neochoanodera is made a synonym of Choanodera and Choanodera ghanensis comb. nov. is proposed. Species within the Apocreadiinae and Postporinae are reviewed and the following are recorded or described from Australian fishes: Homalometron wrightae sp. nov. from Achlyopa nigra, H. synagris comb. nov. from Scolopsis monogramma, H. stradbrokensis sp. nov. from Gerres subfasciatus, Marsupioacetabulum opallioderma sp. nov. from G. subfasciatus, Neoapocreadium karwarensis comb. nov. from G. subfasciatus, N. splendens sp. nov. from S. monogramma and Callohelmis pichelinae gen. et sp. nov. from Hemigymnus melapterus, H. fasciatus, Stethojulis bandanensis and Choerodon venustus. Callohelmis is recognised by the combination of absence of tegumental spines, caeca terminating midway between the testes and posterior end of body, ventral sucker enclosed in a tegumental pouch, prominent muscles radiating through the body from the ventral sucker, vitelline follicles not extending into the forebody, and a very short excretory vesicle that opens ventrally. New combinations for species previously recognised within Crassicutis are proposed as follows: Neopocreadium caranxi comb. nov., N. gerridis comb. nov., N. imtiazi comb. nov. and N. marina comb. nov. The host-specificity and zoogeography of the Apocreadiinae are considered.