An updated concept and revised composition for Hamacreadium Linton, 1910 (Opecoelidae: Plagioporinae) clarifies a previously obscured pattern of host-specificity among species Author Martin, Storm B. Author Cutmore, Scott C. Author Ward, Selina Author Cribb, Thomas H. text Zootaxa 2017 4254 2 151 187 journal article 33240 10.11646/zootaxa.4254.2.1 64b0d4b0-479e-484a-aaf5-d5237292d4a5 1175-5326 545862 0BDF72E4-5330-4EE7-8560-DF44E71C1F41 Allocreadium fasciatusi Kakaji, 1969 Synonyms: Psilostomum chilkai Chatterji, 1956 ( Psilostomidae Looss, 1900 ); Staffordiella chilkai ( Chatterji, 1956 ) Mehra, 1966 ; Hamacreadium chilkai ( Chatterji, 1956 ) Yamaguti 1971 . Records. From the barramundi, Lates calcarifer (Bloch) ( Perciformes : Latidae ), in Lake Chilika, a brackish coastal lagoon in Odisha , India , by Chatterji (1956) . From the banded gourami, Trichogaster fasciata Bloch & Schneider ( Perciformes : Osphronemidae ) [as T . fasciatus Bloch & Schneider ], from Lucknow, Uttar Pradesh , India by Kakaji (1969) . From the ricefish, Oryzias melastigma (McClelland) ( Beloniformes : Adrianichthyidae ) [as Aplocheilus melastigma McClelland ], the blue panchax , Aplocheilus panchax (Hamilton) ( Cyprinodontiformes : Aplocheilidae ), the flying barb, Esomus danricus (Hamilton) (Cyprinidae) , and the spotted snakehead, Channa punctata (Bloch) ( Perciformes : Channidae ) [as Ophiocephalus punctatus Bloch ], in a freshwater stream near Visakhapatnam, Andhra Pradesh , India by Madhavi (1978) . Remarks. Yamaguti (1971) transferred this species to Hamacreadium but Madhavi (1978) considered it synonymous with A . fasciatusi . Chatterji (1956) originally considered this species to be a psilostomid because of the absence of a seminal receptacle, but psilostomids are bird and mammal parasites and Madhavi (1978) suggested that Chatterji (1956) was mistaken, as the seminal receptacle was small and inconspicuous in her specimens of A . fasciatusi . Even if the seminal receptacle is present, this species, as described by Chatterji (1956) , does not belong in Hamacreadium because the genital pore is medial and pre-bifurcal, the testes tandem, the ovary distinctly sinistral, the cirrus-sac distinctly anterior to the ventral sucker, the oral and ventral suckers equal in size and the eggs large (140–154 × 70–98 µm). This species might belong in Eucreadium , which comprises species from freshwater fishes of India , but the large eggs described by Chatterji (1956) are more consistent with A . fasciatusi . This combination is reasonable for the present but requires further investigation. Species of Allocreadium typically use lamellibranch bivalves as first intermediate hosts and are characterised by small eggs, the intestine bifurcating at the posterior margin of the ventral sucker, and vitelline follicles often restricted to the hindbody ( Caira & Bogéa 2005 ). Allocreadium fasciatusi uses a gastropod as the primary host ( Madhavi 1978 ), has large eggs, the intestine bifurcates in the forebody, and the vitelline follicles enter the forebody.