Purpose The stomachs and spiral valves of sharks and rays were examined for their trypanorhynch (Cestoda) parasite fauna and dietary items to infer feeding ecology. In Indonesia, sharks and rays have been experiencing increasing awareness and conservation in the recent years due to high fisheries activities and to avoid future species extinction. Methods The samples were collected in 2009 from two different sampling sites at the southern coasts of Java and Bali in Indonesia. The parasite fauna was studied for 41 elasmobranch fishes. Amongst these, three shark species, Carcharhinus sorrah, Carcharhinus sp. I and Squalus megalops and seven ray species, Brevitrygon heterura, B. cf. heterura, Gymnura zonura, Maculabatis gerrardi, Mobula kuhlii, Neotrygon cauruleopuncatata and Rhinobatos penggali were studied. Four additional specimens, belonging to the shark species Carcharhinus sp. II and Mustelus cf. manazo and the ray species Maculabatis gerrardi were studied from the waters of South Bali. Results Analyses of the feeding ecology of the ray M. gerrardi revealed distinct differences between both sampling sites, indicating the presence of ecological differences between the geographically independent regions. A total of 11 different trypanorhynch species/taxa belonging to the five families Eutetrarhynchidae (5), Gilquiniidae (1), Lacistorhynchidae (1), Pterobothriidae (1) and Tentaculariidae (3) were found. Ten trypanorhynch species from Penyu Bay and four species from South Bali could be identified. Two taxa that might represent new species were collected: Dollfusiella sp. from Brevitrygon heterura and Prochristianella sp. from Maculabatis gerrardi. Conclusions The present paper gives insights in using the trypanorhynch cestode community in combination with feeding ecology analyses to support conservation of elasmobranchs in Indonesian waters.

The aim of the present study was to identify the parasite fauna of cultured rainbow trout (Oncorhynchus mykiss Walbaum, 1792) and Arctic charr (Salvelinus alpinus (L.)) from a flow-through aquaculture system at Lake Tollense in northern Germany.The fish were sampled during different seasons in 2018 from an open freshwater raceway. For rainbow trout, 10 different parasite species were isolated, belonging to Monogenea (1), Cestoda (2), Crustacea (2) and Digenea (5), including the eye flukes Tylodelphys clavata Niewiadomska, 1984, Diplostomum pseudospathaceum and Diplostomum spathaceum (Rudolphi, 1819) Olsson, 1876, the latter representing a potential pathogenic species, which was molecularly identified and reported as a core species with prevalences of 80.0%-100.0% and high mean abundances of 42.8-55.0. Arctic charr only harboured T. clavata and D. spathaceum. Other taxa were found with low prevalence in the summer season exclusively, indicating strong seasonality of the detected parasites. Statistical correlation was positively tested for coherences of eye fluke burden and fish growth, weight and performance between seasons, recommending implementation of an enhanced aquaculture management for the surface waterdependent flow-through aquaculture system at Lake Tollense.

Taxonomic issues within Trypanorhyncha, e.g., the inaccurate light microscopic visualisation of the hook patterns, are solvable by confocal laser scanning microscopy (CLSM). We applied CLSM imaging to study Trygonicola macropora (Shipley et Hornell, 1906) and Dollfusiella michiae (Southwell, 1929) from Neotrygon caeruliopunctata Last, White et Séret from Bali, Indonesia. To illustrate the strength and limitations of CLSM, images of Otobothrium cysticum (Mayer, 1842) and Symbothriorhynchus tigaminacantha Palm, 2004, both permanent mounts from a collection, were also processed. The CLSM created image stacks of many layers, and edited with IMARIS Software, these layers resulted in three-dimensional images of the armature patterns and internal organs of both species. BABB (benzylalcohol and benzylbenzuolate) clearing was applied to T. macropora. We conclude that trypanorhynch cestodes stained with Mayer-Schuberg's acetic carmine permanently mounted in Canada balsam are suitable for CLSM, allowing detailed analyses of museum type-material as well as freshly collected and processed worms. BABB resulted in imaging the testes in detail, suggesting other stains to be used for CLSM in trypanorhynch cestode research. Application of CLSM for studies of other cestode groups is highly recommended.

Background The most convincing species of Allopodocotyle Pritchard, 1966 (Digenea: Opecoelidae) are known overwhelmingly from groupers (Serranidae: Epinephelinae). Six species of Allopodocotyle have been reported, collectively, from species of Cromileptes Swainson, 1839, Epinephelus Bloch, 1793 and Plectropomus Oken, 1817. These are A. epinepheli (Yamaguti, 1942), A. heronensis Downie & Cribb, 2011, A. manteri (Saoud & Ramadan, 1984), A. mecopera (Manter, 1940), A. plectropomi (Manter, 1963) and A. serrani (Yamaguti, 1952). In addition, a not yet fully described and unnamed seventh species, morphologically and phylogenetically close to A. epinepheli, was isolated from the orange-spotted grouper Epinephelus coioides (Hamilton, 1822) off Bali, Indonesia in 2016. An eighth species, again from E. coioides off Bali is described herein. Methods Morphological and phylogenetic analyses justify the recognition of A. palmi sp. nov., which is also genetically different from the as yet unnamed congener from the same host and locality. For the first time, 3D confocal laser scanning microscopy was applied to study and distinguish Digenea taxonomically. We introduce the ‘Palm pattern’, a new simplified way to visualise morphometric differences of related digenean taxa. Results Allopodocotyle palmi sp. nov. is distinguished from its congeners that infect groupers by its elongate body with a size > 2.7 mm and diagonal testes. The ovary is located mainly, and the anterior testis completely, in the posterior half of the body; the uterine coils are in the fourth eighth of the body. The cirrus-sac is 0.75–1.4 (1.1) mm long, its posterior extremity is well separated from the anterior extent of the vitelline fields, just reaching the anterior border of uterine coils. In addition, Prosorhynchus maternus Bray & Justine, 2006 (Bucephalidae) was isolated from E. coioides, representing the first record in Indonesia and the third record for this fish species. Conclusion The biodiversity research in Indonesia is enhanced with a new species description based on modern and newly applied techniques.