Development of Oral Structure in Salmonema emphemeridarum (Nematoda: Cystidicolidae)

This paper examines the development of the oral morphology of the parasite Salmonema emphemeridarum (Nematoda: Cystidicoidae) using Scanning Electron Microscopy. Larvated eggs, taken from female worms collected from brook trout, Salvelinus fontinalis, were fed to mayflies (Ephemeroptera) where larvae developed to the third larval stage. First stage larvae possessed an oral opening, boring tooth and secretory pore. Second stage larvae possessed a circular oral opening and amphids. Third stage larvae included all the features of adult worms include pseudolabia, submediant labia, sublabia, amphids and four oral papillae. The advanced development of oral structures of third stage larvae allows the identification of larval worms to genus and in some cases species and is consistent with the precocious reproductive development of infective larvae in the Cystidicolidae

Spiral valve parasites of blue and common thresher sharks as indicators of shark feeding behaviour and ecology

Open Access via the Jisc Wiley agreement Acknowledgements This work would not have been possible without the assistance and samples provided by the National Marine Fisheries Service (NMFS) Southwest Region Fishery Observer Program and the participating drift gillnet fishermen. A. Arevalo, E. Reed, H. Colley, J. Williams, J. Tamez and K. Tran assisted with spiral valve dissections and parasite sorting in the lab. D. Losey helped with library research. D. Sweetnam, A. Yau, A. Thompson, M. Craig, S. Stohs, G. DiNardo provided constructive critiques that helped improve the manuscript. This research was supported by the National Oceanographic Atmospheric Administration (NOAA).Peer reviewedPublisher PD

Development of Oral Structure in Salmonema emphemeridarum (Nematoda: Spirurida: Cystidicolidae)

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Experimental Elucidation of the Life Cycle of Rhinebothrium urobatidium (Cestoda: Rhinebothriidea) From the Round Stingray (Urobatis halleri: Myliobatiformes) To First And Second Intermediate Hosts

Abstract - The life cycle of the cestode Rhinebothrium urobatidium, whose final host is the round stingray Urobatishalleri, includes a copepod as the first intermediate host and small benthic fishes as second intermediate hosts. Hexacanth embryos within nonoperculate, untanned eggs collected from U. hallerideveloped in the copepod Tigriopus californicusinto caudate procercoids with an apical organ/sucker and cercomer, and rarely, bothridia. The procercoids, which developed in the body cavity within a membrane, adhered to the copepod intestine, were infective to arrow gobies (Clevelandia ios) within 15 days of exposure at 21°C. When infected copepods were fed to arrow gobies, procercoids developed into nonlacunate plerocercoids each bearing individually retractable bothridia and an apical sucker. Within 10 days of exposure to the second intermediate host, the larvae had migrated up the bile/cystic duct into the gall bladder, where they developed bothridia similar to those of adult worms. Between 30 to 51 days post-infection in the goby, plerocercoids approached the size of larvae found in natural infections, and the scolex became morphologically similar to that of adult worms from round stingrays. Only presumptive filiform microtriches (filitriches) were present on procercoids while both filitrichs and spiniform microtriches (spinitrichs) were present on plerocercoids. Identification of plerocercoids from experimental infections as those of R. urobatidiumwas confirmed through morphology of the scolex and using cytochrome c oxidase I sequences. The experimental transmission of R. urobatidiumto first and second intermediate hosts provides improved understanding of the transmission and ontogeny of shark tapeworms. The biological characteristics of U. halleri,with its diverse parasite fauna, provide significant opportunities to examine the biology of an array of elasmobranch tapeworm taxa