Hemiurid Trematodes (Digenea: Hemiuridae) from Marine Fishes off the Coast of Rio de Janeiro, Brazil, with Novel Molecular Data

Parasaturnius maurepasi n. gen. et n. comb. (Digena: Bunocotylidae) from the stomach of the silver mullet, Mugil curema (Perciformes: Mugilidae) in coastal lagoons of northern Yucatán, Mexico

Bunocotylid trematodes represent a group of 149 species with a rather complex taxonomic history. The current concept of the subfamily only includes three genera, Bunocotyle, Saturnius, and Robinia. Specimens of a bunocotylid were collected from the silver mullet, M. curema, from a coastal lagoon of Yucatán and identified as belonging to Saturnius. Further detailed morphological study revealed they corresponded to S. maurepasi, a species previously reported from the stripped mullet, Mugil cephalus in Mississippi, USA. Specimens were sequenced for the LSU of nuclear ribosomal RNA gene (28S) to test their phylogenetic position. We discovered that they do not belong in Saturnius since they nest as an independent lineage which is the sister taxa of a clade formed by Robinia, and Saturnius + Bunocotyle; additionally, the new genus exhibits high genetic divergence (10-12%) with respect to species allocated in the other bunocotylid genera. The species S. maurepasi was then transferred to the new genus as Parasaturnius maurepasi n. gen., n. comb. that was created to accommodate it, and was redescribed based on newly sampled specimens.

Morphological and molecular characterization of Stomachicola muraenesocis Yamaguti, 1934 (Digenea: Hemiuridae) from the daggertooth pike conger Muraenesox cinereus (Forsskål)

Hemiurid digeneans conspecific with Stomachicola muraenesocis Yamaguti, 1934 (the type species of the genus Stomachicola Yamaguti, 1934) were collected from the stomach of the daggertooth pike conger Muraenesox cinereus (Forsskål) off the Persian Gulf of Iran. This study aimed to provide a detailed characterization of Stom. muraenesocis, including measurements, illustrations and scanning electron microscopy (s.e.m.) representations. Comparisons with the original and previous descriptions revealed morphological and metrical variations in several features (i.e. body size and shape, arrangement of reproductive organs, soma to ecsoma length ratio, position of genital opening, number of vitelline tubules and extension of uterine coils) between Stom. muraenesocis from different hosts and localities. This study presents the first molecular sequence data associated with the small (18S) and large (28S) subunit nuclear ribosomal RNA genes (rDNA) for Stom. muraenesocis. Phylogenetic analyses of the 18S dataset placed Stom. muraenesocis as sister lineage to a clade formed of a group of species of Lecithaster Lühe, 1901 (Lecithasteridae Odhner, 1905). In contrast, phylogenetic analyses based on the 28S consistently recovered a sister relationship between Stom. muraenesocis and representatives of the Hemiuridae Looss, 1899. Further comprehensive phylogenetically based classification in light of morphology and taxonomic history of the Hemiuridae and Lecithasteridae is required to infer phylogenetic affinities and historical biogeography of Stomachicola. A comprehensive list of previously reported species of Stomachicola together with their associated hosts, localities and morphometric data is provided.

Polyphyly of the Dinurinae Looss, 1907 (Digenea: Hemiuridae) and resurrection of the Mecoderinae Skrjabin & Guschanskaja, 1954 based on novel collection of Tubulovesicula laticaudi Parukhin, 1969 from marine elapid snakes in Sri Lanka

With one exception, the only known hemiurid trematodes that do not use teleost fishes as definitive hosts instead occur in marine elapid snakes. These comprise six species across four genera and three subfamilies, and so presumably indicate at least three independent invasions of marine snakes from teleost fishes. Here, one of these taxa, Tubulovesicula laticaudi Parukhin, 1969 (= T. orientalis Chattopadhyaya, 1970 n. syn.) is reported from Sri Lanka, collected from Shaw's sea snake Hydrophis curtus (Shaw) (Elapidae: Hydrophiinae: Hydrophinii), the annulated sea snake H. cyanocinctus Daudin and the yellow sea snake H. spiralis (Shaw) off Nayaru in the Bay of Bengal, and from H. spiralis in Portugal Bay, Gulf of Mannar. Novel molecular data, for COI mtDNA and ITS2 and 28S rDNA, are the first for a species of Tubulovesicula Yamaguti, 1934. Nominally, Tubulovesicula belongs in the Dinurinae Looss, 1907, but in phylogenetic analyses based on 28S rDNA, our sequences for T. laticaudi resolved relatively distant from that for representatives of Dinurus Looss, 1907, the type-genus, rendering the subfamily polyphyletic. Tubulovesicula laticaudi resolved closest to data for the type-species of the Plerurinae Gibson & Bray, 1979, but that subfamily is also polyphyletic. These findings lead us to re-evaluate an alternative classification considered by Gibson & Bray (1979). We propose restricting the Dinurinae for forms with a permanent sinus-organ (Dinurus, Ectenurus Looss, 1907; Erilepturus Woolcock, 1935; Paradinurus Vigueras, 1958; Qadriana Bilqees, 1971) and resurrect the Mecoderinae Skrjabin & Guschanskaja, 1954 for forms with a temporary sinus-organ (Mecoderus Manter, 1940, Allostomachicola Yamaguti, 1958, Stomachicola Yamaguti, 1934 and Tubulovesicula).