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This study reports Peruvian freshwater species of Stenostomum (Catenulida) from the upper Yurúa River of the Amazon Basin. A total of 11 species were found. One of them, Stenostomum ashanika, sp. nov., is described. It can be distinguished by: a pre-pharyngeal constriction; a small cauda; a small, rounded, mobile and ventrally directed pharynx; and a tri-radiate mouth. The remaining 10 species are reviewed and illustrated; eight are first records for Peru. A preliminary phylogenetic analysis of neotropical stenostomid species based on morphological data is undertaken, including all Rhynchoscolex, Stenostomum and Myostenostomum species described for the area. The Rhynchoscolex species are basal and paraphyletic; the species of Myostenostomum are monophyletic, within the Stenostomum clade, supported by the presence of a muscular gizzard in the anterior region of the intestine. Ciliated pits and rhabdoids are synapomorphies of the Stenostomum + Myostenostomum clade. This is the first morphological study of the relationships between stenostomid species. The most relevant characters in the phylogenetic analysis are those related to cerebral brain lobes. The results also show that many of the morphological characteristics of the species under study are poorly known and should be studied in more depth. [ABSTRACT FROM AUTHOR]

From 1997 to 1999, the fauna of free-living Platyhelminthes of the rias ecosystem was studied along the Galician and Cantabrian coast in northern Spain. In total, 72 platyhelminth species are listed in this study. Forty-two species represent new records for the Iberian Peninsula, three of which represent new genera records. A new species belonging to the genus Djeziraia (Polycystididae, Kalyptorhynchia), Djeziraia longistyla sp. nov., is described in this paper. In this broad-scale study, a large data set (27 localities) of the estuaries of northern Spain allowed an analysis of the turbellarian species assemblages and the relation of species distributions to salinity, conductivity, oxygen, temperature, and sediment characteristics. Species assemblages (species diversity) of each habitat of the brackish water ecotone are shown. The present study contributes to knowledge on the ability of adaptation of free-living Platyhelminthes to regimes of brackish water ecotones. [ABSTRACT FROM AUTHOR]

This paper revises the genusStenostomumbased on a rich collection of species from Argentina and on a review of bibliographical resources of all known South American species. The description of South American species is standardized. The new genusAnokkostenostomumis established and several species ofStenostomumare transferred to it based on the absence of light-refracting bodies and the presence of a metameric anterior brain lobe. We report fiveStenostomumspecies and threeAnokkostenostomumspecies new to Argentina and present an identification key for South American species. Finally, all the world species are compiled, with an overview of their distribution. © 2005 The Linnean Society of London,Zoological Journal of the Linnean Society, 2005,144, 37–58. [ABSTRACT FROM AUTHOR]

A new species of polyclad flatworm, Idiostylochus tortuosus gen. nov., sp. nov. (Polycladida, Idioplanidae), from Arcachon Bay (France) is described. This description is based on a morphological analysis and a molecular analysis using partial sequences of the 28S and cytochrome Oxidase I ( COI ) genes. After the molecular analysis Idiostylochus gen. nov. appears to be the second genus of the Family Idioplanidae and closely related to the family Latocestidae as well as the genera Leptostylochus and Mirostylochus . The molecular data revealed that the new species may belong to an Indonesian or Indo-Pacific family, closely related to genera with origins in South Pacific Ocean waters. This species was found feeding on the oysters and mussels of the Arcachon farms.