161 The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 2011 27: 161–177 New Dinematichthyini (Teleostei: Bythitidae) from the Indo-west Paciic, with the description of a new genus and ive new species WERNER SCHWARZHANS 1 and PETER RASK MØLLER 2 1 Ahrensburger Weg 103, 22359 Hamburg, GERMANY wwschwarz@aol.com. ²Natural History Museum of Denmark, Zoological Museum, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø, DENMARK pdrmoller@snm.ku.dk ABSTRACT After completion of the revision of the dinematichthyine ishes (Ophidiiformes: Bythitidae: Brosmophycinae) of the Indo-west Paciic based on more than 6500 specimens in 2008, extensive additional material was reviewed from the collections of the Western Australian Museum and the South African Institute of Aquatic Biodiversity. This material has not only led to a better deinition of the species Brosmolus longicaudus but also to a recognition of the following new taxa: Didymothallus nudigena sp. nov. from northwestern Australia, Paradiancistrus christmasensis sp. nov. from Christmas Island (Indian Ocean), Nielsenichthys pullus gen. nov., sp. nov. from Nusa Penida, Indonesia, Majungaichthys agalegae sp. nov. from northern Madagascar and Agalega Islands and Mascarenichthys remotus sp. nov. from Rodrigues Island. The status of Alionematichthys sp. 2 in Møller and Schwarzhans (2008) is resolved and placed into A. crassiceps Møller and Schwarzhans, 2008, thereby extending the distribution of the species to northwestern Australia. Keywords: Viviparous brotulas, Indo-west Paciic, Australia, Indonesia, Madagascar, Rodrigues Island, coral reef ishes, Dinematichthyini, new genus, new species. INTRODUCTION The review of the dinematichthyine ishes of the Indo- west Paciic was published in four parts between 2005 and 2008 (Schwarzhans et al. 2005; Møller & Schwarzhans 2006, 2008; Schwarzhans & Møller 2007). Since then, two additional major collections have been made available for review. These were the ichthyological collection of the Western Australian Museum (WAM) at Perth, Western Australia, which was visited by both authors during the occasion of the Indo-Paciic Fish Congress in Perth in 2009, and from the South African Institute of Aquatic Biodiversity (SAIAB) at Grahamstown. The WAM material provided extensive material from the Western Australian shelf with a number of specimens that allow redeinition of the rare and hitherto poorly deined Brosmolus longicaudus, placement of Alionematichthys sp. 2 of Møller and Schwarzhans (2008) to Alionematichthys crassiceps and the description of Didymothallus nudigena sp. nov., which was previously only known from a few female or juvenile male specimens tentatively placed in Didymothallus mizolepis. Material obtained from Christmas Island in the Indian Ocean has revealed the fourth species of the genus Paradiancistrus – P. christmasensis sp. nov. Finally, recently collected ish from the shores of Sumbawa Island, Indonesia, has yielded another new genus and species – Nielsenichthys pullus gen. nov., sp. nov. This discovery proves that the Indonesian Archipelago still represents one of the areas where dinematichthyine knowledge remains poorly known and new data have to be expected from there. A male specimen from northwestern Madagascar proved to represent the same species previously recorded only from female specimens from the nearby Agalega Islands, which was tentatively placed in Majungaichthys simplex by Schwarzhans and Møller (2007), and is now described as Majungaichthys agalegae sp. nov. The material made available for review by SAIAB was primarily collected along the eastern African shores, Madagascar and the islands of the western Indian Ocean. It has added important information about the areal distribution of Mascarenichthys heemstrai and yielded a new species of the same genus – Mascarenichthys remotus sp. nov. – endemic to the remote Rodrigues Islands. MATERIAL AND METHODS Nearly 6500 specimens of Indo-west Pacific Dinematichthyini have been reviewed for the revision published in four parts between the years 2005 and 2008. The additional material studied at WAM and from SAIAB comprised about 1000 additional specimens. However, only the material of SAIAB and speciic loans from WAM are