Description of a new and widely distributed species of Bathypathes (Cnidaria: Anthozoa: Antipatharia: Schizopathidae) previously misidentified as Bathypathes alternata Brook, 1889.

For many years an undescribed species of the genus Bathypathes has been misidentified as Bathypathes alternata Brook, 1889 (a species currently re-assigned to the genus Alternatipathes). This new species is rather common at mid- and lower bathyal depths of the Pacific, Atlantic and Indian oceans, often in areas with high concentrations of commercially valuable cobalt-rich ferromanganese crusts, where it was observed in underwater photo and video transects to occur in high densities. Under the name B. alternata this species is recorded in several inventories and databases. There is an urgent need for a formal description of this misidentified and widely distributed species to avoid further confusion. The new species is superficially similar to A. alternata in having a monopodial corallum and simple, bilateral and alternately arranged pinnules. However, it differs from the former in that it has an upright corallum with a straight pinnulated part (vs. a horizontally bent pinnulated part), pinnules of uniform length and density (vs. decreasing regularly distally), and a constant distal angle formed by the pinnules and the stem along different parts of the corallum (vs. a decreasing distal angle near the top). The new species can therefore be easily distinguished from A. alternata in underwater imagery. We formally describe this new species in the genus Bathypathes and assign it the new name B. pseudoalternata. An extensive synonymy list with previous misidentified records is provided. To evaluate the distributional patterns of the new species we review the geographic distribution of antipatharians reported below 800 m. The majority of the hitherto described lower bathyal and abyssal species have been recorded from one biogeographic province; however, 20 species are known from more than two provinces, and only three species are widely distributed (>5 provinces), including the newly described Bathypathes pseudoalternata. Members of the family Schizopathidae, to which the new species belongs, represent the majority of the lower bathyal (50.54%) and abyssal (82.35%) species.

Annelids of the eastern Australian abyss collected by the 2017 RV 'Investigator' voyage.

In Australia, the deep-water (bathyal and abyssal) benthic invertebrate fauna is poorly known in comparison with that of shallow (subtidal and shelf) habitats. Benthic fauna from the deep eastern Australian margin was sampled systematically for the first time during 2017 RV 'Investigator' voyage 'Sampling the Abyss'. Box core, Brenke sledge, and beam trawl samples were collected at one-degree intervals from Tasmania, 42°S, to southern Queensland, 24°S, from 900 to 4800 m depth. Annelids collected were identified by taxonomic experts on individual families around the world. A complete list of all identified species is presented, accompanied with brief morphological diagnoses, taxonomic remarks, and colour images. A total of more than 6000 annelid specimens consisting of 50 families (47 Polychaeta, one Echiura, two Sipuncula) and 214 species were recovered. Twenty-seven species were given valid names, 45 were assigned the qualifier cf., 87 the qualifier sp., and 55 species were considered new to science. Geographical ranges of 16 morphospecies extended along the eastern Australian margin to the Great Australian Bight, South Australia; however, these ranges need to be confirmed with genetic data. This work providing critical baseline biodiversity data on an important group of benthic invertebrates from a virtually unknown region of the world's ocean will act as a springboard for future taxonomic and biogeographic studies in the area.