Sabellida Levinsen, 1883 is a large morphologically uniform group of sedentary annelids commonly known as fanworms. These annelids live in tubes made either of calcareous carbonate or mucus with agglutinated sediment. They share the presence of an anterior crown consisting of radioles and the division of the body into thorax and abdomen marked by a chaetal and fecal groove inversion. This study synthesises the current state of knowledge about the diversity of fanworms in the broad sense (morphological, ecological, species richness), the species occurrences in the different biogeographic regions, highlights latest surveys, provides guidelines for identification of members of each group, and describe novel methodologies for species delimitation. As some members of this group are well-known introduced pests, we address information about these species and their current invasive status. In addition, an overview of the current evolutionary hypothesis and history of the classification of members of Sabellida is presented. The main aim of this review is to highlight the knowledge gaps to stimulate research in those directions.

Serpulidae Rafinesque, 1815 is a speciose group of polychaetes that all inhabit calcareous tubes. The family was traditionally subdivided into Serpulinae, Filograninae, and Spirorbinae. Recent phylogenetic analyses have suggested that both Filograninae and Serpulinae are paraphyletic, though with limited sampling. Here we report the first phylogenetic analysis of Serpulidae based on comprehensive sampling of genera (though excluding most spirorbin genera). We include a much-needed revision of serpulid taxonomy based on a phylogenetic hypothesis derived from both morphological and molecular data. We analysed 18S, 28S, histone H3 ribosomal nuclear DNA and cytochrome b (cytb) mitochondrial sequences, combined with morphological data. The proposed new classification includes the re-formulated Serpulinae (with tribes Serpulini and Ficopomatini), Spirorbinae, and Filograninae, with apomorphies highlighted for major taxa.

Serpulidae (Annelida) of Lizard Island, Great Barrier Reef, Australia

In May-June 2017 an expedition on board RV 'Investigator' sampled benthic communities along the lower slope and abyss of eastern Australia from off Tasmania to the Coral Sea. Over 200 sabellariid specimens of the genera Phalacrostemma and Gesaia were collected during the voyage and deposited in the Australian Museum. Here we describe two new species Gesaia csiro n. sp. (4414-4436 m) and Phalacrostemma timoharai n. sp. (1013-1093 m). We did not formally describe another species of Phalacrostemma due to poor condition of the single specimen. Gesaia csiro n. sp. is the first record of the genus from Australian waters (only a planktonic larva attributed to the genus has previously been recorded), and it can be distinguished from other congeners by the smooth surface of inner paleae, distal thecae of outer paleae with long, irregular and expanded distal fringe and circled distal margin. Phalacrostemma timoharai n. sp. differs from congeners by the following combination of characters: presence of the buccal flap, absence of tentacular filament, 18-22 pairs of outer paleae, two pairs of neuropodial cirri on first thoracic segment, and only one pair of lateral lobes on second thoracic segment. Morphological descriptions are accompanied by mitochondrial cytochrome c oxidase subunit 1 (COI) and ribosomal (16S, 18S and 28S) sequence data. A key to all Australian species of sabellariids is given.

New abyssal Melinna species from Australia