Redescription of Manayunkia caspica Annenkova, 1929 and M. danubialis Băcescu, 1944 n. comb. (Fabriciidae, Sabellida, Polychaeta)

The spread of the subspecies M. caspica danubialis Băcescu, 1944, which has been found in the Danube since 1944, into the upper section of the Danube as far as Austria was the reason for describing the characters of this species and comparing it with the nominotypical subspecies M. caspica caspica Annenkova, 1929, which lives in the Caspian Sea. Both subspecies are similar in the most important diagnostic characters, such as the number of branches of the radioles and the presence and number of pseudospatulate chaetae on thoracic chaetigers. However, they differ in other, less conspicuous characters, such as the number of thoracic uncini and the length of chaetigers. But these characters vary depending on the size of the specimens. Both subspecies inhabit completely different habitats. Based on the ecological species concept, the spatially and ecologically separated populations are regarded as distinct species, M. caspica, and M. danubialis n. comb. The occurrence of transitional uncini in both species and the presence of a brood chamber in the females of M. caspica are described for the first time. The structure of the radiolar crown is also described for both species. A molecular barcode for M. danubialis n. comb., a 654 base pair fragment of cytochrome c oxidase I is presented, allowing a fast and simple identification of this species by using a robust PCR/sequencing approach.

Fanworms: Yesterday, Today and Tomorrow

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.

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.

Black spicules from a new interstitial opheliid polychaete Thoracophelia minuta sp. nov. (Annelida: Opheliidae)

The phylum Annelida exhibits high morphological diversity coupled with its extensive ecological diversity, and the process of its evolution has been an attractive research subject for many researchers. Its representatives are also extensively studied in fields of ecology and developmental biology and important in many other biology related disciplines. The study of biomineralisation is one of them. Some annelid groups are well known to form calcified tubes but other forms of biomineralisation are also known. Herein, we report a new interstitial annelid species with black spicules, Thoracophelia minuta sp. nov., from Yoichi, Hokkaido, Japan. Spicules are minute calcium carbonate inclusions found across the body and in this new species, numerous black rod-like inclusions of calcium-rich composition are distributed in the coelomic cavity. The new species can be distinguished from other known species of the genus by these conspicuous spicules, shape of branchiae and body formula. Further, the new species' body size is apparently smaller than its congeners. Based on our molecular phylogenetic analysis using 18S and 28S sequences, we discuss the evolutionary significance of the new species' spicules and also the species' progenetic origin.

Comparative ultrastructure of the radiolar crown in Sabellida (Annelida)

Three major clades of tube-dwelling annelids are grouped within Sabellida: Fabriciidae, Serpulidae and Sabellidae. The most characteristic feature of these animals is the often spectacularly colorful and flower-like radiolar crown. Holding up such delicate, feathery appendages in water currents requires some sort of internal stabilization. Each of the above-mentioned family-ranked groups has overcome this problem in a different way. Herein we describe the arrangement, composition and ultrastructure of radiolar tissues for fabriciids, sabellids and serpulids using transmission electron microscopy, histology and immunohistochemistry. Our sampling of 12 species spans most of the phylogenetic lineages across Sabellida and, from within Sabellidae, includes representatives of Myxicolinae, Sabellinae and the enigmatic sabellin Caobangia. We further characterize the ultrastructure of the chordoid cells that make up the supporting cellular axis in Sabellidae and discuss the evolution of radiolar tissues within Sabellida in light of the recently published phylogeny of the group.

Mitochondrial genome of the freshwater annelid Manayunkia occidentalis (Sabellida: Fabriciidae)

Here, we report the 15,103 bp mitochondrial genome of the freshwater fabriciid tubeworm Manayunkia occidentalis. We recovered 13 protein-coding genes, 2 rRNA, and 22 tRNA. The gene order is consistent with the conserved pattern observed in most annelids.

Three species of Amphicorina (Annelida, Sabellida, Sabellidae) from Japan, with descriptions of two new species

We describe two new species and redescribe one in the polychaete genus Amphicorina Claparède, 1864 (Sabellidae) from Hokkaido, Japan. Amphicorina ascidicolasp. n. differs from its 38 congeners chiefly in the reduction of the collar, but also in having three pairs of radioles, one pair of ventral radiolar appendages, a bifurcate ventral lobe on the anterior peristomial ring, six abdominal chaetigers, and a large anterior tooth on the abdominal uncini. Amphicorina ezoensissp. n. has a crenulated collar, three pairs of radioles, and more than eight (12) abdominal chaetigers; Amphicorina ezoensis shares these character states with Amphicorina anneae (Rouse, 1994), Amphicorina eimeri (Langerhans, 1880), and Amphicorina persinosa (Ben-Eliahu, 1975), but differs from them in having two pairs of ventral radiolar appendages and a non-oblique collar. Amphicorina mobilis (Rouse, 1990) was previously known only from the type locality (New South Wales, Australia), but we identify our Japanese material as conspecific on the basis of morphological and molecular similarity.