Taxonomy, phylogeny, and biodiversity of Lumbrineridae (Annelida, Polychaeta) from the Central Pacific Clarion-Clipperton Zone.

The DNA taxonomy of six species of the annelid family Lumbrineridae collected from the Clarion-Clipperton Zone (CCZ) in the Central Pacific, an area of potential mining interest for polymetallic nodules, is presented. Lumbrinerids are an ecologically important and understudied annelid family within the deep sea, with many species still undescribed. This study aims to document the taxonomy and biodiversity of the CCZ using specimens collected from the UK-1, OMS, and NORI-D exploration contract areas and Areas of Particular Environmental Interest. Species were identified through a combination of morphological and molecular phylogenetic analysis. We present informal species descriptions associated with voucher specimens, accessible through the Natural History Museum (London) collections, to improve future taxonomic and biodiversity studies of this region. Five taxa in this study had no morphological or genetic matches within the literature and therefore are possibly new to science, but their suboptimal morphological preservation prevented the formalisation of new species. The most abundant taxon Lumbrineridescf.laubieri (NHM_0020) was compared with the holotype of Lumbrinerideslaubieri Miura, 1980 from the deep Northeast Atlantic. Currently no reliable morphological characters separating the Pacific and Atlantic specimens have been found and molecular data from the Atlantic specimens was not available.

Jaw morphology and function in Drilonereis cf. filum (Oenonidae, Annelida).

Representatives of the extant family Oenonidae (Annelida, Eunicida) have a prionognath jaw apparatus, with maxillae having forceps-like elements, a number of asymmetrical dentate plates and long slender carriers, which is characteristic of some fossil forms known from the Paleozoic epoch. Therefore, data on the fine structure and functional morphology of Oenonidae jaws are helpful for the interpretation of fossil materials. The fine structure of the jaw apparatus and the ventral pharyngeal organ is studied in one species of the Oenonidae (Annelida)-Drilonereis cf. filum. The material was collected in the soft bottom of Marseille Bay (Mediterranean) and examined with the help of TEM and histological techniques. A three-dimensional (3D) reconstruction was made from a complete series of semithin sections. The entire jaw apparatus is about 500 µm in length; it includes ventral mandibles and four pairs of maxillae, connected with long paired dorsal carriers and an unpaired ventral carrier. While retracted, it reaches the VIII-XI chaetigers. The most solid part of the maxillary apparatus, that is, maxillae I and II, are 2.5-5 µm thick. The plate consists of a monolithic array of merged scleroprotein granules in which perforations, that is, spaces remaining from microvilli, are visible; the basal part of the maxillary plate is a layer of loosely arranged collagen fibers penetrated with microvilli and has no signs of sclerotization. A study of the jaws of Drilonereis cf. filum showed the presence of common jaw patterns in Eunicida order. Like the jaws of Dorvilleidae, Eunicidae, Onuphidae, and Lumbrineridae, the jaws of Drilonereis are formed at the basis of a typical annelid cuticle's transformation with epi- and basicuticular layers, and its impregnation by merging scleroprotein granules. Through the nature of sclerotization, the jaws of D. cf. filum are similar to those of Dorvilleidae, Histriobdellidae, and the juvenile jaws of Mooreonuphis stigmatis (Onuphidae). Analysis of the 3D-reconstructions of the D. cf. filum jaw apparatus shows that the MxI of this species, and probably of other Oenonidae with dorsal and ventral carriers, can make grasping motions by fixing the joint of the right and left MxI in the two-door hinge type. In general, the overall structure of the jaw apparatus of D. cf. filum and the mechanics of its work shows greater similarity with that of Dorvilleidae than with the jaw apparatus of extant Labidognatha and Simmetrognatha (Onuphidae, Eunicidae, Lumbrineridae). The need for compactization of the jaw apparatus when moving in dense sediment or in the burrows is probably one of the factors determining its structure.

Phylogeny and Cryptic Diversity of Diopatra (Onuphidae, Annelida) in the East Atlantic.

Diopatra Audouin & Milne-Edwards, 1833 is a species rich genus that is common in tropical and subtropical regions. The genus is readily identified by its striking, spiral branchiae, but species identification has historically been challenging due to a high variation in diagnostic characters used. This study aims to reconstruct the phylogeny of Diopatra with molecular markers and assess the species diversity of West African Diopatra with the species delimitation programs bPTP and BPP. Specimens were collected from Morocco to Angola, and the markers COI, 16S and 28S were sequenced from 76 specimens. The constructed phylogeny retrieved Diopatra as monophyletic, as well as five well supported clades within the genus. All clades were defined by morphological characters, some of which have previously not been considered to have high phylogenetic or taxonomical value. Species delimitation analyses recovered 17 new species, several of which were not readily identified morphologically. One species complex comprising between one and 12 species was left unresolved due to incongruence between the species delimitation methods and challenging morphology. Our results indicate that the diversity of Diopatra is significantly underestimated, where this regional study near to doubled the number ofknown species from the East Atlantic.

Phylogenomics resolves ambiguous relationships within Aciculata (Errantia, Annelida).

Aciculata (Eunicida + Phyllodocida) is among the largest clades of annelids, comprising almost half of the known diversity of all marine annelids. Despite the group's large size and biological importance, most phylogenomic studies on Annelida to date have had a limited sampling of this clade. The phylogenetic placement of many clades within Phyllodocida in particular has remained poorly understood. To resolve the relationships within Aciculata we conducted a large-scale phylogenomic analysis based on 24 transcriptomes (13 new), chosen to represent many family-ranked taxa that have never been included in a broad phylogenomic study. Our sampling also includes several enigmatic taxa with challenging phylogenetic placement, such as Histriobdella, Struwela, Lacydonia, Pilargis and the holopelagic worms Lopadorrhynchus, Travisiopsis and Tomopteris. Our robust phylogeny allows us to name and place some of these problematic clades and has significant implications on the systematics of the group. Within Eunicida we reinstate the names Eunicoidea and Oenonoidea. Within Phyllodocida we delineate Phyllodociformia, Glyceriformia, Nereidiformia, Nephtyiformia and Aphroditiformia. Phyllodociformia now includes: Lacydonia, Typhloscolecidae, Lopadorrhynchidae and Phyllodocidae. Nephtyiformia includes Nephtyidae and Pilargidae. We also broaden the delineation of Glyceriformia to include Sphaerodoridae, Tomopteridae and Glyceroidea (Glyceridae + Goniadidae). Furthermore, our study demonstrates and explores how conflicting, yet highly supported topologies can result from confounding signals in gene trees.

New insights into the morphology and evolution of the ventral pharynx and jaws in Histriobdellidae (Eunicida, Annelida).

The jaw apparatus in several annelid families represents a powerful tool for systematic approaches and evolutionary investigations. Nevertheless, for several taxa, this character complex has scarcely been investigated, and complete comparative analyses of all annelid jaws are lacking. In our comprehensive study, we described the fine structure of the jaw apparatus and the ventral pharyngeal organ (VPO) in Histriobdella homari - a minute ectocommensal of lobsters putatively belonging to the Eunicida - using different comparative morphological approaches, including SEM, TEM, CLSM and subsequent 3D reconstruction. The H. homari jaw apparatus is composed of ventral paired mandibles and dorsal symmetrical maxillae consisting of numerous dental plates, ventral carriers and an unpaired dorsal rod, and the general assemblage and arrangement of the different parts are highly comparable to those of other eunicid families. The jaw ultrastructure of histriobdellids resembles that of the families Dorvilleidae and (juvenile) Onuphidae. Furthermore, our data reveal that in the process of development of the jaw apparatus, the mandibles, maxillae II and unpaired dorsal rod are formed first, and the remaining maxillae and ventral carriers appear later. Notably, the muscular apparatus differs from that in Dorvilleidae and Onuphidae in terms of the number and arrangement of muscle fibers encompassing the jaws - not only because of the very small size of Histriobdella but also because histriobdellid maxillary protraction occurs due to straightening of the dorsal rod and thus requires a different muscular scaffold. Based on our investigations, the arrangement of the muscular apparatus of the jaws, the presence of paired ventral carriers and the dorsal rod, and the morphology of the ventral pharyngeal organ represent a histriobdellid autapomorphy. Our datasets form a basis for further comparative analyses to elucidate the evolution of Eunicida and jaw-bearing Annelida.

Two new species of Mooreonuphis (Annelida: Onuphidae) from Australia.

Two new species of Mooreonuphis, a genus best known from the coasts of the Americas, are described from Australia, bringing the number of recognized Mooreonuphis species to 23. Mooreonuphis ariasi n. sp. was collected from off Sydney to Wollongong, New South Wales in sandy sediments, in depths of 25-50 m and M. wilsoni n. sp. in the Bass Strait and Tasmania, in 89-130 m. The two new Australian species are among the smallest and the only known abranchiate species in the genus. The summer collections of M. ariasi n. sp. contained a large number of brooders with their young undergoing asynchronous direct development in the parental tube. Nothing is known about the development of M. wilsoni n. sp.

Three new species of Aponuphis (Annelida: Onuphidae) from eastern Australia.

The genus Aponuphis, previously known from the eastern North Atlantic and the Mediterranean, is newly reported from Australia. Three new species are described from off Sydney to Wollongong, New South Wales in sandy sediments, in depths of 25-70 m, bringing the number of recognized Aponuphis species to ten. Aponuphis annae n. sp. and A. bellani n. sp. are abranchiate, whilst A. danicae n. sp. has branchiae over a short region of its body. The tubes of A. annae and A. danicae have a fragile mucous consistency with attached sand grains and that of A. bellani is transparent, tight-fitting and smooth. Two specimens of A. annae were collected with developing juveniles in their tubes demonstrating their direct development but the reproductive mode of the other two species is not known. The distinguishing characteristics of all recognized species are tabled and a key to the three Australian species is presented.