Searching for a Home Port in a Polyvectic World: Molecular Analysis and Global Biogeography of the Marine Worm Polydora hoplura (Annelida: Spionidae).

The spionid polychaete Polydora hoplura Claparède, 1868 is a shell borer widely occurring across the world and considered introduced in many areas. It was originally described in the Gulf of Naples, Italy. Adult diagnostic features are the palps with black bands, prostomium weakly incised anteriorly, caruncle extending to the end of chaetiger 3, short occipital antenna, and heavy sickle-shaped spines in the posterior notopodia. The Bayesian inference analysis of sequence data of four gene fragments (2369 bp in total) of the mitochondrial 16S rDNA, nuclear 18S, 28S rDNA and Histone 3 has shown that worms with these morphological features from the Mediterranean, northern Europe, Brazil, South Africa, Australia, Republic of Korea, Japan and California are genetically identical, form a well-supported clade, and can be considered conspecific. The genetic analysis of a 16S dataset detected 15 haplotypes of this species, 10 of which occur only in South Africa. Despite the high genetic diversity of P. hoplura in South Africa, we tentatively propose the Northwest Pacific, or at the most the Indo-West Pacific, as its home region, not the Atlantic Ocean or the Eastern Pacific Ocean. The history of the discovery of P. hoplura around the world appears to be intimately linked to global shipping commencing in the mid-19th century, followed by the advent of the global movement of commercial shellfish (especially the Pacific oyster Magallana gigas) in the 20th century, interlaced with continued, complex dispersal by vessels and aquaculture. Given that P. hoplura has been detected in only a few of the 17 countries where Pacific oysters have been established, we predict that it may already be present in many more regions. As global connectivity through world trade continues to increase, it is likely that novel populations of P. hoplura will continue to emerge.

Revision of the Laonice bahusiensis complex (Annelida: Spionidae) with a description of three new species.

The morphological reexamination of specimens previously identified as Laonice bahusiensis Sderstrm, 1920 from North European and Mediterranean collections, supported by the molecular analysis of freshly collected material, enabled the recognition of four different species in the region: the genuine L. bahusiensis, L. irinae n. sp. from North European waters, and L. grimaldii n. sp. and L. mediterranea n. sp. from the Mediterranean Sea. The morphology of these species is described and illustrated, and their distributions are clarified based on old and new materials. A key for their identification is also provided. The Bayesian analysis of the COI sequences (483 bp) showed that these four species form a clade, namely the L. bahusiensis species complex, morphologically characterized by the continuous dorsal crests on postbranchiate chaetigers in the adults. The genetic p-distances between the species of the complex ranged from 13.27% to 17.99%, while the intraspecific variability ranged from 0.6% to 1.57%. Together with the sister species Laonice cirrata (Sars, 1851), the L. bahusiensis complex formed the Laonice (Laonice) clade, which is morphologically characterized by the prostomium fused with the anterior peristomial margin. However, the monophyly of the L. bahusiensis complex, as well as that of the clade Laonice (Laonice), needs to be further supported through the analysis of a greater set of genes from a larger number of species.

A review of the worldwide distribution of Marenzelleria viridis, with new records for M. viridis, M. neglecta and Marenzelleria sp. (Annelida: Spionidae).

Marenzelleria Mesnil, 1896 is a small group of spionid polychaetes comprising five valid species, all of which appear similar to each other. The identification of worms based on morphological features is often confusing, and thus molecular data have been suggested as providing crucial additional diagnostic characters. Here we summarize and map available records of M. viridis (Verrill, 1873) worldwide, and, based on the analysis of fragment sequences of COI, 16S, 18S, 28S and Histone 3, report this species for the first time from Norway. We also summarize and map the records of Marenzelleria from North America, distinguishing those based on morphology and molecular data. We report new records for Marenzelleria sp. from Baffin Is., Nunavut, Canada, and for M. neglecta Sikorski Bick, 2004 from Washington, USA.

Molecular analysis of Spiophanes bombyx complex (Annelida: Spionidae) with description of a new species.

Spiophanes bombyx (Claparède, 1870) from the Gulf of Naples, Tyrrhenian Sea, Italy, was the first described Spiophanes with fronto-lateral horns on the prostomium. It was also considered the only horned species occurring in European waters. Our sequence data of five gene fragments suggest the presence of two horned sibling Spiophanes species in northern Europe: S. cf. bombyx in the North and the Norwegian seas, and S. cf. convexus in Brittany, northern France, and Bay of Biscay, northern Spain. Spiophanes cf. bombyx worms are genetically close to a single examined specimen of S. bombyx from Venice Lagoon, Italy but their conspecificity should be verified by further study. Our sequence data show that horned Spiophanes from the North Pacific are genetically distant from horned European species, and that S. uschakowi Zachs, 1933, originally described from the Sea of Japan (East Sea) is a valid species. The data also suggest the presence of two horned sibling Spiophanes species in the North East Pacific: S. hakaiensis Radashevsky & Pankova, n. sp. distributed from Alaska south to about Point Conception, and S. norrisi Meißner & Blank, 2009, distributed from San Francisco Bay south to Baja California Sur, Mexico. Spiophanes from South America, morphologically similar to S. norrisi, are suggested to belong to a new species. Molecular data also suggest the presence of two sibling species among the worms from northern Europe identified by morphology as S. kroyeri Grube, 1860. Worms from the Barents Sea and northern part of the North Sea are tentatively referred to as S. cf. kroyeri; worms from the northern and central parts of the North Sea and from the Bay of Biscay, northern Spain, are tentatively referred to as S. cf. cirrata M. Sars in G.O. Sars, 1872. Sequence data also show that S. duplex from California is genetically different from morphologically similar worms from South America. The South American worms are referred to resurrected S. soederstroemi Hartman, 1953 which was originally described from off Rio Grande do Sul, Brazil, and then considered as a junior synonym of S. duplex. Analysis of divergence times of Spiophanes lineages suggested that the origin of the most recent common ancestor of horned Spiophanes with metameric nuchal organs was around 11.1 mya (95% HPD: 5.1-19.0 mya) and that the divergence of the North Atlantic and North Pacific lineages was around 7.9 mya (95% HPD: 4.1-13.3 mya). The North Atlantic lineage was estimated to have diverged 4.8 mya (95% HPD: 2.2-8.6 mya), resulting in the origin of S. cf. bombyx and S. cf. convexus. The North Pacific lineage was estimated to have diverged first by the isolation and speciation of S. norrisi 1.7 mya (95% HPD: 2.3-1.0 mya), and then by the isolation and speciation of S. uschakowi and S. hakaiensis n. sp. 1.3 mya (95% HPD: 2.0-0.7 mya). The estimates place the divergences soon after maximum glacial period in the North Pacific (2.4-3.0 mya).

Molecular analysis of six Rhynchospio Hartman, 1936 species (Annelida: Spionidae) with comments on the evolution of brooding within the group.

Rhynchospio Hartman, 1936 is a small group of spionid polychaetes currently comprising ten described species distributed mainly in the Pacific. Five species examined to date are hermaphrodites producing spermatozoa with long nuclei, oocytes with thin and smooth envelopes, and dorsally brooding their offspring. Since our first molecular analysis of four Rhynchospio species, we have collected additional material from Northern Territory, Australia, and Oregon, USA. Herein, we describe the gamete and adult morphology of the newly collected material and use molecular analyses to provide new insight on the phylogenetic relationships of six Rhynchospio species. Adults of R. cf. foliosa from Oregon are hermaphrodites, but in contrast to other Rhynchospio, they produce spermatozoa with short nuclei (ect-aquasperm), oocytes with thick vesiculate envelopes, and likely have a holopelagic larval development. Analysis of four gene fragments, comprising mitochondrial 16S rDNA, and nuclear 18S, 28S rDNA, and Histone 3 (2516 bp in total) showed Rhynchospio to be a monophyletic group, with R. cf. foliosa being a distant sister to the five other species. Rhynchospio cf. foliosa was closer to M. arctia having ect-aquasperm and vesiculate thick-envelop oocytes (p = 14.40%) than to Spioninae members B. proboscidea and P. elegans, having introsperm and oocytes with thin and smooth envelopes (p = 15.39 and 16.54%, respectively). We hypothesize that brooding might have evolved from free-spawning inside the Rhynchospio clade, but this hypothesis should be tested in a future analysis.