Bathy- and mesopelagic annelida from the Arctic Ocean: Description of new, redescription of known and notes on some “cosmopolitan” species
Introduction
In the XIX and first half of the XX centuries, with the beginning of an active discovery of marine zooplankton, many species of pelagic invertebrates were described from different regions of the marine realm (Wagner, 1872; Greeff, 1879; Viguer, 1886, 1911; Reibisch, 1895; Southern, 1909; Bergström, 1914; Fauvel, 1916; Augener, 1922). These initial descriptions based mainly on morphological data were often brief and lacking details, and the respective holotypes were often lost (Wagner, 1872; Greeff, 1879; Viguer, 1886, 1911; Reibisch, 1895; Southern, 1909; Bergström, 1914; Fauvel, 1916; Augener, 1922). This situation was compounded in the first third of the XX century, when the idea of wide distribution areas and high intraspecific variation of pelagic animals widely disseminated among taxonomists (Kramp, 1961; Dales, 1957; Tebble, 1962; Russell, 1970; Nygren, 2014; Hutchings and Kupriyanova, 2017). Particularly, this idea was applied to pelagic polychaetes that were considered showing unusually wide geographic distributions, and, subsequently, many of closely related species from different parts of the world were synonymized (Knox, 1959; Fauvel, 1959; Dales, 1957; Tebble, 1962; Day, 1967; Nygren, 2014; Hutchings and Kupriyanova, 2017). During the last three decades, however, the widespread adoption of molecular methods in zoology has led to another increase in the species diversity, due to rediscovering of misidentificated species, having morphological variation, that not considered of inter-specific importance.
In fact, some species may be sympatric and very similar, whereas other species may be widely-distributed and morphologically variable (Kramp, 1961; Russell, 1970; Knowlton, 1993, 2000; Nygren, 2014; Kolbasova et al., 2014; Hutchings and Kupriyanova, 2017). Molecular methods help to avoid an incorrect synonymisation of different species and a needless production of new species, but as the data on pelagic polychaetes in the genetic databases are few, there is often nothing to compare to make a decision on a species status.
During this study, we focused on investigation of pelagic polychaetes collected with plankton nets in three expeditions to deep basins of the Arctic Ocean in 2011, 2015, and 2016. Our study was aimed to better document diversity of pelagic polychaetes for this region based on critical comparison with data on their diversity that has accumulated over the years of morphological-based taxonomic and systematic studies before the widespread use of molecular approaches (Burnette et al., 2005).
Section snippets
Sampling and preservation
Specimens of polychaetes examined in this study were collected during three cruises of the R/V Polarstern to the deep Arctic Ocean: PS78 in August-September 2011 in the Nansen and Makarov Basins (stations 1 and 7), PS94 in September-October 2015 in the Nansen and Amundsen Basins (stations 2, 3, 5, and 6), and PS101 in September-October 2016 in the Amundsen Basin (station 4) (Fig. 1).
During these expeditions, zooplankton was collected with vertical casts of a plankton net (0.5 m2 mouth opening,
Lopadorrhynchidae Claparède, 1870.
Bathypelagobia gen. nov. Kolbasova, 2020.
Type species. Pedinosoma polaris (Buzhinskaja, 2017) [gender: feminine].
Diagnosis. Prostomium and peristomium fused; two antennae and two palps. Nine segments. Eyes absent, pharyngeal jaws present. Two pairs of tentacular cirri on one segment, chaetae and aciculae present on tentacular segment. Second segment without dorsal cirri. Parapodia uniramous, acicular; dorsal and ventral cirri shorter then parapodial lobes; all chaetae compound spinigers with
Discussion
Pelagic polychaetes represent a common component of zooplankton, but their diversity, taxonomy, and biology are still poorly documented (Dales, 1962; Day, 1967; Dales and Peter, 1972; Ushakov, 1972, 1974; Yingst, 1974a, b; Hartman, 1991; Støp-Bowitz, 1991, 1992; Halanych et al., 2007; Struck and Halanych, 2010). To date, about 140 species from seven holopelagic families (Alciopidae Ehlers, 1864, Lopadorrhynchidae, Iospilidae, Pontodoridae, Tomopteridae Grube, 1850, Typhloscolecidae,
Conclusions
We examined five polychaetes species from families Polynoidae, Lopadorrhynchidae, Typhloscolecidae and Iospilidae collected in the deep basins of the Arctic Ocean. Polynoidae is one of the three largest polychaetes families, and the number of polynoid species increases every year (Read and Fauchald, 2020). Here we described one more new pelagic (or semi-pelagic) polynoid species, Bathypolaria kondrashovi sp. nov. Based on results of our molecular examinations and recent data from Bonifácio and
Funding
The ship time during the PS101 expedition was funded by AWI Grant No. AWI_PS101_01. This study was performed in the framework of the state assignment of IO RAS (theme No. 0149–2019–0008), and partially supported by Russian Science Foundation grant№ 16–14–10173 and by Russian Foundation for Basic Research grants 18–05–60158, 19-04-00501 and 19-04-00955.
Ethical approval
This article does not contain any studies with animals performed by any of the authors.
Sampling and field studies
All necessary permits for sampling and observational field studies have been obtained by the authors from the competent authorities.
Data availability
All data generated or analyzed during this study are included in this published article.
Declaration of competing interest
The authors declare that they have no conflict of interest.
Acknowledgements
We would like to thank Captain S. Schwarze, his crew of the RV “Polarstern” and the chief scientists Dr. Ursula Schauer and Dr. Antje Boetius for their efforts and support during PS78, PS94 and PS101 expeditions; Drs. Nicole Hildebrandt, Barbara Niehoff and Hans-Jürgen Hirche (AWI) for their contribution to organization and implementation of the zooplankton sampling during these expeditions. We acknowledge support of Scientific Committee on Oceanic Research (SCOR) and its Working Group 157
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