Polaruschakov sp.

Gunton, Laetitia M., Kupriyanova, Elena K., Alvestad, Tom, Avery, Lynda, Blake, James A., Biriukova, Olga, Boeggemann, Markus, Borisova, Polina, Budaeva, Nataliya, Burghardt, Ingo, Capa, Maria, Georgieva, Magdalena N., Glasby, Christopher J., Hsueh, Pan-Wen, Hutchings, Pat, Jimi, Naoto, Kongsrud, Jon A., Langeneck, Joachim, Meissner, Karin, Murray, Anna, Nikolic, Mark, Paxton, Hannelore, Ramos, Dino, Schulze, Anja, Sobczyk, Robert, Watson, Charlotte, Wiklund, Helena, Wilson, Robin S., Zhadan, Anna & Zhang, Jinghuai, 2021, Annelids of the eastern Australian abyss collected by the 2017 RV ' Investigator' voyage, ZooKeys 1020, pp. 1-198 : 1

Polaruschakov sp. Fig. 23D

Diagnosis.

Several small specimens, ~ 5 mm long, 1.5 mm wide, some damaged posteriorly, some with palps and many neuropodia missing, with <21 segments. All elytra missing, nine pairs of small elytrophores present on segments 2, 4, 5, 7, 9, 11, 13, 15, 17. Pharynx with two pairs of smooth jaws (denticles absent), seven pairs of distal papillae present, none larger than others. Prostomium bilobed, median antenna, lateral antennae and frontal filaments all absent, eyes absent (or unpigmented), tentacular segment with long tentacular cirri, achaetous. Palps short, smooth, reaching only to chaetiger 3 or chaetiger 4. Segment 2 with long ventral (buccal) cirrus similar in length to tentacular cirri. Segment 3 with long dorsal cirrus, subsequent ones (mostly) missing. Ventral cirri inserted medially on neuropodia, shorter than neuroacicular lobes. Parapodia sub-biramous, with elongate preacicular neuropodial lobe, notopodia inserted on anterodorsal face of neuropodia, conical and much shorter than neuropodia, aciculae penetrating epidermis. Notochaetae long, slender with transverse rows of fine spines along shaft and with blunt tips. Neurochaetae all flattened, coarsely serrated along both margins, tips pointed. Last three or four posteriormost chaetigers reduced. Swollen dorsal structures may be present on some specimens.

Remarks.

These specimens agree with the emended genus diagnosis by Bonifácio and Menot (2018) for Polaruschakov Pettibone, 1976, because of the absence of all antennae combined with smooth jaws (or with a single small secondary marginal tooth) and the absence of flattened scale-like structures on segment 6, but, because of their small size, damaged bodies and posterior ends and missing elytra, they could not be identified to species. There are five species in this genus which has only been reported from deep Arctic waters, off the Mediterranean (in Pettibone 1976) and in abyssal waters of the equatorial eastern Pacific Ocean off Mexico ( Bonifácio and Menot 2018).

Records.

58 specimens. Suppl. material 1: op. 16, 31, 54, 66, 76, 79, 96, 98, 103, 110, 134 (AM). 2 specimens. Suppl. material 1: op. 16 (NHMUK).

Figures

Figure 23. Polynoidae 2 A Harmothoe sp. 5 anterior end, dorsal view, and elytra (AM W. 52581) B Lepidasthenia indet. dorsal view, pharynx extended (AM W. 51580) C Macellicephalinae sp. 5 anterior end, dorsal view (AM W. 52014) D Polaruschakov sp. dorsal view (AM W. 52580). Scale bars: 5 mm.