Potamethus cf. scotiae (Pixell, 1913)

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

Potamethus cf. scotiae (Pixell, 1913) Fig. 26C

Diagnosis.

Eight thoracic and numerous abdominal segments. Branchial crown with 6-9 pairs radioles. Wide ventral ‘flange’ on ventralmost radioles; ventral sacs large, external to crown; ventral shields present on body. Collar with dorsal lamellae and dorsal pockets, prolonged ventrally with large ventral lappets, oblique laterally. Peristomial ring elongate, exposed above collar. Thoracic notochaetae including superior narrowly-hooded chaetae and two inferior rows of paleate chaetae; thoracic uncini avicular with extremely long handles (> 10 × distance of main fang to breast); companion chaetae present, with similarly long handles. Abdominal neurochaetae of two types: short, broadly-hooded with long tips and longer elongate narrowly-hooded chaetae; abdominal uncini avicular with long handles/shafts, but with breast reduced to narrow swelling at curvature. Ventral surface glandular, thoracic shields prominent. Tubes muddy with fine transverse striations.

Remarks.

Four large fragmented specimens were removed from tubes. There are currently no Potamethus species reported from Australia, however, there are museum records of Potamethus collected from deep water east of Tasmania in 1986 (Murray, pers. obs.), and more recently from the GAB surveys in 2015 and 2017 ( MacIntosh et al. 2018: additional file 2). Worldwide, there are 11 nominal species, all described from deep waters, and types would need to be examined to determine to which species these specimens belong, or if it is new. Based on descriptions from the literature, the specimens bear greatest resemblance to P. scotiae (Pixell, 1913) from Antarctic waters.

Records.

4 specimens. Suppl. material 1: op. 53, 122 (AM).

Figures

Figure 26. Sabellidae, Syllidae, Terebellidae. Sabellidae A Sabellidae sp. 1 (AM W. 52133) B Sabellidae sp. 2 (AM W. 52214) C Potamethus cf. scotiae (AM W. 51585). Syllidae D Anguillosyllis sp. (AM W. 52625) E Exogone cf. heterosetosa (AM W. 52329) F Terebellidae (sensu stricto) (AM W. 50426). Scale bars: 1 mm (A, B, D, E); 5 mm (C, F).