Potamethus filatovae (Levenstein, 1961) Tovar-Hernandez & Jirkov, 2024

Tovar-Hernandez, Maria Ana & Jirkov, Igor A., 2024, Jasmineira filatovae Levenstein, 1961, the deepest known sabellid is a Potamethus Chamberlin, 1919: redescription, new combination and generic emendation, Zootaxa 5486 (1), pp. 48-70 : 61

Comparison of Potamethus filatovae and Jasmineira pacifica

Although these two species belong to different genera, a comparison is needed since J. filatovae is being recognized within Potamethus in the present study. The original description of J. filatovae Levenstein, 1961 stated that this species differs from J. pacifica Annenkova, 1937 (pp. 195–196, Pl. V, figs 55–56), the only species known from the Russian Far Eastern seas and originally described from the Northern Sea of Japan to 2900 m depth, by having a smaller number of radioles and by the shape of the anal lobe. In the present study the presence of bayonet chaetae and vascular peristomial loops were not confirmed in J. pacifica ; however, this species is distinct because it has acicular thoracic uncini (avicular in P. filitovae ). Also, J. pacifica has a pygidial cirrus which is absent in P. filatovae (instead, P. filatovae having rounded papillae located on the sides of the anus). These features show that P. filatovae and J. pacifica are different species, which also differ bathymetrically: the former has been reported from 3812 to 9735 m depth, and the latter to 2900 m depth ( Alalykina 2020).