Polacanthoderes shiraseae Yamasaki et al., 2022

Material examined

ANTARCTICA – Antarctic Peninsula • 1 ♂, 1 ♀ (mounted for LM in Fluoromount G on HS slide); CRS 1763; 64°48.41′ S, 65°21.82′ W; 593 m b.s.l.; 3 Apr. 2016; FjordEco2; soft sediment; NHMD 1784624, 1784625 • 2 ♀♀ (mounted for LM in Fluoromount G on HS slide); CRS 1846; 64°47.93′ S, 65°21.23′ W; 572 m b.s.l.; 25 Apr. 2016; FjordEco2; soft sediment; NHMD 1784626, 1784627.

Short description

Four adult specimens (one male and three females) from two different stations (stn 1763 and stn 1846) were measured and examined with light microscopy.All four specimens perfectly fit the species diagnosis of P. shiraseae (see Yamasaki et al. 2022), i.e., without tubes on segment 2 and with the short acicular spines on segment 7 placed in sublateral rather than lateral accessory positions. None of the specimens had short subdorsal acicular spines on segments 4 or 5. On segment 8, two specimens had short acicular spines in positions corresponding to subdorsal sensu Yamasaki et al. (2022), whereas such spines were missing in the other two specimens. All measurements were within the ranges of those reported in the original description of P. shiraseae.

Distribution

Antarctic Peninsula: only on the open continental shelf off the Peninsula, 572 to 593 m b.s.l. (Fig. 1C, Table 1). The species has in addition been recorded at Lützow-Holm Bay, Cape Damley, and near Totten Glacier (Yamasaki et al. 2022), i.e., on the opposite side of the Antarctic continent (see red dots in Fig. 1A).