Freyastera basketa Zhang et al., 2019

Figs 6, 14E

Freyastera basketa: Zhang et al. 2019: 4; Zhang et al. 2024: 2,

Material examined.

RSIOAST 0038 (holotype) . RSIOAST 0006 (paratype); RSIOAST 0008 (paratype); RSIOAST 0039 (paratype) . RSIOAST 0200 (Figs 6 A – F, 14 E); RSIOAST 0201 (Fig. 6 G, H); NHMUK 8963; SO 268-2_174_116. (Suppl. material 1) .

Diagnosis.

Arms 6. Abactinal disk and arm plate each bears one long, sharp spine, about 1 mm in length, not covered by membranous sheath. Enlarged pedicellariae (about 0.3–0.5 mm in length) with curved valves present on oral spines and abactinal surface of disk and arm genital area. Small pedicellariae (less than 0.2 mm in length) cluster in transverse bands on abactinal arm beyond genital area. One aboral furrow spine and one subambulacral spine on each adambulacral plate. Proximal subambulacral spines with truncate end. One lateral spine corresponding to every adambulacral plate beyond genital area. Oral plate bears one actinostomal spine, one suboral spine, and one furrow spine, all covered by large pedicellariae.

Distribution.

Northwest Pacific: Mariana Trench, Yap Trench, Lamont Seamount, Pigafetta Basin; Eastern Pacific: Clarion-Clipperton Zone (CCZ). 4137–4991 m. Type locality: Mariana Trench, Yap Trench, Lamont Seamount, 4798–4991 m.

Remarks.

This species is characterized by having enlarged pedicellariae with curved valves on oral spines and abactinal surface of disk and arm genital area (Fig. 6 A, B, G), and one long, unsheathed spine on each abactinal arm plate. In some specimens, the proximal adambulacral spines are also equipped with large pedicellariae. The large pedicellariae are found in other Brisingida species, such as Freyella macropedicellaria Korovchinsky & Galkin, 1984; Freyella remex Sladen, 1889; and Astrocles japonicus (Korovchinsky 1976), as well as Freyellaster species (Zhang et al. 2024). In Freyastera, only F. basketa and F. mortenseni were found to have large pedicellariae. F. basketa has rather long, sharp spines on abactinal disk and arms, one to each plate, whereas F. mortenseni has several spines on each plate. Furthermore, F. mortenseni was reported at greater depth (5850 to 6200 m) than F. basketa (4137 to 4991 m). The newly examined specimens extend the distribution range of F. basketa to CCZ in the Eastern Pacific (Fig. 1).