Higginsarctus Hansen & Kristensen 2021, gen. nov.

Higginsarctus gen. nov., sp. ind. Material examined

FRANCE • 1 two-clawed larva; North Atlantic Ocean: English Channel, Bay of Morlaix, 48°43′ N, 03°54′ W, depth 20–30 m; 15 Mar. 1982; R.M. Kristensen leg.; Dentalium sand; NHMD293912.

USA • 2 ♀♀, adults; Atlantic Ocean: South Carolina; 33°03.7′ N, 77°22.07′ W; depth 289 m; 19 Nov. 1983; R.P. Higgins (RH 1839); R/V Cape Hatteras; medium phosphorite sand; NHMD-293915, NHMD- 293917 • 1 two-clawed larva; same collection data as for preceding; NHMD-293916.

Among the collected material from South Carolina, USA, two adult females were found, both having large, rigid and backwards bending primary clavae supported by strong internal cuticular structures at their bases, as well as three pairs of lateral alae supported by ramuli. These specimens likely present yet another species of Higginsarctus gen. nov., different to the new species described above. Unfortunately, further details cannot be accessed due to the poor condition of the specimens.

In addition to the two unidentifiable adult specimens of Higginsarctus gen. nov., two larval specimens were found; a 2-clawed larva from Roscoff, France and a 2-clawed larva from South Carolina, USA. Both larvae possess large, rigid and backwards bending primary clavae supported by strong internal cuticular structures at their bases, a character shared by Ligiarctus and Higginsarctus gen. nov. At this larval stage, alae are not present. Co-occurring only with adult specimens of Higginsarctus gen. nov. (no adult specimens of Ligiarctus were found in the samples), these larvae most likely belongs to the new genus. However, the conclusion as to whether they belong to Ligiarctus or Higginsarctus gen. nov. cannot be made with certainty.