Sibogaster bathyheuretor Mah, 2020

FIGURE 10A–E, 19A

Sibogaster bathyheuretor 2020: 234, Figs 15A–E, 16A–D.

Diagnosis

Body stellate (R/r=2.07) with broadly curved to straight interradial arcs. Arms triangular with pointed tips.Abactinal plates flat, smooth bare, no embedded granules, peripheral granules large. Marginal plates similarly bare, surficial granules absent, 20–26 per interradius (arm tip to arm tip). Actinal plates covered by widely spaced granules. Furrow spines 4 to 5 in the Pacific specimen, 7 to 8 in the Atlantic. Large paddle-shaped pedicellariae present on each adambulacral plate, prominent subambulacral spines absent.

Comments

This represents the first occurrence of this species, which was described from the tropical Atlantic, in the North Pacific.Although superficially similar in terms of abactinal, marginal, and actinal plate morphology and arrangement, there is some character variation. Marginal plates, are approximately 25 superomarginals and 25 inferomarginals at R = 3.2 cm versus 20 superomarginals and 22 inferomarginals at R = 2.7 cm in the Atlantic specimen and furrow spines are 4 to 5, at R = 3.2 cm, versus 7 to 8 in the Atlantic form, at R = 2.7 cm.

Occurrence

Perdido Canyon and West Florida Escarpment, Gulf of Mexico. 2597–2777 m and North Pacific, 2843 m.

Material Examined

North Pacific . MCZ AST-154360 North Pacific Ocean, 22.14904616 ° -162.5841846 °, 2843 m. Coll. R/V Nautilus, ROV Hercules with slurp gun. Dec. 18, 2021. 1 wet spec. R=3.2 r= 1.3 cm .