Sibogaster bathyheuretor Mah, 2020

Mah, Christopher L., 2024, New genera and species of deep-sea Goniasteridae (Asteroidea) from the North Pacific, Zootaxa 5543 (4), pp. 451-500 : 481-483

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 .

Figures

FIGURE 10. Sibogaster bathyheuretor Mah 2020. MCZ 154360. A.Abactinal B. Closeup of abactinal plates. C Actinal-lateral view. D. Actinal E. Adambulacral plates showing furrow, subambulacral spines and pedicellariae. Scale bar=5.0 mm: A, D.; Scale bar=2.0 mm: B, E; Scale bar=3.0 mm: C.

FIGURE 15. Circeaster pullus Mah 2006 feeding observations. A–B. Feeding on Narella (Chrysogorgiidae). Santa Rosa North 467.3 m, Lasers on B are 10 cm apart, others lacking scale. C. On bamboo coral, Lone Cone, 1543.8 m. D. On bamboo coral, Unamed Seamount, 1605.8 m E. Johnson Atoll site 1, 520 m. F. feeding on bamboo coral, Johnston Atoll region, 1582 m.

FIGURE 16. Circeaster pullus Mah 2006 feeding observations. A.Feeding on Isididae, Johnston Atoll, 492 m. B–C. Feeding on Isididae, Santa Rosa North site, 467.3 m. Lasers are 10 cm apart. D. Feeding? on stoloniferous soft corals, Sibelius Seamount, 2489 m. Lasers=10cm apart.

FIGURE 19. Sibogaster spp. A. Sibogaster bathyheuretor Mah 2020. MCZ AST-154360, North Pacific, 2843 m. Remaining are S. nieseni, B. Mozart Seamount, Musicians Seamounts, North Pacific, 3810.2 m. C. WAM Z100641, Western Australia, 2519.9 m. D. Wrapped around sponge stalk, Hawaiian Islands, 2411.9 m (R/V Nautilus). E. Johnston Atoll region, North Pacific, 3066 m. F. Mozart Seamount, Musicians Seamounts, North Pacific, 3830 m.