Bathyceramaster kelliottae, Mah, 2024

Mah, Christopher L., 2024, Two New Taxa of Goniasteridae (Asteroidea, Echinodermata) and Noteworthy Observations of Deep-Sea Asteroidea by the NOAA Ship Okeanos Explorer in the North and Tropical Atlantic, Zootaxa 5432 (4), pp. 461-508 : 475-478

Bathyceramaster kelliottae n. sp.

FIGURE 6A–G

Etymology

This species is named for Kelley Suhre (formerly Elliott) Deputy Chief, Explorations & Expeditions Division at NOAA Office of Ocean Exploration and Research to honor her efforts supporting deep-sea research, especially those of NOAA ship Okeanos Explorer.

Diagnosis

A stellate species (R/r=2.22) distinguished by the presence of short, moderate length tabulate plates ( Fig. 6A, B, D ) topped with round and polygonal granules ( Fig. 6B ). Stellate, internally expressed radial ossicles on abactinal plates (as in Mediaster ) absent. Fasciolar grooves present ( Fig. 6D ). Marginal plates, 30 per interradius (at R=6.0) covered with round, coarse granules ( Fig. 6A, C, D ) and small spatulate pedicellariae. Actinal surface covered by granules. Adambulacral plates flanked by a continuous series of actinal plates, each bearing a single large, transversely oriented bivalve pedicellariae, these arranged serially and extending adjacent to the adambulacral plates to the arm tip ( Fig. 6D–G ). Adambulacral plates with spines in four series. Furrow spines, triangular in cross-section, 2 to 6, mostly 5 to 6 decreasing to 2 or 3 distally, adjacent to the terminus. Second and third subambulacral spine series each with four spines with last series showing five spines ( Fig. 6F–G ).

Comments

This is the first Bathyceramaster species known from the Atlantic. The presence of large (i.e. bisect the plate on which they sit), serial bivalve pedicellariae adjacent to the adambulacral plates ( Figs. 6E–G ) distinguishes this species apart from Bathyceramaster inornata Mah 2022 and Bathyceramaster smithi (Fisher, 1913) which completely lack pedicellariae. Bathyceramaster teres Mah 2016 , Bathyceramaster careyi Mah 2016 , and Bathyceramaster elegans (Ludwig, 1905) possess either small tong-shaped or clam-shaped bivalve pedicellariae similar in size to adjacent granules. Subambulacral and furrow spines on Bathyceramaster kelliottae n. sp. occur in two distinct series separated from one another ( Figs. 6F–G ). This is distinctly different from other Pacific Bathyceramaster species which show dissimilar morphologies and spine number (see Mah 2016, 2022).

Bathyceramaster kelliottae n. sp. also invites comparison with Peltaster nidarosiensis (Storm, 1888) an apparent synonym of P. placenta characterized by the presence of a similar series of pedicellariae on the actinal plate series adjacent to the adambulacral series. While Bathyceramaster bears some general similarity with Peltaster (e.g. granules cover abactinal, marginal and actinal surfaces), it differs in possessing well-developed tabulate plates and fasciolar grooves versus abutted plates with indirect or shallow fasciolar grooves. Also, marginal plates are fewer in Peltaster (approximately 15 at R= 4.7 cm in USNM 38229) versus 30 in B. kelliottae n. sp. (R=6.0 cm), and B. kelliottae n. sp. has a much more strongly stellate shape with well-developed arms whereas Peltaster tends to be pentagonal (R/r=1.6) as outlined in Clark and Downey (1992). In the holotype (USNM 1660278) of B. kelliottae , pedicellariae are present in series along the actinal series adjacent to the adambulacral plates to the arm tip, but irregularly so in Peltaster , and 3 to 4X longer than those in the specimens of Peltaster nidarosiensis (USNM 38229, USNM 1225448) examined. Adambulacral spines in Peltaster are also quadrate in cross section and easily 2 to 3X the thickness of those in Bathyceramaster . Finally, Bathyceramaster kelliottae n. sp. is consistent with other Bathyceramaster in occurring at lower bathyal-abyssal depths, 1386–1699 m whereas Peltaster showing the “ nidarosiensis ” morphology are present at shallower depths, 316– 336 m.

Occurrence

Deep Mound 2, Blake Plateau and Yakut Seamount, North Atlantic Ocean, 1386–1699 m.

Description

Body stellate (R/r=2.22), arms triangular, interradial arcs round, weakly curved. Marginal plates forming a thick, rolled lateral edge. Arms upturned (Figs A, C).

Abactinal plates tabulate (i.e. moderate length shaft with coarse granular cover) with well developed fasciolar grooves ( Fig. 6A, D ). Internal plate bases round to polygonal, lacking stellate bases. Abactinal plates hexagonal in outline on central region of disc ( Fig. 6B ) and arms becoming smaller, more irregular and quadrate in outline interradially, especially adjacent to the contact with superomarginal plates. Plates interradially, adjacent to superomarginals closely arranged, in ordered series ( Fig. 6D ). Abactinal plates on disc and radial regions widely spaced. Papulae single pores, present on basal arm regions. Plates covered by 10–40 coarse, round to irregular closely arranged, evenly spaced granules ( Fig. 6B ). Each plate with 4 to 5 granules in series along each edge, central region with 5 to 15 granules present.Abactinal pedicellariae narrow spatulate, some with 3 to 4 teeth per valve. Most pedicellariae with two valves, but one with three. Approximately 5 to 10 pedicellariae with one pedicellariae present per plate especially around the basal region on the arm, loosely associated with the papular regions.Anus surrounded by four large abactinal plates, each of these with enlarged peripheral granules, approximately twice to 3X the size of the central granules, with some enlarged peripheral granules triangular in shape. Madreporite quadrate in shape, surrounded by six abactinal plates, two plates bearing pedicellariae. Abactinal plates extending to arm tip.

Marginal plates 30 per interradius (15 per arm) forming distinct dorsal-facing border, especially along distalmost regions along arm, where they occupy approximately 50% of the width (0.3/ 0.6 cm) occupied by superomarginal plates ( Fig. 6A ). Superomarginal plates proximally largest, becoming smaller distally ( Fig. 6A, C, D ). Interradial superomarginal plates quadrate with angular corners ( Fig. 6D ). Superomarginal and inferomarginal plates slightly offset forming an irregular zigzag contact between them. Marginal plates covered by even but closely arranged homogeneously sized granules, round, 200 to 400 with approximately 15–20 in series along each side. Pedicellariae small, spatulate in shape, present one per plate, approximately 5 to 10 per interradius mostly centered on plates adjacent to the disc ( Fig. 6D ).

Actinal plates in 7 to 8 regular series in chevron arrangement. Individual actinal plates quadrate in shape. Individual plates covered by 12–25 evenly spaced granules, round, sometimes in even series. Peripheral granules distinct, with 4 to 5 granules per edge. Actinal plates extending along arm to within 6 to 8 plates of the arm terminus where actinal plates decrease to three then one series of plates between adambulacral and inferomarginal plates. Actinal plates adjacent to the adambulacral plates each with a large, i.e. bisecting the plate on which they sit, bivalve pedicellariae each with two large clam-shaped valves ( Fig. 6E–G ) each bearing 15–20 small teeth along the edge of each valve. Serial pedicellariae present on every plate proximally but gradually disappearing approximately 10 plates short of the arm terminus.

Adambulacral plates with four spine series ( Fig. 6G ). Furrow spines, triangular in cross-section, 2 to 6, mostly 5 to 6 decreasing to 2 or 3 distally, ( Fig. 6F–G ) adjacent to the terminus. Second and third subambulacral spine series each with four spines ( Fig. 6F–G ) with last series adjacent to actinal plates showing five spines. Second subambulacral spines blunt-tipped, thickened, each approximately twice as thick as furrow spines. Third and fourth subambulacrals blunt, short, approaching granules in overall shape ( Fig. 6G ). Oral plates with furrow spines 11, blunt, each triangular to quadrate in shape, close set to one another. Oral plate surface covered by 12–15 angular to triangular granules showing continuity with subambulacral granules ( Fig. 6F ). Granules on oral plates separated by fossae dividing oral plates on either side of the inter radii.

Living color was white ( Fig. 6C ).

Material Examined

Holotype. USNM 1660278 Deep Mound 2, Blake Plateau, North Atlantic Ocean. 30.848, -77.3075, 1386 m. Coll. NOAA Ship Okeanos Explorer (A. Collins & S. Farrington) , EX2107, 2 Nov. 2021, 1 wet spec. R =6.0 cm r= 2.7 cm.

EX2107_IMG_20211102T203617Z_ROVHD.jpg

Other Images

Yakut Seamount (deep), North Atlantic, 35.261862 -48.001104, 1699 m.

EX2104_IMG_20210713T193336Z_ROVHD.jpg

EX2104_IMG_20210713T193321Z_ROVHD.jpg

Figures

FIGURE 6. Bathyceramaster kelliottae n. sp. (Goniasteridae) A. Abactinal. B. Abactinal plates, closeup. C. In situ image. D. Abactinal-superomarginal edge. E. Actinal. F. Actinal view, oral region, large bivalve pedicellariae. G. Actinal viewadambulacral plates, large bivalve pedicellariae. Scale: A, E=10.0 mm, B,F,G=2.0 mm, D=3.0 mm,