Bathyceramaster careyi, Mah, Christopher L., 2016

Mah, Christopher L., 2016, Deep-sea (> 1000 m) Goniasteridae (Valvatida; Asteroidea) from the North Pacific, including an overview of Sibogaster, Bathyceramaster n. gen. and three new species, Zootaxa 4175 (2), pp. 101-141 : 106-108

Bathyceramaster careyi n. sp.

Figure 1 A–F

(as Mediaster elegans abyssi ) Carey 1972: 38, 42; Maluf 1988: 34, 118.

Etymology. This species is named for Dr. Andrew “Drew” Carey, Professor Emeritus, Oregon State University, who was the first to have collected and published on this species.

Comments. Based on notes in the former Oregon State University collection at the California Academy of Sciences, a large number of individuals listed below identified as “ Mediaster elegans abyssi Ludwig 1905 ” (considered as a synonym of Bathyceramaster elegans below) were used in Carey’s (1972) feeding study on abyssal asteroids in the Northeast Pacific Ocean.

Comparison of the species used by Carey (1972) with the holotype of Mediaster elegans (USNM 34443) reveals that Carey’s species differs substantially from Ludwig’s (1905) holotype for M. elegans . The holotype shows a greater number of furrow spines (9 or 10), and very coarse-grained granulation on each abactinal plate, which are arranged in regular transverse rows versus those in Carey’s specimens which show four to six furrow spines (at r=2.5–6.0), an irregularly distributed abactinal plate arrangement along with finer and more heterogeneous abactinal granules. The M. elegans holotype shows more elongate arms with a higher R:r ratio (R/ r=3.73) versus Carey’s specimens which, in most specimens (up to R=5.3) is about 1.89–2.9.

Occurrence. Cascadia Plain, Taney Seamount, central North Pacific Ocean. 1700–3363 m.

In situ Observation: Observations of this species by MBARI show it hunched over a dead sponge holdfast, presumably feeding. Although examination of gut contents in these specimens was inconclusive, Carey (1972: 42) stated that the gut contents of five out of the 19 specimens recorded showed silicious sponge spicules and sediment.

Description. Body stellate (R/r= 1.89–3.83). Disk thick, arms upturned. Arms triangular in shape, some elongate whereas others are broader. Interradial arcs weakly curved to straight ( Fig. 1 A).

Abactinal surface with tabulate plates (i.e. extensions above body planar surface). Abactinal plates dense, with 30–40 plates present in line across base of arm, narrowing to one or two at armtip ( Figs. 1 B, D). Abactinal tabulae round to polygonal in cross-section and closely abutting along their bases ( Fig. 1 C). Stellate projections absent from the base of each plate. Each plate covered by 10–50 coarse granules with two types present on peripheral and central plate regions ( Figs 1 B, D). Peripheral granules five to 40, quadrate-angular in outline, edging each plate ( Fig. 1 B). Plate central surface with three to 20 round to polygonal granules, two to three per 1.0 mm numbering three to 15 per plate. Granule types less differentiated on distal arm regions on smaller abactinal plates becoming more distinct proximally (i.e. on disk). Disk plates with roughly 30–40 peripheral plates and 10–20 central ones. Central granules, especially on disk, are strongly convex, and are densely distributed forming a mound-like mosaic on each plate ( Fig. 1 B). Each tabulae is smaller and more polygonal distally becoming larger and more round proximally when viewed abactinally. Tabulae more dense distally, adjacent to contact with superomarginal plates. Two of the specimens (USNM 1407934, 1407935) with simple straight tong-like pedicellariae irregularly present. Pedicellariae present on approximately 75% of the plates present on the abactinal surface. Pedicellariae small, comparable in size to one or two granules. Papulae present in single or pairs, at angles of each abactinal plate but only evident on abactinal surface with no openings visible from coelom. Madreporite with well-developed sulci, surrounded by eight to ten abactinal tabulae.

Marginal plates 50–60 per interradius (both superomarginals and inferomarginals). In smaller individuals (R=2.1–2.6, CASIZ 143470, 143562) number of superomarginals ranging from 24–30. Marginal plates forming thickened edge around periphery. Both series with 1:1 correspondence interradially but becoming more offset forming zigzag contact distally, along arm. Plates of both series covered by densely arranged round granules, 20–70, similar to those on abactinal surface ( Fig. 1 D). Granules cover the marginal plates obscuring boundaries between plates, especially distally at armtip. Granules on proximal plates forming distinct boundary around each plate becoming more poorly defined distally. Contact line between superomarginal and inferomarginals lacking granules. Where pedicellariae are present on an individual plate, they are identical to those on abactinal surface and occur one per plate on up to 10% of the total number of superomarginal and/or interradial plates. They occur inconsistently and may be absent from one interradius and present in another on one individual. Marginal plates quadrate in outline, wider interradially (proximally) becoming more square-shaped distally. Terminal plate surface bare, rounded to triangular in shape.

Actinal surface three to six chevrons composed of irregularly arranged quadrate to polygonal plates. Each plate surface covered by round to polygonal granules, four to 10 densely covering plates and obscuring boundaries between plates ( Fig. 1 E, F). When present, pedicellariae identical to those on abactinal and marginal plates occur one per plate ( Fig. 1 E, inset).

Furrow spines mostly six, but ranging four to seven. Small individuals (e.g., CASIZ 143562, R=2.8) with four furrow spines ( Fig. 1 F). Spine shape, blunt with rounded, blunt tips but variably oriented either as straight to weakly curved. Subambulacral spines three to four, mostly three, but about twice as thick as each furrow spine. Each subambulacral spine diamond to polygonal in cross-section. Subambulacral granules, seven to 15, polygonal to angular in cross-section, similar in size to those on adjacent actinal plate surface but more widely spaced relative to densely packed actinal granules. Oral plates with 12–15 furrow spines per plate with apical furrow spine directed into mouth ( Fig. 1 F). Oral plate surface, each with 10–15 paired angular spinelets, widely spaced (20–30 on each pair of oral plates). Pyloric caeca well-developed.

Color in life light yellow/white to light orange.

Material examined. Holotype. CASIZ 143606 , Cascadia Plain , 44º00, 34.50N, 128º 21.50’W, 2820 m, Coll. A. Carey aboard R/ V Cayuse. 1 dry spec. R=3.5, r=1.5. Paratypes . CASIZ 117953 , off Oregon coast, 44º00, 38.80N, 125º 26’W, 2992 m. Coll. R / V Yaquina. 1 dry spec. R=2.5, r=1.3 ; CASIZ 121370 off Oregon coast, 43º00, 44.70N, 127º 36.80’W, 2816 m . Coll. R / V Yaquina 1 wet spec. R=4.9, r=2.5; CASIZ 108575 Off Oregon coast, 44º00, 28.40N, 125º 12.20’W, 1700–2000 m . Coll. R / V Wecoma. 1 wet spec. R=5.2, r=1.9; CASIZ 143562 Off Oregon coast, 44º00, 45.00N, 127º 24’00W, 3000 m . Coll. R / V Yaquina 1 wet spec. R=2.8, r=1.2; CASIZ 143470 Cascadia Plain , off Oregon coast, 45º00, 56’N, 127º 36.10’W, 2763 m. Coll. R / V Yaquina 1 wet spec. R=2.1, r=1.0 ; CASIZ 121673 Cascadia Plain , off Oregon coast, 45º00, 35’N, 126º 20.50’W, 2666 m . Coll. R / V Yaquina 1 wet spec. R=4.9, r=2.1; CASIZ 118406 Off Oregon coast, 44º00, 4.20’N, 125º 24’10W, 2938 m. Coll. R / V Yaquina. 3 wet specs. R=4.9, r=2.0; R=4.8, r=1.9; R=4.3, r=2.1 ; CASIZ 115059 Off Oregon coast, 44º00, 28.40N, 125º 12.20’W, 1700–2000 m. Coll. R / V Wecoma. 2 wet specs. R=5.6, r=2.2; R=4.7, r=2.9 . CASIZ 122039 . Cascadia Plain , off Oregon coast, 44º00, 58.50’N, 125º 44.30’W, 2790 m. Coll. R / V Yaquina 3 wet specs. R=5.9, r=2.2; R=6.8, r=2.4; R=6.8, r=2.2 ; CASIZ 143769 Cascadia Plain , off Oregon coast, 44º00, 41.80’N, 127º 22.70’W, 3021 m . Coll. R / V Yaquina 1 wet spec. R=2.6, r=0.9; CASIZ 129004 ; Off Oregon coast. 44º00, 36.00’N, 126º 7.80’W, 2850 m. Coll. R / V Acona. 2 wet specs. R=5.6, r=2.2; R=6.0, r=2.3 ; CASIZ 108576 off Oregon coast, 44º00, 28.40’N, 125º 12.20’W, 1700–2000 m . Coll. Paul Yancy aboard R/ V Wecoma. 1 wet spec. R=6.4, r=2.6. USNM 1407934 North Escanaba Trough (central), North Pacific Ocean , 40.989707, -127.485775, 3266 m, Coll . MBARI, T891-A4. 1 wet spec. R=6.4, r=3.1), PARATYPE USNM 1407935 North Escanaba Trough (south), North Pacific Ocean , 40.88961, -127.480461, 3363 m, Coll . MBARI T889-A5, 1 wet spec. R=4.1, r=1.7; PARATYPE: USNM 1407936 Taney A Seamount, east cones, 36.834561, -125.558235, 3067 m. coll. MBARI D176-A9. 1 wet spec. R=5.3, r=2.2.

Figures

FIGURE 1. Bathyceramaster careyi n. gen. n. sp. USNM 1407936. Scale bar = 5.0 mm. A. Abactinal surface. B. Granules on tabulae. Scale = 1.5 mm C. Round bases of abactinal plates viewed from coelomic cavity (stellate radiating plates absent). Scale = 1.5 mm. D. Lateral view showing marginal plate series and abactinal plates. E. Actinal surface. Inset shows pedicellariae, granules and other detail (each about 1.0 mm across). F. Closeup of actinal surface showing furrow spines, actinal accessories, oral region.