Bathyceramaster smithi ( Fisher 1913 ) Mah, 2022

Mah, Christopher L., 2022, New Genera, Species and Occurrences of Deep-Sea Asteroidea (Valvatacea, Forcipulatacea, Echinodermata) collected from the North Pacific Ocean by the CAPSTONE Expedition, Zootaxa 5164 (1), pp. 1-75 : 34-36

Bathyceramaster smithi ( Fisher 1913) nov. comb.

FIGURE 11A–E

Ceramaster Fisher 1913: 640 ; 1919: 257

Diagnosis. Body weakly pentagonal to pentagonal (R/r=1.75–2.0), arms broadly triangular.Abactinal plate surfaces hexagonal with central round granules, 5–50 (mostly 20–30), with slightly larger, polygonal to quadrate granules, 10 to 40 forming periphery of each plate. Shallow fasciolar grooves present. Marginal plates forming rolled edge along periphery, plates covered by round, densely but evenly packed granules in ordered series, similar to those on abactinal plates, approximately 10 along a 1.0 mm line. Plate surface covered by 10–30 coarse, evenly spaced granules, approximately four to five along a 1.0 mm line. Granules round to weakly polygonal, with flattened surface, larger centrally on plate, smaller around plate periphery in one to three rows. Granular cover dense, forming consistent covering over actinal plates, obscuring contact between them as well as between actinal and inferomarginal plates. Adambulacral spines, coarse 4–5 with 3–4 enlarged subambulacral spines. No pedicellariae observed (but pedicellariae present for other specimens)

Comments. The specimen collected herein shares several characters with Ceramaster smithi ( Fisher 1913) including overall stellate shape, low abactinal tabulae with hexagonal crowns along the radial regions, similar wide superomarginal plates, a distinctly rolled marginal edge, adambulacral spines with four or five coarse furrow spines, and three or four enlarged subambulacral spines. Although there are character differences, such as the absence of pedicellariae and coarser granules on the abactinal plates, the characters observed on this specimen are broadly consistent with Fisher’s description for this species. Marginal plate number for specimens with R=6.0 cm was 18 (36 total) versus the individual herein with 9 (18 total) at R=2.8.

Examination of this specimen and the taxonomic concept of Ceramaster smithi also presented an opportunity to consider these taxa as they compared to the recently established Bathyceramaster . In both cases, a relatively stellate body shape, shallow fasciolar grooves (i.e., low tabulate plates), complete marginal plate granular cover and a relatively thick marginal edge were comparable to Bathyceramaster teres n. sp. Based on these characters I argue that this genus is better placed within the genus Bathyceramaster rather than Ceramaster which better characterized by a well-developed fasciolar groove (taller tabular plates) as well as more strongly developed pentagonal body shape and a bald patch present on the superomarginal surface of most species.

Bathymetric range, 685–1215 m. Predation on glass sponge prey is consistent with other Bathyceramaster spp. ( Mah 2016a, and herein).

Occurrence: Palawan Passage to Leyte, Philippine Islands. 686–1215 m

Description. Body weakly stellate (R/r=1.75) with arms broad, triangular, upturned with blunt tips. Marginal edge thickened ( Fig. 12A ).

Abactinal plates tabulate, fasciolar grooves shallow. Plate surfaces distinctly hexagonal along widely spaced radial regions, interradial plates round to polygonal, smaller than radial regions, crowded ( Fig. 11B ). Abactinal plate surfaces with central round granules, 5–40 (mostly 20–30), with slightly larger, polygonal to quadrate granules, 10–40 forming periphery of each plate. Central granules relatively fine, approximately 10 along a 1.0 mm line. Granules more homogeneous interradially, showing greatest difference in shape between central and peripheral granules along radial regions. Abactinal plate region on arm narrows towards arm tip to a single plate distally on arm adjacent to arm terminus. Madreporite polygonal to irregularly round, sulci shallow, flanked by 10–12 abactinal plates. Pedicellariae not observed.

Marginal plates 18 superomarginals, 20 inferomarginals per interradius (arm tip to arm tip). Each series slightly offset resulting in a zig-zag contact. Superomarginals quadrate interradially becoming wider distally. Marginal plate boundary thick, rolled upwards ( Fig. 11A ). Superomarginal border forms 18.7% (3/16) of distance “r” on disk. Distalmost superomarginals converge over single abactinal plate on arm forming either weak or no contact, but superomarginal plate thickness forms over 80% (4/ 5 mm width) of distalmost arm width. Superomarginal surface covered by round, densely but evenly packed granules in ordered series, similar to those on abactinal plates, approximately 10 along a 1.0 mm line. Abactinal surface of superomarginal with a round, oblong to lobate, raised bald patch on the superomarginal surface. Bald patches increase in size distally covering majority of plate surface adjacent to terminus. Abactinal surface of superomarginal plate otherwise covered by approximately 60–300, mostly about 150–250, deciduous granules. Peripheral granules more quadrate, approximately 20–30 per side. Inferomarginals also covered by round granules ( Fig. 11D ) similar to those on superomarginals, approximately 100–500, mostly about 200–400 per plate surface. Peripheral inferomarginal granules identical to those present around superomarginals with small concave pitting now present where granules have been lost. Proximal inferomarginal surface covered with granules but distalmost inferomarginals with large bald patches ( Fig. 11D ), granules apparently absent. Terminal plate triangular with a prominent short spine on tip. No pedicellariae observed on marginal plates.

Actinal regions with four fully developed series in chevron like formation and one or two irregular series interradially adjacent to the inferomarginal contact ( Fig. 11C ). Individual plates quadrate to irregularly polygonal in shape with rounded edges. Plate surface covered by 10–30 coarse, evenly spaced granules, approximately four to five along a 1.0 mm line. Granules round to weakly polygonal, with flattened surface, larger centrally on plate, smaller around plate periphery in one to three rows. Granular cover dense, forming consistent covering over actinal plates, obscuring contact between them as well as between actinal and inferomarginal plates.

Furrow spines four or five in straight series ( Fig. 11E ), each spine flattened with blunt tip, quadrate in cross section. Central spines longest with shortest spines (about 50% of height) at edges of each furrow spine series on each adambulacral plate. Adjacent subambulacral spine series set off from furrow spines by a distinct space, subambulacral spines two or three ( Fig. 11E ). Central two subambulacral spines enlarged, each twice as thick as a single furrow spine, but slightly shorter, approximately 90% of the height of the furrow spines. Third subambulacral sits proximally on the subambulacral series, is triangular in cross-section, but offset from the remainder of the series at a jagged angle away from the other two spines, and is about 50% of the height of the adjacent subambulacral spines. Remainder of adambulacral plate covered with two further series of two or three short spines, then four to six granules, the latter like those on the actinal plate surface. Oral plates with approximately 12–15 furrow spines similar in appearance to those on other adambulacral spines ( Fig. 11E ). Six subambulacral spines sit on the oral plate, each approximately two to four times as thick as the furrow spines. One to three large, jagged spines, triangular to irregular in cross section on the oral plate surface. Each oral plate with five or six paired granules on either side of a central fossae sitting between each plate. No pedicellariae observed.

Specimen was collected from inside the chamber of a hexactinellid sponge, no in situ imagery was taken. Color in life was tan to off-white.

Material Examined: USNM 1424227 Seamount SW of Wake Island, 18.32295, 165.97904, 1215 m, Coll. NOAA ship Okeanos Explorer with ROV Deep Discoverer. EX 1606 , 14 Aug 2016. 1 wet spec. R =2.8 r=1.6. No. image

Image Examined

Whaley Seamount , Central Pacific 1.07816824, -161.2864519, 863 m EX1705 _IMG_20170508 T024148 Z_ ROVHD.jpg

Figures

FIGURE 11. Bathyceramaster smithi (Fisher, 1913) USNM 1424227. A. Abactinal view. Scale bar=3.0 mm. B. Close-up of abactinal plates. Scale bar=1.0 mm. C. Actinal view. Scale bar=3.0 mm. D. Lateral view showing inferomarginals. Scale bar=2.0 mm. E. Close-up of oral and adambulacral spination. Scale bar=1.0 mm.

FIGURE 12. Bathyceramaster teres n. sp., USNM 1453747 Holotype. A. Abactinal view. Scale bar=5.0 mm. Inset showing granulation on abactinal plates. Diameter of individual plate=0.75 to 1.0 mm. B. Abactinal-lateral view showing granulation on superomarginal plates. Scale bar=3.0 mm. C. Actinal view. Scale bar= 5.0 mm. D. Close-up showing bald spots on distal superomarginal plates. Scale bar=2.0 mm. E. Actinal view closeup showing pedicellariae on actinal and adambulacral plates. Scale bar=1.0 mm. F. Adambulacral spination, showing furrow and subambulacral spines. Scale bar=1.0 mm. G. In situ observation of the paratype of B. teres feeding on the glass sponge, Waltheria. R of specimen is 2.3 cm.