Alloceramaster grenadensis ( Perrier, 1881 ) Mah, 2025

Alloceramaster grenadensis ( Perrier, 1881) View in CoL nov. gen. nov. comb.

Figures 3A–E

Pentagonaster grenadensis Perrier, 1881: 19 View in CoL ; 1884: 168,181, 186, 232–233, pl. 8, fig. 2; Sladen, 1889: 265, 266, 744; Perrier, 1894: 39, 390. Ceramaster grenadensis Verrill, 1915: 222 View in CoL ; Halpern, 1970: 213, figs. 8–9; Downey, 1973: 49, pl. 17 figs. C, D.

Material Examined. MCZ Holotype. AST–416, Off Grenada, 12° 3' 55.0002" N - 61° 49' 39.9966" W, 1053 m. Coll. Alexander Agassiz, USCSS Blake Expeditions, 2 March 1879. 1 dry spec. R = 2.6 r = 1.7. GoogleMaps

USNM E12700 About USNM . NW of Montserrat, Caribbean Sea , North Atlantic Ocean, 589 m. Coll . R / V Oregon II. 8 December 1969. 1 dry spec . R = 3.1 r = 1.8.

USNM E12702 About USNM . Northeast of Honduras, Caribbean Sea, North Atlantic, 16° 31' 48" N, - 83° 24' 0" W, 914 m. Coll. U.S. Fish and Wildlife Service, 24 October 1970. 3 dry specs GoogleMaps . R = 3.7 r = 2.0, R = 3.1 r = 1.5, R = 2.6 r = 1.5.

USNM E12780 About USNM . North of St. Eustatius, St. Kitts and Nevis, Caribbean Sea, North Atlantic Ocean. 17° 46' 11.9994" N, 62° 58' 47.9994" W, 649– 668 m. Coll GoogleMaps . R / V Oregon , 18 May 1967. 4 dry specs . R = 2.5 r = 1.3 R = 2.3 r = 1.1, R = 1.8 r = 1.1, R = 2.0 r = 1.1

USNM E12781 About USNM . East of Saint Christopher, Saint Christopher and Nevis Island, Caribbean Sea, North Atlantic Ocean. 17° 15' 0" N, 62° 22' 11.9994" W, 580 m. Coll GoogleMaps . R / V Oregon II, 8 December 1969. 1 dry spec . R = 3.0 r = 1.6

USNM E12782 About USNM . NE of St. Kitts, St. Kitts and Nevis, Caribbean Sea , North Atlantic Ocean. 17° 23'59.9994" N, 62° 32' 59.9994" W, 644 m. Coll GoogleMaps . R / V Oregon II. 8 December 1969. 1 dry spec . R = 2.1 r = 1.3.

USNM E12783 About USNM . East of Saint Christopher, Saint Christopher and Nevis Island, Caribbean Sea, North Atlantic Ocean. 17° 23'59.9994" N, 62° 28' 11.9994" W, 629 m. Coll GoogleMaps . R / V Oregon II, 8 December 1969. 2 dry specs . R = 2.2 r = 1.2, R = 3.5 r = 1.8.

USNM E13218 About USNM . Honduras, Caribbean Sea , North Atlantic Ocean. 16° 43' 11.9994" N, 82° 37' 47.9994" W, 430– 612 m. Coll GoogleMaps . R / V Alaminos , 12 July 1970. 1 dry spec . R = 2.1 r = 1.3.

USNM E19089 View Materials . West of Los Roques Islands , Caribbean Sea, North Atlantic, 11° 46' 0.12" N, 67° 5' 41.9994" W, 1098–1175 m. Coll. 24 July 1968. 1 dry spec GoogleMaps . R = 2.7 r = 1.7.

USNM E19094 View Materials . North of Portland Rock , Pedro Bank , Jamaica, Caribbean Sea, North Atlantic, 17° 21' 24.12" N, 77° 34' 47.9994" W, 805–1089 m. Coll GoogleMaps . R / V Pillsbury , 15 July 1970. 1 dry spec . R = 1.4 r = 0.9.

USNM E22187 About USNM . Off NE coast of Nicaragua, Caribbean Sea, North Atlantic Ocean. 15° 1' 47.9994" N, - 81° 4' 47.9994" W, 439– 631 m. Coll GoogleMaps . R / V Alaminos , 13 July 1970. 1 dry spec . R = 2.3 r = 1.5.

USNM 1233808 About USNM . N of Black Rocks, St. Kitts and Nevis, Caribbean Sea , North Atlantic. 17° 33' 0" N, 62° 46' 12" W, 668 m. Coll GoogleMaps . R / V Oregon II, 9 December 1969. 1 dry spec . R = 3.5 r = 2.0.

USNM 1241639 About USNM . East of Paraguana Peninsula , Venezuela, Caribbean Sea, North Atlantic Ocean. 11° 49' 12" N, 69° 24' 0" W, 549 m. Coll GoogleMaps . R / V Oregon , 3 October 1963. 1 dry spec . R = 2.7 r = 1.7.

Diagnosis. Abactinal plates of papular region, polygonal to round in shape, with peripheral granules distinctly trapezoidal, triangular in shape. Superomarginal plates 12–15 per interradius. Bare patch small, irregular in shape. Furrow spines 4–9, blunt, quadrate in cross-section, mostly 7 to 8. Subambulacralspinesinoneortworows, eachwithapproximately three blunt, spines in each series, quadrate in cross-section

Comments. Alloceramaster grenadensis nov. comb. is considered herein a distinct species and a separate taxon from C. patagonicus contrary to the taxonomic conclusion outlined by Clark and Downey (1992) which concluded C. patagonicus was a subspecies of C. grenadensis with the implication of C. grenadensis as “the most widely distributed, as well as one of the most abundant shallow-water asteroid species in the world”. ( Clark and Downey, 1992: 237). This is especially disagreeable given that no members of C. grenadensis are known below 430 m.

The basis of C. patagonicu s as a subspecies seems largely tied to Clark and Downey’s (1992) statement that southern hemisphere C. patagonicus differed only in “minor (subspecific) characters from C. grenadensis ” which I could not confirm based on available material or descriptions. Clark and Downey (1992) do not outline characters for this conclusion. Character evidence as outlined for Alloceramaster supports C. grenadensis in a distinctly separate genus from C. patagonicus which, based on the larger abactinal granules, and more well-developed abactinal fasciolar grooves and marginal plate shape is more similar to the typological C. granularis . All known species of Alloceramaster also occur at much deeper depths (greater than 1000 m) than C. patagonicus and related species.

Alloceramaster grenadensis displays characters similar to Alloceramaster minus n. sp., in that the abactinal plates for the papular region are round to polygonal, each with triangular to trapezoid-shaped peripheral granules. The bare spots on A. minus are larger, occupying much more of the superomarginal surface. A. grenadensis differs from the other tropical Atlantic species in that the abactinal plates on the papular region are polygonal to round with triangular to trapezoidal peripheral granules. This contrasts with those in A. affinis which displays triangular abactinal plates on the papular region with slender, rectangular peripheral granules.

Occurrence/Distribution. Tropical West Atlantic, Grenada, Caribbean Sea, St. Kitts and Nevis, Honduras, Nevis Island, Los Roques Island, Jamaica, Nicaragua. 430–1175 m.

Eastern Atlantic. Azores, Canary Islands, Mediterranean

Sea, Corsica. 540–2220 m.

Description. Body pentagonal to stellate, R/r = 1.4 to 1.9, arms triangular, disk broad. Interradial arcs curved. Abactinal plates tabulate, plates weakly convex, mound-shaped, round to polygonal in outline, but with shallow fasciolar grooves. Fascioles around radial papular regions ( Fig. 3A, B) well developed, weakly present elsewhere. Abactinal surface covered primarily by granules, round, 4 to 60, mostly 20–50, covering plate surface in ordered concentric series. Radial papular regions with distinct angular peripheral granules, variable dimensions, mostly rhombus-shaped ( Fig. 3B) but with some more slender shaped in smaller individuals.

Marginal plates, 12–15, forming wide periphery when viewed from dorsal surface. Distalmost superomarginals, 1 to 3, mostly 2 abutted over midline. Superomarginal surface with a centrally bald region, which varies in size from small, discrete, raised patch ( Fig. 3C), approximately 15% of complete dorsal superomarginal plate surface to covering 70–80% of plate surface. Remainder of marginal plates surface covered by variably round, evenly spaced granules, 40–400, which cover lateral and inferomarginal surface ( Fig. 3C).

Actinal region in full series, 3 to 4, chevron-like formation with irregular plates present adjacent to contact with inferomarginal plates. Actinal plates covered by granules, 5–40, mostly 10–30 ( Fig. 3D). When removed they leave a shallow concavity on actinal plate surface.

Furrow spines 4–9, blunt, quadrate in cross-section, mostly 7 to 8 ( Fig. 3E). Subambulacral spines in one or two rows, each with approximately three blunt, spines in each series, quadrate in cross-section. Remainder of adambulacral plate covered by granules 3–8 round to rough tipped, similar to identical with those on actinal plates. Oral plates with blunt, 9 to 15, polygonal to quadrate in cross section, oral plate surface with approximately 8–10 granules, each blunt but quadrate to polygonal in cross-section, present along either side of the central diastema between paired oral plates.