Alloceramaster affinis Perrier, 1884

Alloceramaster affinis Perrier, 1884 View in CoL nov. gen, nov. comb.

Figures 2A–F

Pentagonaster affinis Perrier, 1884: 168 View in CoL , 183, 186, 243, pl.8 fig. 4; Sladen, 1889: 265, 267, 744; Perrier, 1894: 40, 390; Halpern, 1970: 216.

Tosia affinis Perrier, 1884: 183 View in CoL .

Pyrenaster affinis Verrill, 1899: 168 View in CoL , 1915: 222.

Material Examined. MCZ AST–404. Paratypes for Pentagonaster affinis Off Cuba, north of Navassa Island, Western Central Atlantic. 19º 5' 55" N, 74º 49' 5" W, 2194.5 m, Coll. Alexander Agassiz GoogleMaps , USCSS Blake Expedition, 1877–1880, 19 December 1878. 3 dry specs . R = 1.4 r = 0.9, R = 1.3 r = 0.8, R = 1.6 r = 0.9

USNM E45324 View Materials . Exuma Sound , Bahamas, North Atlantic Ocean. 23° 51' 0" N, - 75° 49'47.9994" W, 1853–1858 m. Coll GoogleMaps . R.S. Carney , R / V Columbus Iselin , 3 September 1980. 6 dry specs . R = 2.7 r = 1.5, R = 3.1 r = 1.9, R = 3.1 r = 1.7., R = 2.5 r = 1.4, R = 2.6 r = 1.6, R = 2.2 r = 1.3.

USNM E53737 View Materials . Serrana Bank , Nicaragua, Caribbean Sea, North Atlantic Ocean. 14° 33' 0" N, - 79° 46' 11.9994" W, 2341 m. Coll. W. E. Pequegnat, 14 July 1970. 6 dry specs GoogleMaps . R = 1.7 r = 1.0, R = 1.6 r = 0.9, R = 1.6 r = 0.9, R = 1.5 r = 0.9, R = 1.4 r = 0.9, R = 1.5 r = 0.9

USNM E11257 About USNM . NW of Libreville, Gabon, Gulf of Guinea, North Atlantic. 1° 13' 0.1194" N, 7° 46' 0.12" E, 2525 m. Coll GoogleMaps . R / V Pillsbury , 17 May 1965. 1 dry spec .

USNM E11260 About USNM . NW of Libreville, Gabon, Gulf of Guinea, North Atlantic. 1° 13' 0.1194" N, 7° 46' 0.12" E, 2525 m. Coll GoogleMaps . R / V Pillsbury , 17 May 1965. 44 dry specs .

USNM E19088 View Materials . Off west coast of Jamaica, Long Bay , Caribbean Sea, North Atlantic. 18° 16' 0.12" N, 78°31' 5.8794" W, 1244–1830 m. Coll GoogleMaps . R / V Pillsbury , 8 July 1970. 1 dry spec .

USNM E19090 View Materials . West of Cape Falls , Dominican Republic, Caribbean Sea, North Atlantic. 17° 52' 59.8794" N, 71° 58'59.8794" W, 1893–3109 m. Coll GoogleMaps . R / V Pillsbury , 17 July 1970. 5 dry specs .

USNM E19091 View Materials . SE of Acklins Island, Mayaguana Passage , Bahamas, North Atlantic. 21° 58' 0.012" N, - 73° 41' 30.1194" W, 1650 m. Coll GoogleMaps . R / V Pillsbury , 22 July 1971. 5 dry specs .

USNM E19003 View Materials . NE of Cape Dame-Marie, Haiti, Caribbean Sea , North Atlantic. 18° 51' 0" N, 74° 30' 0" W, 2545 m. Coll GoogleMaps . R / V Pillsbury 1 July 1970. 14 dry specs .

USNM 1664246 About USNM . Exuma Sound , Bahamas, North Atlantic Ocean. 24° 0' 0" N, - 75° 19' 59.988" W, 1884 m, Coll GoogleMaps . R / V Columbus Iselin , 4 March 1973. 1 dry spec . R = 1.7 r = 1.0

USNM 1664247 About USNM . Exuma Sound , Bahamas, North Atlantic Ocean. 24° 8' 59.9994" N, 75° 54' 0" W, 1842 m. Coll GoogleMaps . R / V Columbus Iselin 9 Nov 1974, 3 dry specs .

USNM 1664249 About USNM . NW of Great Inagua Island , Bahamas, North Atlantic. 21° 19' 12" N, 73° 45' 29.88" W, 2523 m. Coll GoogleMaps . R / V Pillsbury 21 July 1971. 3 dry specs .

USNM 1607692 About USNM . Caribbean Sea 12° 24' 6.0006 “N, 75° 24' 0" W, 2353– 2303 m, Coll GoogleMaps . R / V Columbus-Iselin, 7 September 1980. 12 dry specs .

Diagnosis. Identified by papular regions proximally on arm with elongate, rectangular peripheral granules, abactinal plates triangular to irregularly round, each with well-developed fasciolar grooves. Marginal plates elongate when viewed dorsally. Furrow spines 2–5 at R = 1.5 (on paratype) to 5–7 at R = 3.0, spatulate, varying from pointed and triangular to blunt, quadrate in shape. Subambulacral spinelets, 3 to 5.

Comments. Perrier’s P.affinis should be reinstated as an accepted species, herein as A.affinis n. comb. Halpern (1970:216) argued that C. affinis ( Perrier, 1884) was a synonym of C. grenadensis ( Perrier, 1881) based on the assertion that the “only difference” was based on the granulation of the radial plates which he correctly observed as being elongate rather than being more square, as in C. grenadensis . Halpern further argued that these peripheral granules ran a wide spectrum of intermediate forms within C. grenadensis with a tendency towards elongation of these granules in deeper-water forms. The distinction between deep and shallow peripheral granules in these species is confirmed, but it is argued that this represents a distinction between species in different settings rather than simple variation. No examples of intermediate morphologies could be located which supported his claim of intermediate forms. Similarly, Halpern argued (1970: 218) that the “state of relaxation or contraction was important in the appearance of the radial plates”. Examination of a range of specimens, which were consistent with the type specimens of “ P. affinis ” as well as C. grenadensis did not provide the same conclusion. The material examined by Halpern (1970) was also from a range of depths, most of which were shallower than those of specimens with the “ affinis ” type morphology. This species was recorded from abyssal depths: 1650–3109 m.

Although distinguished from other Alloceramaster based on the trapezoidal/triangular abactinal plates in the papular regions, this character is also observed in the South Pacific Sphaeriodiscus maui , which bears a similar appearance, but displays fewer marginal plates per interradius (n = 8 versus n = 15 in A.affinis ), more abundant, denser abactinal granulation, and is overall less stellate, lacking the tapering distal arm tip. In comparing other tropical Atlantic Alloceramaster , A. affinis displays triangular abactinal plates on the papular region with slender, rectangular peripheral granules whereas A. grenadensi s has round to polygonal abactinal plates on the papular region with trapezoidal to triangular peripheral granules.

Occurrence. Tropical Western Atlantic, Cuba, the Bahamas, Dominican Republic, Haiti, Nicaragua Gabon, Gulf of Guinea, 1650–3109 m.

Description. Body shape pentagonal to weakly stellate, R/r = 1.5–1.8, arms triangular, acutely tapering to pointed tip. Abactinal plates convex, mound-shaped, round to polygonal in outline. Fasciolar grooves shallow to absent around most plates save for specific radial papular regions ( Fig. 2A–B), which are deeper and more well developed. Abactinal plates covered by round granules, 2 to 15 per plate, covering complete surface, evenly spaced save for those plates present radially, on proximal arm region, ranging from 4 to 10 which possess narrow rectangular peripheral granules ( Fig. 2B). Central surface of these plates with round granules.

Marginal plates, 11–13 per interradius (arm tip to arm tip), but not clearly associated with size. When viewed dorsally, marginal plates elongate, forming narrow edge along periphery. Distalmost superomarginal plates abutted. Superomarginal plate surface ( Fig. 2C) devoid of granules or other accessories, but with a pattern present with a wrinkled ornament on the surface. Inferomarginal plates similarly devoid of surficial accessories, covered with a pronounced wrinkle-like pattern on plate surface. Marginal plate periphery with 20 to 40 granules, round, approximately 8 to 10 per side. Superomarginals and inferomarginals slightly offset forming zigzag contact.

Actinal plates irregular to polygonal in shape, covered by granules, 6–15 similar to those on abactinal surface ( Fig. 2E). Plates in 2 to 3 full series in chevron-like arrangement. Fasciolar grooves present but shallow.

Furrow spines 2–5 at R = 1.5 (on paratype) to 5–7 at R = 3.0, spatulate, varying from pointed and triangular to blunt, quadrate in shape ( Fig. 2F). Adambulacral plate surface adjacent to furrow spines with a single row of short subambulacral spinelets, 3 to 5, with a distinct space separating them from both the furrow spines (and the adambulacral edge) and on the other side, contact with the actinal plates and granules. Oral plates with 9–10 furrow spines, one large spine projecting into mouth on each oral plate (two projecting into mouth per interradius). Oral plate surface with 6 jagged spines along the edge of the diastema between plates ( Fig. 2D), each quadrate to polygonal in cross-section. Similar spines, 4–6 present on oral plate surface, all widely spaced to absent.