Kanakaster discus

Mah, Christopher L., 2017, Overview of the Ferdina - like Goniasteridae (Echinodermata: Asteroidea) including a new subfamily, three new genera and fourteen new species, Zootaxa 4271 (1), pp. 1-72 : 30-32

Kanakaster discus nov. sp.

Figure 9 A–F

Etymology. This species is named for its round, disk-like shape.

Diagnosis. This species is distinguished primarily based on its distinctive and consistent pentagonal to weakly stellate body form (R/r=1.1–1.5). Kanakaster discus n. gen, n. sp. is completely covered by granular tegument and lacks the small bare patches on the marginal plates. Glassy or crystalline nodules present in the surface of the abactinal plates (below granular tegument). The body shows four to six marginal plates per interradius with marginal plates forming a distinct peripheral frame around the body. Interradial arcs weakly curved.

Taxonomic comments. Although superficially similar to K. plinthinos n. gen. n. sp. this species lacks the small bare patches present in K. plinthinos n. gen. n. sp. Specimens of K. discus n. gen. n. sp. at comparable size (R=1.0 cm) to K. plinthinos n. gen. n. sp. show weakly curved to straight interradial arcs and display crystalline nodules arranged in more radiate or curved patterns. Crystalline nodules in K. plinthinos n. gen. n. sp. are circular and occur in more discrete granular form.

Occurrence. Off coast of SE New Caledonia. 275–500 m.

Description. Body round/pentagonal to very weakly stellate flattened. R/r=1.1–1.5 (at R= 0.7–2.1 cm) ( Fig. 9 A). The latter stellate form shows more triangular arms with broadly curved interradial arcs. Granulated tegument continuous, present on abactinal, marginal, actinal body surfaces.

Abactinal surface flattened, same plane as marginal plate series ( Figs 9 A, C). Primary plates large, polygonal to round in outline, carinal plates variably number three to eight from primary circlet to end of abactinal plates on arm. Surface covered by coarse granulated tegument (approximately four to six granules along a 1.0 mm line), which were abraded in many of the specimens examined revealing several of the plate surfaces ( Figs. 9 B, D). Abactinal plates polygonal to round/ovalate ( Figs 9 A, B, D). Denuded abactinal, marginal, and actinal plate surfaces covered by crystalline bosses arranged in radial patterns ( Fig. 9 D). Madreporite flanked by three to four plates.Papulae six per plate. Papular regions present over radial plates, absent interradially but sometimes pairs of papulae present at abactinal plate and superomarginal plate contact. No pedicellariae observed.

Marginal plates wide with rounded edges ( Figs 9 B, C); primarily four per interradius (from arm tip to arm tip) in three paratype specimens (MNHN-IE-2013-6887, MNHN-IE-2013-6848, both at R= 1.2 cm) and six per interradius in the holotype ( Fig. 9 A, R= 2.1 cm). Superomarginal and inferomarginals show 1:1 correspondence. In most specimens superomarginal and inferomarginal plates adjacent to the terminals are at least twice as large as those in each interradius and approximately triangular in shape. Granules form continuous cover but becoming coarser, perhaps twice as large as the more abundant granules, at superomarginal-inferomarginal contact. Other than granules, no other surficial accessories present on marginals ( Fig. 9 C). No bare regions present on either marginal plate surface. When granules denuded from supero- and inferomarginal plate surfaces, the surfaces display extensive covering of evenly distributed, embedded crystalline structures forming lobate to wave-like patterns on superomarginals ( Fig. 9 D) but more boss-like structures on the inferomarginals, 20–80. Terminal plate triangular ( Fig. 9 B), relatively large with a short pine. No pedicellariae observed.

Actinal intermediate regions relatively small with two chevrons ( Fig. 9 E), composed of relatively few plates. Actinal regions with coarse granular tegument continuous with marginal plate series. Plate outlines visible but no distinction between specific peripheral versus central surface granules. No pedicellariae observed. Continuous granulation covers actinal surface and adambulacral plate surface to base of adambulacral furrow.

Furrow spines two or three, blunt, present on each adambulacral plate in a single series ( Figs. 9 E, F). No subambulacral or other adambulacral spines on adambulacral plate. Denuded actinal plates show crystalline bosses on all plate surfaces. Furrow spines on oral plates nearly identical to those on other adambulacral plates. All furrow spines form a close-set, continuous series along adambulacral series ( Fig. 9 F). Oral plates with coarse granules on surface adjacent to oral furrow spines but no other surface spines or accessories.

Color in life was white to light orange.

al examined. Holotype: MNHN-IE-2013-6897; New Caledonia, 22°47’S, 167°22’E, 390 m .; Coll. C. Vadon aboard N/ O Vauban, MUSORSTOM 4, DW 226; 1 wet spec. R=2.1, r=1.3. Paratypes: MNHN-IE-2013-6848; SE Slope of New Caledonia, 22˚52’11”S, 167˚15’7”E, 468– 500 m .; Coll NORFOLK 2, DW 2156; 1 dry spec. R=1.2, r=0.8. MNHN-IE-2013-6887; SE Slope of New Caledonia, 22˚52’11”S, 167˚15’7”E, 468– 500 m .; Coll NORFOLK 2, DW 2156; 2 dry specs. R=1.2, r=0.9; R=0.9, r=0.8. MNHN-IE-2013-6889; Off Noumea, New Caledonia, 22°39.1’S, 167°7.3’E, 225 m .; Coll. VAUBAN-ORSTOM, st. 387; 1 dry spec. R=1.1, r=0.9. MNHN- IE- 2013-6891 ; Crypthelia Bank , New Caledonia 23°17’S, 168°14’E, 275–348 m ; Coll. Lozouet, Samadi & Richer de Forges, NORFOLK 2, DW 2125; 1 dry spec. R=0.7, r=0.5; MNHN-IE-2013-8398; New Caledonia, 410–440 m; Coll. C. Vadon, MUSORSTOM 4, N/ O Vauban; 6 wet specs. R=1.2 r=0.9; R=1.2 r=0.8; R=1.3 r=0.7; R=1.1 r=0.7; R=1.1 r=0.8; R=0.9 r=0.5.

Figures

FIGURE 9. Kanakaster discus n. gen., n. sp. Holotype, MNHN-IE- 2013 - 6897. Scale Bar = 2.0 mm. A. Abactinal surface. B. Details on abactinal surface showing plate shape, and distal superomarginals. C. Superomarginal plate surface detail. D. Granules and denuded abactinal plates showing glassy nodules. E. Oral surface. F. Actinal surface showing furrow spination and oral region.