Kanakaster convexus

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 : 27-29

Kanakaster convexus nov. sp.

Figure 8 A–F

Etymology. This species epithet alludes to the strongly convex arch of the body observed in this species.

Occurrence. New Caledonia, Lord Howe Rise (Tasman Sea), Fiji. 215–430 m.

Diagnosis. This species is distinguished by its stellate shape, flattened abactinal plates, strongly arched, convex body form, the distinctive convex arching of the body and the thickened disk as well as by the absence of pea-shaped granules. Glassy nodules are completely absent from marginal plates on smaller individuals (R<3.0) but only absent from marginal plates on the arms in larger individuals (R>3.0 cm). The surface of the body, including the abactinal, marginal and actinal surface is covered by a very fine granular tegument.

Description. Body stellate (R/r= 2.0–2.6) with thick, sharply arched disk ( Fig. 8 D), although smaller individuals are thinner and not as strongly arched. Arms triangular, short with blunt tips. Interradial arcs curved to linear ( Fig. 8 A). Body surface smooth, covered with a thin, rough, finely granulate tegument.

Abactinal plates flush with one another and mostly contiguous with superomarginal plates ( Figs 8 A, B, C). Fasciolar grooves absent. Plates abutting, each primarily polygonal in outline ( Fig. 8 B, C). Plate patterns very distinct with boundaries observable under the tegument. Plates on the disk near the primary circlet are more rounded and nearly circular whereas those on arms, especially those along the carinal and adradial series are more oval-shaped or oblong with rounded edges. Plates bimodal in size with larger plates more abundant proximally and smaller plates, approximately 25% of the size, present distally adjacent to the superomarginal contact. Carinal plates round (width approximately equal to length) and polygonal on disk becoming more oblong (width>length) more distally along arm. Plates paired in each interradius where midline-disk depression is present in each interradius ( Fig. 8 C). In addition to the fine granulate tegument covering the abactinal plates, embossed crystalline structures ( Fig. 8 B), approximately 20–50 nodules, present as either multiple, small bosses or an elaborate lobate, stellate radiating pattern present on each plate. These patterns are observed only after tegument has been removed.

Other than the fine granulate tegument, no other accessory structures (e.g larger granules, etc.) are present. Tegument with five to eight granules present along a 1.0 mm line but becomes denser with coarser granules at contact between disk and superomarginal plates. Madreporite triangular, flanked by three enlarged polygonal, mostly hexagonal, plates. Papulae present along radial regions, absent interradially approximately six surrounding each plate at each angle point. No pedicellariae on abactinal surface.

Superomarginal and inferomarginal plates ranging from 18–26 (arm tip to arm tip at R=2.0 to 4.9 cm, respectively) ( Fig. 8 A), corresponding 1:1 interradially becoming more offset with zig-zag contact distally along arms. Distalmost three to five superomarginal plates abutted over midline ( Fig. 8 A). Plates wide (width>length), broader interradially becoming narrower distally ( Fig. 8 D). Each plate with weakly convex contact on abactinal surface, edges of plate distinct. Plate surface covered by finely granulate, continuous tegument ( Fig. 8 C). Where granules are approximately five to eight along a 1.0 mm line on superomarginals, they are approximately three to four along a 1.0 mm line on inferomarginals. Contact zone between superomarginal and inferomarginals with coarse granular tegument identical to that present on the inferomarginal surface ( Fig. 8 C, D). Where granular tegument has been removed, surface plates mostly bare and smooth with no accessory structures (e.g., granules) present on most plates ( Fig. 8 C) especially in individuals with R<4.0. Larger individuals (R>4.0) glassy nodules present on interradial marginal plates but absent more distally, especially along the arm. No pedicellariae observed. No other accessories present on marginal plate surface or on periphery. Terminal plate triangular with central spinelike projection.

Actinal plate surface flush with inferomarginals ( Fig. 8 E). Actinal surface covered by coarse granular tegument identical to that on inferomarginal surface but coarser than the one present on the abactinal surface ( Figs 8 F, G). Actinal plates arranged in three to four series arranged in distinct chevrons ( Fig. 8 E). Continuous tegument covers all of actinal surface. No other accessories present on surface or periphery of actinal plates.

Furrow spines mostly three, a minority with two blunt spines forming a single series along edge of tube foot furrow ( Fig. 8 F) but with a minority of them weakly tilted with each spine series at an angle. Each spine triangular to irregularly quadrate in cross-section with most arranged in complimentary formation on each plate. Remainder of adambulacral plate surface devoid of any further spination but instead covered by actinal granular tegument which extends up to the base of furrow spines. Granules at the base of furrow spines coarser, larger than those present on the actinal surface. Oral plate furrow spines identical to those on other adambulacral plates. Paired spines projecting from oral plate into mouth, each triangular in cross-section ( Fig. 8 F). Oral plate surface with two four, most commonly two, large blunt spines closely abutting the furrow spines near the oral plate apex.

Material examined. Holotype: MNHN-IE-2013-6835; Southern New Caledonia, 23˚21’S 168˚05’E, 215– 260 m .; Coll. N/O Alis, Campagne SMIB 4. st. DW 55, 0 9 March 1989; 1 dry spec. R=4.9, r=2.3. Paratypes: MNHN- IE- 2013-6836 ; Southern New Caledonia, 23˚41’S, 168˚01’E, 240–300 m ; Coll. B. Richer de Forges, 20 Oct 1992, N/O Alis campagne BERYX 11, st. DW 40; 2 dry specs. R=3.8, r= 1.9 cm; R=3.6, r=2.1. MNHN-IE-2013-6837; Southern New Caledonia, 23˚41’S 168˚01’E, 245–260 m; Coll. N / O Alis Campagne SMIB 4 , st. DW 51, 0 9 March 1989; 1 dry spec. R=4.6, r=2.3. MNHN-IE-2013-6838; Noumea , New Caledonia. 23˚15.7’ S, 168˚4.4’E, 305–335 m.; Coll. ORSTOM, SMIB 5 , st. DW 104. 14 Aug, 1989. 1 dry spec. R=3.2, r=1.4. MNHN-IE-2013-6839 ; Southern New Caledonia, 23˚3.4’S, 167˚00’E, 350–400.0 m.; Coll. Bouchet & Richer de Forges, N / O Alis. Campagne BATHUS 2 CP 737; 1 dry spec. R=4.9, r=2.2. MNHN-IE-2013-6840 ; Northern New Caledonia,18˚56’S 163˚23’E, 430 m; Coll. MUSORSTOM 4 st. CP 193, 19 Sept. 1985; 1 dry spec. R= 5.0, r=2.6. MNHN-IE-2013- 6841 ; New Caledonia, 21˚31’ S 166˚22’E, 330–335.0 m.; Coll. Guille and Menou, 8 Sept. 1985,.N/O Jean- Charcot BIOCAL, Sta. CP 105; 1 dry spec. R=3.4, r=1.5. MNHN-IE-2013-6842; 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=3.3, r=1.7. MNHN-IE-2013-6843; Brachiopod Bank , New Caledonia, 23°28’S, 167°51’E, 370– 371 m .; Coll. Lozouet et al., NORFOLK 2, DW 2024; 2 dry specs. R=3.1, r=1.5; R=5.4, r=2.7. MNHN-IE-2013-6844; l’Île des Pins, New Caledonia, 22°42’S, 167°10’E, 313– 315 m .; Coll. NORFOLK 2, CP2160; 1 dry spec. R=3.9, r=1.5. MNHN-IE-2013-6846; West Jumeau Bank , Norfolk Ridge, New Caledonia, 23°41’S, 168°00’E, 320–397 m ; Coll. Lozouet et al. aboard N/ O Alis, NORFOLK 1, CP 1671; 1 wet spec. R=5.0, r=2.4. MNHN-IE-2013-6847; Banc N , Norfolk Ridge, New Caledonia, 23°27.3’S, 167°50.4’E, 276– 350 m .; Coll. Lozouet et al. aboard N/ O Alis NORFOLK 1, DW 1651; 1 wet spec. R=4.3, r=2.0. MNHN-IE-2013-6881; New Caledonia, 250 m.; Coll. SMIB 5, 13 Sept. 1989;1 dry spec. R=2.2, r=1.2. MNHN-IE-2013-6858 ; New Caledonia, 250 m .; Coll. SMIB 5, 13 Sept. 1989; 1dry spec. R=2.1, r=1.0. MNHN-IE-2013-12032; Grand Passage , New Caledonia 18°55’S 163°24’E, 370– 405 m .; Coll. BATHUS 4, DW 925, 8 July 1995;1 wet spec. R=3.5 r=1.7. IE- 2007-1650 ; New Caledonia, 19°00’S 163°28’E, 272 m.; Coll. CONCALIS, N/ O Alis R =4.1 r=1.9. MNHN-IE-2013-12060; Grand Passage , New Caledonia, 19°04’S 163°28’E, 252– 258 m .; Coll. BATHUS 4, CP 936; 1 wet spec. R=4.0 r=1.6; MNHN-IE-2007- 1721; New Caledonia, 18°15’S 163°06’E, 274 m.; Coll. CONCALIS CP 2976, aboard N/ O Alis; 1 wet spec. R=4.1, r=2.0. MNHN-IE-2013-8391 ; Norfolk Ridge, New Caledonia 23°29’S 167°52’E, 305– 322 m .; Coll. NORFOLK 1, no station. N/ O Alis. 2 wet specs. R=4.2 r=2.0 R=4.3 r=2.2. MNHN-IE-2013-8392; New Caledonia, 23° 28' S, 167° 52' E, 328– 340 m .; Coll. NORFOLK 1, DW 1653; 1 wet spec. R=3.4 r=1.7. MNHN-IE-2013-8393; New Caledonia, 23° 16' S, 168° 3' E, 300 m .; Coll. Bouchet, Crosnier et al. CHALCAL 2, st. CH 9; 1 wet spec. R=3.8 r=1.8. Fiji. MNHN-IE-2013-6845; Fiji, 19˚39’S 178˚10’W, 316–340 m.; Coll. Bouchet, Warén and Richer de Forges, 0 8 March 1999, N/ O Alis, BORDAU 1, St. CP 1474;1 dry spec. R=3.0, r=1.5. Tasman Sea. MV F123369; Lord Howe Rise, site 7 , Tasman Sea, 29˚3’7”S,159˚0’25” E, 292–330 m; Coll. NORFANZ TAN 0308 /55; 1 wet spec. R=3.2, r=1.5.

Figures

FIGURE 8. Kanakaster convexus n. gen., n. sp. Holotype, MNHN-IE- 2013 - 6835. A. Abactinal surface. Scale bar = 6.0 mm. B. Abactinal plate detail. Scale bar = 2.0 mm. C. Superomarginal-abactinal plate contact. Scale bar = 3.0 mm. D. Lateral view showing disk arching and superomarginals. Scale bar = 5.0 mm. E. Oral surface. Scale bar = 5.0 mm. F. Oral surface detail showing oral region, furrow spines. Scale bar = 2.0 mm.