Astroglypha pyramidata, Mah, 2021

Mah, Christopher L., 2021, The East Pacific / South Pacific Boundary: New taxa and occurrences from Rapa Nui (Easter Island), New Caledonia and adjacent regions, Zootaxa 4980 (3), pp. 401-450 : 419-421

Astroglypha pyramidata n. sp.

Figure 7A–D

Etymology. The species epithet pyramidata is Greek meaning “pyramid” and alludes to the triangular shape of the arms.

Diagnosis. This species is distinguished primarily by the differing number of furrow spines present per plate, the absence of pedicellariae (relative to A. passiflora ), the higher number of papular pores and superomarginals and the relatively broad disk.

Occurrence. New Caledonia & Norfolk Ridge , 305–788 m.

Description. Body thick, strongly stellate (R/r= 3.0–4.0, ranging from R=1.2–2.7). Interradial arcs acute. Disk is strongly thickened in largest specimen (R=2.7, MNHN IE-2013-6619), with wider proximal arm width relative to smaller individuals (R<2.0). Arms triangular in outline, pentagonal in cross-section. Disk approximately twice as thick relative to arms. Ossicles massive. Body covered by continuous granular tegument, composed of relatively coarse granules. Approximately 12–15 counted along a 1.0 mm line. Where granules have been inadvertently denuded in specimens, a bare smooth surface is present with no pitting. Four series of papular pores (one intermarginal series on each side, one series present between superomarginal and carinal series per side) in ordered row along each arm. Pedicellariae not observed.

Abactinal skeleton composed of relatively few components, composed of carinal series, adradials as well as primary circlet and relatively few disk plates. Specimens at R=1.4 with eight or nine strongly convex carinal plates. Carinals decreasing in size from disk to arm tip with distalmost plate, adjacent to terminal plate smallest. Larger specimens (R=2.7) with 12 carinals and four to six adradial plates. Carinal plates wide in outline. Adradials “pinch out” halfway along arm. Papular pores, one to three, mostly one or two, present between carinal and marginal plate series. Papulae absent from contacts between plates on primary circlet but present between primary circlet and superomarginal plates. Madreporite triangular (teardrop shaped), flanked by three disk plates. Anus present on disk center, flanked by five to six scalar granules. Papulae more consistently two in larger individuals (R=2.7).

Marginal plates 12–20 (20 at R=2.7) per interradius. Superomarginals and inferomarginals massive with strongly convex surfaces, round in cross-section. Interradial inferomarginals more compressed but most marginals globose. Distalmost inferomarginal adjacent to terminal plate, smallest in size. Inferomarginal directly abuts with adambulacral plates approximately midway along arm. One to four papulae present at contact between superomarginal and inferomarginal plates, emerging between granular tegument. One or two present in smaller individuals. Terminal plate polygonal to heart-shaped, surrounded by granular ring.

Actinal region relatively small, composed of eight to 26 plates present primarily on disk with smaller distalmost plates extending about halfway along arm. Actinal surface covered by granular tegument but also by one, exceptionally two in specimens with R=2.7, large, flat, elongate spine present on each actinal plate. These spines similar to those present on adambulacral plates.

Adambulacral plates with one large flat, square-shaped spine per plate. The larger specimen with especially thick spines, which are quadrate in cross-section. Two subambulacral spines present. The smaller adjacent to the furrow spine which is approximately the length of one furrow spine about 1/4 the length of the second subambulacral spine. The second subambulacral spine is similar to identical to that of the other spines on the actinal plate surface, flattened and oval in shape. Oral plates with two furrow spines per plate with one of these projecting into mouth.

Material examined. Holotype: MNHN IE-2013-6801 (EcAs 12367). Norfolk Ridge , New Caledonia 23º41′S, 168º15.0′E, 383–408 m. Coll. Bouchet et al. BATHUS 3 , CP 811, 1 wet spec. R =2.4, r=0.8.

Paratypes: MNHN IE-2013-6618 (EcAs 12454). Banc Jumeau west, southern New Caledonia. 23º40.4′S, 168º15.0′E, 389– 404 m. Coll. Richer IRD, aboard N/O Alis , LITHIST CP 15, 12 Aug. 1999. 1 dry spec. R =1.4, r=0.4. MNHN IE-2013-6619 (EcAh 4995). Banc Brachiopode , Norfolk Ridge, New Caledonia, 23°26′S, 167°50′E, 305– 332 m. Coll. Lozouet, Boisselier & Richer-IRD, NORFOLK 1 , DW 1657, 1 wet spec. R =2.7, r=0.9. MNHN IE-2013-6622 . Banc Jumeau East , Norfolk Ridge, New Caledonia. 23°45′S, 168°17′E, 386– 426 m. Coll. Lozouet, Boisselier & Richer-IRD, NORFOLK 1 , DW 1710. 1 wet spec. R =1.8, r=0.5. MNHN IE-2013-6620 . Banc Brachiopode , Norfolk Ridge, New Caledonia, 23°27′S, 167°50′E. 320– 336 m. Coll. NORFOLK 1 , DW 1658, 1 wet spec. R =1.2, r=0.4. MNHN IE-2013-6623 . New Caledonia, 23°44 ′S, 168°17′E to 23°43′S, 168°16′E. Coll. NORFOLK 1 , DW 1706. 1 wet spec. R =1.8, r=0.5. MNHN IE-2013-6621 . Banc Brachiopode , Norfolk Ridge, New Caledonia, 23°26′S, 167°50′E, 276– 350 m. Coll. Lozouet, Boisselier & Richer-IRD, NORFOLK 1 , DW 1651. 2 wet spec. R =2.6, r=0.8; R =1.3, r=0.3. MNHN IE-2013-6769 . Norfolk Ridge , New Caledonia. 23º20′S, 168º16.0′E, 310– 788 m. Coll. Lozouet et al. IRD, NORFOLK 1 , CP 1731 1 wet spec. R =1.6, r=0.4. MNHN IE-2016-1551 . New Caledonia 23°46 ′S, 168°17′E to 23°45′S, 168°16′E. Coll. NORFOLK 1 , CP 1705, 1 wet spec. R =2.0, r=0.6 .

Figures

FIGURE 7. Astroglypha pyramidata n. sp. Holotype, MNHN IE-2013-6801 (New Caledonia): A. Abactinal surface. Scale bar equals 0.5 cm. B. Close-up of abactinal surface. Scale bar equals 0.2 cm. C. Actinal surface. Scale bar equals 0.5 cm. D. Closeup of actinal surface showing actinal spines and furrow spination. Scale bar equals 0.1 cm.