Nymphaster moebi ( Studer 1884 )

Mah, Christopher L., 2018, New genera, species and occurrence records of Goniasteridae (Asteroidea; Echinodermata) from the Indian Ocean, Zootaxa 4539 (1), pp. 1-116 : 68-69

Nymphaster moebi ( Studer 1884)

Figure 26 A–F

Studer 1884: 30, 35 [as Pentagonaster (Dorigona) ]

Sladen 1889: 869; Döderlein 1924: 55; Macan 1938: 375; H.L. Clark 1946: 87; A.M. Clark 1993: 266 (checklist); Rowe & Gates 1995: 67; A.M. Clark 1993: 266 (as N. moebi )

Alcock 1893: 95 (as Nymphaster protentus )

Alcock 1893: 95 (as Nymphaster basilicus )

Koehler 1909: 54, pl. viii, figs 5, 6 (as Dorigona ternalis )

Koehler 1909: 61, pol. ix, figs 5, 6 (as Dorigona ludwigi )

Koehler 1909: 58, pl. viii, figs. 2,3,4; James 1983: 89 (checklist) (as Dorigona belli )

Clark, H.L. 1916: 36 (as N. pentagonus )

Diagnosis. Abactinal plates covered by coarse granules, fourteen to eighteen on carinal plates. Eight to ten superomarginals form edge around disk, approximately 12 or more Furrow spines seven, then eleven distally, compressed in palmate arrangement. Mouth plates with ten or eleven furrow spines (see Macan. 1938 for full description, diagnosis).

The diagnosis provided above is incomplete pending a full global review of Nymphaster sep.

Comments. Macan (1938) reconciled several of the Indian Ocean species as a widely occurring and variable Indian Ocean species, Nymphaster moebii , suggesting a wide range of continuous variation parallel with the Atlantic Nymphaster arenatus (summary in Clark and Downey 1992). Rowe and Gates (1995:67) synonymized Nymphaster pentagonus H.L. Clark 1916 within N. moebii indicating that the holotype of Nymphaser pentagonus and a “range of specimens” fell “well within the range of structural variation exhibited by Nyphaster moebii . ” No other argumentation was provided.

Occurrence. Off northwest coast of Australia (New South Wales, Victoria, South Australia, Western Australia), Madagascar, Mozambique Channel, Mascarene Islands, Off coast of Kenya (Zanzibar Island region). 195 – 1655 m.

Description. Body stout, strongly stellate (R/r=3.0–4.4), arms elongate, sharply triangular in shape, acutely tapering. Interradial arcs curved to straight ( Fig. 26A ).

Abactinal plates weakly tabulate, surface outline polygonal to round, radial and adradial plates hexagonal or nearly so ( Fig. 26B ). Shallow fasciolar grooves present. Abactinal plate surface covered by coarse, round granules, four to 40 total, fundamentally homogeneous, but forming a single- series peripheral series, widely spaced from one another, approximately, five to 25 with a variable number and arrangement of central granules, numbering three to 20 ( Fig. 26B ). Individuals from the Mascarene Islands and one lot, IE-2007-1059 ( Madagascar) show one to three large central tubercle-like granules, approximately twice the size of the other granules located centrally on each plate. Some individuals show these central plates set off from the peripheral granules by a discrete space, whereas others show these plates more closely distributed near one another. Other plates more similar to those showing homogeneous coarse granular cover as seen on other individuals present on radial and especially interradial plate surfaces. Non-Mascarene specimens show more homogeneous granule cover on central abactinal plates. Pedicellariae not observed on abactinal surface. Papulae primarily centered around radial regions, but absent interradially. Madreporite polygonal to round, variably quadrate to hexagonal, weakly convex with well-developed sulci, flanked by four to six abactinal plates.

Superomarginal plates, abutted over midline for the nearly complete arm distance ( Fig. 26A, C ). Arm tips on nearly all specimens broken, but superomarginals per interradius, approximately 40–70 with approximately (26/70 to 18/40) 37–45% of superomarginals in contact. Superomarginals elongate, with variably angular to rounded lateral edges. Superomarginal and inferomarginal plates form discrete border around abactinal surface with plates forming variably wide periphery. The largest, observed specimen, IE-2007-1059 ( Madagascar) shows inferomarginals slightly jutting out from under the superomarginals with strongly swollen surface with bumpy curves between plates versus others, such as the Mozambique specimen, IE-2013-9105 with more angular edges which show surfaces that are more flattened with a flush surface. Superomarginal and inferomarginal surface, covered by 200–500 polygonal, coarse grained granules, evenly, and widely distributed over plate surface ( Fig. 26C ). Peripheral granules number about 12–15 along short edge, 20–30 along elongate edge. Actinolateral edge along inferomarginal series variably round (IE-2007-3980) to angular (on IE=2013-9105). No pedicellariae observed.

Actinal intermediate region large, approximately four full series in chevron formation with a small number of irregular plates present adjacent to inferomarginal contact ( Fig. 26D ). Individual plates variably quadrate to polygonal in shape. Surface covered by variably shaped coarse, granules. Some displaying strongly homogenous granules in terms of shape and size (IE-2007-3980) versus others which are more heterogeneous with enlarged central granules, one to three (IE-2007-17280).

Furrow spines, six to nine at R= 4.1 cm, seven to eight at R= 5.6 cm, eight to ten at R= 6.1 cm, and six to 12 at R= 9.5 cm ( Fig. 26E ), all on a straight to palmate arrangement on each plate. A wide spread of continuous furrow spine counts suggests these are variable across this species’ range. In addition to the overlapping furrow spine counts, morphology of these spines also shows some variation. Relatively smaller specimens (e.g., IE-2013-9105 from Mozambique, IE-2013-17283 from Mascarene Islands) show relatively slender spines, round to quadrate in cross-section. The largest known specimen (IE-2007-3980) shows, thick, wide spines which are rectangular to quadrate in cross-section. A discrete space separates the furrow spines from the subambulacral series behind it. Subambulacrals number three to six, but mostly four to five. One to three of the central subambulacral spines, thickened and enlarged, approximately twice as thick as the furrow spine ( Fig. 26E ).

In IE-20070-3980, subambulacrals wide and thick, about three times as thick as furrow spines set back a considerable distance from the tube foot groove. Subambulacrals vary in shape, from those which show wider wedge shaped to blunt, cylindrical spines, round in cross-section to more club-shaped spines. Remaining subambulacrals granular to pointed, about 20% of distance of subambulacral spination. Oral plate with approximately 10–12 furrow spines similar to identical with furrow spines on other plates. Single spine, triangular in cross-section present on each oral plate, two total for each interradius. Oral plate surface with approximately six to eight blunt spines present along the edge of each sulcus directed along the middle of the oral plate.

Material Examined. Madagascar : IE-20070-3980 Madagascar 25°35’S 44°15’E, 910 m, coll. Samedi et al. ATIMO VATAE, aboard N/O Nosy Be 11 CP 3595, 12 May 2010. 1 wet spec. R=9.5 r=3.1 . IE-2007-1053 . Madagascar , 12°40’S, 48°12’E, 524 m. Coll. Bouchet, Puillandre & Richer, 26 June 2009 . MIRIKY, N/O Miriky CP 3184, 1 wet spec. R=4.9, r=1.9 (arms broken) ; IE-2007-1062 . Madagascar , 15°31’S, 45°42’E, 800 m. Coll. Bouchet & Kantor aboard N/ O Miriky, CP 3270, 11 July 2009, 2 wet specs. R=8.4, r=2.4; R=8.0, r=1.8 ; IE-2007- 1066 . Madagascar , 15°22’S, 45°57’E, 1020 m. Coll. Bouchet & Kantor aboard N/ O Miriky, CP 3279, 12 July 2009 ,1 wet spec. R=6.2, r=2.8 ; IE-2007-1059 . Madagascar, 12°36’S, 48°16’E, 364 m. Coll. Bouchet, Puillandre, & Richer de Forges aboard N/ O Miriky, CP 3182, 26 June 2009, 6 wet specs. Note some arm tips broken R=6.3, r=1.7; R=5.0, r=1.6; R=4.9, r=1.2; R=5.3, r=1.7; R=3.9, r=.9; R=1.1, r=0.3 ; IE-2013-6643 Madagascar , 21°25.5’S, 43°14.5’E, 425– 550 m. Coll. A. Crosnier, 26 Nov. 1973 ,1 dry spec. R=5.2, r=1.8, arms broken . IE-2013-9105 Betsiboka, North of Madagascar , 15°30,9’S, 45°43,7’E, 801– 811 m. Coll. Pamela , IFREMER MOZ01 , CP04 . 1 wet spec. R=6.2 r=2.2 (arm tips broken). Mascarene Islands . IE-2013-17280 Mascarene Islands . 22°12.3’S 43°8.2”E, 300– 320 m. Coll . CLEVA, Mascarene Islands III. 12 Dec. 1985 2 dry spec. R=6.4 r=1.5 R=5.7 r=1.5 . IE- 2013-17282 Mascarene Islands . 22°24.8’S 43°5.3”E, 425– 450 m. Coll . CLEVA, Mascarene Islands III. 12 Dec. 1985 2 dry spec. R=4.1 r=1.2 R=4.5 r=1.3 (arms broken) . IE-2013-17283 Mascarene Islands . 22°19.2’S 43°6.8”E, 400– 410 m. Coll . CLEVA, Mascarene Islands III. 12 Dec. 1985. 7 dry specs. R=5.5 r=1.3, R=5.4 r=1.4, R=5.4 r=1.4, R=5.5 r=1.3, R=5.2 r=1.1, R=4.1 r=0.8, R=3.3 r=0.8 . Kenya. USNM E51267 , NE of Mombasa, Kenya. 2°49.8’S, 164°45.25 (-2.83, 40.52), 290 m. Coll . IIOE aboard R/ V Anton Bruun. 2 wet specs. R=4.8 r=1.5 R=4.7 r=1.4 (arms broken). Zanzibar Island . USNM E10598, Zanzibar Island , Tanzania. Coll. John Murray Expedition st. 122. 4 wet specs. R=4.8 r=1.1, R=5.5 r=1.8 R=5.1 r=1.5 R=-4.6 r=1.3 .

Figures

FIGURE 26. Nymphaster moebii Specimen IE-2007-1066. R=6.2 r=2.8 cm. A. Abactinal surface. Scale bar=1.0 cm. B. Closeup of abactinal plates. Scale bar=0.2 cm. C. Closeup of superomarginal plate surface and abutting over midline. Scale bar=0.2 cm. D. Actinal surface. Scale bar=1.0 cm. E. Furrow spines and adambulacral details. Scale bar=0.5 cm.