Valettaster argus ( Spencer, 1907 )

Gale, Andrew Scott, 2021, Taxonomy and phylogeny of the ‘ football stars’ (Asteroidea, Sphaerasteridae), Journal of Systematic Palaeontology 19 (10), pp. 691-741 : 733

Valettaster argus ( Spencer, 1907)

( Figs 6H–K, N, O , 7P, R , 8K, M , 22L , 23B–P )

1850 fragment of an Oreaster Forbes in Dixon: pl. 21, fig. 16.

$1907 Stauranderaster argus Spencer : 99, pl. 29, fig. 8.

1913 Tholaster argus (Spencer) ; Spencer: 138, pl 13, fig. 25.

1914 Valettaster ocellatus (Forbes) ; Valette: 60, fig. 20.

1985 Valettaster argus (Spencer) ; Breton: 91, fig. 6.

Type. An individual (not figured) from the Marsupites Zone of Brighton, southern England ( NHMUK E 5109 ) is the holotype .

Diagnosis. Valettaster in which the abactinal ossicles possess small external faces and bear a reticulate sculpture.

Material. A well-preserved specimen from the coranguinum Zone of Micheldever, Hampshire ( NHMUK E 20294) and a partly articulated specimen from the same zone at Thanet, Kent, provide many details of the ossicles and nature of the abactinal surface ( NHMUK EE 17637).

Occurrence. Valettaster argus is present in the Turonian to Campanian Chalk of the United Kingdom.

Remarks. The new material provides information on the nature of the exterior surface of this species ( Fig. 23H–K ). The spaces between the large abactinal ossicles are packed with smaller, secondary ossicles of various sizes ( Fig. 23H ), creating a smooth surface made up of the exposed summits of the larger ossicles and the smaller plates ( Fig. 23 I, J ). There are spaces between the smaller ossicles, which might represent papular pores ( Fig. 23J ), or where secondary ossicles have fallen out. It is important to point out that the reconstruction of Breton (1985, fig. 4), which shows the surface of the asteroid with a thick dermis, containing numerous small ossicles, is incorrect.

Figures

Figure 6. Ambulacrals of sphaerasterids. A–D, Sphaeraster tabulatus (Goldfuss, 1833); A, B, proximal ambulacral in actinal and proximal/distal aspects, respectively (NHMUK EE 17633); C, D, actinal views of ambulacrals from mid-radius (NHMUK EE 17623a, 17634). E, P, Q, Podosphaeraster pulvinatus Rowe & Nichols, 1980; E, enlargement of actinal view of base of ambulacral; P, Q, actinal and proximal/distal views of ambulacral, respectively (Mnhnl OPH176). F, G, Eosphaeraster amellagensis gen. et sp. nov., ambulacral in actinal and proximal/distal views, respectively (NHMUK EE 17635). H–K, N, O, Valettaster argus (Spencer, 1907). H–K, proximal/distal views of ambulacral, note cavity replacing articulation facet (I); L, M, Bulbosphaeraster valettei gen. et sp. nov., ambulacral in actinal and proximal/distal views, respectively (NHMUK EE 17636); N, O, actinal views of ambulacrals (NHMUK EE 17637a, b). Provenance: A–D are from the upper Oxfordian, Hypsilum ammonite Zone, Plettenberg, near Balingen, Germany. F, G are from the upper Pliensbachian, outcrop on south side of wadi immediately to west of road, 0.5km south of the Kasbah of Amellago, Atlas Mountains, Morocco. L, M are from the lower Bathonian, Zigzagiceras zigzag ammonite Zone at La Pouza, near La Voulte-sur-Rhone, Ard̀eche, France. H–K, N–O are from the coranguinum Zone, Santonian, Broadstairs, Kent, UK. E, P, Q are Recent, Philippines. Scale bars: A, B, D, F, G, J–Q = 0.5mm; C = 1 mm; E, H, I = 0.2 mm.

Figure 7. Adambulacrals of sphaerasterids. A, B, Stauraster primaevus (von Zittel, 1880), adambulacrals in abactinal and proximal/ distal views, respectively (NHMUK EE 17638, 17632). C–H, L, N, Q, Sphaeraster tabulatus (Goldfuss, 1831); C, G, L, N, abactinal views (NHMUK EE 17623h–k); D, F, proximal/distal views (NHMUK EE 17623l, m); H, internal, Q, external views (NHMUK EE 17623n). I–K, M, Eosphaeraster amellagensis gen. et sp. nov.; I, J, proximal/distal and internal views (NHMUK EE 17639); K, M, proximal/distal views (NHMNUK EE 17640, 17641). O, S, T, Podosphaeraster pulvinatus Rowe & Nichols, 1980, adambulacrals in proximal/distal, internal and actinal views, respectively (MhnhL OPH174–176). P, R, Valettaster argus (Spencer, 1907), adambulacrals in abactinal and actinal views, respectively (NHMUK EE 17637f, g). Provenance: A, B are from the lower Oxfordian, Cardioceras bukowskii ammonite Subzone, basal Couches de Passage, Andelot Morval, Jura, France. C–H, L, N, Q are from the upper Oxfordian, hypsilum ammonite Zone, Plettenberg, near Balingen, Germany. I–K, M are from the upper Pliensbachian, outcrop on south side of wadi immediately to west of road, 0.5km south of the Kasbah of Amellago, Atlas Mountains, Morocco. P, R are from the coranguinum Zone, Santonian, Broadstairs, Kent, UK. O, S, T are Recent, Philippines. Scale bars: A, C–E, L–O, Q–T = 0.5 mm; B, F–K = 1 mm; P = 0.2 mm.

Figure 8. Oral ossicles of sphaerasterids. A–E, Sphaeraster tabulatus (Goldfuss, 1833); A, D, interradial view of orals of smaller individuals (NHMUK EE 17642, 17643); B, E, interradial (B) and radial (E) views of small oral (NHMUK EE 17644); C, large oral, interradial view (NHMUK EE 17623b). F, I, Eosphaeraster amellagensis gen. et sp. nov., oral in interradial and radial views, respectively (NHMUK EE 17645). G, oral ossicle of possible stauranderasterid or sphaerasterid, interradial view (MnhnL OPH173). H, oral ossicle, probably from Bulbosphaeraster valettei gen. et sp. nov., interradial view (NHMUK EE 17646). J, L, oral ossicle of Podosphaeraster pulvinatus Rowe & Nichols, 1980, in interradial and radial views, respectively (MhnhL OPH174–176). K, M, oral ossicle of Valettaster argus (Spencer, 1907), in interradial and radial views, respectively (NHMUK EE 17637h). N, interradial view of oral ossicle of Manfredaster bulbiferus (Forbes, 1848) (NHMUK EE 17647a). Provenance: A–E are from the upper Oxfordian, Hypsilum ammonite Zone, Plettenberg, near Balingen, Germany. F, I are from the upper Pliensbachian, outcrop on south side of wadi immediately to west of road, 0.5 km south of the Kasbah of Amellago, Atlas Mountains, Morocco. G is from the Carnian (Upper Triassic), Cortina d’Ampezzo, Italy. H is from the lower Bathonian, Zigzagiceras zigzag ammonite Zone at La Pouza, near La Voulte-sur-Rhone, Ard̀eche, France. K, M, N are from the coranguinum Zone, Santonian, Broadstairs, Kent, UK. J, L are Recent, Philippines. Scale bars: A, D, G, H, K, M = 0.5mm; B, E = 0.2 mm; C, F, I, J, L, N = 1 mm.

Figure 22. A–D, G, J, Valettaster digitatus (Quenstedt, 1858), abactinal ossicles, in external view (A, C, D, G, J) and lateral view (B) (GPIT/A5/50). E, Valettaster ocellatus (Forbes, 1848), abactinal ossicle, in external view (NHMUK EE 17696). F, I, Pouzaster pocknotata gen. et sp. nov., abactinal ossicles in external view (MHNML 2020.1.2, 1.3). H, K, Valettaster granulatus (Brunnich Nielsen, 1943), abactinal ossicles, external view (SNSB-BSGP 2020 XLV1, 2). L, Valettaster argus (Spencer, 1907), articulated group of abactinal ossicles (NHMUK EE 17637f). M, N, Valettaster thuyi sp. nov., holotype, abactinal ossicle in external and lateral views, respectively (MHNML 2020.1.1). Provenance: A–D, G, J are from the Oxfordian of Oerlingen, south Germany. B is from the Santonian of East Kent, UK. F, I are from the serpentinus ammonite Zone, Toarcian at Fougerolles, France. H, K are from the lower Maastrichtian of R¨ugen, Germany. M, N are from the bifrons ammonite Zone, Toarcian, Fougerolles, France. L is from the coranguinum Zone, Santonian, Broadstairs, Kent, UK. Scale bars: A–E, G, H, J, K = 5 mm; F, I, L = 0.5mm; M, N = 0.2 mm.

Figure 23. A, Valettaster ocellatus (Forbes, 1848), oblique actinal view of well-preserved individual (NHMUK E 5012). B–P, associated ossicles and fragments of Valettaster argus (Spencer, 1907); B–E, articulated adambulacrals, bearing subadambulacral spines (NHMUK EE 17637i–l); F, G, ambulacral ossicle, in proximal and distal views, to show bulbous swelling from ambulacral base ((NHMUK EE 17637m); H, external surface with ossicles in place (NHMUK EE 17637n). Note smaller secondary ossicles infilling gaps between external surfaces of larger abactinals, creating a smooth surface; I, J, fragments with articulated abactinal ossicles (NHMUK EE 17637o, p), showing smaller secondary plates and possible papular notches; K, fragment with madreporite and two abactinal ossicles (NHMUK EE 17637q); L, adambulacral in proximal/distal view, to show lack of adadm site and internally directed ledge (NHMUK EE 17637r); M–P, adambulacral ossicles; M, abactinal view of ossicle in which three of the articular surfaces each bear a cavity (NHMUK EE 17637f); N, proximal/distal view to show adadm site (oval depression) (NHMUK EE 17637s); O, oblique actinal view (NHMUK EE 17637t); P, actinal view, to show rugose perforate stereom and furrow spine attachment sites (NKMUK EE 17637g). Provenance: A, Santonian, Marsupites Zone, Brighton, Sussex, UK. B–P, Santonian, coranguinum Zone, level of Whitaker’s Flint, Broadstairs, Kent, UK. Distal adambulacrals marked with arrow. Scale bars: A = 10 mm; C = 1 mm; B, D–P = 0.5 mm.