Valettaster ocellatus ( Forbes, 1848 )

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

Valettaster ocellatus ( Forbes, 1848)

( Figs 22E , 23A , 25G)

$1848 Oreaster ocellatus Forbes : 468.

1850 Oreaster ocellatus Forbes in Dixon: 329, pl. 21, fig. 13.

1907 Pentaceros ocellatus (Forbes) ; Spencer: 85, pl. 25, fig. 4.

1913 Tholaster ocellatus (Forbes) ; Spencer: 138, pl. 13, fig. 24.

1914 Valettaster ocellatus (Forbes) ; Valette: 57, fig. 19.

1943 Valettaster ocellatus (Forbes) ; Brunnich Nielsen: 65, pl. 4, fig. 29.

1950 Valettaster ocellatus (Forbes) ; Wienberg Rasmussen: 94, pl. 10, figs 22–23.

1985 Valettaster ocellatus (Spencer) ; Breton: 91, figs 2–5.

2000 Valettaster gr. ocellatus (Forbes) ; Jagt: 91, pl. 20, fig. 29; pl. 21, figs 1–7.

Type. The partly articulated individual figured by Forbes (in Dixon 1850, pl. 21, fig. 13) is the holotype. ‘ Upper Chalk , Sussex and Kent’. The present whereabouts of this specimen are unknown .

Diagnosis. Abactinal ossicles with a broad flat outer surface that bears dense, irregularly radiating ridges and beads of imperforate stereom.

Material. A partly articulated individual from the coranguinum Zone of Micheldever, Hampshire ( NHMUK E 5019) and a well-preserved specimen from the Marsupites Zone of Brighton, Sussex ( NHMUK E 5012) are described. Additionally, isolated abactinal plates from the coranguinum Zone of Thanet, Kent are identified ( NHMUK EE 17696–17697).

Occurrence. Valettaster ocellatus is present in the Cenomanian to Maastrichtian of the Anglo-Paris Basin ( UK and France), and the Maastrichtian of Germany, the Netherlands and Denmark.

Remarks. Valettaster ocellatus differs from V. argus in the broad external surface of the abactinal ossicles and the fine radial sculpture ( Fig. 22E ); in V. argus , the imperforate stereom forms an irregular reticulum ( Fig. 22L ). Specimens figured by Jagt (2000, pl. 20, figs 25–28) perhaps represent a form transitional to V. granulatus (see below). Breton (1985) reconstructed the surface of V. ocellatus as possessing a thick epidermis in which were set smaller secondary ossicles, decreasing in size progressively towards the outer surface ( Breton 1985, fig. 4). The new material figured here demonstrates that the secondary ossicles were positioned in grooves between the external surfaces of the primary abactinals, and their sculptured external surfaces were flush with those of the primary ossicles.

Figures

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.