Vologesia toucasi ( Lambert, 1911 )

Schlüter, Nils & Wiese, Frank, 2017, Late Cretaceous species of Vologesia (Echinoidea, Cassiduloida) from northern Spain, Zootaxa 4306 (2), pp. 261-270 : 267

Vologesia toucasi ( Lambert, 1911)

( Figs. 5 C, E, G, 7)

1911 Clypeolampas toucasi Lambert , p. 155, pl. 3, Figs. 1–3 .

2014 Hungaresia toucasi (Lambert) , Saura & García p. 306, pl. 104, Figs. 1 a –c.

Type. Holotype, by monotypy, is the specimen illustrated by Lambert (1911, pl. 3, Figs. 1–3 ), in the Lambert Collection at the Muséum national d’Histoire naturelle, Paris (MNHN.F.J01723) (not seen). It is from Sougraigne in the Corbières (Aude, France), having been collected from the “couches Hippurites ... avec Actinocamax Grossouvrei. Lambert (1911) considered those strata to be of Campanian age. According to the revised stratigraphy by Christensen et al. (1993), these levels are of late Santonian age ( Placenticeras polyopsis / Texanites gallicus Zone ).

Material. A single near-complete and four fragmentarily preserved specimens (MB.E.11463-11467) from the top of Bed 200, upper Santonian ( Placenticeras polyopsis Zone ), deposited in the Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung (Berlin, Germany).

Diagnosis. Small species with a domed to conical test and a flattened oral surface. The tetrabasal apical disc, with a prominent madreporite, is in a central position. The pentagonal, laterally elongated peristome is positioned close to the anterior margin. The phyllodes are short and slightly sunken, with an inner and an outer series of pore pairs; bourrelets are weakly developed.

Description. Vologesia toucasi is a small species with a maximum test length of c. 35 mm. The oval tests are domed to conical in profile, with its longest axis along the anterior-posterior direction in cross section. The ambitus is positioned close to the oral surface, in the lower quarter of test height. The apical disc is positioned at 47% of test length to the anterior margin. The apical disc is not completely preserved; it was presumably tetrabasal, with the madreporite formed by the large genital plate 2, occupying the centre of the apical disc, while other genital plates are much reduced in size ( Fig. 5 G).

Petaloid ambulacra are present adapically; pore counts are not available due to poor preservation. The straight petals are relatively short, not reaching below the upper third of test height. Conjugate anisopores can be recognised within the petals.

The small peristome is laterally elongated and has a pentagonal outline. It is positioned anteriorly, with a distance to the anterior margin of 29% of test length (at a length of 29.8 mm). A weakly pronounced floscelle structure can be seen; the bourrelets are only weakly swollen, in combination with only slightly sunken phyllodes. The phyllodes are short, with an outer series of 10–11 pores, including small buccal pores, and an inner series of 3–4 pores (see Fig. 4 C). The oval periproct is inframarginal.

The tubercules generally are small, largest on the oral surface and decreasing in size in aboral direction. A narrow, granular band without tubercles extends from the peristome to the periproct.

Discussion. Our record of V. toucasi from the upper Santonian of Langre is in accordance with the stratigraphic position of the type series from the Corbières, southern France and extends the known geographic range of the species to Spain. Vologesia toucasi differs from V. rollingstones sp. nov. by its subconical to conical profile and in phyllode structure that generally reveals a floscelle on account of more pronounced bourrelets. This species has a more inflated and circular shape in comparison to V. rawdahensis and V. tataosi . In addition, the apical disc is more central. Lambert (1919) mentioned Vologesia acuta (Des Moulins, 1837) from the Santander region. This is better referred to Clypeolampas (see Smith, 1995) and differs to Vologesia by a more centrally positioned peristome and better-developed bourrelets.

Figures

FIGURE 1. Simplified map of the vicinity of the village of Langre, showing the origins of Vologesia toucasi (Lambert, 1911) (A) and Vologesia rollingstones sp. nov. (B).

FIGURE 2. Stratigraphy and lithology of the Langre section.

FIGURE 3. Vologesia rollingstones sp. nov.; A – C, holotype, MB. E. 6224; B, paratype, MB. E. 6225; in oral (A, D), apical (B, E) and left lateral (C, F) views. Langre, Cantabria, northern Spain, Sponge Rhythmites (Scaphites hippocrepis III Zone, lower Campanian). Both specimens coated with ammonium chloride prior to photography. Scale bar equals 10 mm.

FIGURE 4. Vologesia rollingstones sp. nov.; A, holotype, MB. E. 6224, detail of apical area; B, paratype, MB. E. 6225, detail of peristomial area; both from Langre, Cantabria, northern Spain, Sponge Rhythmites (Scaphites hippocrepis III Zone, lower Campanian). Both specimens coated with ammonium chloride prior to photography. Scale bars equal 5 mm.

FIGURE 5. Drawings of plating style; A – B, D, F, Vologesia rollingstones sp. nov.; A, D, MB. E. 6226, A: oral view, D: detail of peristomial area; B, holotype, MB. E. 6224, apical view; F, MB. E. 6227, apical disc; A – B, D, F: Langre, Cantabria, northern Spain, Sponge Rhythmites (Scaphites hippocrepis III Zone, lower Campanian); C, E, G, Vologesia toucasi (Lambert, 1911); C, MB. E. 11644, C: oral view, E: detail of peristomial area; G, MB. E. 11645, apical disc; C, E, G: Langre, Cantabria, northern Spain, Bed 200, upper Santonian (Placenticeras polyopsis Zone). Scale bars equal 10 mm (A – C) and 2 mm (D – G).