Democrinus elongatus ( Roux, 1978c )

Roux, Michel, Martinez, Alain & Vizcaïno, Daniel, 2021, A diverse crinoid fauna (Echinodermata, Crinoidea) from the Lower Eocene of the Gulf of Languedoc (Corbières, Aude, southern France), Zootaxa 4963 (2), pp. 201-242 : 226-227

? Democrinus elongatus ( Roux, 1978c)

Fig. 8G–I

Synonymy. Conocrinus elongatus Roux, 1978c: 265–266 , fig. 1A; Roux et al. 2019: 66, 77; Bourgueticrinus sp. Zamora et al. 2018: 788, 791, fig. 10G;? Democrinus elongatus Roux et al. 2019: 67 , fig. 8G–J.

Type material. The holotype ( UCBL-FSL 19210 A) is from the Bartonian at Biarritz (Côte des Basques , Villa Marbella ) .

Material examined. 4 aboral cups from Lavade; specimen A ( MNHN.F. A82010 ) is Fig. 8G–I , the other three are in the Martinez Collection.

Locality. Lavade near Fontcouverte (middle Ilerdian, NP11).

Description. Main variations in quantitative characters of aboral cups given in Table 13. Very elongated aboral cup, with H/D>3.1, except in specimen B, maximum D in upper third, progressive variation of D along height in smallest specimen ( Fig. 8G ), very weak in others; adoral face with wide, pentagonal central cavity (Dd/Dr ~0.40), muscular areas more developed than ligament areas, discrete interradial crest with marked bending of inner side of radials ( Fig. 8H–I ), stalk insertion occupying aboral face. Specimen C with additional circle of plates (H 1.25 mm) prolonging basals, likely resulting from regeneration.

Remarks. Distal face of aboral cup of specimens here attributed to? Democrinus elongatus show same characters as those from Bartonian of Biarritz ( Roux et al. 2019: fig. 8G–J). It can be distinguished from Pseudoconocrinus doncieuxi suboblongus n. subsp. by radial circlet with adoral face having muscular areas more developed than ligament areas and interradial bending of the lateral edges of muscular fossae, absence of conspicuous interradial crests and wide, pentagonal to slightly star-shaped central cavity as observed in extant Democrinus ( Roux et al. 2019) . Lacking these characters, these two species cannot be separated when aboral cups are very elongated. Mesistele columnals from Lavade with no mid-height swelling and with H/D ~1.6 ( Fig. 13 ) could belong to this species. Similarly, rare distal columnals from the Tuilerie de Fontcouverte show an extension of ligament depressions on either side of the fulcral crest ( Fig. 8E ) as observed in some extant species of Democrinus ( Roux 1977) ; but no aboral cup of? D. elongatus has ever been identified at this site despite the abundance of material. Excess basals due to regeneration anomaly, as observed in specimen C, are frequent in extant Democrinus japonicus ( Gislén, 1927) . The aboral cup of? D. elongatus is easily distinguished from that of D. londinensis ( Forbes, 1852) , a Ypresian species from the London Clay whose sutures between plates are conspicuous and Hc/Dc <1.20 ( Rasmussen 1972). Zamora et al. (2018) attributed to Bourgueticrinus sp. an elongated aboral cup from the middle Ilerdian of Puebla de Roda (Graus-Tremp basin, Spain). The distal face of this cup has the typical characters of? Democrinus elongatus , which attests to the presence of this species in the south Pyrenean Ilerdian basin. Klikushin (1982) referred to a fragment of an aboral cup from the Upper Eocene of Crimea as “ Conocrinus ” cf. elongatus , but failed to present any conclusive character to confirm such an attribution.

Occurrence. Early Ypresian (Ilerdian) of the French-Spanish Pyrenean basin (gulfs of Languedoc and of Graus-Tremp); Bartonian of Biarritz (Côte des Basques, Villa Marbella).

Figures

FIGURE 8. Aboral cups and columnals of Pseudoconocrinus doncieuxi and aboral cup of?Democrinus cf. elongatus. A–F: P. doncieuxi suboblongus n. subsp.; A–C: holotype from Fontcouverte à l’Estagnol (MNHN.F.A81998), A: lateral view, B: distal face of radial circlet, C: aboral face with stalk insertion with proximalmost columnals preserved; D–F: paratypes, D–E: from Lavade (MNHN.F.A81999), F: from Réqui (MNHN.F.A82000), D: oblique lateral view showing stalk insertion, E: oblique lateral view of same specimen showing proximal face of radial circlet, F: distal face of radial circlet; G–I:?D. elongatus from Lavade (MNHN.F.A82010), G: lateral view, H: distal face of radial circlet, I: detail of H showing interradial crest and muscular synarthrial facet; J–Q: columnals of P. doncieuxi from Fontcouverte à l’Estagnol (MNHN.F.A69946), J–K: columnal of middle mesistele, K: detail of fulcral ridge; L–N: columnals of dististele, L: oblique proximal view, M: lateral view, N: distal facet, O–Q: columnal of distal mesistele, Q: detail of fulcral ridge. Scale bar equals 1 mm (A–B, D–F, G), 0.5 mm (C, H–I, L–P), 0.25 mm (J, Q) and 0.12 mm (K).

FIGURE 13. Variation in main quantitative characters of columnals from Lavade. Other species: columnals that can be attributed to?Democrinus elongatus. To make the scatter plot clearer, only ~50% of columnals bearing rhizoids were represented. Envelopes encompass at least 90% of all groups of columnals. D and d used as growth index. Values in mm, except for ratios H/D (black straight lines at left). See Fig. 2 for abbreviations.