Pseudoconocrinus doncieuxi suboblongus, Roux & Martinez & Vizcaïno, 2021

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 : 218-219

Pseudoconocrinus doncieuxi suboblongus n. subsp.

Figs. 8A–F , 9

Type-material. Holotype ( MNHN.F. A81998 ; Fig. 8A–C , Plaziat Collection), from Fontcouverte (à l’Estagnol); paratype A ( MNHN.F. A81999 ; Fig. 8D–E ), from Fontcouverte (Lavade); paratype B ( MNHN.F. A81999 ; Fig. 8F ) from Montlaur (Réqui).

Etymology. In reference to the oblong shape of the aboral cup.

Material examined. In addition to the type series, 10 aboral cups from the Tuilerie de Fontcouverte (in UCB-FSL 170248 b, and Martinez Collection); 125 aboral cups and 238 columnals from Réqui, some aboral cups and columnals from other sites (see Table 2) in the Martinez and Vizcaïno collections .

Diagnosis. Variety with often very elongated aboral cup, Hc up to 155 mm, H/D most often> 2.5 and sometimes up to 5.7, Dc maximum located in central or adoral third, aboral third in inverted truncated cone with base corresponding to stalk insertion, adoral third truncated conical or subcylindrical in shape, distal face of radial circlet almost flat with marked star-shaped central depression in largest specimens, stalk insertion wide (Dp/Dr>050), columnals usually without marked bulge at mid-height.

Description. Quantitative characters of the three aboral cups of the type series listed in Table 3. Holotype: aboral cup with maximum Dc in central swollen third ( Fig. 8A ); adoral third in truncated cone, distal surface flat entirely occupied by insertion of arms, strongly star-shaped central cavity ( Fig. 8B ); aboral third in inverted truncated cone with flat base entirely occupied by stalk insertion housing proximalmost discoid columnals ( Fig. 8C ). Paratype A: aboral cup similar in shape to holotype but more elongated (H/D 2.5) and illustrating general trend of aboral cups from the Lavade and Requi sites ( Fig. 8D–E ). Paratype B: exceptionnally well-preserved, almost flat adoral face showing moderately protruding interradial ridges, with large, slightly star-shaped central cavity, and aboral and inner ligament areas of synarthries better developed than muscular areas ( Fig. 8F ).

Tables 5 and 6 list the general quantitative characters of aboral cups and columnals from the Réqui site where this variety strongly predominates; these specimens display a much smaller size than those of P. doncieuxi from the Tuilerie de Fontcouverte and a tendency towards greater and earlier elongation (Hc/Dc from 2.5 to 5.73 for 1.7<Dc<3.0 mm) ( Fig. 8 ).

Remarks. Pseudoconocrinus doncieuxi suboblongus n. subsp. is present at numerous sites, but with widely varying frequencies. In the particular environment of Réqui (see above), this variety strongly predominates in several of the marl layers sampled. Aboral cups with Dc> 1.7 mm have a much less variable shape than those with Dc>2.5 from the Tuilerie de Fontcouverte ( Fig. 9 ). This suggests a tendency for elongation during ontogeny that was channeled by environmental factors early during growth. At Réqui, the absence of brachials and rhizoid segments, the abnormal relative abundance of aboral cups compared to columnals (about 3 columnals per 1 aboral cup), as well as the poor preservation due to attrition and biocorrosion indicate a displacement of the ossicles that does not allow us to estimate average stalk length.

Occurrence. Early Ypresian (middle Ilerdian, NP 10–11), Corbières.

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 9. Variations in main quantitative characters related to columnal shape and aboral cups of P. doncieuxi suboblongus n. subsp. from Réqui. The coloured envelopes cover more than 90% of specimens; straight lines indicate values of H/D (left) and Hc/Dc (right) (in purple: specimens from Réqui, and, for comparison, in green: P. doncieuxi from the Fontcouverte sites, except for Lavade, in red: P. lavadensis n. sp. from Lavade). Dp and red bar: range of stalk insertion diameter (= proximalmost stalk diameter) measured on aboral cups from Réqui. Values in mm, except for ratios (black straight lines). See Fig. 2 for abbreviations.