Pseudoconocrinus doncieuxi ( Roux, 1978a )

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 : 212-218

Pseudoconocrinus doncieuxi ( Roux, 1978a)

Figs. 5–7 , 8A–F, J–Q

Synonymy. Conocrinus pyriformis Doncieux, 1911: 157 ; Conocrinus thorenti Doncieux, 1911: 159 ; Conocrinus sp. Doncieux, 1911: 159 ; Conocrinus doncieuxi Roux, 1978a: 797–800 , figs 1, 2a.—1978b: 219, 226, fig. 12a, pl. 2-2.— Roux and Plaziat, 1978: 301; Pseudoconocrinus doncieuxi Roux et al., 2019: 66–67 , 79, fig. 8A–F, K–N.

Type material. The type series is housed in the palaeontological collections of the Claude Bernard University Lyon 1, and comprises 20 aboral cups and 20 columnals ( UCBL-FSL 170248 a) selected from a sample of 160 aboral cups and 460 columnals ( UCBL-FSL 170248 ) with the mention “Fontcouverte, sud-ouest du village” (i.e., the outcrop here called Les Lanes Sud). The holotype is an aboral cup whose adoral face was illustrated in the original paper ( Roux 1978a, fig. 2a) .

Material examined. Three aboral cups from the Bories Collection ( Fig. 6A–F, I ); 4 columnals from the Plaziat Collection ( Fig. 8J–M, O–Q ). Numerous columnals and aboral cups from various sites in the Martinez Collection (see Table 2), numerous brachials ( Figs. 6J–T and 7 ) and rhizoid fragments from the Martinez Collection from the ancient Tuilerie de Fontcouverte and Ribaute; specimens here figured are housed at the MNHN (see catalogue numbers, Tables 1, 3–4).

Type stratum. Lower blue marls of middle Ilerdian age (early Ypresian), NP10–lower NP11.

Type locality. Les Lanes Sud, southwest of the village of Fontcouverte (Aude).

Diagnosis. Aboral cup of highly variable shape (usually 1.2<Hc/Dc<2.8, which can vary from 1.0 to 5.0), variation due to basal height without correlation with Dc growth; maximum value of Dc in aboral third or at mid-height, more rarely proximally; always Dr <Dc, Dc reaching 5 mm and Hc 15. 3 mm; constriction at radial/basal boundary or proximally absent or weak; adoral face of radial circlet forming more or less marked pyramid, central depression often star shaped, Dd <0.26 Dr; sutures between basals occasionally conspicuous even in large specimens, aboral face with stalk insertion of variable size (Dp reaching 0.54 Dc, sometimes <0.30). Arms divided at IBr2ax, as high (sometimes less) as wide, synostosis at IBr1+2ax with lumen of neural canal subcircular, presence of small IIBrax substantially higher than wide, free arms composed mainly of succession of brachial pairs with alternating synostoses and muscular synarthries. Very rare flat-facetted discoid columnals of proxistele, less than half of other columnals with mid-height swelling, most often moderate; ~50% of the columnals with rhizoid sockets, less than half with 2 sockets (rarely 3) and H<D; columnals without rhizoid most often with H/D>1.5.

Description. Roux (1978a, b) presented a brief description, outlining the main quantitative characters of the aboral cups and columnals belonging to historical specimens from MNHN and UCBL-FSL collections and more recent collections by J.C. Plaziat. Here we provide additional data on the aboral cups, particularly on their extremes in variation. Screenwashing at the ancient Tuilerie de Fontcouverte and its immediate surroundings has provided numerous other ossicles, notably brachials and rhizoids.

Aboral cups ( Figs. 5 , 6A–I , 8A–F ; Table 3): Hc up to 15.5 mm, but usually <8.5 mm, equal Dc or up to five times that ( Fig. 5 ), shape variation due to lengthening of basal circlet independent of diameter growth, tendency to elongation increasing during growth in most specimens with 2.5<Dc<4.0 mm ( Fig. 5 ), Dc usually <4.0 mm and rarely reaching 5.0 mm; maximum value of Dc in aboral third or at mid-height ( Fig. 6A, D ), more rarely above ( Fig. 6H–I ), usually Dr/Dc<0.8, always Dr<<Dc; constriction at radial-basal transition or at level of radial circlet absent or weak; adoral face of radial circlet forming more or less marked pyramid, each articular facet mainly occupied by ligament areas, more or less rectilinear interradial ridges sometimes terminated by abrupt widening on inner end ( Fig. 6F ), more or less star-shaped central depression with Dd/Dr<0.26; sutures between basals may be conspicuous even in large specimens ( Fig. 6A ); aboral face with insertion of stalk generally well defined, often relatively large but highly variable (0.3<Dp/Dc<0.5, 0.35<Dp/Dr<0.7).

Brachials ( Figs. 6J–T , 7A–R ; Table 4): Quantitative characters of different types of brachials given in Table 4. Robust axillary primibrachial (IBr2ax) ( Fig. 6P ), subpentagonal with concave aboral distal edges, often almost as wide as high ( Fig. 6J, M ), sometimes clearly wider than high with H/W’ down to 0.65, pentagonal shape little marked in juveniles, well developed distal muscular synarthries forming marked protuberance at junction on the inner brachial side ( Fig. 6J, O–P ); subrectangular axillary secundibrachials (IIBr2ax) with angle formed by distal articular facets poorly marked ( Fig. 6R–S ), aboral ligamentary depressions of distal muscular synarthries deep and narrow ( Fig. 6T ), wide adoral groove ( Fig. 6Q ); proximal synostoses of axillary concave with circular neural canal. Non-axillary brachials with muscular synarthry on one side and synostosis with circular neural canal on other, aboral (external) surface often with discrete ornamentation ( Fig. 7I ); no IBr1 observed; IIBr1 with adoral (inner) face concave probably corresponding to overhanging of adjacent tegmen ( Fig. 7C, G ), largest IIBr1 observed ( Fig. 7A–C ) with narrow, asymmetrical proximal facet, reduced muscular areas and slightly oblique fulcral ridge; other IIBr smaller, less asymmetrical, distal facet more or less concave with occasional trace of axial fulcral ridge ( Fig. 7E–F ); one IIBr probably belonging to second pair of pinnuless IIBr (IIBr3+4), with rectangular (external) aboral face, concave adoral (internal) face forming broad groove, synostosal facet almost flat with circular axial canal ( Fig. 7D ); other non-axillary brachials ( Fig. 7J–R ) with flat synostosal facet of width less than that of muscular articular facet, some IIBr with Wd> 1 mm, H and pinnule insertion> 0.6 mm; smallest Br (IIIBr?) with Wd<0.9 mm, H<0.6 mm and pinnule socket <0.45 mm.

Columnals ( Fig. 5 , 8J–Q ): Proximal columnals present but rare, some remaining attached to base of aboral cup ( Figs. 6E , 8C ), discoid with flat facet, D 1.49–1.84 mm, H/D 0.36–0.59. Mesistele columnals without rhizoids substantially higher than wide, H/D>1.2, usually 1.0<D<2.5 mm; most often minimum diameter at mid-height ( Fig. 8J ), fulcral ridge with more or less regular secondary crenularium separated by axial groove ( Fig. 8K ). Columnals of distal part of stalk recognisable by rhizoid sockets starting from one or both ends of fulcral ridge of proximal facet ( Fig. 8L–M ); H/D<1.3 decreasing to 0.6, usually 25<D<34 mm, largest columnals with H 50 mm and D 40 mm; columnal body developing bulge with diameter greater than d ( Fig. 8M ), rarely than D ( Fig. 8O ), ~25% of columnals with well-marked bulge; fulcral ridge with regular secondary crenularium in parallel lines separated by groove or more rarely by dense calcite band ( Fig. 8P–Q ); few distal columnals showing depressed ligament area on each side of fulcral ridge segments ( Fig. 8N ); pluricolumnals of 2 to 4 ossicles with well-developed cirrus sockets as well as ~50% of isolated columnals. Rhizoids similar to those described below for P. lavadensis n. sp.

Remarks. Most non-axillary brachials have a synostosial facet, which indicates that the arms were mainly composed of a succession of brachial pairs, like in most extant rhizocrinids, at least proximally. About a quarter of brachials collected do not have a pinnule socket, the first pinnule was carried by an IIBr which was likely located beyond the two proximal pairs. As IIBrax are relatively rare and small, second divisions appear to be occasional and also located beyond the second pair of IIBr. Within the morphospace describing the shape of aboral cups, a group of specimens is set aside and attributed herein to a new subspecies, P. doncieuxi suboblongus n. subsp. Aboral cups within this variety tends to be very elongated and display a general oblong shape. Moreover this is the only shape collected in some of the explored outcrops ( Table 2, see below).

Screenwashing at the Tuilerie de Fontcouverte has provided 387 columnals (excluding proxistele columnals) and 7 aboral cups, i.e., an average of 55 columnals per individual suggesting a stalk length of approximately 165 mm. Half of these columnals have well-developed rhizoid sockets and correspond to the distal stalk. The erect part should, on average, be in the order of 80 to 90 mm (about 30 columnals excluding proxistele). Gislén (1927) described a population of the extant rhizocrinid, Democrinus japonicus , with one phenotype converging with that of P. doncieuxi : highly variable aboral cup with Hc/Dc up to 4.5, proxistele restricted to the transition with the mesistele, rhizoids appearing near the thirtieth columnal for preserved stalk lengths varying from 50 to 100 mm with 35 to 61 columnals articulated by synarthries (H/D ~1.6–1.7).

Occurrence. Early Ypresian (Ilerdian, NP10–11), north Pyrenean basin especially in Corbières ( Roux and Plaziat 1978; present study) and south Pyrenean basin of Graus-Tremp ( Gaemers 1978; Leturcq 1999).

Figures

FIGURE 5. Variations in the shape of columnals and aboral cups of Pseudoconocrinus doncieuxi (sites near Fontcouverte, with the exception of Lavade). The colour envelopes cover more than 90% of specimens; black lines indicate the values of H/D (left) and Hc/Dc (right). Values in mm, except for ratios (black straight lines). See Fig. 2 for abbreviations.

FIGURE 6. Aboral cups and axillary primibrachials of Pseudoconocrinus doncieuxi. Provenance: A–I, M–T: Tuilerie de Fontcouverte, J–L: Ribaute. A–C: MNHN.F. A69944a, A: lateral view showing sutures between basals, B: oblique view of radial circlet, C: distal face of radial circlet; D–F: MNHN.F.A81993, D: oblique view showing distal face of radial circlet, E: aboral face with proximalmost columnals preserved; F: distal face of radial circlet; G–H: MNHN.F.A81996, G: view of small stalk insertion, H: slightly oblique lateral view showing radial circlet; I: MNHN.F.A69944b, slightly oblique lateral view showing distal face of radial circlet; J–L: MNHN.F.A81997, IBr2ax of large specimen; J: external view, K: distal view showing muscular synarthrial facets, L: oblique view showing concave proximal synostosial facet; M–T: MNHN.F.A81994, axillary brachials. M–P: IBr2ax of medium-sized specimens, M: external view, N: inner/lateral view of same Br, O–P: another Br, O: inner view, P: inner/lateral view; Q–T: juvenile IBr2ax or IIBrax, Q: oblique inner-proximal view, R–S: another Br, R: external view, S: inner view, T: distal muscular synarthrial facets. Scale bars equal 1 mm (A–P) and 0.5 mm (Q–T).

FIGURE 7. Non-axillary secundibrachials of Pseudoconocrinus doncieuxi from the Tuilerie de Fontcouverte (MNHN. F.A81995). A–C: IIBr1 of a large individual, A: proximal muscular synarthry, B–C: distal synostosis, B: oblique external view, C: oblique inner view; D: IIBr3, distal synostosis, oblique external view, arrow indicating inner axial gutter; E–F: IIBr, distal face with rudimentary axial ligament synarthry, E: oblique lateral view; G–I: IIBr1 of medium-sized individual, G: oblique lateral-distal view, H: oblique lateral-proximal view, I: detail of ornamentation of external surface; J–N: proximal IIBr without pinnular insertion, J: external oblique view of pair of IIBr joined by synostosis indicated by arrow heads, K–N: brachials of dissociated pairs, K: oblique view of muscular synarthrial facet, L–M: oblique views of synostosial facet, N: lateral view; O–Q: IIBr with pinnular insertion, O: episynostosial IIBr, P–Q: free Br with two muscular synarthrial facets, Q: detail of pinnular insertion; R: proximal muscular synarthrial facet of hyposynostosial IIBr. Scale bar equals 0.5 mm, except in I, J and Q, where it equals 0.25 mm.

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).