Metacrinus berthei
Creators: name: Roux, Michel
name: Philippe, Michel
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Crinoidea
Isocrinida
Pentacrinitidae
Metacrinus
Metacrinus berthei

description: Metacrinus berthei (Nicolas, 1897)
Figs. 4–5 (morphotype B), 6, 8–12A–C; Tables 5–7
Synonymy. Pentacrinus berthei Nicolas, 1897: 79–80, fig. 12; Pentacrinus miocenicus de Loriol, 1897: 127–129 pars., figs. 15–16; Pentacrinus berthei Nicolas, 1898: 396–398, fig. 1; Pentacrinus berthae Lambert, 1899: 122; Pentacrinus berthei Biese and Sieverts-Doreck, 1939: 45.
Type material. The original description (Nicolas 1897) is based on a type series comprising 1 distal stalk fragment (Fig. 8A–B), 2 Plc (Fig. 8E–F) and 2 isolated IN (Fig. 8C–D). There was no indication of the original collector. The Nicolas collection housed at UCBL-FSL comprises 2/3 of the stalk fragment (UCBL-FSL 19.099 - 1) (Fig. 8B) and 1 Plc (UCBL-FSL 19.099 - 2) (Fig. 8F). In the Châtelet collection housed at the Requien Museum in Avignon, we found the proximal third of the stalk fragment (MRA 3.009.192) (Fig. 7A) and the two isolated IN (MRA 3.009.194.1-2). The stalk fragment (Fig. 8A +B) is here designated as syntype 1, the Plc (Fig. 8F) as syntype 2, the first isolated IN (Fig. 8C) as syntype 3, and the second (Figs. 8D, 9A) as syntype 4. The syntype 5 (Fig. 8E) can be considered lost.
Etymology. Nicolas dedicated this species to Berthe Sinard who firstly suggested that the Miocene environment at Les Angles was deeper than previously interpreted (Sinard 1892).
Material examined. Les Angles (10 Plc, 21 isolated IN, 2 N); Avignon (111 Plc, 613 isolated IN, 49 isolated N, numerous Br and Ci), Le Barroux (9 Plc, 1 IN); Beaucaire (4 Plc, 10 isolated IN), Entrechaux Ferme Pie (2 Plc, 25 isolated IN, 1 N), Entrechaux Pont Saint-Michel (1 IN), Notre-Dame du Château (22 Plc, 19 isolated IN, 2 isolated N), Picabrier (15Plc, 106 isolated IN, 17 isolated N), Vedènes (1 Plc, 12 isolated IN, Brs), Tarascon (9 Plc).
Type stratum. Late Burdigalian.
Type-locality. Ancient quarries, Les Angles (Gard).
Emended diagnosis. Pentagonal columnals with often rounded edges, most proximal internodals and nodals slightly star-shaped, frequent inter-articular pores; maximum diameter 6.7 mm, often very variable height within one nodotaxis even distally, maximum number of internodals per nodotaxis 19, average 16–17; symplexies with closed petaloid zones separated by marked grooves, number of crenulae per petaloid zone 15–16 rarely 17, crenulae of about the same size, ligament areas usually twice as long as wide (often less); nodals with oval cirrus sockets not exceeding their height; cryptosymplexy with regular symmorphy often marked and discrete marginal crenularium, facets without interpetaloid furrow; ornamentation absent or discrete, sometimes small knob or ridge at mid-height giving a more rounded to subcircular columnal section. Primibrachiales in number equal or superior to 6 with large pinnular sockets, IBr1+2 synostosis with aboral marginal crenularium, IBr3+4 synostosis smooth with aboral growth lines.
Description of syntypes. Distal stalk fragments, IN pentagonal or subpentagonal, N slightly starry. Syntype 1: L 47.4 mm composed of 1 complete Ndx of 19 IN (L 30.5 mm) + 1 incomplete Ndx of 15 IN (Fig. 8A–B), Ndx with marked curvature, no inter-articular pores, proximal end of complete Ndx with smooth, slightly convex infraN facet, N with 4 cirrals connected; internodal D reaching 6.5 mm proximally and decreasing to 6.2 mm at distal end; proximal Ndx with higher IN alternating with slightly lower IN of similar D; nodal H reaching a maximum of 2.2 mm; smaller differences in intermodal H in distal Ndx; smooth and slightly convex columnal side faces. Syntypes 2 and 5: incomplete curved Ndx (8 and 13 IN respectively) with distal N, similar in morphology to syntype 1, differences in H and D between IN more pronounced in syntype 2 (Fig. 8F). Syntypes 3 and 4 (Fig. 8C–D): IN with the same characters (D 6.1 mm, H/D 0.26, maximum Cr/PZ 17), syntype 4 moderately star-shaped with PZ still slightly open (Fig. 9A).
Other specimens from Les Angles. Plc with at most 7 IN; 60% of symplexies with 16 Cr/PZ, only one case with 17, all PZ closed, internal crenularium poorly differentiated, cryptosymplexy preservation not allowing a detailed description. Quantitative characters including type series in Table 7.
Specimens from Notre-Dame du Château. Quantitative characters including 2 Plc from type series of Pentacrinus miocenicus (de Loriol 1897, figs. 15–16) given in Table 7; most Co pentagonal; Plc with maximum of 14 successive IN, ~50% with inter-articular pores more or less marked; most proximal Plc (de Loriol 1897, fig. 16) with columnal H markedly unequal, inter-articular pores widely open, IN star-shaped and a single N without cryptosymplexy despite cirrus sockets being well-developed; another proximal Plc (de Loriol 1897, fig. 15) more distal with IN becoming subpentagonal (Fig. 9B–C); oval cirrus sockets 1.7 times wider than high and tangential to N facet borders (Fig. 9D); all Co with smooth sides. Symplexies most often (62%) with 15–16 Cr/PZ, PZ closed, inner crenularium poorly differentiated. Distal N facet (cryptosymplexy) smooth, slightly concave with 7–8 small marginal Cr/PZ.
Specimens from Avignon. Exceptional variety of Br types preserved (Fig. 10); 9 IBr identified with maximum D 5.17 mm (mean 4.3 mm), muscular synarthries with moderately developed muscle areas and fulcral ridge perpendicular to dorso-ventral axis (Fig. 10C–D), IBr1+2 synostosis with narrow marginal symplexial crenularium (Fig. 10A–B), IBr2 with proximal synostosial facet slightly convex and bearing a large pinnule socket (Fig. 10D–E), IBr4+5 synostosis with aboral growth lines underlined by a thicker stereom (Fig. 10G, J); all Brax with proximal muscular synarthry, fulcral ridges of distal synarthries forming acute angle (Fig. 10H), IBrax with 0.65<H/D<0.87; free IIBr or IIIBr most abundant with oblique fulcral ridge, muscle areas remaining small only in the most proximal IIBr (Fig. 10I) and lengthening distally (Fig. 10K–L), pinnule socket on IBr and IIBr remaining large and limiting width of adjacent muscle area on distal Br facet (Fig. 10K), distal IIBr or IIIBr with D<2.5 mm very asymmetrical (Fig. 10L) allowing great flexibility of arm movements. External columnal morphology variable (quantitative characters given in Table 6, Fig. 11); symplexies most often (62%) with 13–14 Cr/PZ; differences in columnal H remaining small in distal Plc from young individuals but increasing during individual growth (Fig. 11A–C); some small Plc with more or less marked bulges on the lateral faces (Fig. 11A–B) becoming less frequent or smooth with growth (Fig. 11F), either widening and making IN subcircular (Fig. 11H) or splitting into granules forming a discrete ornamentation; juvenile Co with H/D>0.5 having subcircular section and symplexies of open PZ (Fig. 12C), N with ligament areas wide (Fig. 11E), cirrus sockets subcircular and occupying only 2/3 of nodal H (Fig. 11D); cirrus sockets becoming more oval with growth (Fig. 11C) and tangential to nodal facet borders (Fig. 13J); 1 N abnormal with only a single cirrus socket; ~50% of symplexial facets having IPZ with narrow and well-marked grooves extended to inner crenularium (Fig. 11G); cryptosymplexies often well preserved, distal N facet (Fig. 11J) moderately concave with a more or less developed marginal crenularium, proximal infraN facet (Fig. 11K) convex with more attenuated marginal crenularium and IPZ without axial groove, axial canal filled by dense secondary stereom with a 5-lobed secondary lumen (Fig. 11L); two Plc having symplexies with four PZ, one of irregular subcircular section (Fig. 12A), the other of quadrangular section (Fig. 12B).
Specimens from other sites. In Beaucaire, Co and Plc belonging to individuals of sizes like in Avignon (see Table 6), one complete Ndx 13.3 mm long with 13 IN; qualitative characters as in Avignon except side faces smooth without ornamentation. In Tarascon, Plc with maximum of 10 successive IN, 5.16<D<7.00 and 0.15<H/D<0.55, ~50% of symplexies with conspicuous furrow at the IPZ axis, external morphology very close to Plc from Les Angles. Among 9 Plc from Le Barroux, 2 with N located at middle length (Fig. 9E), only 1 Plc with 8 successive IN, longest Plc with discrete inter-articular pores and IN of various D and H; symplexies with 13 to 16 Cr/ZP; all pentagonal IN with more or less convex external faces; N with cirrus sockets 1.6 times wider than high with two well-developed culminae (Fig. 9E); 1 N with 4 cirrus sockets. In Picabrier (quantitative characters given in Table 5), symplexies most often (52%) with 15–16 Cr/PZ, two Plc with 10 successive IN; most IN with qualitative characters (Fig. 11F–I) identical to those in Avignon, ~30% of IN with lateral faces more convex in center and more prominent angles (Fig. 11H–J), sometimes forming rougher angles on some Plc (Fig. 11K); cryptosymplexies rarely well-preserved, symmorphy of variable amplitude, patches of denser stereom in place of symplexal crenularium pre-existing articulation ankylosis, ZIP without axial grooves (Fig. 9J). Co from other sites with Co characters entering in main field of variation of those from Picabrier. One IBrax (possibly IBr4ax) with proximal synostosial facet from Vedène.
Remarks. The two species P. berthei and P. miocenicus were published in the same year of 1897. Pentacrinus berthei was based on distal stalk fragments that clearly distinguish it from the species gastaldii, one of them with a complete Ndx, while the type-series of P. miocenicus contains specimens belonging to two different species. In addition, the two Plcs belonging to berthei figured by de Loriol (1897) are very proximal showing symplexies with specific characters incompletely developed. Therefore, we have given priority to the species whose type-series allows an unambiguous determination. Nicolas (1897, 1898) refers to another species, Pentacrinus allardi, found in Avignon molasse and from Beaucaire. Without description or figuration, it remains a nomen nudum. It most probably corresponds to our morphotype C. Metacrinus mazarronensis Roux and Montenat, 1977 is very close to M. berthei. It differs in having ZIP of cryptosymplexies with axial groove. Metacrinus berthei and M. mazarronensis share symplexies with characters very close to those of the extant species M. interruptus Carpenter, 1884 from the northwestern Pacific (Roux 1981, pl. 6–3 and pl. 7–5).
Occurrence in southeastern France. Avignon (Palais des Papes), Les Angles (ancient quarry), Le Barroux, Beaucaire (ancient quarry), Caumont-sur-Durance (Picabrier), Entrechaux (Pont Saint-Michel), Entrechaux (Ferme Pie, marnes de Faucon), Saint-Etienne du Grès (Notre-Dame du Château), Tarascon, Vedènes, and possibly Villeneuve-lès-Avignon (Pierre Longue) and Saint-Rémy de Provence (= P. miocenicus after Joleaud 1907). Late Burdigalian-Early Langhian.
description: Published as part of Roux, Michel & Philippe, Michel, 2021, Early Miocene stalked crinoids (Echinodermata) from the southern Rhodanian basin (southeastern France). Paleoenvironments and taxonomy, pp. 301-331 in Zootaxa 5052 (3) on pages 317-323, DOI: 10.11646/zootaxa.5052.3.1, http://zenodo.org/record/5572077