Metacrinus berthei ( Nicolas, 1897 )

Roux, Michel & Philippe, Michel, 2021, Early Miocene stalked crinoids (Echinodermata) from the southern Rhodanian basin (southeastern France). Paleoenvironments and taxonomy, Zootaxa 5052 (3), pp. 301-331 : 317-323

publication ID	https://doi.org/ 10.11646/zootaxa.5052.3.1
publication LSID	lsid:zoobank.org:pub:1EB14EF1-E205-4E37-85F9-DFD97BE93058
DOI	https://doi.org/10.5281/zenodo.5578560
persistent identifier	https://treatment.plazi.org/id/AD1B87AD-FFF3-CC6A-FF25-066BFE54FD36
treatment provided by	Plazi
scientific name	Metacrinus berthei ( Nicolas, 1897 )
status

Treatment

Metacrinus berthei ( Nicolas, 1897)

Figs. 4–5 View FIGURE 4 View FIGURE 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 View FIGURE 8 ), 2 Plc ( Fig. 8E–F View FIGURE 8 ) and 2 isolated IN ( Fig. 8C–D View FIGURE 8 ). 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 View FIGURE 8 ) and 1 Plc ( UCBL-FSL 19.099 - 2 ) ( Fig. 8F View FIGURE 8 ). 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 View FIGURE 7 ) and the two isolated IN ( MRA 3.009.194.1-2). The stalk fragment ( Fig. 8A View FIGURE 8 +B) is here designated as syntype 1, the Plc ( Fig. 8F View FIGURE 8 ) as syntype 2, the first isolated IN ( Fig. 8C View FIGURE 8 ) as syntype 3, and the second ( Figs. 8D View FIGURE 8 , 9A View FIGURE 9 ) as syntype 4. The syntype 5 ( Fig. 8E View FIGURE 8 ) 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 View FIGURE 8 ), 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 View FIGURE 8 ). Syntypes 3 and 4 ( Fig. 8C–D View FIGURE 8 ): 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 View FIGURE 9 ).

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 View 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 View 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 View FIGURE 9 ); oval cirrus sockets 1.7 times wider than high and tangential to N facet borders ( Fig. 9D View FIGURE 9 ); 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 View FIGURE 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 View FIGURE 10 ), IBr1+2 synostosis with narrow marginal symplexial crenularium ( Fig. 10A–B View FIGURE 10 ), IBr2 with proximal synostosial facet slightly convex and bearing a large pinnule socket ( Fig. 10D–E View FIGURE 10 ), IBr4+5 synostosis with aboral growth lines underlined by a thicker stereom ( Fig. 10G, J View FIGURE 10 ); all Brax with proximal muscular synarthry, fulcral ridges of distal synarthries forming acute angle ( Fig. 10H View FIGURE 10 ), 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 View FIGURE 10 ) and lengthening distally ( Fig. 10K–L View FIGURE 10 ), pinnule socket on IBr and IIBr remaining large and limiting width of adjacent muscle area on distal Br facet ( Fig. 10K View FIGURE 10 ), distal IIBr or IIIBr with D<2.5 mm very asymmetrical ( Fig. 10L View FIGURE 10 ) allowing great flexibility of arm movements. External columnal morphology variable (quantitative characters given in Table 6 View TABLE 6 , Fig. 11 View FIGURE 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 View FIGURE 11 ); some small Plc with more or less marked bulges on the lateral faces ( Fig. 11A–B View FIGURE 11 ) becoming less frequent or smooth with growth ( Fig. 11F View FIGURE 11 ), either widening and making IN subcircular ( Fig. 11H View FIGURE 11 ) 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 View FIGURE 12 ), N with ligament areas wide ( Fig. 11E View FIGURE 11 ), cirrus sockets subcircular and occupying only 2/3 of nodal H ( Fig. 11D View FIGURE 11 ); cirrus sockets becoming more oval with growth ( Fig. 11C View FIGURE 11 ) and tangential to nodal facet borders ( Fig. 13J View FIGURE 13 ); 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 View FIGURE 11 ); cryptosymplexies often well preserved, distal N facet ( Fig. 11J View FIGURE 11 ) moderately concave with a more or less developed marginal crenularium, proximal infraN facet ( Fig. 11K View FIGURE 11 ) 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 View FIGURE 11 ); two Plc having symplexies with four PZ, one of irregular subcircular section ( Fig. 12A View FIGURE 12 ), the other of quadrangular section ( Fig. 12B View FIGURE 12 ).

Specimens from other sites. In Beaucaire, Co and Plc belonging to individuals of sizes like in Avignon (see Table 6 View 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 View FIGURE 9 ), 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 View FIGURE 9 ); 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 View FIGURE 11 ) identical to those in Avignon, ~30% of IN with lateral faces more convex in center and more prominent angles ( Fig. 11H–J View FIGURE 11 ), sometimes forming rougher angles on some Plc ( Fig. 11K View FIGURE 11 ); 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 View FIGURE 9 ). 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.