Jurienella, Pictet & Bulot, 2025
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publication ID |
https://doi.org/10.1186/s13358-024-00343-4 |
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persistent identifier |
https://treatment.plazi.org/id/AC080812-335F-1602-3EDE-96C1886D8C66 |
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treatment provided by |
Felipe |
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scientific name |
Jurienella |
| status |
gen. nov. |
Jurienella gen. nov. peyroulensis ( Atrops, Autran &
Reboulet, 1996)
Fig. 9A–E View Fig
1977 Acanthodiscus ? sp. inc.—Tieuloy, p. 119, pl. 7, fig. 5
1996 Breistrofferella n. sp. 1—Reboulet, p. 121, pl. 14, fig. 13.
1996 Breistrofferella n. sp. 2—Reboulet, p. 122, pl. 14, fig. 9a, 9b, 14a, 14b, 20.
*1996 Breistrofferella peyroulensis —Atrops, Autran & Reboulet, p. 721, photo 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12.
1996 Breistrofferella varappensis (Baumberger) -Atrops,
Autran & Reboulet, photo 15, 16, 17, 18.
Material. A cast (cat no MGL.110469, Fig. 9B–D View Fig ) and two original specimens (cat no MGL.110468, Fig. 9A View Fig and MGL.110470, Fig. 9E View Fig ) are housed in the Muséum des sciences naturelles at Lausanne. Tey originate from the upper part of the Hauterive Member of the Pateroux section, Gorges de l’Orbe ( Vaud, Suisse).
Diagnosis. As for the genus.
Description. Specimen MGL.110468 ( Fig. 9A View Fig ) is a small-sized calcareous mould (D = 29.94 mm) of grey colour. Suture lines are not visible. Te specimen is moderately evolute (U/D = 0.27). Te whorl section is subquadrate in inner whorls to polygonal and slightly higher than wide (Wb/Wh = 0.81) for outer whorls. Te venter is large, slightly rounded and smooth. Te umbilical wall is vertical and low, while the umbilical shoulder is formed by a rounded angle. Te ribs begin on the umbilical wall where they are radial, developing a pinched bulla on the shoulder. Ten then become falcate, slightly provers up to the middle of the flank, where they make a concave inflection in the upper part of the flanks. Te inflection point is marked by discreet node, from which it bifurcates in two secondary ribs. In some instances, an intercalated rib is present, originating from a bifurcation of the umbilical bulla or from the umbilical shoulder. All ribs join the ventro-lateral border with the same strength, forming a small spiny bulla with a relatively radial direction. Te suture line is not visible.
Specimen MGL.110469 ( Fig. 9B–D View Fig ) is a small-sized calcareous mould (D = 44 mm) of grey colour, slightly crushed laterally. Te phragmocone and the body chamber are preserved. Te specimen is moderately evolute (U/D = 0.33). Te whorl section is subquadrate to polygonal, slightly higher than wide (Wb/Wh = 0.91). Te venter is large, relatively flat and smooth. Te umbilical wall is vertical and low and the umbilical shoulder is formed by a rounded angle. Te ribs begin on the umbilical wall, where they are radial, developing a pinched bulla on the shoulder. Tey then become falcate, slightly provers up to the middle of the flank, where they make a concave inflection in the upper part of the flanks. Te inflection point is marked by a discreet node. Occasionally, an intercalating rib is present, while on the body chamber, it is present between each pair of ribs, sometimes originating from a bifurcation of the umbilical bulla or more frequently from the middle of the flank. All ribs join the ventrolateral border with the same strength, where they form a small spiny bulla with a relatively radial direction. During the ontogeny, a bifurcation emerges from the lateral node. On the body chamber, the primary ribs exhibit a pronounced reinforcement on the lower half of the flank and form a distinct V-shaped chevron on the venter. Te venter becomes well rounded at the end of the body chamber. Te suture line is not visible.
Specimen MGL.110470 ( Fig. 9E View Fig ) is a small-sized calcareous mould (D = 45.9 mm) of grey colour, more heavily crushed laterally. Only the end of the phragmocone and the body chamber are preserved. Te specimen is moderately evolute (U/D = 0.31). Te whorl section is subquadrate to polygonal, slightly higher than wide (Wb/ Wh = 0.93). Te venter is large, relatively flat and smooth. Te umbilical wall is vertical and low, while the umbilical shoulder is formed by a rounded angle. Te ornamentation is identical to that observed in the previous specimen, with the exception of the absence of intercalated ribs. Te suture line is not visible.
Measurements (in mm):
Te U/D and Wb/Wh ratios are equivalent to those of the type specimens, which are U/D = 0.27 to 0.33 and Wb/Wh = 0.82 to 0.95.
Discussion. Te internal whorls of Jurienella peyroulensis gen. nov. exhibit certain similarities with the juvenile whorls of the genus Acanthodiscus (see Atrops et al., 1996; Reboulet, 2002) with a relative isometric whorl section, with a rough ornamentation composed by coarse, rigid and bituberculated primary ribs, growing from the umbilical wall up to mid-flank, and bifurcating from the mediolateral tubercle in two secondary ribs ending with a ventro-lateral tubercle. Beyond a diameter of 3–4 cm, Acanthodiscus can be distinguished from Jurienella gen. nov. by the presence of lateral tubercles ( Fig. 10 View Fig ). Conversely, Jurienella gen. nov. rapidly loses its tuberculiform elevations.
Te species was initially attributed to the genus Breistrofferella due to its identical body chamber in mature specimens, as well as for the ogival whorl section and the ornamentation style, which is characterised by falcate ribbing with primary ribs growing from an umbilical bulla and which is projected forward near the venter, alternating with shorter intercalated ribs arising in the middle of the flanks ( Fig. 10 View Fig ). Nevertheless, the genus Jurienella gen. nov. is readily distinguishable from Breistrofferella by its phragmocone, which is subquadrate to polygonal, nearly isometric, and exhibits a nearly radial direction of the bullae on the ventrolateral shoulder. At same size, the internal whorls of Breistrofferella exhibit significant differences in whorl shape and ornamentation. Tey are subrectangular, higher than wide and smooth, sometimes exhibiting constrictions crossing the venter. It is only in the body chamber, and particularly at the end of it, that the two genera share their sections and ornamentations. Tis is characterised by a subangusti-umbilical and ovoid section and by ribs becoming strongly projected forward and tending to join the venter with a marked chevron.
Te Jura specimens exhibit a robust morphology particularly that is similar to the paratype n° JU4 (coll. Davoux) figured by Atrops et al., (1996, figs. 5–6) from Peyroules. Tis specimen displays a greater number of intercalated ribs on the body chamber .
Stratigraphic and geographic distribution. As for the genus.
| MGL |
Musee Geologique de Lausanne |
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