Pronucellopsis pacaudi, Merle & Pacaud & Ledon & Goret, 2024

Merle, Didier, Pacaud, Jean-Michel, Ledon, Daniel & Goret, Bernard, 2024, New Cenozoic Muricidae (Mollusca: Gastropoda) from Europe, Geodiversitas 46 (15), pp. 495-551 : 540-543

Pronucellopsis pacaudi Merle, Ledon & Goret, n. gen., n sp.

( Figs 24 ; 28H, I )

urn:lsid:zoobank.org:act:A1CD0282-7026-43EB-9992-5C106808B8CA

Murex (Muricopsis) multistriatus – Cossmann 1889: 129 [non Deshayes, 1865].

Jania (Muricopsis) multistriatus – Cossmann 1892: 69 [non Deshayes, 1865].

Muricopsis multistriatus – Cossmann & Pissarro 1911: pl. 36, fig. 169bis-5 [non Deshayes, 1865].

“ Murex ” multistriatus – Glibert 1963: 30, no. 8 [non Deshayes, 1865].

Trophonopsis multistriata – Le Renard & Pacaud 1995: 114, Ref.GA-169bis-5 [non Deshayes, 1865].

TYPE MATERIAL. — Holotype. France • Paris Basin , Marne , Châlons-sur-Vesle ; Sables de Châlons-sur-Vesle , biozone NP9; Paleocene (Thanetian); MNHN.F.J02587 (Cossmann coll.), figured specimen in Cossmann & Pissarro (1911: pl. 36, fig. 169bis-5), H: 22 mm ( Figs 24A, B ; 28H ).

Paratypes. France • 3 spm; same as for the holotype; MNHN.F.A90831 (Pacaud coll.) • 2 spm; idem; MNHN.F.A90832 ( MNHN coll.) • 7 spm; Paris Basin , Marne, Jonchery-sur-Vesle ; Paleocene (Thanetian); MNHN.F.A90833 (Staadt coll.) • 1 spm; idem; MNHN.F.A90829 (Pacaud coll.) ( Figs 24C, D ; 28I ) • 8 spm; idem; MNHN.F.A90830 (Pacaud coll.) • 6 spm; Paris Basin , Oise, Abbecourt (Bois-des-Godins), Paleocene (Thanetian); MNHN.F.A90834 (Pacaud coll.).

ADDITIONAL MATERIAL. — 1 spm; Paris Basin, Marne, Jonchery-sur-Vesle; Paleocene (Thanetian); UPMC (Munier-Chlamas coll.), figured specimen of Merle (1999: pl. 66, b-d) ( Fig. 24E, F ) • 1 spm; idem; MNHN-IM (Staadt coll.), figured specimen of Merle (1999: pl. 66, c-e) ( Fig. 24G, H ) • 5 spm; idem; MNHN.F.A91007 (Staadt coll.).

ETYMOLOGY. — Dedicated to Jean-Michel Pacaud (MNHN) who has for a long time observed that Murex multistriatus Deshayes, 1865 is a junior synonym of Fusus angusticostatus Melleville, 1843 (now Lyrofusus angusticostatus ).

TYPE HORIZON. — Sables de Châlons-sur-Vesle, biozone NP9, see Huyghe et al. (2015: fig. 2), Paleocene (Thanetian).

TYPE LOCALITY. — France, Paris Basin, Marne, Châlons-sur-Vesles, see Fritel (1910: 77).

DISTRIBUTION. — Paris Basin ( France), Paleocene (Thanetian), Sables de Bracheux and Sables de Châlons-sur-Vesle.

DESCRIPTION

Unknown protoconch. Teleoconch, up to 22 mm in height, up to 12.5 mm in width, subfusiform in profile, composed of seven whorls. High spire with rounded whorls. Last whorl up to 67% of total length. Apical angle 45°. Spiral sculpture with weak primary cords. First and second whorls: no spiral scultpure; third and fourth whorls, P1 weak. Fifth whorl: appearance of P2. Sixth whorl: appearance of s1. Last whorl and seventh whorl: P1 to P6, s1, s2, s3 and s4 (convex part of whorls), ADP, MP (siphonal canal). Axial sculpture on first to second whorl: not observed; third whorl: nine varices; fourth whorl: 14 varices; fifth whorl: 14-16 varices; sixth whorl: 11-19 varices; seventh whorl: 12-23. Varices finely lamellose. No spine on P1. Wide, ovate aperture up to 45% of diameter and up to 84% of length of last whorl (including siphonal canal). Posterior sinus deep, no shoulder sinus. Columella slightly angular. Columellar lip smooth, narrow and adherent. Outer lip with occasional denticles. D1 to D6 small, poorly developed, ID missing. Siphonal canal, short, open, up to 23% of aperture length, slightly dorsally recurved. Pseudoumbilicus narrow.

COMPARISONS Deshayes (1865) described Murex multistriatus and illustrated a specimen bearing a buccinid shape (pl. 88, fig. 810). In fact, this species is a junior synonym of Fusus angusticostatus Melleville, 1843 (now Lyrofusus angusticostatus ). However, Cossmann (1889) andCossmann & Pissarro (1911) confused this buccinoid species with a Thanetian Muricidae , which they mistakenly called Murex multistriatus . We described this species as Pronucellopsis pacaudi Merle, Ledon & Goret , n. gen., n. sp. It can be compared to Nucellopsis ponsi Merle,

2005c or N. plicatilis ( Deshayes, 1835) from the late Paleocene-early Eocene of the Paris Basin. Juveniles of P. pacaudi Merle, Ledon & Goret , n. gen., n. sp. share with these Nucellopsis a buccinid shape, but at the end of its growth P. pacaudi Merle, Ledon & Goret , n. gen., n. sp. displays a subfusiform shape with a high spire. The sculptures (both axial and spiral) of P. pacaudi Merle, Ledon & Goret , n. gen., n. sp. and the internal denticles of outer lip are also less developed. Because of its high spire, P. pacaudi Merle, Ledon & Goret , n. gen., n. sp. resembles some elongated Beyregrex sarroniensis ( Carez, 1879) , n. comb. but in B. sarroniensis n. comb. the spiral sculpture and the internal denticles are always more strongly developed. In addition, P1 spine is present in B. sarroniensis n. comb., whereas it is missing in P. pacaudi Merle, Ledon & Goret , n. gen., n. sp.

CONCLUSION

Based on new field material and a re-examination of collection material, this paper presents 24 new species, four new genera, one new subgenus and one new subfamily and therefore it deeply increases the knowledge of muricid paleobiodiversity. At species level, this paper highlights the strong diversity of the Eocene Timbellus which was underestimated. In addition, with 19 new species, this paper highlights the species richness of European Paleogene muricids and allows updating the diagram showing its evolution given by Merle et al. (2011: 36, fig. 21b). This update ( Fig. 29 ) illustrates the high muricid species richness in the Lutetian and confirms the Switch phase (Oligocene) which displays an increase of the proportion of Tethysian and Pacific species after the Eocene.

At supraspecific level, this paper improves the understanding of European Eocene-Oligocene basal muricids ( Pronucellopsis n. gen, Beyregrex Merle , n. gen, Pseudotrophonopsis Merle , n. gen., Nucellopsinae Merle , n. subfam.), that have, until now, been shoehorned uncomfortably into extant genera and subfamilies. Supraspecific taxonomy today relies heavily on molecular data, but this paper illustrates the value of using precise homologies basing data gathered on the careful observation of shell characters with which one can construct fossil phylogenies of groups that have no living descendants (see also Merle 2002, 2005b, c).

Figures

FIG. 24. — Spiral cords and internal denticles of the outer lip in Pronucellopsis pacaudi Merle, Ledon & Goret, n. gen, n. sp.: A, B, holotype, MNHN.F.J02587 (Cossmann coll.), Châlons-sur-Vesle, Marne, Paris Basin,France, late Paleocene (Thanetian), France; C, D, paratype, MNHN.F.A90829 (Pacaud coll.), Joncherysur-Vesle, Marne, late Paleocene (Thanetian); E, F, specimen UPMC (Munier-Chlamas coll.), from a drawing of Merle (1999: pl. 66, b-d), Châlons-sur-Vesle; G, H, specimen MNHN-IM (Staadt coll.),from a drawing of Merle (1999: pl. 66,c-e), Châlons-sur-Vesle.Scale bars:5 mm. Credits:A-D,P. Loubry (MNHN/CNRS).

FIG. 28. — New species of Flexopteron Shuto, 1969, Crassimurex (Pliocrassimurex) n. subgen., Nucellopsis Merle, 2005 and Pronucellopsis Merle, n. gen.: A, B, Flexopteron liancurtense n. sp.: A, holotype, MNHN.F.J02578 (Cossmann coll.), Liancourt-Saint-Pierre, France, Ypresian; B, paratype: MNHN.F.A77758 (Merle coll.), Liancourt-Saint-Pierre; C-E, Crassimurex (Pliocrassimurex) hirtus n. subgen., n. sp.: C, paratype (juvenile), MNHN.F.A77753, Molins del Rei, Spain, Zanclean; D, paratype, MNHN.F.A77752, Molins del Rei; E, holotype, MNHN.F.A77751 (MNHN coll.), Molins del Rei; F, G, Nucellopsis parisiensis n. sp.: F, holotype, MNHN.F.R64955 (Merle coll.), Saint-Witz (Le Guépelle), France, Bartonian; G, paratype, MNHN.F.A90963 (Faullummel coll.), Saint-Witz (Le Guépelle); H, I, Pronucellopsis pacaudi Merle, Ledon & Goret, n. gen., n. sp.: H, holotype, MNHN.F.J02587 (Cossmann coll.), Châlons-sur-Vesle, France, Thanetian; I, paratype, MNHN.F.A90829 (Pacaud coll.), Jonchery-sur-Vesle, France, Thanetian. Scale bars: 5 mm. Scale bar: A, B, 3 mm; C, D, F-I, 5 mm; E, 10 mm. Credits: P. Loubry (MNHN/CNRS).

FIG. 29. — Histogram showing the evolution of the species richness during the Paleogene in Western and Eastern Atlantic, Tethys and Austral Pacific (original histogram of Merle et al. (2011: 38, fig. 11B) updated from this paper, Pacaud 2018; Pacaud et al. 2017; Merle & Pacaud 2019; Kovács & Vicián 2019; Merle & Landau 2020; Ledon et al. 2023; Lozouet 2023). It illustrates the Switch phase with the increase of the proportion of the Tethysian and Pacific species.