Timbellus occidentalis Merle, Pacaud, Ledon & Goret, 2024, n. sp.
Creators: name: Merle, Didier
name: Pacaud, Jean-Michel
name: Ledon, Daniel
name: Goret, Bernard
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Neogastropoda
Muricidae
Timbellus
Timbellus occidentalis

description: Timbellus occidentalis n. sp.
(Figs 8 A-C; 26A, B)
urn:lsid:zoobank.org:act: 53A32E50-A05D-4A09-B8B1-6CA776FDC29F
Murex (Pterymurex) tripteroides – Cossmann & Pissarro 1901: 78, pl. 13, fig. 29 [non Lamarck, 1822].
Timbellus cf. tripteroides – Merle et al. 2011: 446, pl. 101, figs 1, 2.
TYPE MATERIAL. — Holotype. France • Normandy, Manche, Fresville; Calcaire de Fresville; middle Eocene (uppermost Lutetian); MNHN.F.A90533 (ex A24100 ex galerie de zoologie coll., Le Marchand coll.), H: 20 mm (Figs 8A, B; 26A).
Paratypes. France • 1 spm; same as for the holotype; MNHN.F.A90534 (ex A24100 ex galerie de zoologie coll., Le Marchand coll.) • 4 spm; idem; MNHN.F.B63570 (de Morgan coll.) • 1 spm, MNHN.F.A90532 (de Morgan coll.) • 1 spm; Normandy, Manche, Hautteville-Bocage; middle Eocene (upper Lutetian); MNHN.F.A90531 (ex B63609, de Morgan coll.) • 1 spm; idem; MNHN.F.B63609 (de Morgan coll.) • 35 spm; idem; MNHN.F.B63610 (de Morgan coll.) – Gourbesville, Manche, middle Eocene (upper Lutetian) • 3 spm; idem; MNHN.F.A24128 (Munier-Chalmas coll.) • 10 spm; Loire Basin, Loire-Atlantique, Saffré (Bois-Gouët); middle Eocene (lower Bartonian); MNHN.F.A29658 (Pacaud coll.) • 1 spm; idem; MNHN.F.A24031 (Vasseur coll.), figured in Merle et al. (2011: pl. 101, fig 1) as Timbellus cf. tripteroides (Lamarck, 1822) (Figs 8C; 26B) • 1 spm; idem; MNHN.F.J06383 (Vasseur coll.), figured in Merle et al. (2011: pl. 101, fig 2) as Timbellus cf. tripteroides (Lamarck, 1822).
ETYMOLOGY. — From the Latin occidentalis meaning west, considering the geographic range of this species in Normandy and in the Loire Basin.
TYPE HORIZON. — Calcaire de Fresville, middle Eocene (uppermost Lutetian), see Bignot et al. 1968).
TYPE LOCALITY. — France, Normandy, Manche, Fresville, see APGN (2024).
DISTRIBUTION. — Normandy (Calcaire de Fresville and Faluns de Hautteville) middle Eocene (uppermost Lutetian) and Loire Basin (Sables du Bois-Gouët), lowermost Bartonian see Mathelin & Bignot (1989).
DESCRIPTION
Smooth, bulbous protoconch of 1.25 whorls. Teleoconch up to 26.6 mm in height, up to 15.3 mm in width, biconic in profile, composed of five whorls. Moderately high spire. Last whorl up to 85% total length. Apical angle 64° excluding spines, 91° including spines. Spiral sculpture with weak primary cords in adult specimens. First to fourth whorl, no cord. Fifth whorl: P1 to P3. Sixth whorl: P1 to P6 weak, s2 and no other cord below, ADP and MP occasional. On first whorl, eight protovarices. From second to last whorl, three varices and one intervarix intercalated Higher relief of intervarices on P2-P3. Varices lamellose, winged on last whorls. Appearance of short, straight P1 spine on third whorl. Sinus of P1 spine narrow and pointing adapically. On last whorl alate varices. Ovate aperture up to 9% of diameter and up to 80% of length of last whorl (including siphonal canal). Columellar lip smooth, narrow, slightly erect anteriorly, forming curved inductura at base. Parietal lip slightly adherent. Outer lip with denticles ID (occasional), D1 to D6, D1 and D2 more strongly developed. Outer lip not crenulate. Siphonal canal narrow, open, up to 49% of apertural length. Pseudo-umbilicus narrow.
4
3
cm
in
Width 2
1
0 0 1 2 3 4 5 6 7
Total length in cm
COMPARISONS
This species was previously attributed to Murex tripteroides Lamarck, 1822 by Cossmann & Pissarro (1901) and later with some doubts by Merle et al. (2011). According to those authors, there are apparently strong similarities with T. tripteroides such as: a bulbous protoconch, an elongate shape, developed internal denticles, and few and weak cords. However, T. occidentalis n. sp. is smaller and does not exceed 26 mm for five teleoconch whorls. At the same size and same number of whorls T. tripteroides is still juvenile, does not bear internal denticles, and their axial wings are only developed on the last whorl (Fig. 8D, E). Adults of T. tripteroides can reach more than 60 mm height at 7-8 whorls. A bivariate diagram (Fig. 9) illustrates the differences in size between T. occidentalis n. sp. from Normandy and T. tripteroides from the Paris Basin. In addition, the spiral cords of T. tripteroides (Figs 6; 8D, E) are usually more marked than those of T. occidentalis n. sp. (Fig. 8 A-C) Finally, T. occidentalis n. sp. could be regarded as a progenetic species of Timbellus, because it associates a small size with adult characters comparable to T. tripteroides. Moreover, the two species never co-occur. Timbellus occidentalis n. sp. ranges between the uppermost Lutetian (Normandy) and the lowermost the Bartonian (Loire-Atlantique), whereas T. tripteroides ranges from the lower to the middle Lutetian in the Paris Basin and in the Hampshire Basin during the Bartonian.
description: Published as part of Merle, Didier, Pacaud, Jean-Michel, Ledon, Daniel & Goret, Bernard, 2024, New Cenozoic Muricidae (Mollusca: Gastropoda) from Europe, pp. 495-551 in Geodiversitas 46 (15) on pages 512-513, DOI: 10.5252/geodiversitas2024v46a15, http://zenodo.org/record/13985760