Seraphs subconvolutus (d’Orbigny, 1852), Rupelien

Caze, Bruno, Merle, Didier, Pacaud, Jean-Michel & Saint Martin, Jean-Paul, 2010, First Systematic Study using the Variability of the Residual Colour Patterns: The Case of the Paleogene Seraphsidae (Mollusca, Gastropoda, Stromboidea), Geodiversitas 32 (3), pp. 417-477 : 438-440

Seraphs subconvolutus (d’Orbigny, 1852) ( Fig. 14 )

Terebellum subconvolutum d’Orbigny, 1852: 9 , no. 140.

Terebellum convolutum – Grateloup 1834: 314, no. 604; 1846: pl. 1 [42] fig. 1. Non Lamarck, 1802.

Terebellum fusiforme – Grateloup 1834: 315, no. 605; 1846: pl. 1 [42] figs 2, 3. Non Lamarck, 1802.

Terebellum subfusiformis d’Orbigny, 1852: 9 , no. 141.

Terebellum (Seraphs) subconvolutum – Cossmann 1904: 46.

Terebellum (s.s.) subconvolutum – Magne 1940: 33.

Terebellum subconvolutum – Vergneau 1967: 203, 206. — Bosatta et al. 1973: 190.

Seraphs subconvolutus – Jung 1974: 26, 27, pl. 8, figs 1-10, text-fig. 18.

TYPE LOCALITY. — Gaas (Landes, France), Rupelian (Oligocene).

TYPE MATERIAL. — Seraphs subconvolutus : the illustrated syntype ( UBT 65-2-120, Grateloup. coll.) of Grateloup (1834) has been selected unambiguously by Jung (1974:26) as lectotype, using wrongly the term of holotype: “They therefore represent the holotypes of S. subconvolutus ...”. But in the original work of d’Orbigny (1852), no holotype was designated for the taxon. In accordance with article 74.6 of the ICZN (1999), Jung’s stipulation constitutes a lectotype fixation.

Terebellum subfusiformis : the illustrated syntype (UBT 65-2-121, Grateloup coll.) of Grateloup (1834) has been selected unambiguously by Jung (1974: 26) as lectotype, using wrongly the term of holotype: “They therefore represent the holotypes of S. subconvolutus and S. subfusiformis respectively”. But in the original work of d’Orbigny (1852), no holotype was designated for the taxon. In accordance with article 74.6 of the ICZN (1999), the Jung stipulation that the illustrated specimen is the holotype constitutes a lectotype fixation.

OTHER MATERIAL EXAMINED. — See Appendix 1.

DESCRIPTION

Shell

Shell up to 31 mm in height and 8 mm in diameter moderately slender with acute apical part. Aperture long and narrow. Callus of the inner lip thin, but well delineated, extending towards the apex and forming a narrow band parallel to the outer lip. Columella slightly bent backwards near the base of the shell. Outer lip slightly thickened and somewhat prosocyrt, in labral view, below the adapical end of the aperture ( Jung 1974). Outer lip extending onto the posterior part of the shell, but bent towards the dorsal side ( Fig. 14B, C, E ) and “reaching the apex after about half a volution” ( Jung 1974). Siphonal notch moderately deep. Surface sculpture of narrow oblique grooves observable on the ventral side near the base ( Fig. 14F ).

Colour pattern

No residual pattern is observed under UV light. Nevertheless, the studied specimens seem slightly corroded and we cannot preclude the possibility that the species originally had a colour pattern.

COMPARISONS OF THE SHELL MORPHOLOGY Seraphs subconvolutus is similar to S. chilophorus and S. peterjungi n. sp. ( Fig. 15 ) in sharing an abapical part of the columella slightly bent backwards, narrow oblique grooves on the ventral side near the base and a well delineated callus ( Fig. 14D ) of the inner lip forming adapically a narrow band parallel to the outer lip. However, this species is the only Seraphs having an opisthocline extension of the outer lip on the posterior part of the shell. The outer lip does not continue directly to the apex, but is bent towards the dorsal side reaching the apex after about half a volution ( Fig. 14B, C, E ). This feature of S. subconvolutus resembles that of members of Paraseraphs ( Jung 1974) , but the shell is involute as in other Seraphs .

Figures

FIG. 14. — Seraphs Montfort, 1810 shells in normal light: A, B, holotype of S. subconvolutus (d’Orbigny, 1852), UBT 65-2-120 (Grateloup coll.), Gaas (Lesbarritz), Landes, France, Rupelian; A, ventral view; B, dorsal view; C, holotype of S. subfusiformis d’Orbigny, 1852 (labral view), UBT 65-2-121 (Grateloup coll.), Gaas (Lesbarritz), Rupelian; D-F, MNHN A28967 (Aucoin coll.), Gaas (Espibos), Rupelian; D, ventral view; E, dorsal view; F, detailed view of the oblique grooves. Scale bars: A-E, 10 mm; F, 5 mm. Photographs by C. Lemzaouda (MNHN).

FIG. 15. — Seraphs Montfort, 1810 shells in normal light; A-I, S. chilophorus (Cossmann, 1889); A-E, MNHN A28779 (Ledon coll.), Chaussy (Les Garennes), Val d’Oise, France, Lutetian; A, ventral view; B, labral view; C, detailed view of the apical part; D, dorsal view;E, detailed view of the apical part; F-H, MNHN A28780 (Ledon coll.), Chaussy (Les Garennes), Lutetian;F, ventral view;G, dorsal view; H, detailed view of the apical part; I, MNHN A27783, detailed view the oblique grooves (leg. Pacaud), Saint-Lubin-de-la-Haye, Eure-et-Loir, France, Lutetian; J-N, S. peterjungi n. sp., holotype MNHN A28578 (Pacaud leg.), Chaussy (Les Garennes), Lutetian; J, ventral view; K, labral view; L, detailed view of the apical part; M, detailed view the oblique grooves; N, dorsal view. Scale bars: A-B, D, F-G, J-K, N, 10 mm; C, I, 5 mm; E, H, L, M, 2 mm. Photographs by C. Lemzaouda (MNHN).