Diameza, Deshayes, 1865

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 : 446-448

Diameza (s.s.) fragilis ( Defrance, 1825) ( Figs 20 A-E; 21)

Ovula fragilis Defrance, 1825: 132 .

Rostellaria macroptera Lamarck, 1803: 220 , no. 1 partim (testa junior, incompleta), vélin 4, fig. 5a-c. — Palmer 1977: 15, vélin 4, fig. 5a-c.

Ovula intermedia Deshayes, 1835: 718 , pl. 95, fig. 34- 37. Non Sowerby, 1830.

Ovula media Deshayes & Milne-Edwards, 1844: 479 , 480 (nomen novum pro Ovula intermedia Deshayes, 1835 non Sowerby, 1830). — Deshayes 1865: 572.

Ovula (Diameza) media – Fischer 1884: 665.

Diameza media – Cossmann 1889: 99, pl. 3, fig. 16. — Cossmann & Pissarro 1911: pl. 32, fig. 159-1.

Terebellum (Diameza) media – Cossmann 1904: 48, pl. 3, figs 9-12.

Terebellum (Diameza) medium – Wenz 1940: 939, fig. 2744. — Glibert 1963: 40.

Seraphs (Diameza) intermedius – Jung 1974: 30, pl. 9, figs 10-12, text-figs 19, 20. — Savazzi 1991: 324, fig. 13L. — Le Renard 1992: 6.

Seraphs (Diameza) fragilis – Le Renard & Pacaud 1995: 112. — Pacaud & Le Renard 1995: 162. — Le Renard 2001: 17, 18.

TYPE LOCALITY. — Villiers-Saint-Frédéric (Yvelines, France), Lutetian (Middle Eocene).

TYPE MATERIAL. — Ovula fragilis : syntype (s) from Grignon (Yvelines, France), not found.

Ovula media : lectotype designated by Jung (1974) from the Deshayes collection and now deposited at the UCBL, not found ; paralectotypes ( UCBL, Deshayes coll.), not found .

A neotype designation is needed to clarify the taxonomic status of this species. A neotype from the locality Villiers-Saint-Frédéric ( MNHN A28939 , leg. Pacaud, Fig. 21 A-F), near Grignon (Yvelines) is accordingly chosen here. Th is initiative conforms to the rules specified by the ICZN (1999: art. 75), as regards the designation of a neotype.

OTHER MATERIAL EXAMINED. — See Appendix 1.

DESCRIPTION

Shell

Inflated shell up to 11 mm in height and 4 mm in diameter. Aperture long and narrow. Callus of inner lip clearly delineated, but weakly developed. Columella slightly bent backwards near the base. Outer lip thickened and extended above the apex. Outer lip forming an acute structure ( Fig. 20B ) hiding the actual apex ( Jung 1974). Outer lip sinuous, prosocyrt on the abapical part and opisthocyrt on the adapical part of the shell ( Fig. 20C ). Siphonal notch moderately deep. Surface sculpture of narrow oblique grooves near the base ( Fig. 20D ).

Colour pattern

The residual pattern is composed of two levels of residual pigmentation: dark lines on a lighter background. Th ese lines are axial and from wavy to zigzagging ( Fig. 21A, G, H , L-N). They usually cover the outer lip and the extremities of the shell. On the median part, the shells show a gradual transition from wavy lines to a chessboard pattern ( Meinhardt 1998) ( Fig. 21A, B, D, E ).

VARIABILITY

The lines can be more or less wavy. Some specimens have only axial straight lines on the whole shell surface ( Fig. 21C, J, K ), while other specimens have a chessboard pattern on the median part of the shell.

Figures

FIG. 20. — Diameza Deshayes,1865 shells in normal light:A-E, Diameza (s.s.) fragilis (Defrance,1825),MNHN A28784 (Faullummel coll.), Villiers-Saint-Frédéric,Yvelines,France,Lutetian;A, ventral view;B, detailed view of the apical part;C, labral view;D, detailed view of the oblique grooves; E, dorsal view;F-J, Diameza (Miniseraphs) eratoides (Cossmann,1889);F-H, MNHN A28785 (Faullummel coll.),Chaussy (Les Garennes),Val d’Oise,France,Lutetian; F, ventral view;G, labral view;H, dorsal view;I, MNHN A28934 (detailed view of the oblique grooves) (leg.Pacaud),Fontenay-en-Vexin (Beauregard),Eure,France,Lutetian; J, MNHN B63254 (dorsal view) (Lhomme coll.),Hervelon, Marne, France, Lutetian; K-O, Diameza (Miniseraphs) Isabella (Bernay in Deshayes, 1865); K, L, MNHN A28782 (leg.Pacaud), Parnes, Oise, France, Lutetian; K, ventral view; L, dorsal view; M-O, MNHN A28783 (leg. Pacaud), Cauvigny, Oise, France, Lutetian; M, ventral view; N, labral view; O, dorsal view. Scale bars: A, C, E-H, J-O, 5 mm; B, D, 1 mm; I, 2 mm. Photographs by C. Lemzaouda (MNHN).

FIG. 21. — Diameza (s.s.) fragilis (Defrance, 1825) under UV light: A-F, neotype, MNHN A28939 (leg. Pacaud), Villiers-Saint-Frédéric, Yvelines,France,Lutetian;A, dorsal view;B, detailed view of the chessboard pattern;C, labral view;D, abapertural view;E, detailed view of the chessboard pattern;F, detailed view of the lines;G-I, MNHN A28940 (Faullummel coll.),Villiers-Saint-Frédéric,Lutetian;G, dorsal view; H, detailed view of the zigzagging lines; I, labral view; J, K, MNHN A28784 (Faullummel coll.), Villiers-Saint-Frédéric, Lutetian; J, dorsal view; K, labral view; L-N, MNHN A28942, Villiers-Saint-Frédéric,Lutetian; L, dorsal view; M, detailed view of the zigzagging lines; N, labral view. Scale bars: A, C-D, G, I-L, N, 5 mm; B, E, F, 1 mm; H, M, 2 mm. Photographs by C. Lemzaouda (MNHN).