Paraseraphs armoricus ( Vasseur, 1882 )

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 : 456-460

publication ID	https://doi.org/ 10.5252/g2010n3a4
persistent identifier	https://treatment.plazi.org/id/03A69848-FFB0-1E74-FD38-F9F7FE2BFAFC
treatment provided by	Marcus
scientific name	Paraseraphs armoricus ( Vasseur, 1882 )
status

Treatment

Paraseraphs armoricus ( Vasseur, 1882) ( Figs 29 View FIG A-C; 30)

Terebellum armoricum Vasseur, 1881: 174 , no. 22 and p. 245, no. 43 (nomen nudum).

Terebellum armoricum Vasseur, 1882 : pl. 2, fig. 20; pl. 3, fig. 55.

Terebellum cylindricum Cailliaud, 1856: 42 (nomen nudum). — Cailliaud in Vasseur 1881: 232 (nomen nudum).

Terebellum fusiforme – Cailliaud 1856: 42. — Vasseur 1881: 232. Non Lamarck, 1802.

Terebellum View in CoL (s.s.) armoricense – Cossmann 1898: 340, pl. 8, fig. 10 and 15, unjustified emendation; 1904: 44.

Terebellum armoricensis – Cossmann 1917: pl. 2, fig. 20; pl. 3, fig. 55.

Paraseraphs armoricensis – Jung 1974: 36, 37, pl. 9, figs 19-25, text-fig. 28.

TYPE LOCALITY. — Saffré, Bois-Gouët (Loire-Atlantique, France), Bartonian (Middle Eocene).

TYPE MATERIAL. — Th e type material of Vasseur (1882) was lost ( Cossmann 1898). Accordingly, Cossmann (1898: pl. 8, figs 10, 15) designated a neotype from the Dumas collection deposited in MNHN, but this specimen has not been found either. Later, Jung (1974: 36) wrongly considered the neotype of Cossmann to be the holotype of this species.

OTHER MATERIAL EXAMINED. — See Appendix 1.

SHELL DESCRIPTION

Shell 73 mm in height and 13 mm in diameter, slender and elongated. Shell evolute with distinct suture. Aperture long and narrow. Callus of the inner lip well developed and clearly delineated ( Fig. 29A, B View FIG ). Abapical part of the columella bent backwards. Outer lip, almost straight ( Fig. 29C View FIG ), not thickened except near the adapical end of the aperture. Outer lip running towards the apex and slightly bent on the dorsal side of the shell (following Jung [1974], our material being broken). Siphonal notch moderately deep on the dorsal side. No sculpture on the surface of the shell.

COLOUR PATTERN DESCRIPTION

Paraseraphs armoricus bears numerous and variablesized dots on a lighter background ( Fig. 30 View FIG ). These dots, generally circular, spread over the whole surface of the shell. Th ey show 2 levels of residual pigmentation ( Fig. 30B, C, E View FIG ): 1) round dark spots orientated toward the inner lip; and 2) white fluorescent, crescent-like spots orientated towards the growing edge. Th ese 2 components form the dots. The density of dots is low, with little coalescence ( Fig. 30B View FIG ).

COMPARISONS OF THE THREE SPECIES

OF PARASERAPHS : P.TETANUS, P.PLACITUS

AND P.ARMORICUS

Shell

These species of Paraseraphs are easily distinguishable from the species of Seraphs by their evolute spire ( Figs 24 View FIG ; 29 View FIG ). Moreover, the shells are usually more slender. According to our observations, several differential characters attributed by Jung (1974) to distinguish Paraseraphs tetanus and P. placitus seem to be erroneous. Jung (1974) believed that P. tetanus is more slender than P. placitus . In fact, the shape of P. tetanus is variable and some specimens can be as inflated as P. placitus ( Fig. 24F, L View FIG ). Furthermore, Jung (1974) suggested that, on the posterior part of the shell, the outer lip of P. tetanus is bent towards the dorsal side, while that of P. placitus runs directly to the apex. For P. tetanus , his observations seem correct, but in P. placitus , the outer lip can continue directly to the apex or can be bent towards the dorsal side ( Fig.24H, M View FIG ). Accordingly,this character is not consistent to distinguish the two species.On the other hand, contrary to Jung assumptions, the shell of P. tetanus does not show oblique grooves near the base. The Bartonian species P. armoricus is very similar to the other species, but much bigger ( Fig. 29 View FIG A-D).

Residual colour pattern

The dots constituting the pattern of P. placitus ( Fig. 28 View FIG ) appear very similar to those of S. volutatus , S. sopitus and S. olivaceus ( Figs 7-10 View FIG View FIG View FIG View FIG ). However, the dots are clearly ordered in these Seraphs , while no axial rows of dots have been observed in P. placitus . Regarding P. armoricus ( Fig. 30 View FIG ), the orientation of the two components of the dots is inversed in comparison to P. placitus and even Seraphs . The darker spots are orientated towards the outer lip in P.armoricus and towards the inner lip in P. placitus . Furthermore, the shape of the dots is obviously different between P. placitus and P. armoricus . It is generally triangular for P. placitus ( Fig. 28C, F, L View FIG ), while it is circular for P. armoricus ( Fig. 30B, E View FIG ). The pattern of P. tetanus is quite variable, but differs sharply by the occurrence of axial rows and by lacking of white fluorescent spots ( Fig. 25 View FIG ).

Using shell characters, it is difficult to separate these three species of Paraseraphs , while using residual colour pattern we can obviously observe differences justifying their distinction.