Natica dillwynii Payraudeau, B. -C. 1826. Catalogue descriptif et méthodique des annelides et des mollus- ques de l'ile de Corse; avec huit planches representant quatre-vingt-huit especes, dont soixante-huit nouvelles. Béchet, Paris, 218 pp., p. 120, pl. 5, figs. 27-28.
Natica dillwynii Payraudeau, 1826. Weinkauff (1867), p. 248; Kobelt (1901), p. 81, pl. 49, Figs. 11 - 10; Hidalgo (1917), p. 483; Villa (1986 b), pp. 179-180, p. 180; Alf et al. (1993), p. 190; Demir (2002), p. 110; Terreni (1981), p. 31
+ Nacca fasciata Risso 1826. Sabelli et al. (1990), p. 169
Natica (Naticarius) dillwynii (Payraudeau, 1826). Settepassi (1972), p. 23, pls. 4, 8
+ Tectonatica operculata farolita Nordsieck, 1973. Bouchet & Warén (1993), p. 759
Naticarius (Naticarius) dillwini (Payraudeau, 1826). Schiró (1978 c), p. 3, fig. 1 (first row)
Naticarius dillwynii (Payraudeau, 1826). Nordsieck (1982), p. 186, pl. 57, fig. 63.13 (Ibiza, Mediterraneo); Sabelli & Spada (1980), pp. 2-3, figs. 4 a-b; Poppe & Goto (1991), p. 119, pl. 17, fig. 23, Barash & Danin (1992), p. 108
Description
Size: Up to 19.7 mm height (Djidjelli, France; MNHN, Paris). Specimens (n = 30) from Giglio Island: 5.5 - 17.0 mm (mean: 11.0 mm ± 0.6 mm) height; 5.2 – 16.8 mm (mean: 10.8 ± 0.6 mm) width. Ratio [h/w] = 1.03 ± 0.006. Aperture approximately 80 % of shell height. The larval shell has a diameter of approx. 135 µm. General shape: Globose, slightly elevated spiral whorls, rather thin, 5.5 [teleoconch: 4] whorls. Sculpture: Axial wrinkles on shoulder; fine growth striae.
Shell color: Whitish-cream, yellowish-grey or light-brown with three distinct horizontal white bands with chevron-shaped brown marks; one band on shoulder, one around periphery, broadest band with somewhat fuzzy marks encircles umbilicus; in addition, unmarked yellowish band below suture. Protoconch: Dark protoconch, 1.5 embryonal whorls.
Aperture & outer lip: Aperture half-moon shaped, oblique, angled at the top; outer lip simple, sharp; basal lip slightly drawn out.
Umbilical area: Open umbilicus; relatively large, centrally located whitish funicle; funicular callus slightly enlarged, merging anteriorly with columellar callus which is tapering towards basel lip; distinctive sulcus; distinct, whitish parietal callus.
Operculum: Calcareous, glossy, with a deep, broad (as broad as ribs) furrow in front of two distinctive, massive ribs separated by a narrow ridge next to outer lip.
Animal: Propodium and mesopodium translucent whitish-grey, speckeled with red, irregularly shaped dots; dots more dense on propodium, which appears darker colored than mesopodium; when extended, mesopodium twice the length of the shell; propodium about as long as the shell; tentacles nearly as long or longer than propodium, colored with red dots on a whitish grey background, similar to coloration of foot.
Egg mass: Rigid, multispiral, even-walled coil of mucus-cemented sand grains (Figs. 3, 11 C,D,E/c,d,e), 3–5 circles; outer diameter 20–40 mm (N = 6; mean: 30.25 mm ± 7.961 [SD]).
Differential diagnosis: This species cannot be confused with any other Mediterranean species; distinct morphological features include the operculum with the furrow in front of two distinctive, thick ribs next to the outer lip; the reddish color pattern of the shell and foot, the long tentacles, and the elongated mesopodium.
Geographical distribution
Giglio Island: Cala dell´Allume (4), Pt. del Corvo (5), Pt. del Morto (6), Cannelle Bay, Pt. della Campana (7), (8), Pt. delle Secche (3)
General distribution: Common in the entire Mediterranean Sea and the Eastern Atlantic, South to Ghana (Villa 1986), and offshore to the Cape Verde Islands (Rolán 2005).