Conus (Eoconus) cambieni (Landau et al., 2020)

Type material ⁽¹⁾

Holotype NHMW 2016/0103/1894, height 74.1 mm, width 14.2 mm;

paratype 1 NHMW 2016/0103/1895, 25.1 mm, width 14.6 mm (juvenile);

paratype 2 NHMW 2016/0103/1896, height 37.1 mm, 19.2 mm (juvenile);

paratype 3 NHMW 2016/0103/1897, height 26.9 mm, 15.2 mm (juvenile), Renauleau.

Paratype 4 RGM.1352471, height 29.4, width 15.9 mm, Sceaux-d’Anjou.

Other material ⁽¹⁾

Maximum height 35.1 mm, width 18.7 mm. Sceaux-d’Anjou:

RGM.1352387 (3), FVD (1). Renauleau: NHMW 2016/0103/1898 (50+ subadults and juveniles), LC (50+ subadults and juveniles), FVD (50+ subadults and juveniles).

Etymology – Named after Jean-Pierre Cambien from Paris, a passionate collector of the French Tertiary, and good friend of the authors. Eoconus gender masculine ⁽¹⁾.

Locus typicus – Renauleau, Maine-et-Loire, NW France ⁽¹⁾.

Stratum typicum – Tortonian, upper Miocene ⁽¹⁾.

Diagnosis – Eoconus species of large size, multispiral protoconch, low spire, whorls with carina placed just above suture, suture deeply impressed, narrowly canaliculated, coarsely beaded early teleoconch whorls and spiral cords on subsutural platform fading by 5-6 whorl, regularly conical last whorl with a few cords restricted to base ⁽¹⁾.

Description ⁽¹⁾– Shell large, with depressed, straight to slightly coeloconoid spire. Protoconch multispiral, tall, consisting of at least three whorls (2.5 whorls preserved). Junction with teleoconch sharply delimited. Teleoconch of up to 11 whorls. Early whorls taller, rapidly becoming depressed. Spire whorls with flat to weakly concave subsutural platform bearing 4-5 weak spirals, roundly angled at beaded carina placed a just above suture, beads prominent extending adapically, crenulating suture.

Suture deeply impressed, narrowly canaliculate. Abapically whorls become more depressed, beading and spiral cords weaken, subobsolete by 5-6 whorls where they become broad undulations at shoulder. Last whorl regularly conical with maximum diameter just below shoulder, hardly constricted at base bearing 8-9 narrow cords over base, strengthening abapically. Subsutural flexure initially shallow, deepening towards aperture, strongly curved, strongly asymmetrical. Aperture moderately narrow, anteriorly broadening; siphonal canal medium length, nearly straight; fasciole not well demarcated, weakly swollen with prominent growth lines; inner lip twisted. No colour pattern preserved.

Discussion ⁽¹⁾ – Eoconus cambieni nov. sp. and Eoconus vanhoutenae nov. sp. are closely similar species. They both have strongly beaded early whorls that fade after 5-6 whorls and spiral cords on the subsutural platform. Indeed, we would probably not have separated them if the protoconch had not been preserved. Despite it being incomplete, in E. cambieni it is clearly multispiral, of a planktotrophic type, whilst E. vanhoutenae, in which the protoconch is preserved in numerous juveniles, has a paucispiral protoconch typical of direct development.

Once the shells are separated, other smaller teleoconch differences become apparent. Eoconus cambieni attains a larger maximum size, the spire is even more depressed than in E. vanhoutenae, the suture is deeper, even narrowly canaliculated, and the spiral cords on the subsutural platform are weaker and disappear at about the same time as the beads, on the 5-6 teleoconch whorl, whereas in E. vanhoutenae they remain strong on later

adult whorls.

These are probably the species identified, but not figured, by Brébion (1964, p. 631) as Conus (Lithoconus) mercati var. sharpeanus Pereira da Costa, 1866. However, Monteiroconus mercati (Brocchi, 1814) has no beading or spiral cords on the spire whorls (Landau et al., 2013, p. 242, 245). Monteiroconus sharpeanus does have spiral cords, but does not have tubercles. This is not the species from the middle Miocene Loire Basin described by Peyrot (1938, p. 257) as Conus mercati ligeriana, which was synonymised by Glibert (1952a, p. 372) with C. mercati sharpeanus, as neither of these authors make any mention of tubercles on the early teleoconch whorls. Vaessen (2010, figs 9, 10B, 11-13) figured further specimens from the Loire Basin as C. mercati with spiral sculpture on the subsutural platform, which are not M. mercati, but closer to M. mojsvari (Hoernes & Auinger, 1879). We have not identified any other species belonging to this group in the European Neogene ⁽¹⁾.

Brébion (1964, p. 632) recorded these two species (as Conus (Lithoconus) mercati var. sharpeanus) as occurring in many of the Assemblage I localities (Renauleau, Sceaux-d’Anjou, Thorigné, St-Clément-de-la-Place, Beaulieu, les Pierres Blanches, Contigné). It is not possible to tell which of the two he was referring to, but interestingly all the specimens of E. vanhoutenae, except one, come from St-Clément-de-la-Place, whereas all the specimens of E. cambieni come from Renauleau, where it is not uncommon, but rarely well preserved. Only one specimen of that species attains 74 mm in height, the rest only reach about 35 mm in height. The scarce material at hand from Sceaux-d’Anjou does not have the protoconch preserved, but the cords fade early and are therefore ascribed to E.cambieni ⁽¹⁾.