Conus (Conasprella) dingdenensis (Roosen, Langeveld,2025)

Diagnosis ⁽¹⁾

Small, slender, biconical shells; with a multispiral protoconch, sharp transition from protoconch to teleoconch and one or two deeply incised spiral grooves below the suture on the teleoconch.

Dimensions ⁽¹⁾

NMR-993000210715: SL: 9.3 mm; MD: 4.3 mm; AH: 5.6 mm; PMD: 0.91; RSH: 0.40.

NMR-993000210716: SL: 8.8 mm; MD: 4.1 mm; AH: 5.8 mm; PMD: 0.91; RSH: 0.34.

NMR-993000210717: SL: 8.8 mm; MD: 3.8 mm; AH: 5.9 mm; PMD: 0.95; RSH: 0.33.

Description ⁽¹⁾

Very small, slender biconical shells. Protoconch multispiral, tall, consisting of at least five slightly tumid glossy whorls. Junction with the teleoconch sharply delimited. High, conical spire consisting of 6 teleoconch whorls. Spire whorls with one or two deeply incised spiral grooves just below the suture, creating a subsutural band. On the first teleoconch whorl, the subsutural band is beaded. These fade on the second teleoconch whorl. Last whorl with flat sutural ramp. Growth lines indistinct, subsutural inflexure shallow but symmetrical. Apertural margin subparallel, siphonal fasciole obsolete. Sculpture consists of up to 16 spiral cords, which become more pronounced near the canal. On most specimens, spirals on the upper part of the final whorl become obsolete and cannot be counted.

Type locality ⁽¹⁾

Dingden, outcrop near Köningsmühle (Germany).Breda Formation, Dingden Member, Type stratum Dingdener Feinsand.

Age ⁽¹⁾

Miocene, Reinbekian (late Langhian to Serravallian).

Etymology ⁽¹⁾

The specific epithet is derived from its type locality, Dingden, Köningsmühle (Germany).

Distribution ⁽¹⁾

Middle Miocene: Dingden, Köningsmühle (TL), Middle Miocene of Kevelaer (Janssen & Wienrich, 2007: as Conus cf. clavatulus d'Orbigny, 1852) (Germa-ny); Heist-op-den-Berg (Belgium).

Discussion ⁽¹⁾

Previously shells of this type have been identified as Lautoconus clavatulus (d'Orbigny, 1852). However, this species bears a visible carina with small nodes on its early teleoconch whorls and lacks the groove below the suture. Moreover, at the type locality of C. dingdenensis spec. nov. L. clavatulus is a very rare or absent, making it unlikely that these are growth stages of the same species.

A few species of Conidae of similar size and shape are known from the Miocene of Europe. Conasprella minutissima Harzhauser & Landau, 2016 exhibits some-what similar characteristics to C. dingdenensis spec. nov.

Remarks ⁽¹⁾

Both Janssen (1984) and Janssen & Wienrich (2007) already suggested that these small cone shells might belong to a different species than Lautoconus clavatulus. We follow their suggestion and describe this form as a new species. The multispiral protoconch indicates this species has a planktonic life stage. The small size of all specimens might suggest that the specimens at hand are subadults that did not grow to their full size, whilst adults have not yet been found. However, our material is so different from all other Conidae known from the North Sea Basin, that it cannot be maintained that they are juveniles of Lautoconus clavatulus. That would give the wrong image of Conidae biodiversity in the Miocene of the North Sea Basin.

Bibliografia Consultata

• (1) - Roosen, M.; Langeveld, B. W. (2025). "New species of Conasprella Thiele, 1929 and Plagioconus Tucker & Tenorio, 2009 (Gastropoda, Conidae), previously identified as Lautoconus clavatulus (d'Orbigny, 1852) and Conus aquensis d'Orbigny, 1852, from the Miocene of Winterswijk-Miste (The Netherlands), Dingden and Woltrup (Germany)". Cainozoic Research. 25 (2): 139–148.

• (2) - Janssen, A.W. 1984. Mollusken uit het Mioceen van Winterswijk-Miste. Een inventarisatie, met beschrijvingen en afbeeldingen van alle aangetroffen soorten. Amsterdam (K.N.N.V., N.G.V. & R.G.M.): 1-451, separate atlas of 82 pls.

• (3) - Anderson, H.-J. 1964. Die Miocäne Reinbek-Stufe in Nord- und Westdeutschland und ihre Mollusken-Fauna. Fortschritte in Der Geologie von Rheinland und Westfalen 14: 31-368.