Conus dellabellai

Conus dellabellai (Pavia et al., 2022)

Description ⁽²⁾. Small-sized shell with biconical shape, regular conical spire, subsutural flexure symmetrically curved and deeper than wide, narrow abapical sector. The lecitothrophic protoconch is composed of 1.5 smooth, rounded whorls (Fig. 25 c and Fig. 26 i): its beginning is globular and uncoassial; the next whorl ends with a planar scar. The teleoconch (8.5 whorls in the holotype) shows an angular to rounded shoulder in the upper part of the whorl that coincides with the maximum shell width. The whorl height decreases with growth and produces a stepped profile of the adult shell. The internal side of the spire is oblique, planar or a bit concave where the shoulder is elevated in a sort of carina, and ornated by discontinuous thin furrows; no trace of beads. The spiral sutures are impressed. The siphonal channel is straight with a laminar external lip; the siphonal fasciole is weakly developed. The abapical half part of the shell shows eight to ten furrows that become evanescent upwards. The color pattern consists of quadrangular red spots on the shoulder and dense red dashes aligned on the whorls⁽²⁾.

Diagnosis ⁽²⁾: High conical spire, oblique sutural ramp, lecitotrophic protoconch, angular to rounded adapical shoulder, whorl height reducing with growth⁽²⁾.

Etymology ⁽²⁾: Named from Gino Della Bella who helped in the taxonomic definition and provided the paratype of Fig. 25 d, e.

Type ⁽²⁾: The type-series comes from Bed 9 of the Rio Vaccaruzza site and from the Poggio alla Staffa site (Colle Val d’Elsa, Siena, 43°20’40” N - 11°05’33” E). The holotype is the MGPT-PU 143224 (Fig. 25 a, b). Four paratypes are selected among the specimens of Bed 9: MGPT-PU 143225 (Fig. 26 i), MGPT-PU 143226 (Fig. 26 h), MGPT-PU 143227 (Fig. 25 c), MGPT-PU 110545. A further paratype is GDB-25001 from Poggio alla Staffa (Fig. 25 d, e).

Locus typicus ⁽²⁾: The right bank of the Rio Vaccaruzza, some 500 m northward of the village of Villalvernia municipality (AL, NW Italy).

Stratum typicum ⁽²⁾: The Bed 9 of the Rio Vaccaruzza section, Upper Pliocene.

Material ⁽²⁾: 2 specimens from Bed 3 (MGPT-PU 110518) and 39 specimens from Bed 9 (MGPT-PU 143004, MGPT-PU 143224- 143227, MGPT-PU 143281) of the Rio Vaccaruzza. One specimen from Poggio alla Staffa, Colle Val d’Elsa, Siena, 43°20’40” N - 11°05’33” E

Size ⁽²⁾: Due to the decrease of whorl height with growth, the height of the last whorl (Hw) is related to the shell height (Hs).

The holotype MGPT-PU 143224 measures H = 20.1 mm, W = 9.8 mm, W/H = 0.49, Hw/Hs = 0.64.

The paratypes measure:

MGPT-PU 143225, H = 6.6 mm, W = 3.4 mm, W/H = 0.49, Hw/Hs = 0.73;

MGPT-PU 143226, H = 16.5 mm, W = 8.7 mm, W/H =0.47, Hw/Hs = 0.72;

MGPT-PU 143227, H = 11.7 mm, W = 5.7 mm,W/H = 0.49, Hw/Hs = 0.70;

MGPT-PU 143281, H = 19.1 mm, W =9.6 mm, W/H = 0.50, Hw/Hs = 0.69;

GDB-25001, H = 21.0 mm, W= 10.0 mm, W/H = 0.48, Hw/Hs = 0.73.

Remarks ⁽²⁾. The red spots and dashes are finely recorded on the paratype GDB-25001 (Fig. 25 d, e- Poggio alla Staffa), whereas the Villalvernia specimens (Fig. 25 a-c) register only red traces on the shoulder (Fig. 25 a, b) and dashes on the whorl (Fig. 25 c). The shells of the new taxon show ontogenetic variability in the spire involution; starting from middle growth (Fig. 25 c, Fig. 26 i), the whorl height drops so that the spire is more and more exposed and shapes a stepped profile (Fig. 25 a, d, Fig. 26 h).

A similar architecture is present in Conus taurinensis Bellardi & Michelotti, 1840 that is widespread through the Mediterranean Miocene (Landau et al. 2013: 251) with type-series from the Lower Miocene of the Torino Hills (Sacco 1893 in 1890-1904: 98-99); unfortunately, the shell preservation of neither the syntypes nor the supplementary specimens is sufficient to show the protoconch so that one important parameter of comparison is missing. Nevertheless, C. taurinensis definitely differs for the ovoidal architecture of the shell, higher whorls and cyrtoconoid to mammillate spire.

The specimen figured by Chirli (1997, pl. 3, fig. 9) is conspecific because Conus canaliculatus differs by having a larger size, as well as a depressed and canaliculate spire with narrow grooves below the shoulder (Landau et al. 2013: 254).

Conus dellabellai n. sp. may be compared with the coeval C. striatulus (Brocchi, 1814) for the similar size and the conical spire. C. striatulus is common in the Lower Pliocene of the BTP (MGPT-143228, Fig. 26 g); its differences consist of the multispiral, planktotrophic protoconch and the acute shoulder without furrows in the internal side of the spire.

Distribution ⁽²⁾. Conus dellabellai n. sp. Is firstly recorded from the Piedmont Pliocene. It is widespread in Toscany and, possibly, in Emilia-Romagna (Della Bella, pers. data).