Conus villalvernensis

Conus villalvernensis (Pavia et al., 2022)

Description ⁽²⁾. Medium-sized shell with pointed apex, coeloconoid spire, subsutural flexure asymmetrically curved, main body convex, narrow abapical sector. The lecitotrophic protoconch is composed of 1.5 smooth, rounded whorls (Fig. 26 c, d). The beginning is globular and uncoaxial, the subsequent whorl ends with a planar scar. The teleoconch (9.5 whorls in the holotype) shows an elevated, rounded shoulder that causes a stepped profile of the spire. The internal part of the spire is depressed and ornated by three furrows that run constant with growth up to the aperture. In the first four to five whorls the shoulder bears proverse, well-marked beads; on the fifth whorl, there are 25- 30 beads, and in the following whorls they weaken up into feeble undulations (ripples). A couple of subtle furrows lies just outside of the shoulder. The upper part of the lateral shell side is little convex and the siphonal channel is straight with a laminar external lip; the siphonal fasciole is poorly developed. The anterior half part of the shell shows 9-11 depressed cords, but in general all the lateral surface is covered by evanescent spiral ribbing ⁽²⁾.

Diagnosis ⁽²⁾: Coeloconoid stepped spire, lecitothrophic protoconch, subcarinate to rounded adapical shoulder bearing beads up to the middle whorls⁽²⁾.

Etymology ⁽²⁾: Named from the village of Villalvernia.

Type ⁽²⁾: The type-series comes from Bed 9 of the Rio Vaccaruzza site. The holotype is the MGPT-PU 143216 (Fig. 26 j-l). Six paratypes are selected: MGPT-PU 143217, MGPT-PU 143218, MGPT-PU 143219, MGPT-PU 143220 (Fig. 26 e, f), MGPT-PU 143221, MGPT-PU 143222 (Fig. 26 a, b), MGPT-PU 143223 (Fig. 26 c, d).

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⁾: Three specimens from Bed 3 (MGPT-PU 110520), 20 specimens from Bed 9 of the Rio Vaccaruzza section (MGPT-PU 143007, MGPT-PU 43216-143223).

Size ⁽²⁾: The holotype MGPT-PU 143216 measures H = 31.8 mm, W = 15.6 mm, W/H = 0.49. The paratypes measure:

MGPT-PU 143217, H = 36.8 mm, W = 17.3 mm, W/H = 0.47;

MGPT-PU 143218, H = 31.0 mm, W = 14.7 mm, W/H = 0.47;

MGPT-PU 143219, H = 25.1 mm, W = 12.2 mm, W/H = 0.49;

MGPT-PU 143220, H = 20.3 mm, W = 9.7 mm, W/H = 0.48;

MGPT-PU 143221, H = 12.4 mm, W = 5.8 mm, W/H = 0.47;

MGPT-PU 143222, H = 10.4 mm, W = 5.3 mm, W/H = 0.51;

MGPT-PU 143223, H = 4.3 mm, W = 2.2 mm, W/H = 0.51.

Remarks ⁽²⁾. This conoidean was described by Sacco (op. cit.) as Lithoconus mercati (Brocchi, 1814) var. Caroli (Fucini, 1891) mainly because of the stepped, subcanaliculated spire with furrows and the elevated shoulder. Nevertheless, C. mercati has more massive shells and smooth spire without neither beads nor furrows on the shoulder (cf. Landau et al. 2013: 242). The morphology of these conoideans from Villalvernia may be compared with specimens of Conus caroli Fucini from the Pliocene of Tuscany (Della Bella’s collection); these fossils, topotypical at the basin scale, indicate that C. caroli represents a different species due to the higher, not coeloconoid spire without pearling on the shoulder.

The new taxon shows analogies with Conus virginalis (Brocchi, 1814) for the stepped spire and the furrows on the internal whorls. Nevertheless, C. virginalis shows higher values of the ratio: W/H: 0.62 in the holotype (Rossi Ronchetti 1955) and 0.55 to 0.62 on the specimens described by Sacco (1893 in 1890-1904, see Fig. 26 m) and Chirli (1997); moreover, the protoconch of C. virginalis is multispiral and the adapical shoulder of the teleoconch is keeled with spaced undulations that continue up to the adult stage.

The “Rhizoconus” virginalis var. fusuloligustica described by Sacco (op. cit.: 115, pl. 11, fig. 4) from the Lower Pliocene of Bordighera (Liguria) is reminiscent of C. villalvernensis n. sp. for the narrow W/H = 0.48. However, Sacco’s taxon has a multispiral, planktotrophic protoconch and shows only feeble undulations on the shoulder without any bead; it is here regarded as a separate species (Conus fusoligusticus (Sacco, 1893), lectotype here designated at Fig. 26 n-p) that differs from Brocchi’s taxon for the architecture with conical spire and oblique internal side.

Distribution ⁽²⁾. Conus villalvernensis n. sp. is so far known from:

the Lower Pliocene of the Asti area (Sacco 1893 in 1890-1904, BS.038.02.011 and BS.038.02.011/04),
the Upper Pliocene of Villalvernia (present work and Sacco 1893 in 1890-1904, BS.038.02.011/02)
the Pliocene of Tuscany (Della Bella, pers. comm.). A careful check of the conoidean assemblages from the Mediterranean Pliocene could expand the geographical distribution of the new species.

Sacco (1893, BS.038.02.011/01) discussed a further specimen coming from the Tortona surroundings (dubitatively Tortonian in age). Its preservation state is not equivalent to what we know for the Upper Miocene records of that region. We think that this specimen is a loose fossil reworked from the Pliocene outcrops of the southern “Tortonese” sector.

Potrebbe essere collegato al Conus mamillaris (Doderline).



Conus villalvernensis n. sp. Rio Vaccaruzza, Bed 9 Upper Pliocene (a, b) paratype, MGPT-PU 143222 – mm. 10,4 x 5,3 (c, d) paratype, MGPT-PU 143223 – mm. 4,3 x 2,2 (e, f) paratype, MGPT-PU 143220 – mm. 20,3 x 9,7 (j-l) holotype, MGPT-PU 143216 – mm. 31,8 x 15,6

Stephanoconus exaltatus 5,5 x 2,5 mm. protoconca multispirale, planctotrofica (Giulio Pavia) Middle Miocene gastropods from Korytnica, Poland; Part III Plate 20 fig. 5	Conus villalvernensis Pliocene – Poggio alla Staffa (Toscana) mm. 4 Facebook (Massimo Cresti)