Paropeas achatinaceum (Pfeiffer, 1846)

Bulimus achatinaceus Pfeiffer, 1846: 82. Type locality: “ Java ”. Type material: lectotype no. ZMB Moll. 65746, Zoological Museum, Berlin (Naggs 1994: fig. 1).

Material examined.

Italy • 173 shells and 21 spirit specimens; Padua, Biodiversity Garden (Botanical Garden of Padua); 45 ° 23 ' 52.59 " N, 11 ° 52 ' 50.37 " E; 06 Mar. 2019; D. Barbato leg.; GMC 57373.

Description.

Shell (Figs 21–24). Dextral, medium in size, minutely perforate to imperforate, elongate, slender, conical, rather robust, pearly off-white, opaque, with 7–9 slightly convex whorls, separated by rather deep and in places irregularly crenulate sutures. Apex obtuse, rounded, and smooth. Last whorl ~ 1 / 3 of shell height. Aperture small, ~ 1 / 4 of shell height, obliquely pyriform, slightly prosocline. Peristome interrupted, slightly thickened along outer margin, slightly reflected on columella, with callous rim on parietum and columella; columella straight; outer margin sinuous in lateral view (approximately inverse S-shaped). Protoconch smooth; teleoconch with evident irregular collabral striae. Shell dimensions: SH 9.4–13.1 mm; SD 2.9–3.8 mm; AH 3.0– 3.5 mm; AW 1.8–2.2 mm.

Female distal genitalia (Figs 25, 27). Free oviduct long and wide. Bursa copulatrix sac-like, oval with long slender duct (slightly longer than bursa copulatrix), initially slightly flared, and medially convoluted around free oviduct. Vagina long and wide (longer than free oviduct) with huge proximal lateral bulge containing large ligula.

Male distal genitalia (Figs 25–27). Vas deferens of variable diameter (proximal tract narrow, medial tract slightly wider and final tract very narrow), entering penial complex at its proximal end. Penial complex consisting of epiphallus, penial caecum and penis. Epiphallus very short. Penial caecum very short (as long as epiphallus). Penis very long, distinctly divided into proximal and distal parts by difference in calibre; proximal part longer (almost twice distal penis), slender and thin walled; distal penis shorter (half proximal penis), thick, muscular walled and enveloped by penial sheath. Penial retractor muscle bifid, one branch inserted on proximal end of penis, the other branch on tip of penial caecum.

Genital atrium (Figs 25, 27). Short.

Remarks.

Paropeas achatinaceum is one of the best known subulinids thanks to the excellent anatomical study and the careful taxonomic revision by Naggs (1994). Our anatomical study (Figs 25–27) fully agrees with that of Naggs (1994).

This species is regarded as native to tropical Asia, where it occurs from Nepal and Sri Lanka to South East Asia. Outside this area it is found in Australia and Pacific islands, West Indian Ocean islands, Europe, and the West Asia (see Table 3 for details and references).

The species was found in the Biodiversity Garden (Botanical Garden of Padua), where it forms a well-established population, as in Vienna Zoo, Austria (Horsák et al. 2020). In contrast, the report from Malta is only based on a specimen of unknown origin recovered from sandy detritus collected on a beach (Cilia et al. 2022). This is the first report from Italy and the third from Europe.