Leptochiton bedullii, Dell'Angelo & Palazzi, 1986

Leptochiton bedullii View in CoL Dell’Angelo & Palazzi, 1986

Fig. 12 View FIGURE 12

Leptochiton ( L.) bedullii View in CoL Dell’Angelo & Palazzi, 1986, p. 7, figs 17–18, 23–24, 27–31, 49–50, 58–62; Kaas & Van Belle 1988, p. 12, fig. 4, map 3.

Lepidopleurus ( Leptochiton) bedullii ; Dell’Angelo & Smriglio 1999, p. 71, pls 19–20, figs 28, 29, 29/1, 29/2; Dell’Angelo et al. 2001a, p. 146, fig. 3.

Leptochiton bedullii View in CoL ; Van Belle 1988, p. 92, pl. 39, figs 3–10; Dell’Angelo et al. 2012, p. 57; Dell’Angelo et al. 2013, p. 72, pl. 2, figs H–L; Dell’Angelo et al. 2021b, p. 409, figs 22–29.

non Lepidopleurus ( Leptochiton) boettgeri View in CoL ; Dell’Angelo & Palazzi 1989, p. 72, pl. 20, fig. 1 (= Leptochiton sp. , fide Dell’Angelo et al. 2012: 56).

Lepidopleurus ( Leptochiton) boettgeri View in CoL [non Leptochiton boettgeri ( Šulc, 1934) View in CoL ]; Dell’Angelo & Palazzi 1989, p. 72, pl. 20, figs 2–5, pl. 22, fig. 5.

Lepidopleurus boettgeri View in CoL [non Leptochiton boettgeri ( Šulc, 1934) View in CoL ]; Chirli 2004, p. 4, pl. 1, figs 3–8.

Leptochiton boettgeri View in CoL [non Leptochiton boettgeri ( Šulc, 1934) View in CoL ]; Öztürk et al. 2014, p. 2; mult. auct.

Type material. Holotype: MSNP, a specimen collected on Posidonia at a depth of 10 m ( Figs 12A–D View FIGURE 12 ) . Paratypes: 1 intermediate valve from Porto Cesareo ( MZB) ; specimen from Capraia Island ( AL) ; valves from Elba Island , Vendicari and Creta ( Greece) ( BD 2921 , BD 3031 , BD 3388 ) .

Type locality. Laghi Alimini ( Lecce, Italy) .

Material examined. Lower Pliocene: Italy: Liguria: Borzoli: 2 valves ( BD 344 ), Bussana: 2 valves ( BD 345 ), Genova Sestri: 1 valve ( MZB 45703 , Figs 12E–H View FIGURE 12 ), Rio S. Antonino: 5 valves ( MP), Rio Torsero : 1 valve ( BD 346 ). Pliocene : Italy: Tuscany: Pietrafitta: 3 valves ( BD 347 ), Pietrafitta Melograni: 5 valves ( BD 348 ), Poggio alla Fame: 3 valves ( BD 349 , Figs 12I–J View FIGURE 12 ), Serre di Rapolano : 2 valves ( BD 350 ). Recent : Italy: type material, plus Favignana Island : valves from cruise CS96-88 ( MZB, Figs 12K–L View FIGURE 12 ). Maximum width of the valves: -- / 2.5 / 2.2 mm .

Description. Head valve semicircular, posterior margin widely V-shaped, notched in middle, front slope straight. lntermediate valves broadly rectangular (W/L = 2.28–2.54), rounded to semicarinate in anterior profile, moderately elevated (H/W = 0.38–0.45), anterior margin straight to slightly convex, side margins rounded, posterior margin straight, apex inconspicuous, lateral areas moderately raised. Tail valve elliptical, length 2/ 3 of width (W/L = 1.40), anterior margin consisting of three segments, mucro subcentral, rather prominent, antemucronal slope straight to slightly convex, postmucronal slope concave directly behind mucro.

Tegmentum smooth, space between striae of granules large, up to twice width of the series of granules, growth lines barely noticeable. HV, LA and PMA sculptured with minute roundish united granules partially overlapping, arranged in radial striae, often bifurcating (HV 60 dentating outer margin, about 20 granules per series, LA 6–8, PA 50). CA and AMA sculptured with minute roundish united granules partially overlapping, arranged in longitudinal striae (CA 30) LA and CA connected in very regular and characteristic way. Each granule with a central megalaesthete and many micraesthetes (up to 15 or more) irregularly spaced all along, except on upper side.

Articulamentum lacking insertion laminae, apophyses small, triangular, widely separated by straight sinus, about 1/ 3 width of valve, apical area expanded, quadrangular, with upper edge bisinuated.

Remarks. This elusive species has been described based on three living individuals and a few loose Recent valves collected at Laghi Alimini (Lecce), Capraia Island (Tuscan Archipelago), and Punta Prosciutto (Taranto).

The fossil record of Leptochiton bedullii Dell’Angelo & Palazzi, 1986 is limited to the Lower Pliocene of Liguria ( Dell’Angelo et al. 2013) and Tuscany ( Dell’Angelo et al. 2001a; Chirli et al. 2004). Dell’Angelo & Palazzi (1989) considered Leptochiton bedullii as a synonym of L. boettgeri ( Šulc, 1934) , a species known from the Miocene of Kostej ( Romania) only for two valves (one head and one tail). We consider these two taxa as distinct species (see discussion below regarding Leptochiton boettgeri ). Some reports of Mediterranean specimens considered as Leptochiton boettgeri on the basis of this synonymy (e.g., Öztürk et al. 2014) must therefore be correctly attributed to Leptochiton bedullii .

A single intermediate valve from Altavilla, illustrated by Dell’Angelo & Palazzi (1989: pl. 20, fig. 1) as Lepidopleurus ( Leptochiton) boettgeri (considered by these authors conspecific with Leptochiton bedullii ), was left undetermined at species level by Dell’Angelo et al. (2012); consequently, L. bedullii is excluded from the chiton fauna of the Pliocene of Altavilla.

Comparisons. See Tab. 2 for a comparison with the Leptochiton spp. considered in the present study.

Distribution. Lower Pliocene: central Mediterranean, Italy: Liguria: Borzoli, Bussana, Rio S. Antonino, Rio Torsero, Sestri Ponente ( Sosso & Dell’Angelo 2010; Dell’Angelo et al. 2013, 2021b). Pliocene: central Mediterranean, Italy: Tuscany: Pietrafitta, Serre di Rapolano ( Dell’Angelo et al. 2001a; Chirli 2004), Poggio alla Fame (this study). Recent: Mediterranean Sea: Italy ( Dell’Angelo & Smriglio 1999), Croatia: Mljet National Park ( Dell’Angelo & Zavodnik 2004), Malta, Greece and Aegean Sea Islands ( Strack 1988), Turkey ( Ozturk et al. 2014), Lebanon ( Crocetta et al. 2014), Tunisia ( Kaas 1989; Cecalupo et al. 2008).