Leptochiton algesirensis ( Capellini, 1859 )

Leptochiton algesirensis ( Capellini, 1859) View in CoL

Fig. 10 View FIGURE 10

Chiton algesirensis Capellini, 1859, p. 327 , pl. 12, figs 3a–3c.

Lepidopleurus granoliratus Carpenter View in CoL in Pilsbry, 1892, p. 14, pl. 2, figs 47–53 ( fide Kaas & Van Belle 1985a).

Chiton granoliratus ; Monterosato 1872, p. 28; de Rochebrune 1882, p. 70 ( fide Dell’Angelo & Palazzi 1989).

Chiton cinereus [non Lepidochitona cinerea ( Linnaeus, 1767) View in CoL ]; Brugnone 1877, p. 18; Monterosato 1877, p. 33; Tiberi 1877, p. 140, 156 ( fide Dell’Angelo & Palazzi 1989).

Lepidopleurus ( Leptochiton) algesirensis View in CoL ; Malatesta 1962, p. 151, figs 7–8; Dell’Angelo & Palazzi 1989, p. 61, pls 8–13; Dell’Angelo & Smriglio 1999, p.53, pls 12–13, figs 20–23; Dell’Angelo et al. 2001a, p. 145, fig. 2; Dell’Angelo et al. 2004, p. 26, pl. 2, fig. 3.

Lepidopleurus algesirensis View in CoL ; Bellomo & Sabelli 1995, p. 201; Chirli 2004, p. 3, pl. 1, figs 1–2.

Leptochiton algesirensis View in CoL ; Kaas & Van Belle 1985a, p. 44, fig. 17; Dell’Angelo et al. 2007b, p. 141; Dell’Angelo et al. 2012, p. 56, fig. 3D; Dell’Angelo et al. 2018b, p. 13, fig. 5.

non Leptochiton cf. algesirensis View in CoL ; Cherns & Schwabe 2019, p. 1, fig. 1 [= Leptochiton poirieri (de Rochebrune, 1882) View in CoL , fide Dell’Angelo et al. 2018a: 17].

Lepidopleurus algesirensis View in CoL ; Rado 1969, p. 194, pl. 2. fig. 41.

non Lepidopleurus ( Leptochiton) algesirensis View in CoL ; Dell’Angelo & Palazzi 1989, p. 61, pl. 8, fig. 2, pl. 9, figs 1–2, pl. 10, fig. 2, pl. 12, fig. 2 [= Leptochiton maguntiacus (de Rochebrune, 1882) View in CoL , fide this study].

Type material. Unknown, possibly in École des Mines, Paris ( fide Kaas & Van Belle 1985a: 44) .

Type locality. Algeciras ( Spain) .

Material examined. Miocene (Tortonian): France: Saint-Clément-de-la-Place: 20 valves ( MNHN.F.A67062– A67066, Figs 10A–E View FIGURE 10 , NHMW 2017/0108/0007, RGM.1008428, BD 133); Renauleau: 1 valve ( BD 134). Pliocene: Spain: Estepona: 3 valves ( BD 336). Italy: Tuscany: Colle Val d’Elsa: 3 valves ( BD 337, Figs 10F–H View FIGURE 10 ), Pietrafitta Melograni: 7 valves ( BD 338); Sicily: Altavilla: 1 valve ( BD 339). Upper Pliocene to lower Pleistocene: France:

Bosq d’Aubigny: 7 valves ( RGM.1310182, RGM.1310183). Pleistocene: Italy: Calabria: Musalà: 8 valves ( BD 340), Pecoraro: 3 valves ( BD 341), Pezzo: 8 valves ( BD 342), Sicily: Ficarazzi: 54 valves ( BD 343). Maximum width of the valves: 5 / 5 / 8.7 mm.

Description. Head valve semicircular, posterior margin widely V-shaped, notched in the middle. Intermediate valves broadly rectangular (W/L = 2.70–3.40), moderately elevated (H/W = 0.22–0.40), rounded in anterior profile, anterior margin straight, side margins rounded, posterior margin straight, apex not indicated, lateral areas hardly raised, though clearly indicated. Tail valve semicircular (W/L = 1.66–1.91), front margin convex, mucro central, somewhat swollen but not prominent, antemucronal slope slightly convex, postmucronal slope straight.

Tegmentum rough, space between striae of granules reduced, generally with 4-5 obvious growth wrinkles encircling the shell completely. HV, LA and PMA sculptured with small roundish, united granules arranged in radiating series (HV 100 or more, LA 14–16). CA and AMA sculptured with roundish, united granules arranged in longitudinal series (CA 65–70), the series becoming slightly converging towards the outer margins. Each granule in CA and AMA with a central megalaesthete and a series of micraesthetes (normally 5–6, up to 8 or more) along edge.

Articulamentum lacking insertion laminae, apophyses small, broadly triangular, widely separated, evenly rounded in tail valve.

Remarks. Fossil records for this species are rather scant and historical records require confirmation ( Dell’Angelo & Palazzi 1989; Dell’Angelo & Smriglio 1999).

Dell’Angelo & Palazzi (1989) considered Lepidopleurus maguntiacus de Rochebrune, 1882 from the middle Oligocene of western Germany as a synonym of the present species. The two species undoubtedly have remarkable similarities, discussed by Dell’Angelo & Palazzi (1989), but they differ in a series of characters, highlighted in the discussion of L. maguntiacus (see below), and in the different stratigraphic distribution, limited to the lower Oligocene for L. maguntiacus , not exceeding the Miocene (Tortonian) for L. algesirensis ( Capellini, 1859) .

There is a great variability in the material examined, especially for the shape of intermediate (W/L = 2.70–3.40, H/W = 0.22–0.40) and tail (W/L = 1.66–1.91) valves.

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

Distribution. Upper Miocene: northeastern Atlantic (Tortonian): Anjou, France: Saint-Clément-de-la-Place, Renauleau ( Dell’Angelo et al. 2018b). Pliocene: western Mediterranean, Estepona Basin, Spain: Estepona (Dell’Angelo et al. 2004); central Mediterranean, Italy: Altavilla, Colle Val d’Elsa, Pietrafitta Melograni ( Dell’Angelo & Palazzi 1989; Dell’Angelo et al. 2001a; Chirli 2004; Dell’Angelo et al. 2012). Upper Pliocene to upper Pleistocene: northeastern Atlantic, Ligerian Basin, France: Bosq d’Aubigny ( Dell’Angelo et al. 2018b). Pleistocene: central Mediterranean, S. Italy: Ficarazzi, Musalà ( Dell’Angelo & Palazzi 1989), Pecoraro, Pezzo (this study). Recent: eastern Atlantic Ocean: from Portugal and Berlengas Arch. ( Pisani Burnay 1986; Consolado Macedo et al. 1999) south to Morocco and Senegal ( Leloup 1968), Canary Islands ( Leloup 1968; Hernández & Rolán 2011), Madeira and Selvagens Arch. ( Segers et al. 2009; Kaas 1991); Mediterranean Sea: Italy ( Dell’Angelo & Smriglio 1999), Aegean Sea and Levantine Basin ( Koukouras & Karachle 2005), Tunisia: Gulf of Gabes ( Cecalupo et al. 2008).