Lepidopleurus (Leptochiton) salicensis, Dell’Angelo, Bruno & Bonfitto, Antonio, 2005

Dell’Angelo, Bruno & Bonfitto, Antonio, 2005, Notes on Fossil Chitons. 1. A new species of Lepidopleurus (Mollusca: Polyplacophora) from the Pleistocene of Salice (Sicily, Italy), Zootaxa 821, pp. 1-6 : 2-5

Lepidopleurus (Leptochiton) salicensis n.sp.

( Figures 1–8 )

Diagnosis. Valves solid. Tegmentum uniformly sculptured with well raised, neatly separated rounded/polygonal granules, randomly arranged.

Description. Head valve semi­oval. Intermediate valves broadly rectangular, back evenly rounded, moderately elevated (intermediate valve, height/width 0.51), front margin slightly convex, side margins rounded, hind margin straight, apices inconspicuous, lateral areas not raised. Tail valve semicircular, anterior margin almost straight, mucro not prominent, subcentral, postmucronal slope concave.

Tegmentum uniformly sculptured with well raised, neatly separated roundish/polygonal granules, randomly arranged, diameter about 70–90 µm. The aesthetes are not clearly visible, a central one and 2–3 others (but there should be more) may be identified around the border of some granules.

Articulamentum without insertion laminae. On the ventral side of the intermediate valves the posterior area clearly presents an expanded central zone, with a bisinuate anterior margin. Apophyses small, largely incomplete in the material examined, but probably sharply triangular, widely separated by a large jugal sinus.

Type material. Holotype: MZB 31028 (1 intermediate valve). Paratypes: MZB 31029 (1 head and 1 tail valves); BDA 4662 (2 intermediate and 2 tail valves)

Type locality. Salice (Messina province, Sicily, Italy).

Type stage. Early Pleistocene.

Etymology. From the site of Salice.

Remarks. The genus Lepidopleurus (Leptochiton) is characterized by valves lacking insertion plates, the sutural laminae (apophyses) small and neatly separate, the tegmentum uniformly granulated, and the girdle narrow, covered with scales or with scales and spicules ( Kaas & Van Belle 1985; Dell’Angelo & Smriglio 1999). The granules are generally of small size, with rather regularly arranged aesthetes, and can be arranged in radial or longitudinal series, quincuncially or randomly distributed. Lp. (Lc.) salicensis n.sp. is characterized by the tegmental sculpture consisting of randomly arranged granules.

Another species having the same kind of tegmental sculpture as L. salicensis , is Lp. (Lc.) tavianii Dell’Angelo, Landau & Marquet, 2004, known from the Pliocene of Estepona (Málaga, Spain) (Dell’Angelo, Landau & Marquet 2004: 29, pl.1 figs 1–8, pl.2 figs 1,5), where, however, the granules are characterized by a fungiform section and are arranged in a beehive structure (figs 9–12), not the random distribution seen in L. salicensis .

Also Lp. (Lc.) alveolus (M. Sars MS, Lovén, 1846), a species living in North Atlantic and not known as fossil ( Kaas & Van Belle 1985: 36. fig. 14), has a tegmentum sculptured with neatly separated rounded to oval, raised granules, arranged quincuncially (fig. 16), but the granules are more oval and of different shape (compare fig. 2 and fig. 16), with a characteristic arrangement of aesthetes (fig. 16).

Figures

FIGURES 1 – 8: Lepidopleurus (Leptochiton) salicensis n. sp. Fig. 1. Holotype (MZB 31028), intermediate valve, scale bar = 1 mm. Fig. 2. holotype, detail of sculpture, scale bar = 100 µm. Fig. 3. holotype, outline, scale bar = 1 mm. Fig. 4. holotype, ventral view, scale bar = 1 mm. Fig. 5. paratype, tail valve, lateral view, scale bar = 1. Fig. 6. paratype tail valve, granules, scale bar = 100 µm; Fig. 7. mm paratype (MZB 31029), tail valve, scale bar = 1 mm; Fig. 8. paratype (MZB 31029), head valve, scale bar = 1 mm.