Leptochiton salicensis

Leptochiton salicensis ( Dell’Angelo & Bonfitto, 2005)

Fig. 20 View FIGURE 20

Lepidopleurus ( Leptochiton) salicensis Dell’Angelo & Bonfitto, 2005, p. 2 View Cited Treatment , figs 1–8; Schwabe 2005, p. 102.

Leptochiton salicensis ; Dell’Angelo et al. 2007b, p. 142; Bertolaso et al. 2015, p. 9; Dell’Angelo et al. 2013, p. 71; Dell’Angelo et al. 2016, p. 96; Dell’Angelo et al. 2018b, p. 52.

non Leptochiton salicensis ; Dell’Angelo et al. 2015a, p. 228, pl. 3, figs 12–16 (= Leptochiton sp. , fide this study).

Type material. Holotype: MZB 31028 (1 intermediate valve, Figs 20B–F View FIGURE 20 ). Paratypes: MZB 31029: 2 valves (1 head and 1 tail, Figs 20A, 20G–H View FIGURE 20 ); BD 4662: 4 valves (2 intermediate and 2 tail).

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

Type stage. Lower Pleistocene .

Material examined. Lower Pleistocene: Italy: Sicily: Salice : type material plus 10 valves ( BD 389 ). Maximum width of the valves: 4.3–4.9– 3.9 mm .

Description. Head valve semicircular. Intermediate valves broadly rectangular (W/L = 1.66), rounded in anterior profile, elevated (H/W = 0.51), anterior margin slightly convex, side margins rounded, posterior margin straight, apex inconspicuous, lateral areas not raised. Tail valve semicircular, anterior margin almost straight, mucro subcentral, not prominent, antemucronal slope slightly convex, postmucronal slope slightly concave.

Tegmentum rough, concentric lines of growth well visible, uniformly sculptured with well raised, neatly separated roundish/polygonal granules, randomly arranged, diameter 70–90 μm, aesthetes not clearly visible, a central megalaesthete and 2–3 micraesthetes (but there should be more) around the border of some granules.

Articulamentum without insertion laminae, apophyses small, sharply triangular, widely separated by a large jugal sinus, apical area expanded, with bisinuate anterior margin.

Remarks. The fossil record of Leptochiton salicensis ( Dell’Angelo & Bonfitto, 2005) is limited to the Lower Pleistocene of Salice.

Dell’Angelo et al. (2015) attributed tentatively to Leptochiton salicensis two valves, a head from the lower Miocene of Rocco di Passerano ( Italy) and a tail from the Miocene (Tortonian of Borelli ( Italy). Despite the existing similarity with L. salicensis , it is not possible to identify with certainty these valves, that are discussed and figured in the section dedicated to the “Species of unclear taxonomic position”, and are left in open nomenclature as Leptochiton sp.

Comparisons. See Tab. 5 for a comparison with the Leptochiton spp. considered in the present study.

Distribution. Lower Pleistocene: central Mediterranean: Italy: Salice ( Dell’Angelo & Bonfitto 2005).