Leptochiton serenae, Rochebrune, 1881

Leptochiton serenae Dell’Angelo, Piccioli Resta & Bonfitto, 2007

Fig. 23 View FIGURE 23

Leptochiton serenae Dell’Angelo, Piccioli Resta & Bonfitto, 2007b, p. 140, fig. 2; Brunetti 2011, p. 25, fig. 20.

Type material. Holotype: MZB 23749 (1 tail valve, Isola del Campo , Figs 23A–D View FIGURE 23 ) . Paratypes: MZB 23750 (1 intermediate valve, Cutrofiano , Fig. 23H View FIGURE 23 ); BD 4735 (1 intermediate, and 1 tail valve, Isola del Campo , Figs 23E–G View FIGURE 23 ); GPR (1 intermediate valve, Isola del Campo, and 1 tail valve, Cutrofiano) .

Type locality. Isola del Campo, Gallipoli ( Puglia, Italy) .

Type stage. Lower Pleistocene (Santernian-Aemilian limit) .

Material examined. Lower Pleistocene: Italy: type material. Maximum width of the valves: -- / 4.7 / 4.5 mm .

Description. Head valve not available. Intermediate valves broadly rectangular, subcarinate in anterior profile, moderately elevated (estimated H/W = 0.42), anterior and posterior margins quite straight, side margins slightly rounded, jugal sinus crenulated, apex inconspicuous, lateral areas hardly or not raised, but clearly recognizable by different sculpture. Tail valve semicircular, width more than twice length (W/L = 2.00–2.08), anterior margin almost straight, anterior, prominent mucro, backward directed, antemucronal slope convex, postmucronal slope slightly concave.

Tegmentum rough, space between striae of granules reduced, growth lines thin near margins of LA and stronger on PMA. LA and PMA sculptured with oval granules, separated from each other, developing obliquely from tegmentum, arranged in radiating series (LA 7–8, PMA 36–50). CA and AMA sculptured with oval granules, separated from each other, developing obliquely from tegmentum, arranged in longitudinal series (CA 60, AMA 36–60). Each granule with 3–5 aesthetes of equal width, not differentiated in megalaesthetes and micraestehetes, and not placed in a peculiar order.

Articulamentum without insertion laminae, apophyses wide, triangular in intermediate valves, trapezoidal in tail valve, apical area expanded, with straight anterior edge.

Remarks. The species is known only for the type material, and is characterized by its sculpture of granules developing obliquely from the tegmentum, which differs from that of other known living and fossil Mediterranean and Atlantic Leptochiton species. None of the three intermediate valves is complete, so it has been possible only to estimate in one valve the height/width ratio.

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

Distribution. Lower Pleistocene: central Mediterranean, S. Italy: Cutrofiano, Isola del Campo ( Dell’Angelo et al. 2007b; Brunetti 2011).