Lepidochitona marcoi, Dell'Angelo & Fr. Giusti, 1997

Lepidochitona marcoi View in CoL Dell’Angelo & Giusti, 1997

Fig. 103 View FIGURE 103

Lepidochitona marcoi View in CoL Dell’Angelo & Giusti, 1997, p. 53, figs 8, 10, 12, 13, 15; Dell’Angelo & Smriglio 1999, p. 137; Dell’Angelo & Giusti 2000, p. 56; Dell’Angelo et al. 2001a, p. 148, fig. 13; Schwabe 2005, p. 98.

Type material. Holotype: MZB 11655, intermediate valve. Paratypes: MZB 11656 (3 valves); MZB 12755–12756 (2 valves); Museo di Storia Provinciale di Livorno (3 valves); MNHN (4 valves); private collections (19 valves): BD P224/1 (6 valves, Figs 103A–H View FIGURE 103 ), FG (7 valves), VB 3020a (6 valves) .

Type locality. Capraia Island-Capo Corso, Ligurian Sea, from sediments at -350/ 500 m trawled by fishers.

Type stage. Pleistocene (“ biocenosi tardo quaternarie, in parte almeno dell’ultimo glaciale ”: late Quaternary biocoenoses, partly at least of last glacial age).

Material examined. Pleistocene: Italy: Capraia Island , offshore of Capo Corso: type material, plus 259 valves ( BD 893 ). Maximum width of the valves: 3.3 / 4.2 / 2 mm .

Description. Head valve a little less than semicircular, with 9–10 radial depressions crossing its surface, posterior margin forms a very obtuse angle, front slope slightly convex. Intermediate valves broadly rectangular (W/ L = 2.40–2.79), moderately elevated (H/W = 0.32–0.48), semicarinate in anterior profile, anterior margin slightly concave, side margins rounded, posterior margin straight, with a protruding and well evident apex, lateral areas just raised, practically indistinguishable from central area. Tail valve less than semicircular (W/L = 2.07), anterior margin practically straight between apophyses, mucro subcentral, not prominent, antemucronal slope almost straight or slightly convex, postmucronal slope straight.

Tegmentum rather coarse, uniformly covered with roundish and elevated granules (diameter ca 60–65 µm) arranged in irregular quincunxes; each granule with one central megalaesthete surrounded by up to 15 micraesthetes.

Articulamentum with apophyses wide, more or less triangular, short and well incised teeth, much coarser, thicker and wrinkled in tail valve, slit formula 8 / 1 / 7–9, slits inequidistant, slit rays clearly visible, eaves coarsely spongy.

Remarks. The material here discussed is the one described by Dell’Angelo & Giusti (1997), consisting of numerous loose valves trawled between 350/ 500 m offshore Capo Corso ( Corsica) and Capraia Island, likely pertaining to glacial Pleistocene assemblages.

Comparisons. The two closest species are Lepidochitona caprearum ( Scacchi, 1836) and L. canariensis ( Thiele, 1909) , from which L. marcoi Dell’Angelo & Giusti, 1997 differs by the rather pronounced apex of the intermediate plates (not very evident in L. caprearum ), LA practically indistinguishable from CA (with diagonal folds more or less evident in L. caprearum and L. canariensis ), the more straight postmucronal slope of tail valve, the smaller granules and above all the different stratigraphic distribution, limited to the Pleistocene, presumably last glacial, for L. marcoi , broader, from Miocene to Recent, for L. caprearum and L. canariensis .

Distribution. Pleistocene: central Mediterranean, Italy: Capraia Island-Capo Corso, -350/ 500 m ( Dell’Angelo & Giusti 1997; Dell’Angelo et al. 2001a).