Lepidochitona leognanensis (Cossmann & Peyrot, 1917)

Lepidochitona leognanensis (Cossmann & Peyrot, 1917) View in CoL

Fig. 113 View FIGURE 113

Chiton leognanensis Cossmann & Peyrot, 1917, p. 34 , pl. 2, figs 28–31;? Dolfuss 1920, p. 45; Van Belle 1981, p. 46; Varone 2008, p. 156; Cahuzac et al. 2012, p. 399; Dell’Angelo et al. 2018a, p. 11, 40; Dell’Angelo et al. 2020b, p. 29, fig. 18.

Type material. Unknown, the status of the collection Bial de Bellerade is currently unknown, with some material (no “ type ” specimens), recorded in the University of Talence (Bordeaux) .

Type locality. Le Thil ( France) .

Type stage. Lower Miocene .

Material examined. Lower Miocene: France (Aquitanian): Lariey : 2 valves ( JFL, Figs 113A–C View FIGURE 113 ) . France (Burdigalian): Gamachot : 6 valves ( BD 938 , MZB 50573-50575 , Figs 113D–L View FIGURE 113 ). Maximum width of the valves: 2.6–3.5– 1.5 mm .

Description. Head valve semicircular, posterior margin widely V-shaped, slope slightly convex. Intermediate valves broadly rectangular (W/L = 2.06–2.53), semicarinate in anterior profile, moderately elevated (H/W = 0.44– 0.45), anterior margin slightly convex or weakly sinuose, side margins poorly rounded, posterior margin straight at both sides of prominent apex, lateral areas scarcely differentiated. Tail valve semicircular (W/L = 2.46), anterior margin almost straight, mucro in anterior position, antemucronal and postmucronal slopes almost straight.

Tegmentum entirely covered by randomly arranged elliptical granules, although weak impression of order in radial striae on LA, radiating from area just next to apex.

Articulamentum with large apophyses, triangular in intermediate valves, trapezoidal in tail valve, slit formula: 9 / 2 / 7, slits inequidistant, slit rays clearly visible in head and tail valves.

Remarks. The fossil record of Lepidochitona leognanensis (Cossmann & Peyrot, 1917) is limited to the lower Miocene of the Aquitaine Basin. This species is poorly known, scarcely recorded in the literature since its original description; one record from Rennes Dolfuss (1920) recorded and the material recently reported from Lariey by Cahuzac et al, 2012 (the two intermediate valves here figured, Figs 113A–C View FIGURE 113 ).

Comparisons. See Tab. 18, 19 for more comparison with the other Lepidochitona spp . from the NE Atlantic considered in the present study.

Distribution. Lower Miocene: northeastern Atlantic (Aquitanian-Burdigalian): France, Aquitaine Basin: Gamachot, Lariey, Le Thil (Cossmann & Peyrot 1917; Cahuzac et al. 2012; Dell’Angelo et al. 2020b).