Lepidochitona redoniensis

Lepidochitona redoniensis ( Dell’Angelo, Landau, Van Dingenen & Ceulemans, 2018)

Fig. 118 View FIGURE 118

Tonicella redoniensis View in CoL Dell’Angelo, Landau, Van Dingenen & Ceulemans, 2018b, p. 39, fig. 20; Dell’Angelo et al. 2020b, p. 31, 36, tab. 4, 9; Sirenko & Dell’Angelo 2023, p. 278, fig. 4.

Lepidochitona redoniensis ; Sirenko & Dell’Angelo 2023, p. 280.

Type material. Holotype: MNHN.F. A67131 View Materials , intermediate valve, width 3.6 mm, Figs 118A–C View FIGURE 118 . Paratypes: MNHN. F.A67134–F. A67136 View Materials (3 valves), Figs 118D, 118G–H View FIGURE 118 ; NHMW 2017/0108/0038–2017/0108/0040 (3 valves); RGM.1008360–1008363 (4 valves) .

Type locality. Saint-Clément-de-la-Place ( France) .

Type stage. Miocene (Tortonian).

Material examined. Miocene (Tortonian): Saint-Clément-de-la-Place: type material plus 136 valves ( MNHN.F. A67137 View Materials , Figs 118E–F View FIGURE 118 , MNHN.F. A67138 View Materials , NHMW 2017 /0108/0041, RGM.1008356, RGM.1008364, RGM.1008436, BD 152 ). Maximum width of the valves: 2.8 / 3.6 / 2.2 mm .

Description. Head valve semicircular, with few radial ridges that correspond to slits on insertion lamina. Intermediate valve broadly rectangular (W/L = 2.40–2.65), semicarinate in anterior profile, moderately elevated (H/ W = 0.40–0.47, 0.40 in holotype), side margins rounded, posterior margin almost straight on both sides of prominent apex, lateral areas strongly delimited from central area by diagonal fold, second weaker diagonal fold present on posterior margin. Tail valve elliptical (W/L = 2.08–2.23), anterior margin straight, mucro subcentral, antemucronal slope straight to slightly convex, postmucronal slope concave.

Tegmentum smooth and glossy, with several prominent growth lines, aesthetes of same size.

Articulamentum with apophyses not well preserved, wide, short, anteriorly rounded, separated by narrow straight sinus, insertion plates short, slit formula 9 / 1 / 7–8 (a second slit ray lies close to posterior margin on intermediate valves), teeth irregular, slightly thickened at edges, slit rays conspicuous.

Remarks. This species was initially attributed to the genus Tonicella Carpenter, 1873 by Dell’Angelo et al. (2018b), and later included by Sirenko & Dell’Angelo (2023) in the genus Lepidochitona Gray, 1821 .

The valves are small and not well preserved, only a few are complete, showing little intraspecific variability; some intermediate valves are more elevated (H/W = 0.47) and more rounded in profile ( Figs 118E–F View FIGURE 118 ).

Comparisons. Tonicella marmorea ( Fabricius, 1780) and Boreochiton ruber ( Linnaeus, 1767) differ from Lepidochitona redoniensis (Dell’Angelo, Landau, Van Dingenen & Ceulemans, 2028) by lacking radial ridges on the head valve and the diagonal fold separating lateral and central areas on the intermediate valves and being larger.

Distribution. Upper Miocene: northeastern Atlantic (Tortonian): Ligerian Basin, France: Saint-Clément-de-la-Place ( Dell’Angelo et al. 2018b).