Leptochiton renauleauensis, Dell'Angelo, Landau, Van Dingenen & Ceulemans, 2018

Leptochiton renauleauensis View in CoL Dell’Angelo, Landau, Van Dingenen & Ceulemans, 2018

Fig. 28 View FIGURE 28

Leptochiton renauleauensis View in CoL Dell’Angelo, Landau, Van Dingenen & Ceulemans, 2018b, p. 18, fig. 9; Dell’Angelo et al. 2020b, p. 52, tab. 9.

Lepidopleurus ( Leptochiton) sp. Marquet, 2002, p. 12, pl. 1, fig. 2.

Type material. Holotype MNHN.F.A67076, tail valve, width 3 mm ( Figs 28A–E View FIGURE 28 ) . Paratype: MNHN.F.A67077, intermediate valve, width 3 mm ( Figs 28F–H View FIGURE 28 ) .

Type locality. Renauleau ( Anjou, France) .

Type stage. Miocene (Tortonian).

Material examined. Upper Miocene (Tortonian): France: type material .

Description. Head valve unknown. Intermediate valve broadly rectangular, very elongated (W/L = 3.09), subcarinate in anterior profile, moderately elevated (H/W = 0.33), posterior margin straight, apices not indicated, lateral areas not raised, delimited only by change in sculpture compared to central area. Tail valve oval, mucro not protruding in anterior position, antemucronal slope almost straight, postmucronal slope slightly concave.

Tegmentum rough, granules well separated from each other, growth lines not very evident. LA and PMA sculptured with granules randomly arranged. CA and AMA sculptured with longitudinal series of widely spaced roundish and elevated granules (CA 50–55, AMA 40, more irregular), converging towards outer margins. Each granule with a central megalaesthete and 5–6 micraesthetes irregularly disposed along margin.

Articulamentum without insertion laminae, apophyses wide, not well preserved.

Remarks. The fossil record of Leptochiton renauleauensis Dell’Angelo, Landau, Van Dingenen & Ceulemans, 2018 is limited to the Miocene (Tortonian) of France ( Dell’Angelo et al. 2018b). The two valves found are not complete, quite worn and some characters are not observable. The longitudinal series of granules on the central area of intermediate valves and the antemucronal area of tail valve are quite irregular, so much to give the impression of being randomly arranged in certain areas. Despite this, the sculpture is different from that of the other Leptochiton species known from the European Neogene, and characteristic enough to have been described as a new species by Dell’Angelo et al. (2018b).

We estend the stratigraphic distribution of Leptochiton renauleauensis to the lower Pliocene, attributing to this species also the valves from Kallo ( Belgium) illustrated by Marquet (2002) as Lepidopleurus ( Leptochiton) sp.

Comparisons. The characteristics of the sculpture of Leptochiton renauleauensis agree with the belonging of the species to the Leptochiton cimicoides group.

Distribution. Upper Miocene: northeastern Atlantic (Tortonian): Ligerian Basin, France: Renauleau ( Dell’Angelo et al. 2018b). Lower Pliocene: North Europe, Belgium: Kallo ( Marquet 2002).