Stenosemus praedolii, Dell’Angelo & Sosso & Taviani, 2025

Stenosemus praedolii sp. nov.

Fig. 77 View FIGURE77

Stenosemus dolii View in CoL [non Stenosemus dolii View in CoL ( Van Belle & Dell’Angelo, 1998)]; Dell’Angelo, Giuntelli, Sosso & Zunino 2015a, p. 235, pl. 6, figs 1–9; Dell’Angelo et al. 2016, p. 96.

Ischnochiton ( Simplischnochiton) exaratus View in CoL [non Stenosemus exaratus ( Sars, 1878) View in CoL ]; Dell’Angelo et al. 1999, p. 268, pl. 2, figs 2, 4–7 ( pars) ( fide this study).

Stenosemus sp. B Dell’Angelo, Giuntelli, Sosso & Zunino, 2015a, p. 236, pl. 6, figs 12–13.

Type material. Holotype: MZB 32039, intermediate valve, width 5.7 mm ( Figs 77A–D View FIGURE77 ). Paratype 1: MNHN. F.A98475, intermediate valve, width 4.8 mm ( Fig. 77E View FIGURE77 ) from Borelli ( Italy), Miocene ( Tortonian) . Paratype 2: SMF 380820 About SMF , intermediate valve, width 4.8 mm from Borelli ( Italy), Miocene ( Tortonian) . Paratype 3: MSNG 62654 View Materials , intermediate valve, width 5.6 mm ( Figs 77F–G View FIGURE77 ) from Archi ( Italy), lower Pleistocene . Paratype 4: MSNG 62655 View Materials , intermediate valve, width 4.6 mm ( Fig. 77H View FIGURE77 ) from Archi ( Italy), lower Pleistocene .

Type locality. Montegibbio ( Emilia-Romagna, Italy) .

Type stage. Miocene (Tortonian).

Etymology. The name recalls the morphological resemblance with the extant Mediterranean species Stenosemus dolii ( Van Belle & Dell’Angelo, 1998).

Material examined.Miocene (Tortonian). N. Italy:Borelli: 5 valves( BD 561 , MZB 32041 , MGPT PU 135043 ), Montegibbio: Holotype plus 1 valve ( BD 562 ), Rio di Bocca d’Asino: 1 valve ( BD 563 ). Lower Pleistocene. Italy: Calabria: Archi : 3 valves ( BD 564 ). Maximum width of the intermediate valves: 8.5 mm.

Diagnosis. Intermediate valves broadly rectangular, width more than three times length, carinate, moderately elevated, apex inconspicuous. Tegmentum rough, sculptured with radial striae of small, roundish, elevated, clearly separated granules in LA, longitudinal riblets on each side in CA, more irregular and converging in JA. Articulamentum with apophyses short and wide, insertion lamina with a single slit.

Description. Head and tail valves unknown. Intermediate valves broadly rectangular, width more than three times length (W/L = 3.07–3.18), carinate in anterior profile, moderately elevated (H/W = 0.37–0.50, Holotype 0.46), anterior margin consisting of three segments, two lateral ones straight or slightly concave, and one between apophyses straight or slightly convex, side margins almost straight or slightly rounded, posterior margin practically straight with mucro not very visible, lateral areas moderately elevated.

Tegmentum rough. LA sculptured with 4–8 radial striae of small, roundish, elevated, clearly separated granules. CA sculptured with 15–20 or more longitudinal riblets on each side, normally all reaching anterior margin, more irregular and converging towards jugum, jugal area irregularly covered by converging longitudinal riblets.

Articulamentum with apophyses short and wide, rounded, jugal sinus not very wide, slightly concave, insertion lamina with a single slit.

Remarks. The fossil record of Stenosemus praedolii sp. nov. is limited to the Mediterranean upper Miocene and lower Pleistocene of Italy. Only intermediate valves are present in the material examined. The attribution to the genus Stenosemus is tentative, and the same considerations already expressed for Stenosemus juliuspisai sp. nov. apply (see above).

Comparisons. The more similar species is Stenosemus juliuspisai sp. nov. (see above), from which Stenosemus praedolii sp. nov. differs mainly by the radial sculpture of the lateral areas of the intermediate valves, with 2–4 radial striae of large, quadrangular nodules in S. juliuspisai sp. nov., vs. 5–8 of radial striae of smaller, roundish and spaced granules in S. praedolii sp. nov.

Distribution. Upper Miocene: Proto-Mediterranean Sea (Tortonian): Po Basin, N. Italy: Borelli, Montegibbio, Rio di Bocca d’Asino ( Dell’Angelo et al. 2015a). Lower Pleistocene: central Mediterranean, S. Italy: Archi (this study).