Hanleya schwabei, Dell'Angelo, Sosso & Taviani, 2024

Hanleya schwabei View in CoL Dell’Angelo, Sosso & Taviani, 2024

Fig. 47 View FIGURE 47

Hanleya aff. mediterranea View in CoL (non Hanleya mediterranea Sirenko, 2014 View in CoL ); Dell’Angelo et al. 2021a, p. 131, fig. 5, tab. 3. Hanleya schwabei View in CoL Dell’Angelo, Sosso & Taviani, 2024, p. 197, fig. 3.

Type material. Holotype: MZUB 60338 View Materials , intermediate valve, width 3.8 mm ( Figs 47A–D View FIGURE 47 ) ; Paratype 1: MNHN-IM-2022-2410, intermediate valve, width 3.4 mm from offshore Capraia Island-Capo Corso -350/ 500 m; Paratype 2: MZUB 60339 View Materials , intermediate valve from Tipaza, Algeria, width 3.5 mm ; Paratype 3: SMF 66407 About SMF , intermediate valve from Gorgona island , width 3.5 mm ; Paratype 4: ZISP 2423 View Materials , tail valve, width 2.7 mm from Scilla .

Type locality. Tyrrhenian Sea , Scilla ( Calabria, Italy) .

Material examined. Pleistocene: Italy: Capraia Island-Capo Corso -350/ 500m: type material, Archi S. Francesco: 1 valve ( BD 440 , Figs 47E–H View FIGURE 47 ). Recent : Italy: type material, plus Tuscan Archipelago: Capraia Island: 3 valves ( BD 249 , ZISP 2424 View Materials ), Giglio Island : 1 valve ( BD 250 ) ; Algeria: Tipaza: type material. Maximum width of the valves: -- / 4.0 / 3.7 mm .

Description. Head valve unknown. Intermediate valves trapezoidal (W/L = 1.50–1.84), elevated (H/W = 0.39–0.53), semicarinate in anterior profile, anterior margin greatly splayed laterally, almost straight to slightly concave in jugal area, posterior margin with protruding, well developed apex in middle, lateral areas not raised, only marked by a difference in sculpture, Tail valve circular (W/L = 1.16–1.32), anterior margin almost straight between apophyses, mucro submedian, antemucronal slope convex, postmucronal slope decidedly concave directly behind mucro, straightening near posterior margin.

Tegmentum surface slightly rough, without aesthetes among granules. LA and PMA uniformly sculptured with roundish granules (diameter up to 100 μm), arranged without pattern. PA and AMA sculptured with oval granules (up to 127 μm long) arranged without pattern, JA sculptured with smaller granules, more irregular and closer to each other, without interspaces. Each granule contains one megaesthete in central position surrounded by up to 15 others in CA, AMA, a little less (up to 12) in LA, PMA; all aesthetes more or less of same size, no aesthetes among granules.

Articulamentum strongly developed, apophyses wide, oriented laterally, connected to primordium of insertion plates in intermediate valves.

Remarks. Hanleya schwabei Dell’Angelo, Sosso & Taviani, 2024 has been recently established upon a few valves from various Mediterranean localities, previously labeled as H. aff. mediterranea Sirenko, 2014 in collections. Some such valves were illustrated by Dell’Angelo et al. (2021: figs 5.A–F). A single intermediate valve offshore CapraiaIsland-Capo Corso -350/ 500 m could belong to last glacial Pleistocene assemblages. We found some additional loose valves from the Tuscan archipelago, and a tail valve from the Pleistocene of Archi S. Francesco ( Figs 47E–H View FIGURE 47 ), confirming the presence of H. schwabei as fossil in the Italian Pleistocene.

Comparisons. The most similar species is H. mediterranea Sirenko, 2014 , that shares the tegmentum sculpture characterized by granules arranged without pattern, but differ anyway from H. schwabei by the different sculpture of the tegmentum, with characteristic large granules not present in H. schwabei , which give a different appearance to the valves. Moreover the shape of the tail valves is different, almost circular in H. schwabei , more or less elliptical in H. mediterranea .

Distribution. Pleistocene: central Mediterranean, Italy: Archi S. Francesco (this study), Capraia Island-Capo Corso -350/ 500 m ( Dell’Angelo et al. 2024). Recent: Mediterranean Sea: Italy: Capraia Island, Giglio Island, Scilla and Algeria: Tipaza ( Dell’Angelo et al. 2024; this study).