Hanleya mediterranea Sirenko, 2014

Hanleya mediterranea Sirenko, 2014 View in CoL

Fig. 44 View FIGURE44

Hanleya mediterranea Sirenko, 2014, p. 2923 View in CoL View Cited Treatment , figs 6–8A–J; Dell’Angelo et al. 2015a, p. 232, pl. 4, figs 13–14; Dell’Angelo et al. 2016, p. 96; Dell’Angelo et al. 2020b, p. 52, tab. 9, Dell’Angelo et al. 2021a, p. 129, figs 2–5; Dell’Angelo et al. 2021b, p. 411, figs 38–45.

Hanleya multigranosa View in CoL [non Hanleya multigranosa ( Reuss, 1860) View in CoL ]; Sabelli & Taviani 1979, p. 161, pl. 1, fig. 4 (= H. mediterranea View in CoL , fide Sirenko 2014: 18).

non Hanleya hanleyi View in CoL ; Dell’Angelo & Forli 1995a, p. 225; Dell’Angelo et al. 1998a, p. 244, pl. 2, figs 1–2; Dell’Angelo et al. 1999, p. 262, pl. 1, fig. 3 ( partim); Dell’Angelo & Smriglio 1999, p. 85, pl. 25 figs A–B, E–F, H, pl. 26 figs K, L–P ( partim); Dell’Angelo et al. 2004, p. 30, pl. 2, fig. 8; Dell’Angelo et al. 2012, p. 56, fig. 3F; Dell’Angelo et al. 2013, p. 76, pl. 3, figs D–F ( fide Sirenko 2014; Dell’Angelo et al. 2015a; this study).

Type material. Holotype ZISP 2201 View Materials , length 4.7 mm, now disarticulated, and three paratypes ZISP 2202 View Materials .

Type locality. Mediterranean Sea , off Begur ( Girona, Spain), 200–300 m.

Material examined. Upper Miocene (Tortonian): Italy: Borelli: 1 valve ( MGPT PU 135039); Montegibbio: 2 valves ( BD 433, MZB 32017, Figs 44G–H View FIGURE44 ). Lower Pliocene: Italy: Borzoli: 4 valves ( BD 434), Rio Sant’ Antonino: 3 valves ( MP, MZB 45706), Zinola: 1 valve ( MZB 45705). Pliocene: Spain: Estepona: 1 valve. Italy: Sicily: Altavilla: 1 valve ( BD 435, Figs 44 E–F View FIGURE44 ), Trappeto: 1 valve ( BD 436). Pleistocene: Italy: Tuscany: Capraia Island-Capo Corso - 350m: 4 valves ( BD 437, Figs 44A–C View FIGURE44 ), Riparbella: 2 valves ( BD 438, Fig. 44D View FIGURE44 ); Calabria: Archi S. Francesco: 1 valve ( BD 439). Maximum width of the valves: 3 / 3.8 / 2.8 mm.

Description. Head valve semicircular, posterior margin widely V-shaped, notched in middle. Intermediate valves trapezoidal, width about twice length (W/L = 1.88–1.94), moderately elevated (H/W = 0.40–0.45), semicarinate in anterior profile, anterior margin greatly splayed laterally, with large inward curve 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 more or less elliptical (W/L = 1.43–1.58), anterior margin slightly convex between apophyses, mucro subcentral, clearly indicated, antemucronal slope slightly convex, postmucronal slope decidedly concave directly behind mucro, straightening near posterior margin.

Tegmentum surface smooth, without aesthetes among granules. HV, LA and PMA uniformly sculptured with roundish granules (diameter 70–80 μm), arranged without pattern. CA and AMA sculptured with oval granules (120 × 70 μm) arranged without pattern, several granules join to form larger granules (up to 220 × 160 μm), JA sculptured with oval granules (about 80 × 50 μm) arranged without interspaces or pattern. Each granule contains one central megalaesthete surrounded by 9–16 micraesthetes, megalaesthete slightly larger in some cases, but almost same width.

Articulamentum strongly developed, apophyses wide, oriented laterally, connected to primordium of insertion plates in intermediate valves, insertion plates obsoletely striate in head and tail valves.

Remarks. The fossil record of Hanleya mediterranea Sirenko, 2014 includes the Miocene (Tortonian) of N. Italy, Pliocene of Italy and Spain, and Pleistocene of Italy.

Hanleya mediterranea has been recently described from the Mediterranean Sea, and both the species living in the Mediterranean Sea [ H. mediterranea and H. hanleyi (Bean in Thorpe, 1844)] has been found in fossil deposits from Italy, in some case with both species present in the same site (e.g., in the Upper Miocene of N. Italy, see Dell’Angelo et al. 2015a).

Comparisons. Hanleya mediterranea is distinguished from other species in the genus by the presence of large granules comprising two or more small granules in pleural areas. In H. mediterranea the head valve has more strongly developed insertion plates that are 16–20% the length of the valve, compared with H. hanleyi in which the insertion plates are 3–9% the length of the head valve ( Sirenko 2014).

Distribution.Upper Miocene: Proto-Mediterranean Sea (Tortonian):Po Basin, North Italy:Borelli, Montegibbio (Dell’Angelo et al., 1999, 2015a). Lower Pliocene: central Mediterranean, Italy: Liguria: Borzoli, Rio S. Antonino, Zinola ( Dell’Angelo et al. 2013). Pliocene: western Mediterranean, Spain: Estepona (Dell’Angelo et al. 2004); central Mediterranean, Italy: Altavilla Milicia ( Dell’Angelo et al. 2012). Pleistocene: central Mediterranean, Italy: Riparbella ( Dell’Angelo & Forli 1995a), Torrente Stirone ( Sabelli & Taviani 1979), Capraia Island-Capo Corso - 350 m, Archi S. Francesco (this study). Recent: Mediterranean Sea ( Sirenko 2014; Sirenko et al. 2016; Dell’Angelo et al. 2021a).