Hanleya fratrum, Dell’Angelo & Sosso & Taviani, 2025

Hanleya fratrum sp. nov.

Fig. 41 View FIGURE 41

Type material. Holotype MSNG 62636 View Materials , intermediate valve, width 4.6 mm ( Figs 41E–H View FIGURE 41 , from Salice ( Italy) . Paratype 1, MSNG 62637 View Materials , head valve, width 6.1 mm ( Fig. 41A View FIGURE 41 ), from Pezzo ( Italy) . Paratype 2, MSNG 62638 View Materials , tail valve, width 5.4 mm ( Figs 41I–L View FIGURE 41 ), from Vallone Catrica ( Italy) .

Type locality. Salice ( Sicily, Italy) .

Type stage. Lower Pleistocene .

Etymology. The name honors Giorgio and Pierluigi Taviani, elder brothers of M.T., for their continuous support and encouragement to pursue his vocation for marine sciences and paleontology; from the genitive of fratres (Latin for brothers).

Material examined. Pleistocene: Italy: type material plus Calabria: Musalà : 2 valves ( BD 420 , Figs 41B–D View FIGURE 41 ), Vallone Catrica: 2 valves (AV, BD 421 ) ; Sicily: Pezzo : 7 valves ( BD 422 ) , Maximum width of the valves: 6.1 / 9.2 / 6.5 mm .

Diagnosis. Head valve semicircular, intermediate valves broadly rectangular, moderately elevated, semicarinate, apex well developed, protruding, tail valve semicircular, subcentral protruding mucro. Tegmentum rough, sculptured with numerous oval granules, randomly disposed in HV, LA, PMA, arranged in irregular longitudinal striae in central part of CA, AMA, inclined towards the side margins outside JA, each granule with one subcentral megalaesthete surrounded by 10–12 micraesthetes, almost of same size.

Description. Head valve semicircular. Intermediate valves broadly rectangular (W/L = 1.73–2.13), moderately elevated (H/W = 0.32–0.42), semicarinate in anterior profile, anterior margin convex, side margins rounded, posterior margin practically straight, except for protruding, well developed apex in middle, lateral areas not raised, not differentiated from central area. Tail valve semicircular (W/L = 1.45–1.60), anterior margin straight between apophyses, subcentral protruding mucro, antemucronal slope straight or slightly convex, postmucronal slope practically straight, only slightly concave just below mucro.

Tegmentum surface rough, space between striae of granules reduced. HV, LA and PMA uniformly sculptured with numerous, oval granules, randomly disposed, (length up to 130 µm), very dense and close to each other. CA and AMA sculptured with oval granules (length up to 137 µm), arranged in irregular longitudinal striae in central part of valve (for about ⅓ of total width), inclined towards the side margins outside JA and much more irregular, granules smaller and denser in JA. Each granule contains one subcentral megalaesthete surrounded by 10–12 micraesthetes regularly disposed along edge, megalaesthete slightly larger in some cases, but almost same width.

Articulamentum with apophyses rather large, broadly triangular with rounded top, separated by an almost straight jugal sinus, about a third or a little more than valve’s width, connected to primordium of insertion plates in intermediate valves, insertion plates weakly developed in head and tail valves.

Remarks. The fossil record of Hanleya fratrum sp. nov. is limited to the Pleistocene of South Italy, a few localities from Calabria (Musalà and Vallone Catrica) and Sicily (Pezzo and Salice).

Comparisons. This species is at a first check like Hanleya hanleyi (Bean in Thorpe, 1844), from which, however, it is always recognizable for the greater irregularity of the striae of longitudinal granules (slightly larger, up to 137 µm in H. fratrum sp. nov. vs. up to 100 µm in H. hanleyi ), for the smaller and denser granules in JA and for the longitudinal striae closest to each other, as opposed to the greater width of the intercostal spaces present in H. hanleyi .

Distribution. Pleistocene: central Mediterranean, S. Italy: Musalà, Pezzo, Salice, Vallone Catrica (this study).