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

Dell’Angelo, Bruno, Sosso, Maurizio & Taviani, Marco, 2024, A critical update of Mediterranean chitons (Mollusca: Polyplacophora) with the description of new taxa, Zootaxa 5497 (2), pp. 194-208 : 197-199

Hanleya schwabei new species

( Figure 3 )

Hanleya aff. mediterranea (non Sirenko, 2014); Dell’Angelo et al. 2021, p. 131, fig. 5, tab. 3.

Type material. Holotype: MZUB 60338 , intermediate valve, width 3.8 mm ( Figs 3B–E ) ; Paratype 1: MNHN- IM-2022-2410, intermediate valve, width 3.4 mm ( Fig. 3A ) from offshore Capraia island-Capo Corso -350/ 500 m ; Paratype 2: MZUB 60339 , intermediate valve from Tipaza, Algeria, width 3.5 mm ; Paratype 3: SMF 66407 , intermediate valve from Gorgona island , width 3.5 mm ; Paratype 4: ZISP 2423 , tail valve, width 2.7 mm ( Figs 3F–H ) .

Type locality. Tyrrhenian Sea, Scilla , Calabria .

Etymology. This species is named after Enrico Schwabe in recognition of his important contribution to the study of Polyplacophora.

Material examined. Western Mediterranean, Tyrrhenian Sea, Capraia island: 2 valves (BD 249, ZISP 2424), Giglio island: 1 valve ( BD 250). Maximum width: -- / 3.8 / 2.7 mm.

Diagnosis. Intermediate valves trapezoidal, semicarinate, elevated, apex well developed, tail valve circular, mucro subcentral. Tegmentum slightly rough, sculptured with granules irregularly arranged, oval (up to 127 μm) in PA, AMA, smaller and more irregular in JA, each granule with a central aesthete and 12–15 others, all more or less of same size. Articulamentum strongly developed, apophyses wide, oriented laterally.

Description. Head valve unknown. Intermediate valves trapezoidal (W/L = 1.50–1.60), elevated (H/W = 0.39–0.44), 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), anterior margin almost straight between apophyses, mucro subcentral, antemucronal slope convex, postmucronal slope decidedly concave directly behind mucro, straightening near posterior margin.

Tegmentum surface slightly rough. LA and PMA uniformly sculptured with roundish randomly arranged granules (diameter up to 100 μm). 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 aesthete 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 sp. nov. is recorded from various Mediterranean localities, previously labeled as H. aff. mediterranea in collections. Some such valves were illustrated by Dell’Angelo et al. (2021: figs 5.A– F). A unique intermediate valve offshore Capraia/Capo Corso -350/ 500 m ( Fig. 3A ) could belong to last glacial Pleistocene assemblages.

Comparisons. The most similar species is H. mediterranea , that differs from H. schwabei sp. nov. by the characteristic large granules, not present in H. schwabei sp. nov., Moreover, the shape of the tail valves is different, almost circular in H. schwabei sp. nov., more or less oval in H. mediterranea .

Distribution. Recent: Italy and Algeria (this study); possibly from last glacial Pleistocene assemblages, Western Mediterranean, offshore Capraia island/Capo Corso -350/ 500 m.

Figures

FIGURE 3. Hanleya schwabei sp. nov., Tyrrhenian Sea: A. offshore Capraia island-Capo Corso, depth ca. 350 m, (possibly last glacial Pleistocene), Paratype 1 (MNHN-IM-2022-2410), intermediate valve, width 3.4 mm, dorsal view. B–E. Off Scilla, Holotype (MZUB 60338), intermediate valve, width 3.8 mm, dorsal view (B), close-up of surface ornamentation of pleural (C) and lateral (D) areas, and frontal view (E). F–H. Off Scilla, Paratype 4 (ZISP 2423), tail valve, width 2.7 mm, dorsal view (F), close-up of surface ornamentation of antemucronal area (G) and lateral view (H). Scale bars = 400 μm (G), 100 μm (D), 40 μm (C).