Lepidochitona lepida ( Reuss, 1860 )

Lepidochitona lepida ( Reuss, 1860)

Fig. 125 View FIGURE 125

Chiton lepidus Reuss, 1860, p. 259 , pl. 8, figs 12–13; Boettger 1869, p. 11; Boettger 1870, p. 41; Procházka 1895, p. 99; Procházka 1900, p. 72, 117; Csepreghy-Meznerics 1950, p. 15 ( fide Studencka & Studencki, 1988); Gürs 1995, p. 27.

Chiton lepidus Reuss (non Chiton lepidus Gould, 1859 ); Schwabe 2000, p. 207; ICZN 2003, Opinion 2033.

Tonicia lepida ; de Rochebrune 1882, p. 62.

Middendorffia lepida ; Šulc 1934, p. 10, pl. 1, figs 13–15; Ashby & Cotton 1935, p. 390; Malatesta 1962, p. 157; Bałuk 1965, p. 370; Laghi 1977, p. 106, 108; Janssen 1978, p. 226.

Lepidochitona lepida ; Bałuk 1971, p. 459, pl. 4, figs 6–12 ( partim); Kaas & Van Belle 1981, p. 20; Van Belle 1981 a, p. 47; Bałuk 1984, p. 288, pl. 7, figs 1-3; Macioszczyk 1988, p. 53; Studencka & Studencki 1988, p. 39, pl. 2, figs 1, 3; Dell’Angelo & Forli 1994, p. 228; Dell’Angelo & Smriglio 1999, p. 137, 149; Dell’Angelo et al. 1999, p. 265; Bouchet & Schwabe 2001, p. 227; Dulai 2001, p. 41, pl. 1, figs 1–6; Dulai 2005, p. 36; Dell’Angelo et al. 2007a, p. 47; Dulai & Studencka 2007, p. 17; Studencka & Dulai 2010, p. 267, textfigs 6A–B; Dell’Angelo et al. 2012, p. 63; Dell’Angelo et al. 2013, p. 89; Ruman & Hudácková 2015, p. 164, fig. 5.6; Dell’Angelo et al. 2016, p. 98, tab. 5; Dell’Angelo et al. 2018b, p. 53, tab. 17; Dell’Angelo et al. 2020b, p. 53, tab 9; Dulai & Katona 2024, p. 39, figs 19–26.

Lepidochitona cf. lepida ; Dulai 2025a, p. 10, figs 16–18.

Lepidochitona monterosatoi View in CoL (non Lepidochitona monterosatoi Kaas & Van Belle, 1981 View in CoL ); Macioszczyk, 1988, p. 52, pl. 2, figs 6–8.

Middendorffia boravičensis Šulc, 1934, p. 11 , pl. 1, fig. 16.

Lepidochitona boravičensis ; Van Belle 1981, p. 25; Dell’Angelo et al. 2016, p. 98, tab. 5; Dell’Angelo et al. 2018b, p. 52; Dell’Angelo et al. 2020b, p. 53, tab 9.

Lepidochitona sp. Bałuk, 1965, p. 370, pl. 1, fig. 8 ( fide Bałuk 1971; Ruman & Hudácková 2015).

Type material. Unknown, not present in NHMV.

Type locality. Rudoltice ( Czech Republic) .

Type stage. Middle Miocene.

Material examined. Middle Miocene: Central Paratethys : Romania: Lăpugiu de Sus: 1 valve ( NHMV 2010 /0256/0017), Kostej: 2 valves ( NHMV 2010 /0256/0018, Figs 125E–H View FIGURE 125 , NHMV 2010/0256/0021, Figs 125M– P View FIGURE 125 ); Eastern Paratehys: Ukraine: Varovtsi: 120+ valves ( BD 947 , Figs 125A–C, 125I–L View FIGURE 125 ); Hungary: Letkés: 2 valves ( BD 948 ), Várpalota: 2 valves ( BD 949 , Fig. 125D View FIGURE 125 ). Maximum width of the valves: 3.5–5.2– 2.1 mm .

Description. Head valve semicircular, posterior margin widely V-shaped, with or without presence of radial depressions. Intermediate valves broadly rectangular (W/L = 2.40–2.70), moderately elevated (H/W = 0.30–0.43), semicarinate in anterior profile, anterior margin almost straight to slightly concave, side margins rounded, posterior margin almost straight, with strongly protruded apex, lateral areas slightly raised, not distinctly separated from central area. Tail valve semicircular (W/L = 1.88–2.12), anterior margin almost straight, mucro in variable position, from anterior to posterior, anterior margin almost straight, antemucronal slope straight, postmucronal slope slightly concave.

Tegmentum uniformly covered with fine roundish/oval flat granules irregularly arranged, which give the impression of being arranged in two systems of rows, running irregularly from apex and posterior margin towards anterior margin, almost forming a net-like ornament. Each granule up to 80 µm long, with a central megalaesthete and 7–10 micraesthetes along margin.

Articulamentum with apophyses wide, triangular in intermediate valves, quadrangular in tail valve, slit formula 8–10 / 1 / 12, teeth massive, slightly roughened on outside, eaves spongy.

Remarks. The taxon Chiton lepidus Reuss, 1860 is preoccupied by Chiton lepidus Gould, 1859 , now considered as a synonym of Lepidozona luzonica ( Sowerby, 1842) , an Indo-Pacific species from the Philippines to the Arabian Gulf. Schwabe (2000), the first author noticing this homonymy, proposed to maintain the specific name of Chiton lepidus Reuss, 1860 for a chiton (currently known as Lepidochitona lepida ) from the Middle Miocene of Europe. The International Commission on Zoological Nomenclature (2003) has accepted this proposal (Opinion 2033).

Chiton lepidus was erected by Reuss (1860) based upon an intermediate valve from the Middle Miocene of Rudoltice in the Moravian part of the Carpathian Foredeep Basin, Czech territory. Reuss’ original material is no longer available. Šulc (1934) described and later illustrated a head and a tail valve from the same locality, attributed to this species. The paucity of material and the opinability of intepreting species in Lepidochitona may accounts for the conservative approach by later authors who synonymized C. lepidus with Mediterranean extant taxa; L. caprearum ( Scacchi, 1836) by Malatesta (1962) and Laghi (1977); L. cinerea ( Linnaeus, 1767) by Šulc [1934, = Lepidopleurus marginatus (Pennant) reported by Sacco 1897], Bałuk (1971), and Laghi (1977); L. monterosatoi Kaas & Van Belle, 1981 by Bałuk (1984); L. canariensis ( Thiele, 1909) by Studencka & Studencki (1988). For example, Macioszczyk (1988) considered the valves of L. lepida figured by Bałuk (1971: pl. 4, figs 6–12) as belonging to L. monterosatoi (pl. 4, figs 6, 8, 10) and L. caprearum (pl. 4, fig. 9), while Studencka & Studencki (1988: p. 40) considered the tail valve figured by Bałuk (1971: pl. 4, figs 11–12) not corresponding to the tail valve of L. lepida figured by Šulc (1934: pl. 1, fig. 15).

The inadequacy of the descriptions of Reuss and Šulc, and the scarcity of records in literature (sometimes attributed to different species) prompted our reconsideration of the available material, focusing upon some morphological characters:

- The presence of radial depressions on the head valve is not evidenced in the Šulc’s description, although very slight radial depressions are observable on the head valve ( Šulc 1934: pl. 1, fig. 13). Literature records figure valves with ( Bałuk 1971: pl. 4, fig. 6) and without ( Studencka & Studencki 1988: pl. 2, fig. 1) radial depressions, a situation observed also in our own material both ( Figs 125A, 125D View FIGURE 125 ).

- The evaluation of the tail valve is open to interpretation: Šulc’s description reports the mucro in posterior position, at two-thirds the length, while the few tail valves in our material from Varovtsi ( Ukraine) and Kostej ( Romania) show a mucro slightly in anterior or at most subcentral position ( Figs 125L, 125P View FIGURE 125 ). In literature, only Bałuk (1971: pl. 4, figs 11–12) show tail valves from Korytnica ( Poland) with the mucro in posterior position, while the only other tail valve figured ( Bałuk 1984: pl. 7, fig. 3) show the mucro in anterior or at most subcentral position. For these reasons we consider attributable to Lepidochitona lepida tail valves with the mucro in a wide range of positions.

Therefore, we hypothesize that also the 19 valves (3 head and 16 intermediate) from Węglinek cited by Macioszcsyk (1988) as Lepidochitona monterosatoi Kaas & Van Belle, 1981 , may well fall within the variability of L. lepida .

Šulc (1934) described another species of Lepidochitona (as Middendorffia boravičensis ) upon a single intermediate valve (width 3.3 mm) from Borač ( Czech Republic); this taxon differs from L. lepida basically by its slightly different shape (3.3 x 1.2 mm vs. 4 x 1.1 mm in L. lepida ) and lack of a longitudinal keel, we judge that such features are of little taxonomic significance, and thus consider Lepidochitona boravičensis as a junior synonym of L. lepida .

Comparisons. The closest species is Lepidochitona kieli nov. sp (see below).

Distribution. Middle Miocene. Central Paratethys (Langhian–Serravallian): Slovakia: Devínska Nová Ves, Dubová, Rohožník, ( Ruman & Hudáčková 2015), Czech Republich: Borač, Rudoltice ( Reuss 1860; Šulc 1934), Poland:Korytnica,Lychów,Nawodzice,Niskowa,Rybnica,Węglin,Węglinek( Bałuk1965, 1971, 1984; Macioszczyk 1988; Studencka & Studencki 1988), Romania: Kostej, Lăpugiu de Sus ( Šulc 1934; this study), Hungary: borehole Szokolya-2, Devecser, Hidas, Letkés, Várpalota ( Csepreghy-Meznerics 1950; Dulai 2001, 2025a; Dulai & Katona 2024; this study); Eastern Paratehys: Ukraine: Podhorce, Varovtsi ( Studencka & Dulai 2010; this study).