Gyrogona caelata ( Reid & Groves, 1921 ) Grambast, 1956

Trabelsi, Khaled, Sames, Benjamin, Wagreich, Michael, K ́ azm ́, Miklos, , Andrea Mindszen & Mart ́ ın-Clo, d Carles, 2021, A new diverse charophyte flora and biozonation of the Eocene bauxite cover-sequence at G ant (V ertes Hills, Hungary), Journal of Systematic Palaeontology 19 (7), pp. 541-563 : 548-550

Gyrogona caelata ( Reid & Groves, 1921) Grambast, 1956

( Fig. 8A–V)

1921 Chara caelata sp. nov. Reid & Groves: 184, pl. 4, figs 4–6.

1927 Kosmogyra caelata Pia : 90.

1954 Brachychara caelata Grambast & Grambast : 667.

1956 Gyrogona caelata Grambast : 280.

1977b Gyrogona caelata Feist-Castel : 117.

1981 Gyrogona caelata Grambast & Grambast-Fessard : 22, text-fig. 11a–f; pl. 4, figs 1–9.

1981 Gyrogona cf. caelata Anadon & Feist : 163.

1986 Gyrogona caelata Riveline : pl. 38, figs 1–5, 7, 8.

1989 Gyrogona caelata Choi : pl. 2, figs 1–11.

1991 Gyrogona caelata Weidmann et al. : 900, fig. 3C.

2014 Gyrogona caelata Sanjuan & Mart́ın-Closas: 403, fig. 7 A –C.

Material. Fifty-six gyrogonites in sample G-2.2, 38 in sample G-2.3, 29 in sample G-2.4, 18 in sample G-2.5, and 23 in sample G-6a. Collection numbers of figured specimens: HNHM-PBO 1535–1553.

Description. Medium to large gyrogonites, 600–800 M m high and 700–1000 M m wide with generally oblate to sub-oblate spheroidal shape ( ISI 80–100) and showing laterally 5–7 (usually six) convolutions ( Fig. 9). Apex and base broadly rounded to subtruncate. Apex showing a less-marked spiral cell periapical thinning (e.g. Fig. 8G) and, in some specimens, apical nodules of different shape, generally flat or slightly convex (e.g. Fig. 8S). Base showing a small pentagonal basal pore ( Fig. 8F), sometimes flared by a shallow funnel ( Fig. 8P). Basal plate unicellular and only visible from the gyrogonite interior ( Fig. 8U, V). Spiral cells flat to slightly concave and ornamented with different patterns of tubercles, which allowed Grambast (1958) and Grambast & Grambast-Fessard (1981) to distinguish a number of morphotypes, ranking them as formae of the same species. The following five forms were recognized in the material studied: (1) G. caelata forma caelata characterized by small nodules well-spaced and irregularly ranged along the spiral cell median line (e.g. Fig. 8A, D); (2) G. caelata forma bicincta characterized by nodules irregularly ranged along two lines parallel to spiral cell sutures ( Fig. 8H, I); (3) G. caelata forma monolifera showing medium-sized nodules close to each other, sometimes fused and forming a thin, irregular mid-cellular crest (e.g. Fig. 8L); (4) G. caelata forma baccata characterized by large nodules very closely ranged along the spiral-cell median line (e.g. Fig. 8N–Q); and (5) G. caelata forma fasciata characterized by a broad median band of variable width (e.g. Fig. 8R–T).

Distribution. The species Gyrogona caelata is reported here from Hungary for the first time. According to Riveline (1986), this species was widely distributed in the upper Lutetian–Priabonian non-marine deposits of western Europe. It was first recorded from the Isle of Wight, England by Reid & Groves (1921). Thereafter, it was reported from the upper Lutetian to upper Priabonian of France ( Grambast 1958; Feist-Castel 1971; Feist & Ringeade 1977; Feist-Castel 1977a, b; Grambast & Grambast-Fessard 1981; Ollivier-Pierre et al. 1988), Spain (Anad́on & Feist 1981; Choi 1989; Anadon et al. 1992; Sanjuan & Mart́ın-Closas 2014), Switzerland ( Weidmann et al. 1991), as well as from the middle Eocene of Romania ( Iva 1987). In North Africa, the species has also been documented from the central part of the Sahara, Algeria, by Mebrouk et al. (1997).