Gyrogona tuberosa ( Reid & Groves, 1921 ) Grambast

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 : 550-551

Gyrogona tuberosa ( Reid & Groves, 1921) Grambast in Grambast & Grambast-Fessard, 1981

( Fig. 10A–J)

1921 Chara wrighti var. rhytidocarpa Reid & Groves : 183, pl. 4, fig. 3.

1958 Gyrogona tuberosa Grambast : 139, fig. 54.

1976 Gyrogona tuberosa Feist-Castel : 26.

1981 Gyrogona tuberosa Grambast & Grambast-Fessard : 25, text-fig. 12a–d; pl. 5, figs 1–6.

1986 Gyrogona tuberosa Riveline : pl. 14, figs 8–11.

Material. 35 gyrogonites in sample G-6b. Collection numbers of figured specimens: HNHM-PBO 1554–1563.

Description. Large gyrogonites, 820–1000 M m high and 835–1050 M m wide with generally oblate to sub-oblate spheroidal shape ( ISI 80–100) and showing laterally 6–7 convolutions (usually six). Apex subtruncate ( Fig. 10A, C) to somewhat pointed ( Fig. 10D, G) with spiral cells protruding ( Fig. 10H). Base broadly rounded ( Fig. 10B, F) to slightly tapered ( Fig. 10A, C, E) and showing a small, superficial and pentagonal basal pore, sometimes within a less-marked funnel ( Fig. 10I, J). Spiral cells flat or concave, smooth or somewhat ornamented and separated by protruding narrow to weakly undulated intercellular ridges.

Distribution. Gyrogona tuberosa is reported here from Hungary and central Europe for the first time. According to Riveline (1986) and Riveline & Cavelier (1987), this species was widely distributed in the upper Bartonian non-marine deposits of Western Europe. It was first recorded from the Isle of Wight and Hampshire ( England) by Reid & Groves (1921). Subsequently, it was reported from the upper Bartonian of the Paris Basin ( Grambast 1958; Grambast & Grambast-Fessard 1981; Riveline 1986; Riveline & Cavelier 1987), as well as from several basins in southern France ( Feist-Castel 1976).