Archaeomonas karinae Perch-Nielsen, 1978

Kaczmarska, Irena, Ehrman, James M. & Samanta, Brajogopal, 2025, Oligocene archaeomonad stomatocysts from the Polish Central Paratethys, Acta Palaeontologica Polonica 70 (2), pp. 385-410 : 397-399

Archaeomonas karinae Perch-Nielsen, 1978

Fig. 6E–G .

Material.—Numerous specimens encountered on each SEM stub from Borek Nowy 5, Futoma 17, Łubno 3, 4 (DMF stubs 333-10c, 333-18a, 333-18b), Oligocene of southeastern Poland.

Description.—Cysts spherical, 6.5–9.8 µm in diameter. Pores relatively small, regular, 0.56–0.62 µm in diameter surrounded by externally obconical, internally concave collar ( Fig. 6E ). Collar 2.1–3.1 µm in diameter with 3–6 small marginal conulae ( Fig. 6F ). External and internal layers of cyst wall connected by system of cavities when visible in broken specimens. Cyst wall spines robust, up to 2.1 µm long, with flattened tips. Spine sides adorned with longitudinal ribs radiating from base of the spine outwards, some connecting ribbing of neighbouring spines ( Fig. 6E, F ). Spines regularly dispersed on wall surface, 4–8 in 10 µm.

Remarks.— Perch-Nielsen (1978) described this species from the Vøring Plateau of the Norwegian Sea. Although metric data for those specimens are not given, the size estimates from published images (6–8 µm in diameter and robust ribbed spines, 5–6 in 10 µm) align with the metrics of our specimens. In addition to spherical cysts, one ellipsoidal cyst was found with ribbed spines and similar collar-pore apparatus ( Fig. 6G ). Archaeomonas longispina Rampi, 1948 , is another species with stout interconnected ribbed spines, but the spines appear relatively sparser and longer on the original figure for that species than on our specimens or A. karinae .

Stratigraphic and geographic range.—Eocene of the Vøring Plateau of the Norwegian Sea ( Perch-Nielsen 1978), and Rupelian (lower Oligocene) of southeastern Poland (this study).

Figures

Fig.6.Archaeomonad stomatocysts from Rupelian (lower Oligocene) of Poland.A–C. Archaeomonas anterioconica Kaczmarska sp. nov.A. DMF stub 333- 10 (KRAM A-32) holotype, Łubno 4, in lateral view with best preserved circumcollar spines. B. DMF stub 333-4, Borek Nowy 5A, in lateral view showing profile of anterior pole. C. DMF stub 342-14, Hermanowa 27, in anterio-lateral view showing details of collar. D. Archaeomonas japonica Deflandre, 1933, DMF stub 333-10b, Łubno 4, in lateral view showing collar with uneven rim (arrows). E–G. Archaeomonas karinae Perch-Nielsen, 1978, Łubno 4. E. DMF stub 333-10c, in anterio-lateral view, with typical spherical morphology with spines adorned with longitudinal ribs (arrow). F. DMF stub 333-18a, in anterior view, with typical spherical morphology with spines adorned with longitudinal ribs (arrow). G. DMF stub 333-18b, in anterio-lateral view, with more ellipsoidal cell with more pronounced spine and collar morphology. H–J. Archaeomonas manginii Deflandre, 1932c, illustrating variation in preservation of spines and collars. H. DMF stub 342-13 (B 40 0046308), Łubno 4, in anterio-lateral view, with eroded collar but well-preserved spines.I. DMF stub 349-16a, Futoma 4, stomatocyst with eroded spines but showing thickness and height of preserved collar rim, lateral (I1) and anterio-lateral (I2) views. J. DMF stub 349-2f, Borek Nowy Kawalec, in anterio-lateral view with eroded spines but showing thickness of collar rim. K. Archaeomonas manginii Deflandre, 1932c var.1, DMF stub 349-17c, Futoma 4, in lateral view showing specimen with denser wall spines. Scale bars 2 µm.