Litharchaeocystis centparatethianus Ehrman, 2025

Litharchaeocystis centparatethianus Ehrman sp. nov.

Fig. 9G, H View Fig .

PhycoBank ID: http://phycobank.org/105042.

Etymology: Refers to the name of the ancient basin Central Paratethys in which the species is found.

Holotype: DMF SEM stub 333-10, as preparation KRAM A-25d, sample Łubno 4 ( Fig. 9H View Fig , SEM image of stomatocyst in anterior-lateral view).

Type locality: Futoma, Poland.

Type horizon: Futoma Diatomite Member, Rupelian, lower Oligocene.

Material.—A few specimens encountered on each SEM stub from Futoma 4 (DMF stub 249-17i), Łubno 4 (DMF stub 333-10 as KRAM A-35), Oligocene of southeastern Poland.

Diagnosis.—Ellipsoidal cyst with relatively fine ridges and flaring collar. Collars two-layered. Inner and outer layers connected by septa. Basal part of collar outer wall arches to connect with some surface ridges leaving windows in between.

Description.—Stomatocysts ellipsoidal, anterior end tapering to two-layered collar. Cells 15.1–16.5 µm long and 11.0– 11.4 µm wide at their widest portion. Cyst surface adorned by sharp longitudinal ridges running cell length, approximately 4 ridges in 10 µm. Nine ridges present over visible side of cysts. In appropriate orientation approximately 4 ridges associate with each short, wide-based posterior spine ( Fig. 9G View Fig ). Cyst posterior end flattened and surrounded by a ring of at least 4 stout spines, 1.5–2.1 µm long ( Fig. 9H View Fig ). Collar system complex, two-layered. Inner (primary?) and outer layer ( Fig. 9G View Fig ) connected to each other by perpendicular septa. Collar-system inner layer is conical while outer obconical. Basal part of collar outer layer arches to connect with some surface ridges leaving windows in between ( Fig. 9G View Fig ), thus not grounded on cyst surface. Both layers have serrated apical margins.

Remarks.—Our specimens meet the generic delineation ( Deflandre 1932b), but not any of the currently known species. In addition to the different pattern of ridges and structure of collars, it differs by being more ellipsoidal in shape compared to triangular, bottom-heavy outlines of Litharchaeocystis glabra Rampi, 1948 , L. oamaruensis Deflandre, 1938 , L. talwanii Perch-Nielsen, 1978 , or L. udintsevii Perch-Nielsen, 1978 . Our species is not as ellipsoidal as L. costata Deflandre, 1932b , from which it also differs by being much smaller (31–34 µm vs. 15.5–16.5 µm long; 18–20 µm vs. 11.0–11.4 µm wide) and having a greater number of ridges on the visible side of the cysts (9 vs. 6, respectively). All the species mentioned above are reported from sediments from New Zealand, Russia, and the Vøring Plateau of the Norwegian Sea ( Deflandre and Deflandre-Rigaud 1969; Perch-Nielsen 1978).

Stratigraphic and geographic range.—Rupelian (lower Oligocene) of southeastern Poland (this study).

Genus Litheusphaerella Deflandre, 1932c View in CoL

Type species: Litheusphaerella spectabilis Deflandre, 1932c . Paleocene/Eocene boundary, Fuur Island, North Jutland ( Denmark).

Litheusphaerella spectabilis Deflandre, 1932c (sensu lato)

Fig. 9I, J View Fig .

Material.—Numerous specimens encountered on each SEM stub from Borek Nowy 5, 12B ( DMF stubs 342-15c, 342-15d), Futoma 5, 17, Łubno 2. Oligocene of southeastern Poland.

Description.—Stomatocysts spherical, 7.8–11.2 µm in diameter when measured with spines. Pores approximately 1 µm in diameter, surrounded by low, narrow ring of obconical collar, 1.5–2.0 µm in total diameter. Spines long, robust and widest at base. Longest spines found have broken tips but reach 1.7 µm in length. Spines hollow throughout length but occluded at base ( Fig. 9I View Fig ). Spines regularly dispersed, generally equidistant from each other, 1.8–2.0 µm apart. Narrow spineless ring around collar ( Fig. 9J View Fig ).

Remarks.—Our specimens are most like SEM images published by Deflandre and Deflandre-Rigaud (1969) from the Lower Eocene of Jutland ( Denmark) with both hollowed spines and pore-collar apparatus. Not all such details are obvious on micrographs or drawings of the species published by all authors ( Perch-Nielsen 1975, 1978; Stradner 1971) supporting the notion that L. spectabilis as currently delineated may encompass more than one species ( Deflandre 1932c). There are also reported extant specimens attributed to L. spectabilis ( Mitchell and Silver 1982) while Riaux-Gobin and Stumm (2006, as L. cf. spectabilis ) considered their specimens similar to this species but not without reservations. Somewhat similar specimens are presented by Kato (2019), as Stomatocyst 65 Van de Vijver & Boyens, 2000, but the density of the spines is greater than the density of spines on our specimens.

Stratigraphic and geographic range.—Upper Cretaceous of the Subantarctic Southwest Pacific ( Perch-Nielsen 1975), Paleocene/Eocene boundary of Fuur Island, North Jutland ( Denmark; Deflandre 1932a), Eocene of the Issinsky-Volga Region ( Russia; Deflandre and Deflandre-Rigaud 1969), Eocene of the Vøring Plateau of the Norwegian Sea ( Perch-Nielsen 1978), Rupelian (lower Oligocene) of southeastern Poland (this study), Miocene of Limberg ( Austria; Stradner 1971). Recent reports from the Equatorial Pacific, North Pacific, and South Atlantic ( Mitchell and Silver 1982), the Weddell Sea ( Mitchell and Silver 1986), and Kita-no-seto Strait, Antarctica ( Takahashi et al. 1986).