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Eatonicysta mutabilireta
From Fensome et al., 2019:
Eatonicysta mutabilireta Pearce, 2010, p.60,62, pl.4, figs.1–6. Holotype: Pearce, 2010, pl.4, figs.1–6. Age: early Campanian.
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Diagnosis. A species questionably attributed to Eatonicysta possessing a distinctive ectophragm modified by sub-rounded
perforations of variable size to an irregular meshwork defined by rounded to (more usually) polygonal lumina.
Description. Large chorate dinoflagellate cyst with an oblate spheroidal central body slightly dorso-ventrally compressed, but not lenticular. The body is two-layered and comprised of a smooth and thin endophragm and periphragm, the latter of which forms processes that support a thin and highly irregular ectophragm. The ectophragm completely surrounds the central body and is modified by sub-rounded to oval perforations of varying size to an irregular meshwork defined by rounded to (more usually) polygonal lumina. No indication of apical, lateral or antapical protuberances are observed in the cyst body. The processes are intratabular (but absent on the paracingulum and parasulcus) and solid, of consistent length, and near-constant width and unconnected at the base. The paratabulation is indicated by the position of the processes describing the formula: 4#?, 6$, 0c, 6%, 1p, 1$$, 0s. The archaeopyle is apical (Type tA, operculum detached) and formed by the loss of all apical paraplates.
Comparison. Differs from Eatonicysta exilis sp. nov., Membranilarnacia hapala (Schiøler & Wilson, 1993: 346–347, pl. 2, figs 1–7, text-figs 12a–b) Lachkar & Masure in Fauconnier & Masure (2004) and M. pterococcoides (Wetzel, 1933b: 53, pl. 6, fig. 4) Eisenack, 1963b by possessing a distinctly perforate rather than entire ectophragm. Eatonicysta? mutabilireta sp. nov. closely resembles the type species E. ursulae (Morgenroth, 1966: 20, pl. 3, fig. 11–12) Stover & Evitt, 1978 but differs in the morphology of the ectophragm mesh. In E. ursulae, the mesh is usually uniform with usually polygonal lumina, while in E? mutabilireta sp. nov. the mesh is highly irregular and the lumina vary in size and shape (rounded to polygonal). Glaphyrocysta Stover & Evitt, 1978 differs by being lenticular, strongly dorsoventrally flattened with an offset parasutural notch, and possessing annulate to arcuate penitabular process complexes. The ectophragm in E? mutabilireta, however, is very similar to that of Glaphyrocysta semitectum Bujak in Bujak et al., 1980 (46, 48, 50, pl. 14, figs 2–9; text-fig. 13) but differs by being completely developed. Species of Riculacysta Stover, 1977 also possess solid, normally isolated processes that support an ectophragm, but which differ by possessing ventrolateral processes that are longer than the lateral ones, and where the ectophragm is appressed or close to the autophragm dorsally.
Eatonicysta mutabilireta Pearce, 2010, p.60,62, pl.4, figs.1–6. Holotype: Pearce, 2010, pl.4, figs.1–6. Age: early Campanian.
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Diagnosis. A species questionably attributed to Eatonicysta possessing a distinctive ectophragm modified by sub-rounded
perforations of variable size to an irregular meshwork defined by rounded to (more usually) polygonal lumina.
Description. Large chorate dinoflagellate cyst with an oblate spheroidal central body slightly dorso-ventrally compressed, but not lenticular. The body is two-layered and comprised of a smooth and thin endophragm and periphragm, the latter of which forms processes that support a thin and highly irregular ectophragm. The ectophragm completely surrounds the central body and is modified by sub-rounded to oval perforations of varying size to an irregular meshwork defined by rounded to (more usually) polygonal lumina. No indication of apical, lateral or antapical protuberances are observed in the cyst body. The processes are intratabular (but absent on the paracingulum and parasulcus) and solid, of consistent length, and near-constant width and unconnected at the base. The paratabulation is indicated by the position of the processes describing the formula: 4#?, 6$, 0c, 6%, 1p, 1$$, 0s. The archaeopyle is apical (Type tA, operculum detached) and formed by the loss of all apical paraplates.
Comparison. Differs from Eatonicysta exilis sp. nov., Membranilarnacia hapala (Schiøler & Wilson, 1993: 346–347, pl. 2, figs 1–7, text-figs 12a–b) Lachkar & Masure in Fauconnier & Masure (2004) and M. pterococcoides (Wetzel, 1933b: 53, pl. 6, fig. 4) Eisenack, 1963b by possessing a distinctly perforate rather than entire ectophragm. Eatonicysta? mutabilireta sp. nov. closely resembles the type species E. ursulae (Morgenroth, 1966: 20, pl. 3, fig. 11–12) Stover & Evitt, 1978 but differs in the morphology of the ectophragm mesh. In E. ursulae, the mesh is usually uniform with usually polygonal lumina, while in E? mutabilireta sp. nov. the mesh is highly irregular and the lumina vary in size and shape (rounded to polygonal). Glaphyrocysta Stover & Evitt, 1978 differs by being lenticular, strongly dorsoventrally flattened with an offset parasutural notch, and possessing annulate to arcuate penitabular process complexes. The ectophragm in E? mutabilireta, however, is very similar to that of Glaphyrocysta semitectum Bujak in Bujak et al., 1980 (46, 48, 50, pl. 14, figs 2–9; text-fig. 13) but differs by being completely developed. Species of Riculacysta Stover, 1977 also possess solid, normally isolated processes that support an ectophragm, but which differ by possessing ventrolateral processes that are longer than the lateral ones, and where the ectophragm is appressed or close to the autophragm dorsally.