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Heteraulacacysta pramparoae
Heteraulacysta pramparoae, Sluijs and Brinkhuis, 2024, p. 453-454, pl. 3, 4.
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Original description: [Sluijs and Brinkhuis, 2024, p. 453-454]:
Heteraulacacysta pramparoae sp. nov.
Plates 3, 4, S18, S19
Derivation of name. Named for Mercedes Beatriz Pramparo, in recognition of her achievements in marine palynology, at IANIGLA, CCT-CONICET, Mendoza, Argentina.
Diagnosis. A species of Heteraulacacysta characterized by very thin wall layers, with isolated small rods or pillars, or rows of small “pillars”, supporting the periphragm, notably around the paracingulum. Archeopyle epicystal, Type tAtP. The periphragm often appears wrinkled, but on some specimens this may faintly indicate paratabulation, overall supporting assignment to the Goniodomidae.
Holotype. Plate 3, A–H
Paratypes. Plate 4, A–C, E–H
Material. IODP 302 Hole M0004A, Lomonosov Ridge, Arctic Ocean
Type locality and horizon. IODP 302 Hole M0004A, Lomonosov Ridge, Arctic Ocean, lower Eocene sample 302-4A-27X-3-90/92 cm
Age. Early Eocene
Description.
Shape: (sub)spherical; outline circular to oval in apical/antapical view; combination epicystal archeopyle, Type tAtP.
Wall relationships: two wall layers are apparent; a thin endophragm and a periphragm are closely appressed over large parts of the cysts (“autophragm”, as per Bujak in Bujak et al., 1980). The periphragm is occasionally supported by isolated small rod-like features, or small “pillars”, or even rows of these, most notably around the paracingulum.
Wall features: both wall layers appear completely smooth to psilate, to incidentally microgranulate under light microscopy, except for the rod-like or pillar-like features of low relief that may occur in rows connecting the two wall layers, most notably around the paracingulum.
Processes: absent.
Paratabulation: indicated by the tAtP archeopyle, sometimes by conspicuous folds of the periphragm, and potentially in combination with the rows of small “pillars”, which may also reflect sutural growth bands.
Archeopyle: formed by the release of all the apical and precingular paraplates (tAtP, compound).
Paracingulum: clearly featured by septa formed by the periphragm, supported by rows of small pillars connecting to the endophragm.
Parasulcus: indicated by a small incursion in the paracingular septae only.
Dimensions. Length/width 58 × 85 µm (n = 10).
Holotype. 61 × 77 µm.
Paratypes. 62 × 75 µm.
Stratigraphic range/occurrence. Early Eocene
Remarks. Wall morphologies, ultrastructure, and wall relationships in Heteraulacacysta and in the very similar genus Dinopterygium (Deflandre, 1935). Stover and Evitt (1978) are still unclear on most species of this group of Goniodomidae. SEM/TEM analyses will be required to fully resolve such issues. The “pillars”, and notably the rows of them, including the connections supporting the paracingular rim, separate H. pramparoae from all other described Heteraulacacysta species.
----------------------------------------------------------------------------------------------------------------------
Original description: [Sluijs and Brinkhuis, 2024, p. 453-454]:
Heteraulacacysta pramparoae sp. nov.
Plates 3, 4, S18, S19
Derivation of name. Named for Mercedes Beatriz Pramparo, in recognition of her achievements in marine palynology, at IANIGLA, CCT-CONICET, Mendoza, Argentina.
Diagnosis. A species of Heteraulacacysta characterized by very thin wall layers, with isolated small rods or pillars, or rows of small “pillars”, supporting the periphragm, notably around the paracingulum. Archeopyle epicystal, Type tAtP. The periphragm often appears wrinkled, but on some specimens this may faintly indicate paratabulation, overall supporting assignment to the Goniodomidae.
Holotype. Plate 3, A–H
Paratypes. Plate 4, A–C, E–H
Material. IODP 302 Hole M0004A, Lomonosov Ridge, Arctic Ocean
Type locality and horizon. IODP 302 Hole M0004A, Lomonosov Ridge, Arctic Ocean, lower Eocene sample 302-4A-27X-3-90/92 cm
Age. Early Eocene
Description.
Shape: (sub)spherical; outline circular to oval in apical/antapical view; combination epicystal archeopyle, Type tAtP.
Wall relationships: two wall layers are apparent; a thin endophragm and a periphragm are closely appressed over large parts of the cysts (“autophragm”, as per Bujak in Bujak et al., 1980). The periphragm is occasionally supported by isolated small rod-like features, or small “pillars”, or even rows of these, most notably around the paracingulum.
Wall features: both wall layers appear completely smooth to psilate, to incidentally microgranulate under light microscopy, except for the rod-like or pillar-like features of low relief that may occur in rows connecting the two wall layers, most notably around the paracingulum.
Processes: absent.
Paratabulation: indicated by the tAtP archeopyle, sometimes by conspicuous folds of the periphragm, and potentially in combination with the rows of small “pillars”, which may also reflect sutural growth bands.
Archeopyle: formed by the release of all the apical and precingular paraplates (tAtP, compound).
Paracingulum: clearly featured by septa formed by the periphragm, supported by rows of small pillars connecting to the endophragm.
Parasulcus: indicated by a small incursion in the paracingular septae only.
Dimensions. Length/width 58 × 85 µm (n = 10).
Holotype. 61 × 77 µm.
Paratypes. 62 × 75 µm.
Stratigraphic range/occurrence. Early Eocene
Remarks. Wall morphologies, ultrastructure, and wall relationships in Heteraulacacysta and in the very similar genus Dinopterygium (Deflandre, 1935). Stover and Evitt (1978) are still unclear on most species of this group of Goniodomidae. SEM/TEM analyses will be required to fully resolve such issues. The “pillars”, and notably the rows of them, including the connections supporting the paracingular rim, separate H. pramparoae from all other described Heteraulacacysta species.