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Heteraulacacysta alanoensis
Original description Iakovleva, 2025:
Heteraulacacysta alanoensis sp. nov.
Plate VIII, 1–11
Etymology: Named for the NE Italian town of Alano di Piave, province of Belluno, home to the GSSP for the Bartonian/Priabonian boundary.
Type locality and horizon: Sample A8761, level 87,61 m, Alano di Piave section, Italy.
Holotype: Plate VIII, figs. 1–2, 4–5, 7; Sample A8761, slide 2, EF = S16.
Paratype: Plate VIII, 3, 6, 9; Sample A9001, slide 2, EF = E22–2.
Studied material: Alano di Piave section, Italy.
Stratigraphic horizon: Lower Priabonian.
Diagnosis: A rather large species of Heteraulacacysta characterized by very thin wall layers, with clear parasutural septae, and centrally placed, intratabular sets of pustulae. Archeopyle epicystal, Type tAtP. The reflected paratabulation (‘quinqueform’, ‘exsert’, sensu Evitt, 1985) clearly supports assignment to the Goniodomidae.
Description:
Shape: (sub)sphaerical; 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 (in Bujak's 1980 terms ‘autophragm’). The periphragm displays intratabular, centrally placed clusters of small pustulae.
Wall features: Both wall layers appear completely smooth to psilate, with the exception of the intratabular clusters of pustulae (1–2 μm in width/height).
Processes: None.
Paratabulation: Indicated by distinct parasutural ridges or septae, and the tAtP archaeopyle.
Archeopyle: Formed by the release of all the apical and precingular paraplates (tAtP, compound).
Paracingulum: Clearly featured by septa formed by the periphragm.
Parasulcus: Indicated by septae only.
Dimensions: Holotype. 101 × 92 μm. Paratype. 98 × 95 μm. Total length/width 87 × 105 μm (10 specimens).
Comparison: Wall morphologies, ultrastructure, and wall relationships in Heteraulacacysta and in the very similar genus Dinopterygium (Deflandre 1935) Stover and Evitt, 1978 are quite unclear for most species of this group of Goniodomidae. SEM/TEM analyses will be required to fully resolve such issues. For now, the (very) large size and the distinct centrally placed, intratabular clusters of pustulae separates H. alanoensis sp. nov. from all other described Heteraulacacysta species, including the somewhat similar H. pustulata, which differs by having pustulae all over the periphragm rather than in (small) clusters.
Heteraulacacysta alanoensis sp. nov.
Plate VIII, 1–11
Etymology: Named for the NE Italian town of Alano di Piave, province of Belluno, home to the GSSP for the Bartonian/Priabonian boundary.
Type locality and horizon: Sample A8761, level 87,61 m, Alano di Piave section, Italy.
Holotype: Plate VIII, figs. 1–2, 4–5, 7; Sample A8761, slide 2, EF = S16.
Paratype: Plate VIII, 3, 6, 9; Sample A9001, slide 2, EF = E22–2.
Studied material: Alano di Piave section, Italy.
Stratigraphic horizon: Lower Priabonian.
Diagnosis: A rather large species of Heteraulacacysta characterized by very thin wall layers, with clear parasutural septae, and centrally placed, intratabular sets of pustulae. Archeopyle epicystal, Type tAtP. The reflected paratabulation (‘quinqueform’, ‘exsert’, sensu Evitt, 1985) clearly supports assignment to the Goniodomidae.
Description:
Shape: (sub)sphaerical; 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 (in Bujak's 1980 terms ‘autophragm’). The periphragm displays intratabular, centrally placed clusters of small pustulae.
Wall features: Both wall layers appear completely smooth to psilate, with the exception of the intratabular clusters of pustulae (1–2 μm in width/height).
Processes: None.
Paratabulation: Indicated by distinct parasutural ridges or septae, and the tAtP archaeopyle.
Archeopyle: Formed by the release of all the apical and precingular paraplates (tAtP, compound).
Paracingulum: Clearly featured by septa formed by the periphragm.
Parasulcus: Indicated by septae only.
Dimensions: Holotype. 101 × 92 μm. Paratype. 98 × 95 μm. Total length/width 87 × 105 μm (10 specimens).
Comparison: Wall morphologies, ultrastructure, and wall relationships in Heteraulacacysta and in the very similar genus Dinopterygium (Deflandre 1935) Stover and Evitt, 1978 are quite unclear for most species of this group of Goniodomidae. SEM/TEM analyses will be required to fully resolve such issues. For now, the (very) large size and the distinct centrally placed, intratabular clusters of pustulae separates H. alanoensis sp. nov. from all other described Heteraulacacysta species, including the somewhat similar H. pustulata, which differs by having pustulae all over the periphragm rather than in (small) clusters.