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Xenascus gochtii
From Fensome et al., 2019:
Xenascus gochtii (Corradini, 1973) Stover and Evitt, 1978
Originally Phoberocysta, subsequently (and now) Xenascus.
Holotype: Corradini, 1973, pl.29, figs.1a-b, text-fig.9
Locus typicus: Viano, Reggio Emilia, Italy
Stratum typicum: Senonian
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Original diagnosis: Corradini, 1973, p. 179: Phoberocysta gochtii
Two-layered dinoflagellate cyst with central body flattened dorso-ventrally. Inner body ovoidal and periphragm very irregular in outline. Wide continuous pericoel extending from the antapical to the two lateral horns. Processes of heterogeneous length and shape. Cingulum sometimes present. Alcheopyle apical, with zig-zag margins.
Dimensions--Holotype: width of inner capsule 52 µm, length (without operculum) 46 µm; width of periphragm 100 µm, length 90 µm. Range: width of the capsule 45-(53)-65 µm length (without operculum) 42-(50)-60 µm width of periphragm 80-(93)-110 µm, length 70-(92)-110 µm.
Original description: Corradini, 1973, p. 179: Phoberocysta gochtii
The fairly thin endophragm and the even thinner periphragm are smooth or slightly granular. The inner ends of the outer layers are separated by a wide pericoel, more developed in correspondence with the antapical and the lateral horns. The endophragm and the periphragm are appressed dorso-ventrally, but only in the precingular area of the circumpherential zone of the cyst. From the margins of the periphragm arise denticulate or digitate horns, coarsely palmate wings or processes.
These latter are heterogeneous on the same specimen, being sometimes slender and distally furcated, sometimes larger and medially branched. Again, they may be tubiform or taeniate and distally flared.
Wide areas lacking in processes are present on the dorsal and ventral surfaces, most of the processes being arranged peripherally.
The two lateral horns are normally composed by a periphragm lamella supporting furcated appendages, their increase being connected with the decrease of the pericoel. Antapical horn eccentrical in respect of the apex-antapex axis perpendicular to the plane of the archeopyle, in form of a wide, distally digitate protuberance bearing small heterogeneous appendages.
Well developed ribs sometimes connect the bases of adjacent processes and divide the surface of the central body in a sort of wide poligonal area, never suggesting a welldefined tabulation.
In this case, the processes seem to be gonal or sutural in position.
A fairly large cingulum, delimited by two very low parallel ribs, is sometimes present, never being continuous.
The cyst is always provided with an apical archeopile having zig-zag margins.
Xenascus gochtii (Corradini, 1973) Stover and Evitt, 1978
Originally Phoberocysta, subsequently (and now) Xenascus.
Holotype: Corradini, 1973, pl.29, figs.1a-b, text-fig.9
Locus typicus: Viano, Reggio Emilia, Italy
Stratum typicum: Senonian
----------------------------------------------------------------------------------------------------------------------------------
Original diagnosis: Corradini, 1973, p. 179: Phoberocysta gochtii
Two-layered dinoflagellate cyst with central body flattened dorso-ventrally. Inner body ovoidal and periphragm very irregular in outline. Wide continuous pericoel extending from the antapical to the two lateral horns. Processes of heterogeneous length and shape. Cingulum sometimes present. Alcheopyle apical, with zig-zag margins.
Dimensions--Holotype: width of inner capsule 52 µm, length (without operculum) 46 µm; width of periphragm 100 µm, length 90 µm. Range: width of the capsule 45-(53)-65 µm length (without operculum) 42-(50)-60 µm width of periphragm 80-(93)-110 µm, length 70-(92)-110 µm.
Original description: Corradini, 1973, p. 179: Phoberocysta gochtii
The fairly thin endophragm and the even thinner periphragm are smooth or slightly granular. The inner ends of the outer layers are separated by a wide pericoel, more developed in correspondence with the antapical and the lateral horns. The endophragm and the periphragm are appressed dorso-ventrally, but only in the precingular area of the circumpherential zone of the cyst. From the margins of the periphragm arise denticulate or digitate horns, coarsely palmate wings or processes.
These latter are heterogeneous on the same specimen, being sometimes slender and distally furcated, sometimes larger and medially branched. Again, they may be tubiform or taeniate and distally flared.
Wide areas lacking in processes are present on the dorsal and ventral surfaces, most of the processes being arranged peripherally.
The two lateral horns are normally composed by a periphragm lamella supporting furcated appendages, their increase being connected with the decrease of the pericoel. Antapical horn eccentrical in respect of the apex-antapex axis perpendicular to the plane of the archeopyle, in form of a wide, distally digitate protuberance bearing small heterogeneous appendages.
Well developed ribs sometimes connect the bases of adjacent processes and divide the surface of the central body in a sort of wide poligonal area, never suggesting a welldefined tabulation.
In this case, the processes seem to be gonal or sutural in position.
A fairly large cingulum, delimited by two very low parallel ribs, is sometimes present, never being continuous.
The cyst is always provided with an apical archeopile having zig-zag margins.