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Stichodinium sympagicum
Stichodinium sympagicum Iakovleva, 2016, p.19 (on PDF initially published online), pl.8, figs.1–12; text-fig.4c (part). Holotype: Iakovleva, 2016, pl.8, figs.10–11. Age: earliest Eocene.
Original description (Iakovleva, 2016)
Diagnosis. A species of Stichodinium with a subrounded to rounded pericyst having minute antapical horns or lacking all horns, with sutural and penitabular ornamentation expressed by moderately or well-developed serrate crests and/or processes.
Description. A mid-size narrowly circumcavate cyst with a subrounded to rounded outline. An apical horn is absent or forms only a minute protrusion. Lateral horns are not developed. Antapical horns are either short and usually unequal, or denoted by a swelling of the pericyst, or are completely absent. Periphragm thin, ornamented by sutural crests or membranes that distally are denticulate or bear short (sutural and penitabular) processes that have bulbous extremities. The crests may be especially prominent on the ambital margin of the pericyst. The lateral parts of the periphragm are occasionally ornamented by outgrowths. Endocyst is subcircular, endophragm thin and smooth. The archaeopyle is latiepeliform, with a free or partially attached operculum.
Dimensions.
Holotype: pericyst length 77 µm; pericyst width 78 µm; endocyst length 62 µm; endocyst width 64 µm. Paratype 1: pericyst length 87 µm; pericyst width 83 µm; endocyst length 67 µm; endocyst width 65 µm. Paratype 2: pericyst length 71 µm; pericyst width 80 µm; endocyst length 59 µm; endocyst width 61. Dimensions of measured specimens: pericyst length 63–92 µm (mean value 77 µm); pericyst width 60–90 µm (mean value 77 µm); endocyst length 50–74 µm (mean value 61 µm); endocyst width 51–73 µm (mean value 63 µm). Nineteen specimens measured.
Comparison. Stichodinium sympagicum differs from Stichodinium parisiense and Stichodinium galliciense in having a subrounded to clearly rounded ambitus and by not having lateral horns. It is also differs (paratypes 2 and 3) from other species by its well-developed crests with denticles or processes with bulbous distal endings.
Stratigraphical range. Earliest Eocene.
Derivation of name. From the Greek sympagís (compact), in reference to the compact, narrow pericyst.
Original description (Iakovleva, 2016)
Diagnosis. A species of Stichodinium with a subrounded to rounded pericyst having minute antapical horns or lacking all horns, with sutural and penitabular ornamentation expressed by moderately or well-developed serrate crests and/or processes.
Description. A mid-size narrowly circumcavate cyst with a subrounded to rounded outline. An apical horn is absent or forms only a minute protrusion. Lateral horns are not developed. Antapical horns are either short and usually unequal, or denoted by a swelling of the pericyst, or are completely absent. Periphragm thin, ornamented by sutural crests or membranes that distally are denticulate or bear short (sutural and penitabular) processes that have bulbous extremities. The crests may be especially prominent on the ambital margin of the pericyst. The lateral parts of the periphragm are occasionally ornamented by outgrowths. Endocyst is subcircular, endophragm thin and smooth. The archaeopyle is latiepeliform, with a free or partially attached operculum.
Dimensions.
Holotype: pericyst length 77 µm; pericyst width 78 µm; endocyst length 62 µm; endocyst width 64 µm. Paratype 1: pericyst length 87 µm; pericyst width 83 µm; endocyst length 67 µm; endocyst width 65 µm. Paratype 2: pericyst length 71 µm; pericyst width 80 µm; endocyst length 59 µm; endocyst width 61. Dimensions of measured specimens: pericyst length 63–92 µm (mean value 77 µm); pericyst width 60–90 µm (mean value 77 µm); endocyst length 50–74 µm (mean value 61 µm); endocyst width 51–73 µm (mean value 63 µm). Nineteen specimens measured.
Comparison. Stichodinium sympagicum differs from Stichodinium parisiense and Stichodinium galliciense in having a subrounded to clearly rounded ambitus and by not having lateral horns. It is also differs (paratypes 2 and 3) from other species by its well-developed crests with denticles or processes with bulbous distal endings.
Stratigraphical range. Earliest Eocene.
Derivation of name. From the Greek sympagís (compact), in reference to the compact, narrow pericyst.