Back
Soaniella circularis
From Fensome et al., 2019:
---------------------------------------------------------------------------------------------------
Original description Vasilyeva, 2012:
The name comes from circularis (lat.) – round (in relation to the shape of the cyst).
Diagnosis. A medium-sized, peridinoid, cornucopiashaped, round cyst, weakly compressed in the dorsoventral direction. The apical and left antapical horn are developed. The endocyst is round, dense, but is adjacent to the pericyst. The periphragm is granular, tuberculate. The periphragm is thin. The periarcheopyle is of a combined type: A3I3P(3'+1a-3a+3''-5''). The perioperculum is free. The cingulum is flat, in the form of a double suture.
Description. The pericyst is round, almost spherical, asymmetrical. The epicyst and hypocyst are equal. The epicyst has a small, pointed apical horn. One (left) antapical short pointed horn is formed on the hypocyst. The right antapical horn is not developed or is slightly marked as a bulge on the periphragm, sometimes its position is noted by a cluster of tubercles on the periphragm. The periphragm is dense, granular, tuberculate-striated or shagreen. The distribution of grains is uneven, striated. The endocyst follows the shape of the pericyst. The endophragm is thin, tightly adjacent to the periphragm over the entire surface except for the horn zone. The cyst is cornucopia. The paracingulum is smoothed; On the dorsal and ventral sides of the cyst it is presented in the form of a double flat, slightly sinuous suture with a width of about 5–6 μm. The sulcus is weakly expressed in the form of a wide groove. The archaeopile is of a combined type. The intercalary, three precingular and partially apical plates are involved in the formation of the periarchaeopile, type A3I3P(3'+1a-3a+3''-5''). The perioperculum – the middle intercalary plate (2a) – is usually absent. Paratabulation is expressed by the structure of the archaeopile, cingulum and sulcus.
Holotype. Plate 1, Fig. 5. Ref. SP-1/135-A.
Location. Well SP-1 (Eastern Caspian), Aktobe region, Kazakhstan.
Dimensions (μm). Holotype: pericyst length 72.6, pericyst width 69.3. Other specimens (21 specimens): pericyst length 56–79, pericyst width 56–69.
Comparison. Soaniella circularis sp. nov. differs from the type species in the shape of the pericyst and the structure of the antapical horns. Unlike Soaniella granulata Vozzh. This species usually retains the cyst form after the formation of the archeopyle.
Distribution. Kazakhstan, Sholaksay Formation. Russia; Western Siberia, Nyurol Formation. Eocene (Ypresian-Lutetian).
Note: West Siberian forms are on average smaller than the typical material from Kazakhstan.
---------------------------------------------------------------------------------------------------
Original description Vasilyeva, 2012:
The name comes from circularis (lat.) – round (in relation to the shape of the cyst).
Diagnosis. A medium-sized, peridinoid, cornucopiashaped, round cyst, weakly compressed in the dorsoventral direction. The apical and left antapical horn are developed. The endocyst is round, dense, but is adjacent to the pericyst. The periphragm is granular, tuberculate. The periphragm is thin. The periarcheopyle is of a combined type: A3I3P(3'+1a-3a+3''-5''). The perioperculum is free. The cingulum is flat, in the form of a double suture.
Description. The pericyst is round, almost spherical, asymmetrical. The epicyst and hypocyst are equal. The epicyst has a small, pointed apical horn. One (left) antapical short pointed horn is formed on the hypocyst. The right antapical horn is not developed or is slightly marked as a bulge on the periphragm, sometimes its position is noted by a cluster of tubercles on the periphragm. The periphragm is dense, granular, tuberculate-striated or shagreen. The distribution of grains is uneven, striated. The endocyst follows the shape of the pericyst. The endophragm is thin, tightly adjacent to the periphragm over the entire surface except for the horn zone. The cyst is cornucopia. The paracingulum is smoothed; On the dorsal and ventral sides of the cyst it is presented in the form of a double flat, slightly sinuous suture with a width of about 5–6 μm. The sulcus is weakly expressed in the form of a wide groove. The archaeopile is of a combined type. The intercalary, three precingular and partially apical plates are involved in the formation of the periarchaeopile, type A3I3P(3'+1a-3a+3''-5''). The perioperculum – the middle intercalary plate (2a) – is usually absent. Paratabulation is expressed by the structure of the archaeopile, cingulum and sulcus.
Holotype. Plate 1, Fig. 5. Ref. SP-1/135-A.
Location. Well SP-1 (Eastern Caspian), Aktobe region, Kazakhstan.
Dimensions (μm). Holotype: pericyst length 72.6, pericyst width 69.3. Other specimens (21 specimens): pericyst length 56–79, pericyst width 56–69.
Comparison. Soaniella circularis sp. nov. differs from the type species in the shape of the pericyst and the structure of the antapical horns. Unlike Soaniella granulata Vozzh. This species usually retains the cyst form after the formation of the archeopyle.
Distribution. Kazakhstan, Sholaksay Formation. Russia; Western Siberia, Nyurol Formation. Eocene (Ypresian-Lutetian).
Note: West Siberian forms are on average smaller than the typical material from Kazakhstan.