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Microdinium parvum
From Fensome et al., 2019:
Microdinium parvum Slimani, 1994, p.38–39, pl.6, figs.11–13,28–29. Holotype: Slimani, 1994, pl.6, figs.12,28. Age: late
Campanian–early Maastrichtian.
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Original description (Slimani 1994) (translation PKB 2025):
Microdinium parvum sp. nov. (P1.6, Fig. 11-13, 28, 29)
Name derivation: Latin: parvus, small; referring to the small size of the cyst.
Holotvpe: Turnhout -933 m, preparation 1, E.F. coord. R33/3-4.
Paratype: Turnhout -933 m, preparation 6, E.F. coord. K34.
Type locality: Turnhout -933 m.
Type horizon: Campanian.
Synonymy:
?1992 : Phanerodinium sp. 3 - MARHEINECKË , p. 111-112, pl. 25; fig. 9-10, 13, 14-16.
Diagnosis: Small, subspheroidal, suturocavate cyst, ellipsoidal to polyhedral, with a hypocyst twice as long as the epicyst. It is characterized by densely granulated intratabular areas and suturocavate ridges, glabrous, distally entire, and proportionally wide compared to its small size. The paratabulation is gonyaulacoid and corresponds to the formula: 1 pr, 4', 4a, 7", 7c, 6"', lp, 5s. The archaeopyle is apical and intercalary, type (tAtl)a, with a ventrally attached operculum.
Dimensions: Holotype: maximum diameter: 24 µm. Variations: maximum diameter: 20-27 µm.
Number of specimens measured: 15.
Material: > 40 specimens.
Description: The endophragm and periphragm are in contact in the intratabular areas. The endophragm is thicker and bears dense and regular intratabular granulation that stops at the penitabular borders and draws a rounded penitabular outline of the paraplates. This ornamentation is replaced by the very fine periphragm that rises between the paraplates and forms hollow ridges that are often wider than they are tall (1 to 2 µm in height); they are slightly more prominent to angular at their junction. The hypocystal configuration is partiform. Paraplates 1", 6", and 1'" are small and subtriangular in shape, while 7" is very small. The parasulcus is segmented into four small paraplates (as, fm, rs, is) and a fifth paraplate ps, which is omegaform. The paracingulum (4 pm wide) is slightly laevorotatory with a flagellar pore located ventrally between its two ends. The operculum has 9 small paraplates: 1 preapical, 4 apical and 4 anterior intercalary.
Comparison: This species resembles Microdinium granocarinatum (BELOW, 1987b) LENTIN and WILLIAMS (1989) in its cavate parasutural ridges and in the presence of intratabular granular ornamentation; but it differs mainly in its ridges, which are lower, non-denticulate and wider in relation to the small size of the cyst which bears them; and also in the more rounded outline of the paraplates. A comparison with the specimens of Phanerodinium sp. 3 from the Maastrichtian of Germany described and figured by MARHEINECKE (1992) (see synonymy above) is questionable, because the ornamentation and ridges of the latter are only weakly discernible. Rhiptocorys veligera (DEFLANDRE, 1937b) LEJEUNE-CARPENTIER and SARJEANT (1983) differs from the species studied mainly by its extremely small and ridgeless epicyst. While Microdinium irregulare CLARK E and VERDIE R (1967), which is considered a junior synonym of R. veligera by BELOW (1987b), also differs by its larger size and its higher, wavy ridges. Microdinium parvum sp. nov. differs from M. pauciscabrosum sp. nov. (in this work) which is also small, by the presence of dense intratabular granulation, and by its relatively wider ridges.
Stratigraphic distribution: Turnhout: -956 to -864.60 m, Upper Campanian - Lower Maastrichtian
Microdinium parvum Slimani, 1994, p.38–39, pl.6, figs.11–13,28–29. Holotype: Slimani, 1994, pl.6, figs.12,28. Age: late
Campanian–early Maastrichtian.
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Original description (Slimani 1994) (translation PKB 2025):
Microdinium parvum sp. nov. (P1.6, Fig. 11-13, 28, 29)
Name derivation: Latin: parvus, small; referring to the small size of the cyst.
Holotvpe: Turnhout -933 m, preparation 1, E.F. coord. R33/3-4.
Paratype: Turnhout -933 m, preparation 6, E.F. coord. K34.
Type locality: Turnhout -933 m.
Type horizon: Campanian.
Synonymy:
?1992 : Phanerodinium sp. 3 - MARHEINECKË , p. 111-112, pl. 25; fig. 9-10, 13, 14-16.
Diagnosis: Small, subspheroidal, suturocavate cyst, ellipsoidal to polyhedral, with a hypocyst twice as long as the epicyst. It is characterized by densely granulated intratabular areas and suturocavate ridges, glabrous, distally entire, and proportionally wide compared to its small size. The paratabulation is gonyaulacoid and corresponds to the formula: 1 pr, 4', 4a, 7", 7c, 6"', lp, 5s. The archaeopyle is apical and intercalary, type (tAtl)a, with a ventrally attached operculum.
Dimensions: Holotype: maximum diameter: 24 µm. Variations: maximum diameter: 20-27 µm.
Number of specimens measured: 15.
Material: > 40 specimens.
Description: The endophragm and periphragm are in contact in the intratabular areas. The endophragm is thicker and bears dense and regular intratabular granulation that stops at the penitabular borders and draws a rounded penitabular outline of the paraplates. This ornamentation is replaced by the very fine periphragm that rises between the paraplates and forms hollow ridges that are often wider than they are tall (1 to 2 µm in height); they are slightly more prominent to angular at their junction. The hypocystal configuration is partiform. Paraplates 1", 6", and 1'" are small and subtriangular in shape, while 7" is very small. The parasulcus is segmented into four small paraplates (as, fm, rs, is) and a fifth paraplate ps, which is omegaform. The paracingulum (4 pm wide) is slightly laevorotatory with a flagellar pore located ventrally between its two ends. The operculum has 9 small paraplates: 1 preapical, 4 apical and 4 anterior intercalary.
Comparison: This species resembles Microdinium granocarinatum (BELOW, 1987b) LENTIN and WILLIAMS (1989) in its cavate parasutural ridges and in the presence of intratabular granular ornamentation; but it differs mainly in its ridges, which are lower, non-denticulate and wider in relation to the small size of the cyst which bears them; and also in the more rounded outline of the paraplates. A comparison with the specimens of Phanerodinium sp. 3 from the Maastrichtian of Germany described and figured by MARHEINECKE (1992) (see synonymy above) is questionable, because the ornamentation and ridges of the latter are only weakly discernible. Rhiptocorys veligera (DEFLANDRE, 1937b) LEJEUNE-CARPENTIER and SARJEANT (1983) differs from the species studied mainly by its extremely small and ridgeless epicyst. While Microdinium irregulare CLARK E and VERDIE R (1967), which is considered a junior synonym of R. veligera by BELOW (1987b), also differs by its larger size and its higher, wavy ridges. Microdinium parvum sp. nov. differs from M. pauciscabrosum sp. nov. (in this work) which is also small, by the presence of dense intratabular granulation, and by its relatively wider ridges.
Stratigraphic distribution: Turnhout: -956 to -864.60 m, Upper Campanian - Lower Maastrichtian