Back
Impagidinium caspienense
Impagidinium caspienense Marret in Marret et al., 2004, p.11,13, pl.3, figs.1-8; pl.5, figs.1-2; text-figs.3D-E.
Holotype: Marret et al., 2004, pl.2, figs.1-4.
Age: late Holocene.
Original description (Marret et al., 2004)
Holotype: Recent sediments (0 cm) from US02-1 from Southern Caspian (51º29'E, 39º16'N at a water depth of 315 m). Plate 2: 1-4 (NHM registration number FD644(1)/EF: P43)
Repository: Slide: Natural History Museum of London (UK). Material: Museum d’Histoire Naturelle de Paris (France).
Type locality: Recent sediments from the Southern Caspian.
Derivation of name: Named caspienense from the French name of the Caspian Sea (Mer Caspienne)
Diagnosis: Proximate cyst with subspherical to ellipsoidal ambitus, endophragm and periphragm
appressed and low intratabular linear relief. Gonyaulacacean paratabulation indicated by low parasutural septa and ventral S-type organisation. Paraplate 4' is in contact with paraplate 6''. Prominent septum is developed at the junction of paraplate 1'''' and the sulcus. Apical boss. Archeopyle is precingular (3''). Operculum is free.
Description: The cyst has a subspherical to ellipsoidal ambitus with both hypocyst and epicyst of equal size. The epicyst has a smoothly rounded apex with a pronounced apical boss (2 to 4 µm in height) (Plate 2: 3-4). Endophragm and periphragm are appressed except along the parasutural septa where a small cavation is observed, and form a relatively thin wall layer (1 µm). The surface of the wall has two different types of ornamentation: fine granulation and low intratabular suturo-cavate relief observed on all the paraplates. The parasutural septa are low ( 2 µm), of irregular height, with an undulating margin and are finely granulate. A 2 to 5 µm high septum occurs at the junction of paraplate 1'''' and the sulcus. The parasutural septa delineate a gonyaulacacean paratabulation (4', 6'', 6c, 6''', 1p, 1'''') with the ventral area showing S-type paratabulation. The sulcus is generally not divided into paraplates, although septa can start to develop between sulcal paraplates ps, rs and ls (Fig. 3E). The archeopyle is precingular (paraplate 3'') and the operculum is free. Paraplate 4''' lies posterior to paraplate 3''. Paraplates 4' and 1' are narrow and subparallel. The contact between paraplates 4’ and 6'' is very short, and paraplate 6'' is subtriangular and relatively narrow. All specimens observed are transparent in light microscopy.
Dimensions: Holotype: body length = 40 µm; body width = 31 µm; height of apical boss = 2 µm, thickness of the cyst wall = 1 µm, height of septa (except the antapical septum) = 2 µm. Average measurements on 15 specimens: body length = 35–(39)–50 µm; body width = 30–(35)–43 µm.
Comparisons: The irregular height of septa, the occurrence of a high septum at the junction of paraplate 1'''' and the sulcus, and the low intratabular relief separates Impagidinium caspienense from all other extant Impagidinium species. This species differs from Impagidinium paradoxum in its lack of sulcal paratabulation.
Holotype: Marret et al., 2004, pl.2, figs.1-4.
Age: late Holocene.
Original description (Marret et al., 2004)
Holotype: Recent sediments (0 cm) from US02-1 from Southern Caspian (51º29'E, 39º16'N at a water depth of 315 m). Plate 2: 1-4 (NHM registration number FD644(1)/EF: P43)
Repository: Slide: Natural History Museum of London (UK). Material: Museum d’Histoire Naturelle de Paris (France).
Type locality: Recent sediments from the Southern Caspian.
Derivation of name: Named caspienense from the French name of the Caspian Sea (Mer Caspienne)
Diagnosis: Proximate cyst with subspherical to ellipsoidal ambitus, endophragm and periphragm
appressed and low intratabular linear relief. Gonyaulacacean paratabulation indicated by low parasutural septa and ventral S-type organisation. Paraplate 4' is in contact with paraplate 6''. Prominent septum is developed at the junction of paraplate 1'''' and the sulcus. Apical boss. Archeopyle is precingular (3''). Operculum is free.
Description: The cyst has a subspherical to ellipsoidal ambitus with both hypocyst and epicyst of equal size. The epicyst has a smoothly rounded apex with a pronounced apical boss (2 to 4 µm in height) (Plate 2: 3-4). Endophragm and periphragm are appressed except along the parasutural septa where a small cavation is observed, and form a relatively thin wall layer (1 µm). The surface of the wall has two different types of ornamentation: fine granulation and low intratabular suturo-cavate relief observed on all the paraplates. The parasutural septa are low ( 2 µm), of irregular height, with an undulating margin and are finely granulate. A 2 to 5 µm high septum occurs at the junction of paraplate 1'''' and the sulcus. The parasutural septa delineate a gonyaulacacean paratabulation (4', 6'', 6c, 6''', 1p, 1'''') with the ventral area showing S-type paratabulation. The sulcus is generally not divided into paraplates, although septa can start to develop between sulcal paraplates ps, rs and ls (Fig. 3E). The archeopyle is precingular (paraplate 3'') and the operculum is free. Paraplate 4''' lies posterior to paraplate 3''. Paraplates 4' and 1' are narrow and subparallel. The contact between paraplates 4’ and 6'' is very short, and paraplate 6'' is subtriangular and relatively narrow. All specimens observed are transparent in light microscopy.
Dimensions: Holotype: body length = 40 µm; body width = 31 µm; height of apical boss = 2 µm, thickness of the cyst wall = 1 µm, height of septa (except the antapical septum) = 2 µm. Average measurements on 15 specimens: body length = 35–(39)–50 µm; body width = 30–(35)–43 µm.
Comparisons: The irregular height of septa, the occurrence of a high septum at the junction of paraplate 1'''' and the sulcus, and the low intratabular relief separates Impagidinium caspienense from all other extant Impagidinium species. This species differs from Impagidinium paradoxum in its lack of sulcal paratabulation.