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Hapsocysta kysingensis
Hapsocysta kysingensis Heilmann-Clausen and Van Simaeys, 2005, p.166,168–170, pl.5, figs.1–6; text-fig.7A–C.
Holotype: Heilmann-Clausen and Van Simaeys, 2005, pl.5, figs.1–2; text-fig.7A.
Age: late Eocene.
Original description (Heilmann-Clausen and Van Simaeys, 2005):
Hapsocysta kysingensis sp. nov. Plate 5, figs. 1–6, Text-Figure 7
Synonyms:
Cannosphaeropsis peridictya Eisenack & Cookson 1960; De Coninck, 1986, pl. 1, figs. 21, 22.
?Species 1 Firth, 1966, pl. 21, figs. 1–4.
Description. A dinoflagellate cyst with a thin-walled, subspherical central body surrounded by an open network of smooth parasutural ribbons. The parasutural network is widely separated from the central body, except on the dorsal side where small parts of the sutural ribbons adhere to the central body. The parasutural ribbons are 1–2 µm wide, and are usually taeniate. Sometimes a low septum may be developed on the outer surface of some of the ribbons.
Paratabulation. The Kofoidian paratabulation formula is gonyaulacacean, 0-2 pr, 4', 6'', 6c, 2-4s, 5-6''', 1p, 1''''. This is based on three specimens (Text-Figure 7). The dorsal side shows neutral torsion, with 3'' above 4'''. The ventral organization of the cyst appears to be of S-type, with 6'' apparently subtriangular and with no, or only very little, contact between 6'' and 1'. The paratabulation pattern of the epicyst is variable. It may be insert, with all four apical homologues well developed, and in contact with the apical pore complex, or metasert, with the rudimentary first apical homologue 1' in contact with 2', but not with 3'. The four paraplates 5'', 4', as and 6'' have the 4'/6'' configuration (i.e. 4' in contact with 6'') in each of the three specimens. Paraplates 4', 1', as and 6'' have the 4'/as configuration (Text-Figure 7B, C), or a configuration intermediate between 4'/as and 1'/6'' (Text-Figure 7A). The paratabulation pattern of the hypocyst is sexiform. The first postcingular homologue 1''' may be present (TextFigure 7C), or incorporated into a large undivided parasulcal field (Text-Figure 7A).
Archeopyle. Ruptures on the endocyst in some of the specimens may represent archeopyle sutures, but these are faint, and their nature could not be identified with certainty.
Derivation of name. From the type locality, Kysing.
Designation of holotype. Plate 5, figs. 1, 2 and TextFigure 7A, Slide 2666 G4, England Finder coordinates M25/2. MGUH 27774. Kysing-4 borehole, sample 2666, Upper Eocene. Specimen dimensions: Pericyst maximum diameter 63 µm; pericyst minimum diameter 59 µm; endocyst maximum diameter 35 µm; endocyst minimum diameter 30 µm
Designation of paratype. Paratype 1: Plate 5, figs. 5, 6 and Text-Figure 7B, Slide 2666 G4, England Finder coordinates T45. MGUH 27775. Kysing-4 borehole, sample 2666, Upper Eocene. Paratype 2: Plate 5, figs. 3, 4 and TextFigure 7C, Slide 2666 G4, England Finder coordinates K41/1. MGUH 27776. Kysing-4 borehole, sample 2666, Upper Eocene.
Dimensions of measured specimens. Pericyst maximum diameter 47 (63) 77 µm. Pericyst minimum diameter 44 (54) 62 µm. Endocyst maximum diameter 21 (31) 42 µm. Endocyst minimum diameter 15 (24) 30 µm. (12 specimens measured).
Comparisons. The specimens are superficially similar to two Lower Cretaceous species, Hapsocysta peridictya and Hapsocysta susanae. However, Hapsocysta kysingensis sp. nov. differs from both these taxa in its reduced paratabulation of the sulcus. In Hapsocysta peridictya and Hapsocysta susanae,the tabulation of the sulcal paraplatelets is fully reflected. For Hapsocysta peridictya, this is illustrated in Davey (1979: pl. 4, figs. 2, 5). The reduction or complete absence of paraplate 1''' (probably included in the functional parasulcus of the holotype, Text-Figure 7A) in Hapsocysta kysingensis sp. nov., marks a further difference from Hapsocysta susanae. Further differences are the larger size of Hapsocysta peridictya and the more robust parasutural strands in Hapsocysta susanae. Details of the paratabulation in Hapsocysta peridictyaare not well known and this prevents further comparisons with this species. Hapsocysta fenestrata comb. nov. differs in having pericystal paraplates with intratabular holes, rather than parasutural ribbons. Hapsocysta kysingensis sp. nov. also resembles the Upper Oligocene to Lower Miocene ‘cysts without walls’, Chaenosphaerula magnificaDamassa 1997 and Evittosphaerula paratabulata Manum 1979, described in detail by Damassa (1997). Both differ from Hapsocysta by the lack of endocysts. However Chaenosphaerula magnifica closely resembles Hapsocysta kysingensis sp. nov. in paratabulation, in particular the incompletely delineated sulcal paraplates and the variable epicystal paratabulation.
Holotype: Heilmann-Clausen and Van Simaeys, 2005, pl.5, figs.1–2; text-fig.7A.
Age: late Eocene.
Original description (Heilmann-Clausen and Van Simaeys, 2005):
Hapsocysta kysingensis sp. nov. Plate 5, figs. 1–6, Text-Figure 7
Synonyms:
Cannosphaeropsis peridictya Eisenack & Cookson 1960; De Coninck, 1986, pl. 1, figs. 21, 22.
?Species 1 Firth, 1966, pl. 21, figs. 1–4.
Description. A dinoflagellate cyst with a thin-walled, subspherical central body surrounded by an open network of smooth parasutural ribbons. The parasutural network is widely separated from the central body, except on the dorsal side where small parts of the sutural ribbons adhere to the central body. The parasutural ribbons are 1–2 µm wide, and are usually taeniate. Sometimes a low septum may be developed on the outer surface of some of the ribbons.
Paratabulation. The Kofoidian paratabulation formula is gonyaulacacean, 0-2 pr, 4', 6'', 6c, 2-4s, 5-6''', 1p, 1''''. This is based on three specimens (Text-Figure 7). The dorsal side shows neutral torsion, with 3'' above 4'''. The ventral organization of the cyst appears to be of S-type, with 6'' apparently subtriangular and with no, or only very little, contact between 6'' and 1'. The paratabulation pattern of the epicyst is variable. It may be insert, with all four apical homologues well developed, and in contact with the apical pore complex, or metasert, with the rudimentary first apical homologue 1' in contact with 2', but not with 3'. The four paraplates 5'', 4', as and 6'' have the 4'/6'' configuration (i.e. 4' in contact with 6'') in each of the three specimens. Paraplates 4', 1', as and 6'' have the 4'/as configuration (Text-Figure 7B, C), or a configuration intermediate between 4'/as and 1'/6'' (Text-Figure 7A). The paratabulation pattern of the hypocyst is sexiform. The first postcingular homologue 1''' may be present (TextFigure 7C), or incorporated into a large undivided parasulcal field (Text-Figure 7A).
Archeopyle. Ruptures on the endocyst in some of the specimens may represent archeopyle sutures, but these are faint, and their nature could not be identified with certainty.
Derivation of name. From the type locality, Kysing.
Designation of holotype. Plate 5, figs. 1, 2 and TextFigure 7A, Slide 2666 G4, England Finder coordinates M25/2. MGUH 27774. Kysing-4 borehole, sample 2666, Upper Eocene. Specimen dimensions: Pericyst maximum diameter 63 µm; pericyst minimum diameter 59 µm; endocyst maximum diameter 35 µm; endocyst minimum diameter 30 µm
Designation of paratype. Paratype 1: Plate 5, figs. 5, 6 and Text-Figure 7B, Slide 2666 G4, England Finder coordinates T45. MGUH 27775. Kysing-4 borehole, sample 2666, Upper Eocene. Paratype 2: Plate 5, figs. 3, 4 and TextFigure 7C, Slide 2666 G4, England Finder coordinates K41/1. MGUH 27776. Kysing-4 borehole, sample 2666, Upper Eocene.
Dimensions of measured specimens. Pericyst maximum diameter 47 (63) 77 µm. Pericyst minimum diameter 44 (54) 62 µm. Endocyst maximum diameter 21 (31) 42 µm. Endocyst minimum diameter 15 (24) 30 µm. (12 specimens measured).
Comparisons. The specimens are superficially similar to two Lower Cretaceous species, Hapsocysta peridictya and Hapsocysta susanae. However, Hapsocysta kysingensis sp. nov. differs from both these taxa in its reduced paratabulation of the sulcus. In Hapsocysta peridictya and Hapsocysta susanae,the tabulation of the sulcal paraplatelets is fully reflected. For Hapsocysta peridictya, this is illustrated in Davey (1979: pl. 4, figs. 2, 5). The reduction or complete absence of paraplate 1''' (probably included in the functional parasulcus of the holotype, Text-Figure 7A) in Hapsocysta kysingensis sp. nov., marks a further difference from Hapsocysta susanae. Further differences are the larger size of Hapsocysta peridictya and the more robust parasutural strands in Hapsocysta susanae. Details of the paratabulation in Hapsocysta peridictyaare not well known and this prevents further comparisons with this species. Hapsocysta fenestrata comb. nov. differs in having pericystal paraplates with intratabular holes, rather than parasutural ribbons. Hapsocysta kysingensis sp. nov. also resembles the Upper Oligocene to Lower Miocene ‘cysts without walls’, Chaenosphaerula magnificaDamassa 1997 and Evittosphaerula paratabulata Manum 1979, described in detail by Damassa (1997). Both differ from Hapsocysta by the lack of endocysts. However Chaenosphaerula magnifica closely resembles Hapsocysta kysingensis sp. nov. in paratabulation, in particular the incompletely delineated sulcal paraplates and the variable epicystal paratabulation.