Back
Valvaeodinium hanneae
Valvaeodinium hanneae Piasecki, 2001, p.28–29, figs.5A–L.
Holotype: Piasecki, 2001, fig.5A–B.
Age: latest Bathonian–earliest Callovian.
Original description (Piasecki, 2001)
Diagnosis: Proximate, cavate dinoflagellate cysts with small ellipsoidal to rounded cylindrical bodies of two wall layers separated by structures. The surface of the cyst is smooth and periphragm is thin. The endophragm is thicker, hyaline and separated from periphragm by vertical membranous structures in an irregular pattern with angular meshes. The aracheopyle is situated near the apex and of type AI of one apical and one intercalary plate. Operculum is free and composite of two plates. Paratabulation is not indicated except for the shape of the archaeopyle.
Description: Proximate, holocavate dinoflagellate cysts with small, ellipsoidal to rounded cylindrical bodies. The wall iscomposed of two, hyaline layers, a thin peri- and a thicker endophragm. The wall layers are separated by thin membranous structures; 3-5 µm high and perpendicular to the wall layers. The surface of the wall is smooth but irregular, reflecting the underlying wall structure most comparable to a wrinkled piece of paper. In direct plane view, the pattern of the wall structure forms an irregular reticulum of (tri-) angular meshes. Microscopic thickening of the membranes especially near contact to the periphragm appear like beads in the reticulum just below the surface of the cyst; black or light in high and low focus. In optical section, the wall structure locally shows variation from supporting walls to lower membranes that raise into supporting "processes" where they connect. Tabulation is not indicated by any wall structure but only by the shape of the archaeopyle and its accessory sutures. The archeaopyle is interpreted as combined intercalary and apical, type AI, and the free operculum is composite of two? plates. The position of the archaeopyle near the apex makes interpretation difficult due to the general lateral compression and view. However, the archaeopyle is interpreted as formed by the loss of plate homologues 1a and 3' in accordance with the diagnosis of Valvaeodinium by Below (1987).
Size: Ten specimens were measured. The length varies from 32-50 µm, average 41µm. The width varies from 29-39 µm, average 33 µm. The wall is 3-5 µm thick, average 4 µm. The holotype is 37 µm long, 29 µm wide and the wall is 4 µm thick. The paratype is 50 µm long, 39 µm wide and the wall is 5 µm thick.
Discussion: The overall shape of the cysts and the interpretation of the archaeopyle suggest affinity to the genus Valvaeodinium Below, 1987. This new species deviates from other species of Valvaeodinium by the characteristic wall structure combined with the smooth surface, no reflected tabulation and overall cavate morphology. The morphology of Valvaeodinium hanneae is considered cavate as the species appear overall cavate. It may be related to Valveodnium thereseae Smelror, 1991.
Holotype. Valvaeodinium hanneae, Figs 5A-B, MGUH, GGU sample 433868
Paratype. Figs 5E-F, MGUH GGU sample 433868
Type locality: The Middle Jurassic succession at Stensiö Plateau, northern Hold with Hope.
Type stratum: Pelion Formation.
Age and stratigraphical range: Valvaeodinium hanneae is recorded in Middle Jurassic succession with a stratigraphic restricted occurence in the C. apertum zone at the Bathonian-Callovia transition. The age is latest Bathonian-earliest Callovian.
Geographical occurrence: Hold with Hope, North East Greenland.
Holotype: Piasecki, 2001, fig.5A–B.
Age: latest Bathonian–earliest Callovian.
Original description (Piasecki, 2001)
Diagnosis: Proximate, cavate dinoflagellate cysts with small ellipsoidal to rounded cylindrical bodies of two wall layers separated by structures. The surface of the cyst is smooth and periphragm is thin. The endophragm is thicker, hyaline and separated from periphragm by vertical membranous structures in an irregular pattern with angular meshes. The aracheopyle is situated near the apex and of type AI of one apical and one intercalary plate. Operculum is free and composite of two plates. Paratabulation is not indicated except for the shape of the archaeopyle.
Description: Proximate, holocavate dinoflagellate cysts with small, ellipsoidal to rounded cylindrical bodies. The wall iscomposed of two, hyaline layers, a thin peri- and a thicker endophragm. The wall layers are separated by thin membranous structures; 3-5 µm high and perpendicular to the wall layers. The surface of the wall is smooth but irregular, reflecting the underlying wall structure most comparable to a wrinkled piece of paper. In direct plane view, the pattern of the wall structure forms an irregular reticulum of (tri-) angular meshes. Microscopic thickening of the membranes especially near contact to the periphragm appear like beads in the reticulum just below the surface of the cyst; black or light in high and low focus. In optical section, the wall structure locally shows variation from supporting walls to lower membranes that raise into supporting "processes" where they connect. Tabulation is not indicated by any wall structure but only by the shape of the archaeopyle and its accessory sutures. The archeaopyle is interpreted as combined intercalary and apical, type AI, and the free operculum is composite of two? plates. The position of the archaeopyle near the apex makes interpretation difficult due to the general lateral compression and view. However, the archaeopyle is interpreted as formed by the loss of plate homologues 1a and 3' in accordance with the diagnosis of Valvaeodinium by Below (1987).
Size: Ten specimens were measured. The length varies from 32-50 µm, average 41µm. The width varies from 29-39 µm, average 33 µm. The wall is 3-5 µm thick, average 4 µm. The holotype is 37 µm long, 29 µm wide and the wall is 4 µm thick. The paratype is 50 µm long, 39 µm wide and the wall is 5 µm thick.
Discussion: The overall shape of the cysts and the interpretation of the archaeopyle suggest affinity to the genus Valvaeodinium Below, 1987. This new species deviates from other species of Valvaeodinium by the characteristic wall structure combined with the smooth surface, no reflected tabulation and overall cavate morphology. The morphology of Valvaeodinium hanneae is considered cavate as the species appear overall cavate. It may be related to Valveodnium thereseae Smelror, 1991.
Holotype. Valvaeodinium hanneae, Figs 5A-B, MGUH, GGU sample 433868
Paratype. Figs 5E-F, MGUH GGU sample 433868
Type locality: The Middle Jurassic succession at Stensiö Plateau, northern Hold with Hope.
Type stratum: Pelion Formation.
Age and stratigraphical range: Valvaeodinium hanneae is recorded in Middle Jurassic succession with a stratigraphic restricted occurence in the C. apertum zone at the Bathonian-Callovia transition. The age is latest Bathonian-earliest Callovian.
Geographical occurrence: Hold with Hope, North East Greenland.