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Valvaeodinium leneae
From Fensome et al., 2019:
Valvaeodinium leneae Piasecki, 2001, p.26–28, figs.4A–L.
Holotype: Piasecki, 2001, fig.4D–E (not figs.5D–E, as indicated by Piasecki, 2001, p.27).
Age: middle Bathonian–earliest Callovian.
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Original description (Piasecki, 2001)
Diagnosis: Proximate dinoflagellate cysts with small ellipsoidal to rounded cylindrical bodies of two close wall layers. The surface of the cyst is smooth and periphragm is thin. The endophragm is micro-vermiculate sculptured and appears as a norrow inverse reticulum. The archaeopyle is situated near the apex and is of type AI combined 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. The sulcal region may be indicated by absence of sculpture on the endophragma.
Description: Dinoflagellate cysts with small ellipsoidal to rounded cylindrical bodies with an apical bulge rarely indicated. The length of the body exceeds the width but specimens with borad bodies do occur. The hyaline wall is composed of two close layers, peri- and endophragm. The surface of the wall is smooth in optical section but the surface may corrode so the structure below becomes exposed. The characteristic wall structure is considered sculpture of the endophragm, which is closely vermiculate. The vermiculae are separated by an inverse, narrow micro-reticulum. Dimensionsof sculptural elements are less than 1 µm. The sulcal region may be devoid of wall structure but no other reflection of tabulation is indicated by the wall structure. Tabulation is indicated by the shape of the archaeopyle and its accessory sutures. The archaeopyle is interpreted as combined intercalary and apical, type AI, and the free operculum is composite of two? plate homologues. The margin of the archaeopyle to the precingular plates may indicate 3" and parts of 2" and 4". The position of the archeopyle near to the apex may indicate apical plate homologues to be involved in the formation of the archaeopyle but it also 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 diagnosis of Valvaeodinium by Below (1987).
Size: Thirteen specimens were measured. The length varies from 45-31µm, average 39µm. The width varies from 27-41 µm, average 32 µm. The wall is approximately 1 µm thick. The size of the holotype of Valvaeodinium leneae; length 39 µm, width 33µm. The size of the paratype; length 38 µm, width 28 µm.
Discussion: The shape of the body and the interpretation of the archeopyle clearly suggest affinity to the genus Valvaeodinium Below, 1987. The morphology of V. leneae is acavate like most of the species in Valvaeodinium but in contrast to the other species described from the present Arctic region (V. theresa, Smelror 1991 and V. hanneae). Valvaeodinium leneae deviates from other species of Valvaeodinium by the combined characters of the smooth surface, the internal, closely vermiculate wall structure, no reflected tabulation and acavate morphology.
Holotype: Valvaeodinium leneae, Figs 5D-E, MGUH, GGU sample 360398.
Paratype: Valvaeodinium leneae, Figs 5H, MGUH, GGU sample 360698.
Type locality: Ravn Pynt at the southern part of the east-coast of Store Koldeweg (Piasecki et al. 2000a)
Type stratum: Pelion Formation.
Age and stratigraphical range: Valvaeodinium leneae is recorded in the Middle Jurassic succession in an interval limited by the A. ishmae to C. apertum ammonite Zones at Store Koldewey, middle Bathonian to lowermost Callovian. In the succession at Stensiö Plateau Valvaeodinium leneae is recorded up to a few metres below an ammonite fauna horizon of the C. pertum Zone. So the highest range of Valvaeodinium leneae may mark the Bathonian-Callovian transition or reach into the lowermost Callovian. The occurence of Valvaeodinium leneae is then of Middle Bathonian to the earliest Callovian age.
Geographical occurence: Hold with Hope and Store Koldewey in North East Greenland.
Valvaeodinium leneae Piasecki, 2001, p.26–28, figs.4A–L.
Holotype: Piasecki, 2001, fig.4D–E (not figs.5D–E, as indicated by Piasecki, 2001, p.27).
Age: middle Bathonian–earliest Callovian.
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Original description (Piasecki, 2001)
Diagnosis: Proximate dinoflagellate cysts with small ellipsoidal to rounded cylindrical bodies of two close wall layers. The surface of the cyst is smooth and periphragm is thin. The endophragm is micro-vermiculate sculptured and appears as a norrow inverse reticulum. The archaeopyle is situated near the apex and is of type AI combined 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. The sulcal region may be indicated by absence of sculpture on the endophragma.
Description: Dinoflagellate cysts with small ellipsoidal to rounded cylindrical bodies with an apical bulge rarely indicated. The length of the body exceeds the width but specimens with borad bodies do occur. The hyaline wall is composed of two close layers, peri- and endophragm. The surface of the wall is smooth in optical section but the surface may corrode so the structure below becomes exposed. The characteristic wall structure is considered sculpture of the endophragm, which is closely vermiculate. The vermiculae are separated by an inverse, narrow micro-reticulum. Dimensionsof sculptural elements are less than 1 µm. The sulcal region may be devoid of wall structure but no other reflection of tabulation is indicated by the wall structure. Tabulation is indicated by the shape of the archaeopyle and its accessory sutures. The archaeopyle is interpreted as combined intercalary and apical, type AI, and the free operculum is composite of two? plate homologues. The margin of the archaeopyle to the precingular plates may indicate 3" and parts of 2" and 4". The position of the archeopyle near to the apex may indicate apical plate homologues to be involved in the formation of the archaeopyle but it also 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 diagnosis of Valvaeodinium by Below (1987).
Size: Thirteen specimens were measured. The length varies from 45-31µm, average 39µm. The width varies from 27-41 µm, average 32 µm. The wall is approximately 1 µm thick. The size of the holotype of Valvaeodinium leneae; length 39 µm, width 33µm. The size of the paratype; length 38 µm, width 28 µm.
Discussion: The shape of the body and the interpretation of the archeopyle clearly suggest affinity to the genus Valvaeodinium Below, 1987. The morphology of V. leneae is acavate like most of the species in Valvaeodinium but in contrast to the other species described from the present Arctic region (V. theresa, Smelror 1991 and V. hanneae). Valvaeodinium leneae deviates from other species of Valvaeodinium by the combined characters of the smooth surface, the internal, closely vermiculate wall structure, no reflected tabulation and acavate morphology.
Holotype: Valvaeodinium leneae, Figs 5D-E, MGUH, GGU sample 360398.
Paratype: Valvaeodinium leneae, Figs 5H, MGUH, GGU sample 360698.
Type locality: Ravn Pynt at the southern part of the east-coast of Store Koldeweg (Piasecki et al. 2000a)
Type stratum: Pelion Formation.
Age and stratigraphical range: Valvaeodinium leneae is recorded in the Middle Jurassic succession in an interval limited by the A. ishmae to C. apertum ammonite Zones at Store Koldewey, middle Bathonian to lowermost Callovian. In the succession at Stensiö Plateau Valvaeodinium leneae is recorded up to a few metres below an ammonite fauna horizon of the C. pertum Zone. So the highest range of Valvaeodinium leneae may mark the Bathonian-Callovian transition or reach into the lowermost Callovian. The occurence of Valvaeodinium leneae is then of Middle Bathonian to the earliest Callovian age.
Geographical occurence: Hold with Hope and Store Koldewey in North East Greenland.