Back
Glaphyrocysta coniacia
Glaphyrocysta coniacia sp. nov., Pearce, M. A., 2018, p. 74-76
Holotype: Pearce, M. A., 2018, Pl. 1, figs. 4–5
Type locality and horizon: Upper Chalk Formation (Broadstairs Chalk Member), Micraster coranguinum Zone
Strat. range: Middle Coniacian
Original description: Pearce, M. A., 2018:
Diagnosis:
A species of Glaphyrocysta with a microreticulate endophragm and a weakly fibrous periphragm forming processes of highly variable width, united into linear, arcuate, soleate or annulate complexes that unite distally into wide, perforate, recurved and irregular membranes.
Description:
Medium to large chorate dinoflagellate cyst with a lenticular, dorso-ventrally compressed, central body and an offset sulcal notch. Two weak antapical bulges may be present.
Wall: two-layered, comprising a microreticulate endophragm and a slightly fibrous periphragm that separate in the formation of processes.
Processes: tabular, apparently solid, and well developed around the ambitus of the central body, poorly developed on the mid-dorsal area and typically absent on the mid-ventral area. The marginal processes are of variable width but similar length on individual specimens and appear to be clustered into linear groups that are connected distally and may be connected at the base. The mid-dorsal processes may develop into shorter arcuate, soleate or annulate complexes. Distally, the processes widen into perforated platforms that are irregular in shape and typically recurved. The sulcal
notch is offset to the left; the cingulum is represented by slender processes at margins of the central body.
Archaeopyle: apical, Type tA, typically with a detached operculum.
Dimensions:
Holotype:central body w/ l = 74 × 61 μm, maximum process length = 35 μm;
paratype 1: central body w/ l = 71 × 62 μm, maximum process length = 27 μm;
paratype 2: central body w/ l = 59 × 53 μm, maximum process length = 30 μm;
paratype 3: central body w/ l = 60 × 60 μm, maximum process length = 30 μm;
paratype 4: central body w/ l = 70 × 53 μm, maximum process length = 25 μm;
paratype 5: maximum process length = 36 μm.
Range, central body w/ l = 46(60)74 × 42(55)64 μm, maximum process length = 12(29)36 μm.
Sixteen specimens measured.
Affinities/Comparison:
The closest species to Glaphyrocysta coniacia sp. nov. are G. exuberans (Deflandre and Cookson, 1955 ex Eaton, 1976) Stover and Evitt, 1978, G. intricata (Eaton, 1971) Stover and Evitt, 1978 and G. texta (Bujak, 1976) Stover and Evitt, 1978. Despite being described from the Palaeogene and therefore being significantly younger, Glaphyrocysta exuberans differs with processes that ramify
elaborately halfway along their length, while G. Intricate and G. texta show much less variability in process width. Glaphyrocysta intricata also differs in having processes that bifurcate distally to a variable length and width.
Holotype: Pearce, M. A., 2018, Pl. 1, figs. 4–5
Type locality and horizon: Upper Chalk Formation (Broadstairs Chalk Member), Micraster coranguinum Zone
Strat. range: Middle Coniacian
Original description: Pearce, M. A., 2018:
Diagnosis:
A species of Glaphyrocysta with a microreticulate endophragm and a weakly fibrous periphragm forming processes of highly variable width, united into linear, arcuate, soleate or annulate complexes that unite distally into wide, perforate, recurved and irregular membranes.
Description:
Medium to large chorate dinoflagellate cyst with a lenticular, dorso-ventrally compressed, central body and an offset sulcal notch. Two weak antapical bulges may be present.
Wall: two-layered, comprising a microreticulate endophragm and a slightly fibrous periphragm that separate in the formation of processes.
Processes: tabular, apparently solid, and well developed around the ambitus of the central body, poorly developed on the mid-dorsal area and typically absent on the mid-ventral area. The marginal processes are of variable width but similar length on individual specimens and appear to be clustered into linear groups that are connected distally and may be connected at the base. The mid-dorsal processes may develop into shorter arcuate, soleate or annulate complexes. Distally, the processes widen into perforated platforms that are irregular in shape and typically recurved. The sulcal
notch is offset to the left; the cingulum is represented by slender processes at margins of the central body.
Archaeopyle: apical, Type tA, typically with a detached operculum.
Dimensions:
Holotype:central body w/ l = 74 × 61 μm, maximum process length = 35 μm;
paratype 1: central body w/ l = 71 × 62 μm, maximum process length = 27 μm;
paratype 2: central body w/ l = 59 × 53 μm, maximum process length = 30 μm;
paratype 3: central body w/ l = 60 × 60 μm, maximum process length = 30 μm;
paratype 4: central body w/ l = 70 × 53 μm, maximum process length = 25 μm;
paratype 5: maximum process length = 36 μm.
Range, central body w/ l = 46(60)74 × 42(55)64 μm, maximum process length = 12(29)36 μm.
Sixteen specimens measured.
Affinities/Comparison:
The closest species to Glaphyrocysta coniacia sp. nov. are G. exuberans (Deflandre and Cookson, 1955 ex Eaton, 1976) Stover and Evitt, 1978, G. intricata (Eaton, 1971) Stover and Evitt, 1978 and G. texta (Bujak, 1976) Stover and Evitt, 1978. Despite being described from the Palaeogene and therefore being significantly younger, Glaphyrocysta exuberans differs with processes that ramify
elaborately halfway along their length, while G. Intricate and G. texta show much less variability in process width. Glaphyrocysta intricata also differs in having processes that bifurcate distally to a variable length and width.