Back
Spiniferites frigidus
Spiniferites frigidus Harland and Reid in Harland et al., 1980
Taxonomic junior synonym: Rottnestia amphicavata, according to Bujak (1984, p.191) — however, de Vernal et al. (1992, p.324) retained Rottnestia amphicavata.
Holotype: Harland et al., 1980, figs.2G-J
Age: Recent
Original description (Harland et al., 1980):
Spiniferites frigidus sp. nov. Figs. 2 A-J, 3
1977. Cyst of Gonyaulax sp. A Reid & Harland, pl. 5
Derivation of name. - Latin: frigidus. Cold, with reference to its habitat in Arctic waters.
Diagnosis. - An elongate, proximate cyst made up of a delicate,? two-layered, smooth, microgranulate or micropunctate wall. Paratabulation 4'. 6", 6c, AS, RS, PS, 6"', Ip, 1"" , outlined by parasutures carrying well developed membranous crests. Processes gonal, hollow and erect with bifurcate or trifurcate terminations but not always observed as discrete structures, often included as part of the parasultural crests. Cingulum and sulcus prominent, the first as a laevo-rotatory helicoid, the latter as a sinuous area widening antapically. Archeopyle reduced, precingular formed by the loss of paraplate 3“.
Description. -This cyst possesses a slight apical boss and is made up of a ?two-layered thin and membranous wall. Endophragm is smooth but the periphragm may be smooth, rough, microgranulate or micropunctate. There is some differentiation between the thinner periphragm and somewhat thicker endophragm. A paratabulation of 4’, 6”, 6c, AS, RS, PS, 6”’. Ip, I”” outlined by tall membranous crests is apparent although in some specimens the paratabulation is obscured by the membrane development (Fig. 2 A, B). Paraplates 4’ and I‘ are elongate and form an extension to the sulcal area. The remaining epicystal paraplates are large, conspicuous and rectangular, with the exception of 6“ which is small and triangular. The paracingulum has six square to elongate paraplates and the parasulcus may exhibit the anterior sulcal, AS, the right sulcal, RS, and posterior sulcal, PS, paraplates. The hypocyst is also made up of large, conspicuous rectangular paraplates except for I”’ which is an elongate, triangular plate and Ip which is a small, square paraplate. The antapical plate is large and square. The paracingulum is a laevorotatory helicoid, is not intended, and has a displacement of up to its own width; the sulcus is sinuous and widens antapically. The parasutural membranes are variable in height, to as much as half the cyst diameter, and are always conspicuous all over the cyst. They are present on nearly all parasutures except those dividing paracingulum and parasulcal plates from one another and in those separating paraplates 4’ from 1’. The parasutural membranes are not constant in height, are smooth to micro-ornamented and may be striate, have entire margins and may be slightly more prominent on the hypocyst than on the epicyst (Fig. 2 F). Processes are also present and may be seen as discrete structures with a shaft and tip or may only be recognized by the presence of their distal structure surmounting a parasutural crest at a gonal position. The process shafts appear to form as a coalescence of the parasutural crests and distally the processes bifurcate or trifurcate. The archeopyle is reduced, precingular and formed by the loss of paraplate 3”.
Dimensions. - Holotype: Length (excluding processes and crests) 62.0 µm, breadth 47.0 µm. Range: Length 50.0 (65.1) 87.0 µm, breadth 18.75 (29.38) 50.0 µm. Measured specimens 15.
Holotype. -Specimen MPK 2424, Fig. 2 G-J.
Type horizon. - Recent sediment, Sample CSA 1777, Dome Kopanoar, Canadian Arctic.
Variation. - Infraspecific variation is restricted to size and to the development of the parasutural crests; the holotype of the species has fairly low membranes (Fig. 2 G-J) whereas other specimens have high flamboyant membranes (Fig. 2 A, B) and some even develop a ‘skirt’-like structure around the antapex as a result of particular membrane development on the antapical plate parasutures (Fig. 2 F).
Environmental requirements. - This new dinoflagellate cyst is known, to date, only from the Arctic and has not been observed in temperate. subtropical or tropical Atlantic waters. It is anticipated that it may be a useful indicator of cold environments in high latitudes, but its requirements are not, as yet, known in detail.
Thecal equivalence. - Probably a cyst of Gonyaulax sp. indet., but otherwise unknown.
Remarks. - This species appears to be similar to Spirniferites elongatus Reid which is an elongate species that possesses well developed parasutural membranes in the antapical area. In Spiniferites frigidus the parasutural membranes are developed all over the cyst to the extent that most of the gonal processes are incorporated and can only be recognized from their distal tips surmounting the crests in gonal positions. It is possible that a complex or plexus exists including these two species but for the moment we prefer to see them separated. Spiniferites elongates from Recent sediments in the Firth of Forth is illustrated (Fig. 2K, L) for comparative purposes.
Taxonomic junior synonym: Rottnestia amphicavata, according to Bujak (1984, p.191) — however, de Vernal et al. (1992, p.324) retained Rottnestia amphicavata.
Holotype: Harland et al., 1980, figs.2G-J
Age: Recent
Original description (Harland et al., 1980):
Spiniferites frigidus sp. nov. Figs. 2 A-J, 3
1977. Cyst of Gonyaulax sp. A Reid & Harland, pl. 5
Derivation of name. - Latin: frigidus. Cold, with reference to its habitat in Arctic waters.
Diagnosis. - An elongate, proximate cyst made up of a delicate,? two-layered, smooth, microgranulate or micropunctate wall. Paratabulation 4'. 6", 6c, AS, RS, PS, 6"', Ip, 1"" , outlined by parasutures carrying well developed membranous crests. Processes gonal, hollow and erect with bifurcate or trifurcate terminations but not always observed as discrete structures, often included as part of the parasultural crests. Cingulum and sulcus prominent, the first as a laevo-rotatory helicoid, the latter as a sinuous area widening antapically. Archeopyle reduced, precingular formed by the loss of paraplate 3“.
Description. -This cyst possesses a slight apical boss and is made up of a ?two-layered thin and membranous wall. Endophragm is smooth but the periphragm may be smooth, rough, microgranulate or micropunctate. There is some differentiation between the thinner periphragm and somewhat thicker endophragm. A paratabulation of 4’, 6”, 6c, AS, RS, PS, 6”’. Ip, I”” outlined by tall membranous crests is apparent although in some specimens the paratabulation is obscured by the membrane development (Fig. 2 A, B). Paraplates 4’ and I‘ are elongate and form an extension to the sulcal area. The remaining epicystal paraplates are large, conspicuous and rectangular, with the exception of 6“ which is small and triangular. The paracingulum has six square to elongate paraplates and the parasulcus may exhibit the anterior sulcal, AS, the right sulcal, RS, and posterior sulcal, PS, paraplates. The hypocyst is also made up of large, conspicuous rectangular paraplates except for I”’ which is an elongate, triangular plate and Ip which is a small, square paraplate. The antapical plate is large and square. The paracingulum is a laevorotatory helicoid, is not intended, and has a displacement of up to its own width; the sulcus is sinuous and widens antapically. The parasutural membranes are variable in height, to as much as half the cyst diameter, and are always conspicuous all over the cyst. They are present on nearly all parasutures except those dividing paracingulum and parasulcal plates from one another and in those separating paraplates 4’ from 1’. The parasutural membranes are not constant in height, are smooth to micro-ornamented and may be striate, have entire margins and may be slightly more prominent on the hypocyst than on the epicyst (Fig. 2 F). Processes are also present and may be seen as discrete structures with a shaft and tip or may only be recognized by the presence of their distal structure surmounting a parasutural crest at a gonal position. The process shafts appear to form as a coalescence of the parasutural crests and distally the processes bifurcate or trifurcate. The archeopyle is reduced, precingular and formed by the loss of paraplate 3”.
Dimensions. - Holotype: Length (excluding processes and crests) 62.0 µm, breadth 47.0 µm. Range: Length 50.0 (65.1) 87.0 µm, breadth 18.75 (29.38) 50.0 µm. Measured specimens 15.
Holotype. -Specimen MPK 2424, Fig. 2 G-J.
Type horizon. - Recent sediment, Sample CSA 1777, Dome Kopanoar, Canadian Arctic.
Variation. - Infraspecific variation is restricted to size and to the development of the parasutural crests; the holotype of the species has fairly low membranes (Fig. 2 G-J) whereas other specimens have high flamboyant membranes (Fig. 2 A, B) and some even develop a ‘skirt’-like structure around the antapex as a result of particular membrane development on the antapical plate parasutures (Fig. 2 F).
Environmental requirements. - This new dinoflagellate cyst is known, to date, only from the Arctic and has not been observed in temperate. subtropical or tropical Atlantic waters. It is anticipated that it may be a useful indicator of cold environments in high latitudes, but its requirements are not, as yet, known in detail.
Thecal equivalence. - Probably a cyst of Gonyaulax sp. indet., but otherwise unknown.
Remarks. - This species appears to be similar to Spirniferites elongatus Reid which is an elongate species that possesses well developed parasutural membranes in the antapical area. In Spiniferites frigidus the parasutural membranes are developed all over the cyst to the extent that most of the gonal processes are incorporated and can only be recognized from their distal tips surmounting the crests in gonal positions. It is possible that a complex or plexus exists including these two species but for the moment we prefer to see them separated. Spiniferites elongates from Recent sediments in the Firth of Forth is illustrated (Fig. 2K, L) for comparative purposes.