Back
Valvaeodinium cavum
Valvaeodinium cavum (Davies, 1983) emend. Below, 1987
Originally Comparodinium?, subsequently (and now) Valuaeodinium.
Holotype: Davies, 1983, pl.2, fig.10-11
Locus typicus: Reindeer Peninsula, Ellef Ringnes Island, District of Franklin, Northwest Territories, Canada
Stratum typicum: Toarcian-Bajocian
Translation Below, 1987: Bureau of Translation, Secretary of State Canada, 1988, Part II, p. 194-197
Original description: Davies, 1983, p. 16: Comparodinium? cavum
Diagnosis: A membranate dinoflagellate cyst species with a highly refractive autocyst, ovoidal in shape, and a thin hyaline ectophragm; with bifurcate processes grouped in apical, antapical and cingular locations, and thus developing three ectocoels in separate locations. Tabulation: ?5", 3-?4a, 8"", ?c, 8""", 5p, 2"""", ?s. Archeopyle: 4A[1-4] + 3I[1-3].
Dimensions: length 31(35)37 µm, breadth 22(27)29 µm. 7 specimens measured.
Description (annotated): The bifurcate processes are 2-3 µm long. The cingular processes form a double row which encircles the cyst. On well preserved specimens a thin ectophragm covers the processes creating three ectocoels corresponding to the groups of processes. The cingular ectocoel is widely separated from the polar ectocoels and occasionally may be reduced or faintly evident. Tabulation is indistinct, formed by faint lines on the periphragm and by archeopyle sutures. The archeopyle appears to be a disintegration type as defined by Dörhöfer and Davies (1980). Accessory sutures are found among both the intercalary plates. A long narrow sulcus is present.
Emended description: Below, 1987, p. 70-71: Valvaeodinium cavum
Arrangement of vesicles/plates of the dinoflagellate amphiesma PR, 4", 1a, 5"", 6c, 5""", 1"""", ns; growth of plates peridinoidal.
Cyst habit proximate, holocavate, also acavate mediodorsally, spheroidal, epicyst and hypocyst of equal size; size small; wall composed of pedium and numerous trabeculate luxuriate outgrowths fused distally into a tectum; the trabeculae are very short, solid, cylindrical, basally somewhat wider, distally osculate or also cauliflorate, standing on peniareate and intraareate spaces or nonareately scattered at varying intervals depending on their number; the tectum is glabrous, but pustulate (bearing tubercles with central pits) where the osculate trabeculae fuse with the tectum, so that the areate arrangement of the trabeculae is partially traced on the tectum; areation formula NR PR/PR, NR"/4", NR1a/1a, NR""/5"", NRc/6c, NR"""/5""", NR""""/1"""", NRs/Xs;
- PR a minute, planate field;
- 4 apicals, steno omegaform linteloid 1" (V), inverse camerate 2" (LVL), VI 3" (DL), VI 4" (RVR);
- caroidal 1a (DR);
- 5 anteriorly geniculate precingulars, V-nE 1"" (VVL), V-nE 2"" (LDL), V-nE 3"" (D), V-nE 4"" (RDR), V-nE 5"" (VR);
- cingulum planispiral, nonareate, but with the positions of the 6 homologous thecal plates indicated by alternating wide and narrow distances between cingular margins, lati 1c-5c, iso 6c;
- 5 posteriorly linear postcingulars, IV-nE 1""" (VL), IV-nE 2""" (LDL), IV-nE 3""" (D), IV-nE 4""" (RDR), IV-nE 5""" (VR) and polar VI 1"""";
- sulcus nonpartite with steno quasi-trapezoidal as and narrow, steno inverse-trapezoidal posterior sector;
- archeopyle apical/anterior intercalary, 3" + 1a; operculum solvate, secate, general opercular formula 3"s + 1as.
Affinities:
Davies, 1983, p. 16: Comparodinium? cavum
Comparodinium includes species without cingular processes and ectocoels which are present, however, in C?. cavum; therefore the placement of this species in Comparodinium is tentative. The polar arrangement of the processes, the occasional reduction of the cingular processes and the similarity in archeopyle formation and tabulation indicate strong affinities to Comparodinium. C. lineatum possesses trabeculae and has close affinities to ?C. cavum. The possession of the polar ectocoels and the intercalary plates is similar to ?Gillinia sp. of Dodekova (1975); however, ?Gillinia sp. of Dodekova (1975) does not have supporting processes. Cleistosphaeridium does not have ectocoels nor the alignment of processes shown by this species. Chlamydophorella possesses an entire enveloping ectophragm.
Below, 1987, p. 70-71:
(annotated) The Valvaeodinium-type tabulation of this taxon can be inferred especially from the location and typical contours of the archaeopyle. The complex areation described by Davies (1983, p. 16, fig. 9), ?5", 3a-4a, 8"", ?c, 8""", 5p, 2"""", ?s, with multiareate pre- and postcingular series, anterior intercalaries 1a-4a, and a complete hypocystal intercalary area series, can not be corroborated.
This taxon is very closely related to V. sphaerechinatum, especially if we consider only the endoblast with its arrangement of appendages. V. sphaerechinatum would in that case be V. cavum without the tectate covering. For, it is striking that V. cavum also has cingular, peniareate appendages. Only, as often happens on cavate cysts, the ends of the trabeculae are osculate, or less often capitate.
Originally Comparodinium?, subsequently (and now) Valuaeodinium.
Holotype: Davies, 1983, pl.2, fig.10-11
Locus typicus: Reindeer Peninsula, Ellef Ringnes Island, District of Franklin, Northwest Territories, Canada
Stratum typicum: Toarcian-Bajocian
Translation Below, 1987: Bureau of Translation, Secretary of State Canada, 1988, Part II, p. 194-197
Original description: Davies, 1983, p. 16: Comparodinium? cavum
Diagnosis: A membranate dinoflagellate cyst species with a highly refractive autocyst, ovoidal in shape, and a thin hyaline ectophragm; with bifurcate processes grouped in apical, antapical and cingular locations, and thus developing three ectocoels in separate locations. Tabulation: ?5", 3-?4a, 8"", ?c, 8""", 5p, 2"""", ?s. Archeopyle: 4A[1-4] + 3I[1-3].
Dimensions: length 31(35)37 µm, breadth 22(27)29 µm. 7 specimens measured.
Description (annotated): The bifurcate processes are 2-3 µm long. The cingular processes form a double row which encircles the cyst. On well preserved specimens a thin ectophragm covers the processes creating three ectocoels corresponding to the groups of processes. The cingular ectocoel is widely separated from the polar ectocoels and occasionally may be reduced or faintly evident. Tabulation is indistinct, formed by faint lines on the periphragm and by archeopyle sutures. The archeopyle appears to be a disintegration type as defined by Dörhöfer and Davies (1980). Accessory sutures are found among both the intercalary plates. A long narrow sulcus is present.
Emended description: Below, 1987, p. 70-71: Valvaeodinium cavum
Arrangement of vesicles/plates of the dinoflagellate amphiesma PR, 4", 1a, 5"", 6c, 5""", 1"""", ns; growth of plates peridinoidal.
Cyst habit proximate, holocavate, also acavate mediodorsally, spheroidal, epicyst and hypocyst of equal size; size small; wall composed of pedium and numerous trabeculate luxuriate outgrowths fused distally into a tectum; the trabeculae are very short, solid, cylindrical, basally somewhat wider, distally osculate or also cauliflorate, standing on peniareate and intraareate spaces or nonareately scattered at varying intervals depending on their number; the tectum is glabrous, but pustulate (bearing tubercles with central pits) where the osculate trabeculae fuse with the tectum, so that the areate arrangement of the trabeculae is partially traced on the tectum; areation formula NR PR/PR, NR"/4", NR1a/1a, NR""/5"", NRc/6c, NR"""/5""", NR""""/1"""", NRs/Xs;
- PR a minute, planate field;
- 4 apicals, steno omegaform linteloid 1" (V), inverse camerate 2" (LVL), VI 3" (DL), VI 4" (RVR);
- caroidal 1a (DR);
- 5 anteriorly geniculate precingulars, V-nE 1"" (VVL), V-nE 2"" (LDL), V-nE 3"" (D), V-nE 4"" (RDR), V-nE 5"" (VR);
- cingulum planispiral, nonareate, but with the positions of the 6 homologous thecal plates indicated by alternating wide and narrow distances between cingular margins, lati 1c-5c, iso 6c;
- 5 posteriorly linear postcingulars, IV-nE 1""" (VL), IV-nE 2""" (LDL), IV-nE 3""" (D), IV-nE 4""" (RDR), IV-nE 5""" (VR) and polar VI 1"""";
- sulcus nonpartite with steno quasi-trapezoidal as and narrow, steno inverse-trapezoidal posterior sector;
- archeopyle apical/anterior intercalary, 3" + 1a; operculum solvate, secate, general opercular formula 3"s + 1as.
Affinities:
Davies, 1983, p. 16: Comparodinium? cavum
Comparodinium includes species without cingular processes and ectocoels which are present, however, in C?. cavum; therefore the placement of this species in Comparodinium is tentative. The polar arrangement of the processes, the occasional reduction of the cingular processes and the similarity in archeopyle formation and tabulation indicate strong affinities to Comparodinium. C. lineatum possesses trabeculae and has close affinities to ?C. cavum. The possession of the polar ectocoels and the intercalary plates is similar to ?Gillinia sp. of Dodekova (1975); however, ?Gillinia sp. of Dodekova (1975) does not have supporting processes. Cleistosphaeridium does not have ectocoels nor the alignment of processes shown by this species. Chlamydophorella possesses an entire enveloping ectophragm.
Below, 1987, p. 70-71:
(annotated) The Valvaeodinium-type tabulation of this taxon can be inferred especially from the location and typical contours of the archaeopyle. The complex areation described by Davies (1983, p. 16, fig. 9), ?5", 3a-4a, 8"", ?c, 8""", 5p, 2"""", ?s, with multiareate pre- and postcingular series, anterior intercalaries 1a-4a, and a complete hypocystal intercalary area series, can not be corroborated.
This taxon is very closely related to V. sphaerechinatum, especially if we consider only the endoblast with its arrangement of appendages. V. sphaerechinatum would in that case be V. cavum without the tectate covering. For, it is striking that V. cavum also has cingular, peniareate appendages. Only, as often happens on cavate cysts, the ends of the trabeculae are osculate, or less often capitate.