Back
Imbatodinium
From Williams et al., 2017:
[Imbatodinium, Vozzhennikova, 1967, p. 52-53; Emendations: Dörhöfer and Davies, 1980, p. 36–37; Mehrotra and Sarjeant, 1984a, p. 215; Lentin and Vozzhennikova, 1990, p. 86–87.
Tax. sen. syn.: Pareodinia, according to Wiggins (1975, p.103) and Below (1990, p.64) — however, Dörhöfer and Davies (1980, p.36) and Lentin and Williams (1993, p.345) retained Imbatodinium.
Tax. jun. syn.: Necrobroomea, according to Dörhöfer and Davies (1980, p.36) and by implication in Below (1990, p.52), who considered Necrobroomea to be the taxonomic senior synonym (see discussion under Necrobroomea).
Type: Imbatodinium kondratjevii, Vozzhennikova, 1967 (pl.9, figs.4–5; pl.10, figs.1a–b)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Vozzhennikova, 1967]: (Translation: Sarjeant (ed), 1971, p. 77-78):
Description:
Cells strongly elongated, dorso-ventrally compressed with straight or slightly convex sides. transverse furrow shallow or deep displaced towards the posterior end of the cell.
Longitudinal furrow S-shaped, shallow or deep, extending from the base of the apical process to the end of the antapex.
Epitheca large with a finger-like apical process at the distal end of which there is a palpiform outgrowth which terminates in a knob. The hypotheca comprises one third to one quarter the total length of the cell and has two small antapical,processes which are either equal or unequal in size. The envelope is usually thin. It has a smooth, granular or tuberculate surface and it may be covered with spinules or other outgrowths. The pylome is oval and situated below the apical process.
The archaeopyle is apical and its boundary may extend beyond, or fall short of, the lower boundary of the pylome.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Dörhöfer and Davies, 1980:
Diagnosis:
Elongate proximate dinoflagellate cysts with an apical horn and two hypotractal (antapical) horns; surface of autophragm smooth or with very low granulaes, verrucae, or spines.
Tabulation, when evident, is 4`, 2a, , 6``, 6c, 6-7```, 1-2p, 1````, ?pv, /s. The epitract is enlarged relative to the hypotract leaving the cingulum close to the antapex.
Archaeopyle (4A2I). The operculum occasionally remains attached to the sulcus.
Affinities:
Imbatodinium differs from all pareodiniacean genera by its mode of archaeopyle formation. It differs from Phoberocysta, Pseudoceratium, and Aptea by the lack of ornament, the horn positions, and the posteriorly displaced cingulum. Muderongia, Odontochitina, and Endoceratium are cavate and also possess postcingular horns.
------------------------------------------
Mehrota and Sarjeant, 1984:
Diagnosis:
Elongate proximate cysts of intermediate to large size, having an apical and two relatively short antapical horns, the latter generally showing some proportionate differences in length, the former often lost in archaeopyle formation. Parasutural features not usually observed, although, rarely, faint indications sometimes seen. Autophragm smooth or ornamented with features of low relief - granae, verrucae, spines or vermiculae; sometimes low ridges developed, forming fine-meshed reticulum.
Paratabulation generally indicated by archaeopyle only, rarely by parasutural elements. when determinable, paratabulation is 1-2pr, ?3-4`, 2-?3a, 6``, 6c, 6-?7```, 1-?2p, ?1pv, 1````, ?s.
Archaeopyle of combination type, involving all paraplates of preapical and apical series, one or more paraplates of anterior intercalary series and quite often one paraplate (?4``) of precingular series as well. These may be thrown off as single operculum or as two to five opercular pieces; alternatively, one, more than one, or all opercular pieces may remain attached or adherent.
Cingulum generally not distinct, but may be indicated by marginal or equatorial folds or bulges; it may be median or posterior in position, narrow or broad.
Sulcus usually not distinguishable. irregular opening may be present in dorsal surface of hypotract.
Archaeopyle formulae: The variation in combination archaeopyle types is represented below in the form of the archaeopyle formula, suggested by Evitt (1967) and further elaborated by Lentin and Williams (1976) and Norris (1978):
1 - (tA(1-4)I(2)) or tA(1-4)+I(2) or tA(1-4)a+I(2)a,
2 - tA(1-4)a+I(2)a+P(4)a,
3 - tA(1-4)+(I(2)+P(4)) or (tA(1-4)I(2)P(4)),
4 - tA(1-4)a+I(2)+P(4)a,
5 - tA(1-4)a+I(2)+P(4) or tA(1-4)a+(I(2)P(4)).
Remarks:
1 - Involvement of preapical paraplates is not covered in the above formulae.
2 - The number of paraplates in the apical series is probably four but has not been established conclusively.
3 - For interpreting paratabulation in Imbatodinium we have utilized our own observations, mainly of the epitract and also those of Dörhöfer and Davies (1980, p. 37). Paratabulation on the hypotract is not developed on the Indian specimens.
4 - The archaeopyle formulae are based exclusively on our own observations.
5 - The general size range of species of Imbatodinium is 60-120 µm (overall length); however, in some species (I. longicornutum Alberti, 1961), the overall length has been reported as up to 298 µm.
------------------------------------------
Lentin and Vozzhennikova, 1990:
Description:
Fossil dinoflagellate cyst shape elongate oval with one long apical and two short antapical horns or lobes. Cyst consists of autophragm only; ornamented by elements with low relief which may be larger and more concentrated on the hypocyst aiming the appearance of a thicker wall. Paratabulation indicated only by the archeopyle, paracingulum and parasulcus. Archeopyle sutures located around two intercalary paraplates suggesting a Type 2I archeopyle, however the sutures are rarely open. Paracingulum located low on the cyst dividing it into two unequal parts, the epicyst being twice to three times longer than the hypocyst. Parasulcus usually distinct, sinuous, extending from between the two antapical horns or lobes to just below the apical horn, may be less distinct on the epicyst.
Affinities:
Imbatotinium differs from other genera in the Pareodinia group by the lack of paratabulation, the distribution of the ornamentation, the shape which includes the long epicyst ant short hypocyst and the nature of the sutures around the two intercalary paraplates The function of the sutures on the epicyst appears to provide for the opening of an archeopyle, however, no archeopyle occurs in the specimens from the type material the location of these "archeopyle sutures" indicate that the paratabulation of the genus is similar to that of Cantulodiniuc Alberti.
In Cantulodinium and Imbatodinium two intercalary paraplates are involved in archeopyle formation the smaller of the two has a shape very similar to that of the standard hexa (iso-deltaform) 2a paraplate seen in many Cretaceous and Palaeogene peridinioid cysts (see Text-figure 48b) The second intercalary paraplate in Cantulodinium and Imbatodinium is seven sided and is drawn out in the lateral direction The archeopyle formed by the loss of these two paraplates creates an eleven (11) sited opening which we call a unidenilate archeopyle. The specimens of Imbatodiniuo from the type material are capulate Lentin and Vozzhennikova, 1989, p 220). If the archeopyle sutures in these specimens were open, an unitenilate archeopyle would be formed.
The line drawing and description of Phallocysta Dörhöfer and Davies, 1980, suggest a similarity between that genus and Imbatodinium; however, study of the topotype material provided by Davies shows that there is no similarity between the two genera as Phallocysta is a cavate cyst rather than an autocyst.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Below, 1990, p.52-53:
Affinities: (discussion on Necrobroomea)
Comparison on the basis of SEM studies (annotated):
For species with an appearance similar of Necrobroomea Wiggins 1975, emend. Below 1990, the following genera have been erected in literature:
- Imbatodinim Vozzhennikova 1967, emend. Dörhöfer and Davies 1980,
- Necrobroomea Wiggins 1975,
- Batioladinium Brideaux 1975,
- Aprobolocysta Duxbury 1977, emend. Duxbury 1980.
Necrobroomea (publ. 25-4-1975) has priority over Batioladinium (publ. 15-6-1975).
The position of Imbatodinium has been unclear. Vozzhennikova 1967 describes for Imbatodinium, with type-species I.kondratjevii, an apical archaeopyle. Wiggins 1975, Lentin & Williams 1977 and Stover & Evitt 1978 agree that, from the original photomicrograph, Imbatodinium has an intercalary archaeopyle, and is a synonym of Pareodinia Defl. 1947. Davey 1982 argues that I.kondratjevii has a distinct paracingulum, contrary to Pareodinia, and that the archaeopyle is subject to discussion. Dörhöfer and Davies 1980 emended Imbatodinium and assigned it a 4A2I archaeopyle, and synonymized it with both Batioladinium and Necrobroomea. Below`s 1990 material shows that I.kondratjevii and Pareodinia have an intercalary archaeopyle: 1a[s]+2a[s].
Below`s 1990 conclusions:
- Necrobroomea is synonymous to Mehrota and Sarjeant`s 1984 emendation of Imbatodinium, which disregards the holotype of I.kondratjevi
(discussion in Lentin and Williams 1985),
- Necrobroomea with its apical archaeopyle is valid,
- Necrobroomea has priority over Batioladinium (jr. synonym),
- Necrobroomea is synonymous to Aprobolocysta, being a cavate form
of Necrobroomea.
[Imbatodinium, Vozzhennikova, 1967, p. 52-53; Emendations: Dörhöfer and Davies, 1980, p. 36–37; Mehrotra and Sarjeant, 1984a, p. 215; Lentin and Vozzhennikova, 1990, p. 86–87.
Tax. sen. syn.: Pareodinia, according to Wiggins (1975, p.103) and Below (1990, p.64) — however, Dörhöfer and Davies (1980, p.36) and Lentin and Williams (1993, p.345) retained Imbatodinium.
Tax. jun. syn.: Necrobroomea, according to Dörhöfer and Davies (1980, p.36) and by implication in Below (1990, p.52), who considered Necrobroomea to be the taxonomic senior synonym (see discussion under Necrobroomea).
Type: Imbatodinium kondratjevii, Vozzhennikova, 1967 (pl.9, figs.4–5; pl.10, figs.1a–b)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Vozzhennikova, 1967]: (Translation: Sarjeant (ed), 1971, p. 77-78):
Description:
Cells strongly elongated, dorso-ventrally compressed with straight or slightly convex sides. transverse furrow shallow or deep displaced towards the posterior end of the cell.
Longitudinal furrow S-shaped, shallow or deep, extending from the base of the apical process to the end of the antapex.
Epitheca large with a finger-like apical process at the distal end of which there is a palpiform outgrowth which terminates in a knob. The hypotheca comprises one third to one quarter the total length of the cell and has two small antapical,processes which are either equal or unequal in size. The envelope is usually thin. It has a smooth, granular or tuberculate surface and it may be covered with spinules or other outgrowths. The pylome is oval and situated below the apical process.
The archaeopyle is apical and its boundary may extend beyond, or fall short of, the lower boundary of the pylome.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Dörhöfer and Davies, 1980:
Diagnosis:
Elongate proximate dinoflagellate cysts with an apical horn and two hypotractal (antapical) horns; surface of autophragm smooth or with very low granulaes, verrucae, or spines.
Tabulation, when evident, is 4`, 2a, , 6``, 6c, 6-7```, 1-2p, 1````, ?pv, /s. The epitract is enlarged relative to the hypotract leaving the cingulum close to the antapex.
Archaeopyle (4A2I). The operculum occasionally remains attached to the sulcus.
Affinities:
Imbatodinium differs from all pareodiniacean genera by its mode of archaeopyle formation. It differs from Phoberocysta, Pseudoceratium, and Aptea by the lack of ornament, the horn positions, and the posteriorly displaced cingulum. Muderongia, Odontochitina, and Endoceratium are cavate and also possess postcingular horns.
------------------------------------------
Mehrota and Sarjeant, 1984:
Diagnosis:
Elongate proximate cysts of intermediate to large size, having an apical and two relatively short antapical horns, the latter generally showing some proportionate differences in length, the former often lost in archaeopyle formation. Parasutural features not usually observed, although, rarely, faint indications sometimes seen. Autophragm smooth or ornamented with features of low relief - granae, verrucae, spines or vermiculae; sometimes low ridges developed, forming fine-meshed reticulum.
Paratabulation generally indicated by archaeopyle only, rarely by parasutural elements. when determinable, paratabulation is 1-2pr, ?3-4`, 2-?3a, 6``, 6c, 6-?7```, 1-?2p, ?1pv, 1````, ?s.
Archaeopyle of combination type, involving all paraplates of preapical and apical series, one or more paraplates of anterior intercalary series and quite often one paraplate (?4``) of precingular series as well. These may be thrown off as single operculum or as two to five opercular pieces; alternatively, one, more than one, or all opercular pieces may remain attached or adherent.
Cingulum generally not distinct, but may be indicated by marginal or equatorial folds or bulges; it may be median or posterior in position, narrow or broad.
Sulcus usually not distinguishable. irregular opening may be present in dorsal surface of hypotract.
Archaeopyle formulae: The variation in combination archaeopyle types is represented below in the form of the archaeopyle formula, suggested by Evitt (1967) and further elaborated by Lentin and Williams (1976) and Norris (1978):
1 - (tA(1-4)I(2)) or tA(1-4)+I(2) or tA(1-4)a+I(2)a,
2 - tA(1-4)a+I(2)a+P(4)a,
3 - tA(1-4)+(I(2)+P(4)) or (tA(1-4)I(2)P(4)),
4 - tA(1-4)a+I(2)+P(4)a,
5 - tA(1-4)a+I(2)+P(4) or tA(1-4)a+(I(2)P(4)).
Remarks:
1 - Involvement of preapical paraplates is not covered in the above formulae.
2 - The number of paraplates in the apical series is probably four but has not been established conclusively.
3 - For interpreting paratabulation in Imbatodinium we have utilized our own observations, mainly of the epitract and also those of Dörhöfer and Davies (1980, p. 37). Paratabulation on the hypotract is not developed on the Indian specimens.
4 - The archaeopyle formulae are based exclusively on our own observations.
5 - The general size range of species of Imbatodinium is 60-120 µm (overall length); however, in some species (I. longicornutum Alberti, 1961), the overall length has been reported as up to 298 µm.
------------------------------------------
Lentin and Vozzhennikova, 1990:
Description:
Fossil dinoflagellate cyst shape elongate oval with one long apical and two short antapical horns or lobes. Cyst consists of autophragm only; ornamented by elements with low relief which may be larger and more concentrated on the hypocyst aiming the appearance of a thicker wall. Paratabulation indicated only by the archeopyle, paracingulum and parasulcus. Archeopyle sutures located around two intercalary paraplates suggesting a Type 2I archeopyle, however the sutures are rarely open. Paracingulum located low on the cyst dividing it into two unequal parts, the epicyst being twice to three times longer than the hypocyst. Parasulcus usually distinct, sinuous, extending from between the two antapical horns or lobes to just below the apical horn, may be less distinct on the epicyst.
Affinities:
Imbatotinium differs from other genera in the Pareodinia group by the lack of paratabulation, the distribution of the ornamentation, the shape which includes the long epicyst ant short hypocyst and the nature of the sutures around the two intercalary paraplates The function of the sutures on the epicyst appears to provide for the opening of an archeopyle, however, no archeopyle occurs in the specimens from the type material the location of these "archeopyle sutures" indicate that the paratabulation of the genus is similar to that of Cantulodiniuc Alberti.
In Cantulodinium and Imbatodinium two intercalary paraplates are involved in archeopyle formation the smaller of the two has a shape very similar to that of the standard hexa (iso-deltaform) 2a paraplate seen in many Cretaceous and Palaeogene peridinioid cysts (see Text-figure 48b) The second intercalary paraplate in Cantulodinium and Imbatodinium is seven sided and is drawn out in the lateral direction The archeopyle formed by the loss of these two paraplates creates an eleven (11) sited opening which we call a unidenilate archeopyle. The specimens of Imbatodiniuo from the type material are capulate Lentin and Vozzhennikova, 1989, p 220). If the archeopyle sutures in these specimens were open, an unitenilate archeopyle would be formed.
The line drawing and description of Phallocysta Dörhöfer and Davies, 1980, suggest a similarity between that genus and Imbatodinium; however, study of the topotype material provided by Davies shows that there is no similarity between the two genera as Phallocysta is a cavate cyst rather than an autocyst.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Below, 1990, p.52-53:
Affinities: (discussion on Necrobroomea)
Comparison on the basis of SEM studies (annotated):
For species with an appearance similar of Necrobroomea Wiggins 1975, emend. Below 1990, the following genera have been erected in literature:
- Imbatodinim Vozzhennikova 1967, emend. Dörhöfer and Davies 1980,
- Necrobroomea Wiggins 1975,
- Batioladinium Brideaux 1975,
- Aprobolocysta Duxbury 1977, emend. Duxbury 1980.
Necrobroomea (publ. 25-4-1975) has priority over Batioladinium (publ. 15-6-1975).
The position of Imbatodinium has been unclear. Vozzhennikova 1967 describes for Imbatodinium, with type-species I.kondratjevii, an apical archaeopyle. Wiggins 1975, Lentin & Williams 1977 and Stover & Evitt 1978 agree that, from the original photomicrograph, Imbatodinium has an intercalary archaeopyle, and is a synonym of Pareodinia Defl. 1947. Davey 1982 argues that I.kondratjevii has a distinct paracingulum, contrary to Pareodinia, and that the archaeopyle is subject to discussion. Dörhöfer and Davies 1980 emended Imbatodinium and assigned it a 4A2I archaeopyle, and synonymized it with both Batioladinium and Necrobroomea. Below`s 1990 material shows that I.kondratjevii and Pareodinia have an intercalary archaeopyle: 1a[s]+2a[s].
Below`s 1990 conclusions:
- Necrobroomea is synonymous to Mehrota and Sarjeant`s 1984 emendation of Imbatodinium, which disregards the holotype of I.kondratjevi
(discussion in Lentin and Williams 1985),
- Necrobroomea with its apical archaeopyle is valid,
- Necrobroomea has priority over Batioladinium (jr. synonym),
- Necrobroomea is synonymous to Aprobolocysta, being a cavate form
of Necrobroomea.