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Odontochitina
From Fensome et al., 2019:
Odontochitina, Deflandre, 1937b, p.94.
Emendations: Davey, 1970, p.354; Bint, 1986, p.138; El Mehdawi, 1998, p.174; Núñez-Betelu and Hills, 1998, p.925–926,928; Niechwedowicz, 2018, p.439. This name was not validly published in Deflandre (1935, p.234) since no type was designated, a requirement under the ICZN at that
time.
Type: Deflandre, 1937b, pl.18 (also labelled pl.15), fig.8, as Odontochitina silicorum.
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Original description: [Deflandre, 1935]: (Translation: Stover and Evitt, 1978, p. 67):
Diagnosis:
A curious, apparently chitinous cell, already larger (150µm) than the preceding ones, but for me not suggesting any relationship, even approximately, with a known creature.
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Deflandre, 1937, p. 94:
The chitonoid theca is formed of two parts, one bearing a single horn, considered as upper, the other globular, provided with two more or less divergent horns.
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Emended descriptions:
Davey, 1970:
Diagnosis:
Cavate cysts consisting of spherical inner body and outer membrane. Outer membrane extended into long tapering apical horn and two shorter tapering antapical horns. Very rarely, short, branching precingular and postcingular processes are present.
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Bint, 1986:
Description:
Large cysts with ceratioid outline and three prominent horns, apical, antapical, and right lateral, which may be pointed or blunted distally. Right lateral horn is postcingular and may be straight or recurved with a cingular notch at the point of recurvation.
Cornucavate; endocyst subspherical or produced slightly into the horn bases, with circular equatorial section. periphragm separated from endophragm at horns, but hypocystal pericoels may be enlarged beyond horn bases. Antapical pericoel may have an elongate extension up the left ventral surface as far as the cingulum.
Archaeopyle apical, type (tA), operculum free. Archaeopyle suture rounded to weakly angular; sulcal notch, where discernible, mid-ventral or offset slightly to the left.
Paratabulation usually not expressed, cingulum may be indicated by faint transverse lines, sulcus not indicated.
Affinities:
Odontochitina is most similar to Xenascus, from which it differs in lacking an ornamentation of spines on the periphragm. Pseudoceratium and Endoceratium differ in having a dorso-ventrally compressed body and a strongly offset sulcal notch. Pseudoceratium is usually single-walled but when it has two walls they are linked by numerous connecting structures and Endoceratium is circumcavate, whereas Odontochitina is cornucavate.
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Supplemental diagnosis:
Pocock, 1972, p. 78:
Diagnosis:
Dinoflagellata with an unplaced chitinous theca formed of two parts, one (the epitheca) carrying a single horn, the other (hypotheca) carrying two.
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Modified description:
Stover and Evitt 1978, p. 67-68:
Synopsis:
Cysts cavate, ceratioid, with single long, apical, antapical, and probably postcingular horns; endophragm and periphragm appressed except at the base of the horns (cornucavate); archeopyle apical, Type tA.
Description:
Shape: Ceratoid with three long horns - an apical, an antapical, and a third probably postcingular horn - tips of the horns generally pointed.
Wall relationships: Endophragm and periphragm appressed between the horns, or an antapical pericoel may be present.
Wall features: No parasutural features. Endophragm smooth; periphragm of the body smooth or scabrate; perforations and/or longitudinal striae may be present on the horns of some species.
Paratabulation: Not normally indicated; archeopyle may show angulation.
Archeopyle: Apical, Type tA, principal archeopyle suture smooth to weakly angular; perioperculum includes the apical horn; endoperculum with or without slight protrusion into horn; operculum free.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Large.
Affinities:
Odontochitina differs from Pseudoceratium in being cavate and in having typically longer horns, an uncompressed body, and in lacking projections on the periphragm. On Pseudoceratium the postcingular horn in particular is much shorter than its counterpart on Odontochitina.
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Emended description El-Mehdawi 1998:
Cyst type. Ceratioid, cornucavate to bicavate.
Shape. Pericyst outline ceratioid with three prominent horns, one apical, one antapical and one lateral postcingular in position; horns are hollow, with rounded, pointed or open tips; endocyst subspherical to ovoidal.
Wall relationships. Cyst cornucavate to bicavate; pericoels usually restricted to the bases of horns (cornucavate), or the antapical and lateral margins; connections between lateral pericoel (at base of the lateral horn) and antapical pericoel (at base of the antapical horn) do occur.
Wall features. Parasutural and pandasutural features are indicated by faint to low ridges; periphragm thin, smooth to scabrate, very rarely bearing echinae, short spines or perfora- tions, with three well developed unequal horns. Apical, antapical and postcingular lateral horns, smooth, perforated or with low relief features, straight or recurved, and with pointed, expanded or truncated ends. Endophragm thicker than the periphragm; smooth, scabrate or granulate sometimes with small rounded nipple-like protrusion, due to the protrusion of the endophragm into the base of the apical and antapical horns (PI. 1 fig. 1; PI. 2, fig. 6).
Paratabulation. Indicated either by the archeopyle and rarely by paracingulum, parasutural features, or by pandasutural fea- tures; paratabulation formula: 4, 6 ’ ,5-6c, 6”’,lp, I ” ” , Xs.
Archeopyle. Apical, type [tA], principle archeopyle parasuture smooth, weakly angular to zigzag with an offset parasulcal notch; operculum free or attached.
Paracingulum. If present indicated by faint features or by low relief parasutural ridges.
Parasulcus. Indicated anteriorally by an offset parasulcal notch, or by two parallel longitudinal parasutural ridges in the ventral side of the hypocyst.
Remarks and comparison. Odontochitina Deflandre; emended herein closely resembles Xenascus Cookson & Eisenack, 1969 emend. Stover & Helby (1987), as both have a ceratioid cyst. The latter differs from Odontochitina in having a circumcavate to a cornucavate cyst with variable, large periphragmal processes, whereas the former has a cornucavate to bicavate cyst with very rarely homogeneous, small, closed, spinose processes. Pseudoceratium Gocht; 1957 emend. Stover & Helby (1987) also resembles Odontochitina but differs in having a circumcavate cyst with shorter horns and greater ornamentation.
Discussion. This genus is emended to include species with a cornucavate, and occasionally an epicavate, tabulate cyst in which the paratabulation is defined by parasutural features.
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Emended description Nunez-Betelu and Hills 1998
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Emended description Pearce, 2018:
Emended diagnosis. A cornucavate to hypocavate species of Odontochitina with a widely divergent antapical and lateral horn separated by an angle equal to or greater than 80 .
Emended description. Large ceratioid, cavate dinoflagellate cyst with one apical, antapical and lateral horn of comparable length. The wall is two-layered, comprising a smooth endophragm and smooth, incompletely and faintly striate or distally perforate (although this may be due to corrosion) periphragm. The periphragm and endophragm are appressed in the precingular region with the lateral and antapical horns being either cornucavate or connected by a hypocavation. The endocyst is sub-spherical, lacking obvious projections into the pericoel. The antapical and lateral horns are separated by an angle of greater than 80 . The paracingulum may be indicated by faint ridges on the periphragm. The archaeopyle is apical Type (tA) and the operculum is detached.
Remarks. In the original description of O. diducta, Pearce (2010:62) described the species as having “a welldeveloped cavation connecting the lateral and antapical horns”. However, this feature seems to be gradational to specimens from the same material that are cornucavate and the diagnosis and description are emended here to account for this fact. The specimens referred to as Odontochitina sp. by Cookson and Eisenack (1968) and Costa and Davey (1992) are thus now considered synonymous with O. diducta.
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Emended description Niechwedowicz, 2019:
Emended description. Large-sized ceratiacean cysts, with three hollow and long horns: one apical, one antapical and one right lateral. Horns straight or recurved; antapical and lateral horns parallel to each other or divergent. Horns distally pointed or blunted, rarely with open tips, or multiple-branched and pointed distally. Cyst cornucavate to bicavate. Endocyst subspherical to ovoidal, rarely subtriangular to pear shaped in dorso-ventral outline; in equatorial outline circular or com pressed dorsoventrally (oval to lenticular in apical/antapical views). Rarely, endocyst protrudes slightly into horns. Wall consists of endo- and periphragm; rarely with third wall layer (mesophragm), intermediate in position. Inner and outer wall layers homogeneous, with smooth to scabrate surfaces; periphragm sometimes granulate, or ornamented with striae, echinae, or short spines, or with perforations developed along horns. Meso- phragm, if present, less homogeneous (spongy in structure), giving wall reticulate appearance. Generally, tabulation indi- cated by archeopyle only; rarely, tabulation marked by sulcal notch and sutural alignment of outer wall ornament (low ridges). Archaeopyle apical, type A(1–4'), archaeopyle suture smooth to weakly angular; operculum usually free, rarely adnate.
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Emended diagnosis McLachlan et al., 2025
Emended diagnosis. Ceratiacean cysts that are proximate and cornucavate to circumcavate with three horns—one apical, one antapical, and one right lateral (‘postcingular’). Horns straight or recurved; antapical and lateral horns parallel or divergent. Horns distally acuminate, blunted, or with open terminations that may be branched, ragged, or digitate. Endocyst dorso-ventral ambitus subspherical to ovoidal, rarely subtriangular to pear shaped; equatorial ambitus circular or dorsoventrally compressed (oval to lenticular in apical/antapical views). Rarely, endocyst protrudes slightly into horns. Wall consists of endo- and periphragm, rarely with mesophragm. Inner and outer wall layers usually homogeneous, rarely marked by irregular vesiculation. Periphragm may be psilate, ornamented with features of low relief, or with perforations along horns. Mesophragm, if present, less homogeneous (spongy in structure), appearing reticulate. Generally, tabulation indicated by archeopyle only; rarely, tabulation marked by sulcal notch and sutural alignment of low periphragm ridges which may bear denticles. Archaeopyle apical, type A(1–4′), with smooth to weakly angular suture; operculum usually free, rarely adnate.
Remarks. The emended diagnosis expands the most recent definition of the genus proposed by Niechwedowicz(2019) to allow for circumcavation, denticles, and the presence of vesiculation in the cyst walls. See Fensome et al.(2009) and Soliman et al.(2024) for literature review and discussion of previous emendations.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Odontochitina Deflandre, 1937b, emend. Davey, 1970, emend. Bint, 1986. Odontochitina was emended by Bint (1986, p.138) as follows, Large cysts with ceratioid outline and three prominent horns, apical, antapical, and right lateral, which may be pointed or blunted distally. Right lateral horn is postcingular and may be straight or recurved with a cingular notch at the point of recurvature. Cornucavate; endocyst subspherical or produced slightly into the horn bases, with circular equatorial section. Periphragm separated from endophragm at horns, but hypocystal pericoels may be enlarged beyond horn bases. Antapical pericoel may have an elongate extension up the left ventral surface as far as the cingulum. Archeopyle apical, type (tA), operculum free. Archeopyle suture rounded to weakly angular; sulcal notch, where discernible, mid-ventral or offset slightly to the left. Paratabulation usually not expressed, cingulum may be indicated by faint transverse lines, sulcus not indicated.
Odontochitina, Deflandre, 1937b, p.94.
Emendations: Davey, 1970, p.354; Bint, 1986, p.138; El Mehdawi, 1998, p.174; Núñez-Betelu and Hills, 1998, p.925–926,928; Niechwedowicz, 2018, p.439. This name was not validly published in Deflandre (1935, p.234) since no type was designated, a requirement under the ICZN at that
time.
Type: Deflandre, 1937b, pl.18 (also labelled pl.15), fig.8, as Odontochitina silicorum.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Deflandre, 1935]: (Translation: Stover and Evitt, 1978, p. 67):
Diagnosis:
A curious, apparently chitinous cell, already larger (150µm) than the preceding ones, but for me not suggesting any relationship, even approximately, with a known creature.
-----------------------------------------------------------------------------------------------------
Deflandre, 1937, p. 94:
The chitonoid theca is formed of two parts, one bearing a single horn, considered as upper, the other globular, provided with two more or less divergent horns.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Davey, 1970:
Diagnosis:
Cavate cysts consisting of spherical inner body and outer membrane. Outer membrane extended into long tapering apical horn and two shorter tapering antapical horns. Very rarely, short, branching precingular and postcingular processes are present.
----------------------------------------
Bint, 1986:
Description:
Large cysts with ceratioid outline and three prominent horns, apical, antapical, and right lateral, which may be pointed or blunted distally. Right lateral horn is postcingular and may be straight or recurved with a cingular notch at the point of recurvation.
Cornucavate; endocyst subspherical or produced slightly into the horn bases, with circular equatorial section. periphragm separated from endophragm at horns, but hypocystal pericoels may be enlarged beyond horn bases. Antapical pericoel may have an elongate extension up the left ventral surface as far as the cingulum.
Archaeopyle apical, type (tA), operculum free. Archaeopyle suture rounded to weakly angular; sulcal notch, where discernible, mid-ventral or offset slightly to the left.
Paratabulation usually not expressed, cingulum may be indicated by faint transverse lines, sulcus not indicated.
Affinities:
Odontochitina is most similar to Xenascus, from which it differs in lacking an ornamentation of spines on the periphragm. Pseudoceratium and Endoceratium differ in having a dorso-ventrally compressed body and a strongly offset sulcal notch. Pseudoceratium is usually single-walled but when it has two walls they are linked by numerous connecting structures and Endoceratium is circumcavate, whereas Odontochitina is cornucavate.
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Supplemental diagnosis:
Pocock, 1972, p. 78:
Diagnosis:
Dinoflagellata with an unplaced chitinous theca formed of two parts, one (the epitheca) carrying a single horn, the other (hypotheca) carrying two.
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Modified description:
Stover and Evitt 1978, p. 67-68:
Synopsis:
Cysts cavate, ceratioid, with single long, apical, antapical, and probably postcingular horns; endophragm and periphragm appressed except at the base of the horns (cornucavate); archeopyle apical, Type tA.
Description:
Shape: Ceratoid with three long horns - an apical, an antapical, and a third probably postcingular horn - tips of the horns generally pointed.
Wall relationships: Endophragm and periphragm appressed between the horns, or an antapical pericoel may be present.
Wall features: No parasutural features. Endophragm smooth; periphragm of the body smooth or scabrate; perforations and/or longitudinal striae may be present on the horns of some species.
Paratabulation: Not normally indicated; archeopyle may show angulation.
Archeopyle: Apical, Type tA, principal archeopyle suture smooth to weakly angular; perioperculum includes the apical horn; endoperculum with or without slight protrusion into horn; operculum free.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Large.
Affinities:
Odontochitina differs from Pseudoceratium in being cavate and in having typically longer horns, an uncompressed body, and in lacking projections on the periphragm. On Pseudoceratium the postcingular horn in particular is much shorter than its counterpart on Odontochitina.
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Emended description El-Mehdawi 1998:
Cyst type. Ceratioid, cornucavate to bicavate.
Shape. Pericyst outline ceratioid with three prominent horns, one apical, one antapical and one lateral postcingular in position; horns are hollow, with rounded, pointed or open tips; endocyst subspherical to ovoidal.
Wall relationships. Cyst cornucavate to bicavate; pericoels usually restricted to the bases of horns (cornucavate), or the antapical and lateral margins; connections between lateral pericoel (at base of the lateral horn) and antapical pericoel (at base of the antapical horn) do occur.
Wall features. Parasutural and pandasutural features are indicated by faint to low ridges; periphragm thin, smooth to scabrate, very rarely bearing echinae, short spines or perfora- tions, with three well developed unequal horns. Apical, antapical and postcingular lateral horns, smooth, perforated or with low relief features, straight or recurved, and with pointed, expanded or truncated ends. Endophragm thicker than the periphragm; smooth, scabrate or granulate sometimes with small rounded nipple-like protrusion, due to the protrusion of the endophragm into the base of the apical and antapical horns (PI. 1 fig. 1; PI. 2, fig. 6).
Paratabulation. Indicated either by the archeopyle and rarely by paracingulum, parasutural features, or by pandasutural fea- tures; paratabulation formula: 4, 6 ’ ,5-6c, 6”’,lp, I ” ” , Xs.
Archeopyle. Apical, type [tA], principle archeopyle parasuture smooth, weakly angular to zigzag with an offset parasulcal notch; operculum free or attached.
Paracingulum. If present indicated by faint features or by low relief parasutural ridges.
Parasulcus. Indicated anteriorally by an offset parasulcal notch, or by two parallel longitudinal parasutural ridges in the ventral side of the hypocyst.
Remarks and comparison. Odontochitina Deflandre; emended herein closely resembles Xenascus Cookson & Eisenack, 1969 emend. Stover & Helby (1987), as both have a ceratioid cyst. The latter differs from Odontochitina in having a circumcavate to a cornucavate cyst with variable, large periphragmal processes, whereas the former has a cornucavate to bicavate cyst with very rarely homogeneous, small, closed, spinose processes. Pseudoceratium Gocht; 1957 emend. Stover & Helby (1987) also resembles Odontochitina but differs in having a circumcavate cyst with shorter horns and greater ornamentation.
Discussion. This genus is emended to include species with a cornucavate, and occasionally an epicavate, tabulate cyst in which the paratabulation is defined by parasutural features.
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Emended description Nunez-Betelu and Hills 1998
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Emended description Pearce, 2018:
Emended diagnosis. A cornucavate to hypocavate species of Odontochitina with a widely divergent antapical and lateral horn separated by an angle equal to or greater than 80 .
Emended description. Large ceratioid, cavate dinoflagellate cyst with one apical, antapical and lateral horn of comparable length. The wall is two-layered, comprising a smooth endophragm and smooth, incompletely and faintly striate or distally perforate (although this may be due to corrosion) periphragm. The periphragm and endophragm are appressed in the precingular region with the lateral and antapical horns being either cornucavate or connected by a hypocavation. The endocyst is sub-spherical, lacking obvious projections into the pericoel. The antapical and lateral horns are separated by an angle of greater than 80 . The paracingulum may be indicated by faint ridges on the periphragm. The archaeopyle is apical Type (tA) and the operculum is detached.
Remarks. In the original description of O. diducta, Pearce (2010:62) described the species as having “a welldeveloped cavation connecting the lateral and antapical horns”. However, this feature seems to be gradational to specimens from the same material that are cornucavate and the diagnosis and description are emended here to account for this fact. The specimens referred to as Odontochitina sp. by Cookson and Eisenack (1968) and Costa and Davey (1992) are thus now considered synonymous with O. diducta.
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Emended description Niechwedowicz, 2019:
Emended description. Large-sized ceratiacean cysts, with three hollow and long horns: one apical, one antapical and one right lateral. Horns straight or recurved; antapical and lateral horns parallel to each other or divergent. Horns distally pointed or blunted, rarely with open tips, or multiple-branched and pointed distally. Cyst cornucavate to bicavate. Endocyst subspherical to ovoidal, rarely subtriangular to pear shaped in dorso-ventral outline; in equatorial outline circular or com pressed dorsoventrally (oval to lenticular in apical/antapical views). Rarely, endocyst protrudes slightly into horns. Wall consists of endo- and periphragm; rarely with third wall layer (mesophragm), intermediate in position. Inner and outer wall layers homogeneous, with smooth to scabrate surfaces; periphragm sometimes granulate, or ornamented with striae, echinae, or short spines, or with perforations developed along horns. Meso- phragm, if present, less homogeneous (spongy in structure), giving wall reticulate appearance. Generally, tabulation indi- cated by archeopyle only; rarely, tabulation marked by sulcal notch and sutural alignment of outer wall ornament (low ridges). Archaeopyle apical, type A(1–4'), archaeopyle suture smooth to weakly angular; operculum usually free, rarely adnate.
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Emended diagnosis McLachlan et al., 2025
Emended diagnosis. Ceratiacean cysts that are proximate and cornucavate to circumcavate with three horns—one apical, one antapical, and one right lateral (‘postcingular’). Horns straight or recurved; antapical and lateral horns parallel or divergent. Horns distally acuminate, blunted, or with open terminations that may be branched, ragged, or digitate. Endocyst dorso-ventral ambitus subspherical to ovoidal, rarely subtriangular to pear shaped; equatorial ambitus circular or dorsoventrally compressed (oval to lenticular in apical/antapical views). Rarely, endocyst protrudes slightly into horns. Wall consists of endo- and periphragm, rarely with mesophragm. Inner and outer wall layers usually homogeneous, rarely marked by irregular vesiculation. Periphragm may be psilate, ornamented with features of low relief, or with perforations along horns. Mesophragm, if present, less homogeneous (spongy in structure), appearing reticulate. Generally, tabulation indicated by archeopyle only; rarely, tabulation marked by sulcal notch and sutural alignment of low periphragm ridges which may bear denticles. Archaeopyle apical, type A(1–4′), with smooth to weakly angular suture; operculum usually free, rarely adnate.
Remarks. The emended diagnosis expands the most recent definition of the genus proposed by Niechwedowicz(2019) to allow for circumcavation, denticles, and the presence of vesiculation in the cyst walls. See Fensome et al.(2009) and Soliman et al.(2024) for literature review and discussion of previous emendations.
----------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Odontochitina Deflandre, 1937b, emend. Davey, 1970, emend. Bint, 1986. Odontochitina was emended by Bint (1986, p.138) as follows, Large cysts with ceratioid outline and three prominent horns, apical, antapical, and right lateral, which may be pointed or blunted distally. Right lateral horn is postcingular and may be straight or recurved with a cingular notch at the point of recurvature. Cornucavate; endocyst subspherical or produced slightly into the horn bases, with circular equatorial section. Periphragm separated from endophragm at horns, but hypocystal pericoels may be enlarged beyond horn bases. Antapical pericoel may have an elongate extension up the left ventral surface as far as the cingulum. Archeopyle apical, type (tA), operculum free. Archeopyle suture rounded to weakly angular; sulcal notch, where discernible, mid-ventral or offset slightly to the left. Paratabulation usually not expressed, cingulum may be indicated by faint transverse lines, sulcus not indicated.