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Aprobolocysta
From Fensome et al., 2019:
Aprobolocysta, Duxbury, 1977, p.52.
Emendations: Duxbury, 1980, p.112; Mehrotra and Sarjeant, 1986, p.721; Pourtoy, 1988, p.386,388; Pestchevitskaya, 2006, p.S639,641 -- however, see Duxbury (2018, p.174).
Taxonomic senior synonym: Necrobroomea, according to Below (1990, p.52) -- however, Lentin and Williams (1993, p.31) retained Aprobolocysta.
Stover and Williams (1987, p.19) considered Davey's (1982b, p.21) treatment of Aprobolocysta to be an emendation.
Type: Duxbury, 1977, pl.14, figs.4–5; text-fig.19B, as Aprobolocysta eilema.
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Original description: [Duxbury, 1977]: (Translation Pourtoy, 1988: Fensome et al., 1991, p. 48):
Description:
Proximate cysts. Cyst wall bi-layered. Endophragm elongate ovoidal, epitract longer and more tapering than hypotract. No indication of tabulation other than by periphragm folds and irregular archeopyle margin. Apex and antapex bluntly rounded. The apex bears no prominence and the antapex sometimes possess two low, poorly-developed projections. Archeopyle apical.
Affinities:
In its mode of archeopyle formation and its elongate, apically tapering outline. Aprobolocysta most closely resembles Necrobroomea Wiggins 1975. However, Necrobroomea always posses an apical horn which is usually well-developed, as well as two antapical horns. Aprobolocysta, on the other hand, lacks any apical projection and possesses only very poorly-defined antapical projections, if any at all. Further, Necrobroomea has a single layered cyst wall whereas that of Aprobolocysta is bi- layered, a character clearly seen due to periphragm folding in the species.
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Emended descriptions:
Duxbury, 1980:
Diagnosis:
Distinctly elongate proximate to proximochorate dinoflagellate cysts with bi-layered cyst wall. Paratabulation absent or indistinctly indicated by periphragm folds, parasutural crests and/or irregular archeopyle margin. Apex and antapex bluntly rounded. Archeopyle apical.
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Mehrota and Sarjeant, 1986
Diagnosis:
Cyst proximate to proximochorate, elongate with broadly rounded to blunt apex and antapex. Epitract larger than the hypotract. Cyst wall separation may be distinct or indistinct. Paratabulation may be suggested by periphragm folds or parasutural crests; however, it is sometimes indicated by the archaeopyle margin only or not discernible at all. When determinable: 3-?4`, 5ap, 6``, 6c, 5```, 1pv, 1````. Archaeopyle apical to (?) combination; the latter type might involve one or more paraplates of the postapical series. Operculum free or attached.
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Pourtoy, 1988
Diagnosis:
Cysts proximate to proximochorate, elongate ovoidal in shape, the hypocyst being more rounded than the epicyst, sometimes possessing an apical horn and/or two weakly developed antapical horns or protuberances. The wall consists of a distinct endophragm and a distinct periphragm. The tabulation is generally indicated only by the irregular archeopyle margin and its secondary parasutures. It is sometimes indistinctly marked by folds of the periphragm, even parasutural septa. The archeopyle is presumably apical of type (tA), its outline being longitudinally bisymmetrical, closer to the apex on the dorsal surface and deeply indented on the ventral surface. The operculum is free or in place. The position of the paracingulum, generally indiscernible, may sometimes be marked by folds or parasutural septa, or by fusion of the periphragm and endophragm, at the lower third of the cyst corresponding to its greatest width. The parasulcus is not discernible.
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Modified description:
Stover and Williams 1987, p. 19-20:
Synopsis:
Cysts proximate, endocyst elongate-ovoidal and surrounded by a loosely fitting, variously folded periphragm. Archeopyle supposedly apical, but more likely combined apical and intercalary with a deep sulcal notch and a free operculum.
Description:
Shape: Elongate-ovoidal, apex more narrowly rounded than antapex.
Wall relationships: Endophragm and periphragm distinct; amount of cavation varies depending on the complexity and magnitude of the
periphragmal folding.
Wall features: No clearly delimited parasutural features. Periphragm simply to complexly folded, some folds may simulate parasutural features. Archeopyle: Reported as apical, but more likely a combined apical and intercalary type; principal archeopyle suture closer to apex dorsally than ventrally and longitudinally asymmetrical; left lateral margin with an anteriorly camerate paraplate (2``) separated from the deep sulcal notch by a narrow, anteriorly planate paraplate (1``).
Paratabulation: Partly indicated by archeopyle.
Paracingulum: Not indicated.
Parasulcus: Anterior position inferred by deep sulcal notch; other indications lacking.
Size: Intermediate, about 55 µm to 75 µm in length.
Affinities:
Aprobolocysta differs from Batioladinium Brideaux 1975 in possessing a thin, folded periphragm which is separated from the endophragm over a substantial part of the cyst. In Batioladinium the two wall layers, when discernible, are appressed. The two genera are otherwise similar in shape and have the same type of archeopyle.
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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.
Aprobolocysta Duxbury, 1977, emend. Pourtoy, 1988. According to Stover and Williams (1987, p.19) cysts are proximate, endocyst elongate-ovoidal and surrounded by a loosely fitting, variously folded periphragm. Archeopyle supposedly apical, but more likely combined apical and intercalary with a deep sulcal notch and a free operculum. In actuality, the archeopyle results from the loss of the two Kofoid apical plates, the operculum being federate. The first apical plate (1"), which is exerts, remains part of the loisthocyst.
Aprobolocysta, Duxbury, 1977, p.52.
Emendations: Duxbury, 1980, p.112; Mehrotra and Sarjeant, 1986, p.721; Pourtoy, 1988, p.386,388; Pestchevitskaya, 2006, p.S639,641 -- however, see Duxbury (2018, p.174).
Taxonomic senior synonym: Necrobroomea, according to Below (1990, p.52) -- however, Lentin and Williams (1993, p.31) retained Aprobolocysta.
Stover and Williams (1987, p.19) considered Davey's (1982b, p.21) treatment of Aprobolocysta to be an emendation.
Type: Duxbury, 1977, pl.14, figs.4–5; text-fig.19B, as Aprobolocysta eilema.
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Original description: [Duxbury, 1977]: (Translation Pourtoy, 1988: Fensome et al., 1991, p. 48):
Description:
Proximate cysts. Cyst wall bi-layered. Endophragm elongate ovoidal, epitract longer and more tapering than hypotract. No indication of tabulation other than by periphragm folds and irregular archeopyle margin. Apex and antapex bluntly rounded. The apex bears no prominence and the antapex sometimes possess two low, poorly-developed projections. Archeopyle apical.
Affinities:
In its mode of archeopyle formation and its elongate, apically tapering outline. Aprobolocysta most closely resembles Necrobroomea Wiggins 1975. However, Necrobroomea always posses an apical horn which is usually well-developed, as well as two antapical horns. Aprobolocysta, on the other hand, lacks any apical projection and possesses only very poorly-defined antapical projections, if any at all. Further, Necrobroomea has a single layered cyst wall whereas that of Aprobolocysta is bi- layered, a character clearly seen due to periphragm folding in the species.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Duxbury, 1980:
Diagnosis:
Distinctly elongate proximate to proximochorate dinoflagellate cysts with bi-layered cyst wall. Paratabulation absent or indistinctly indicated by periphragm folds, parasutural crests and/or irregular archeopyle margin. Apex and antapex bluntly rounded. Archeopyle apical.
--------------------------------------------
Mehrota and Sarjeant, 1986
Diagnosis:
Cyst proximate to proximochorate, elongate with broadly rounded to blunt apex and antapex. Epitract larger than the hypotract. Cyst wall separation may be distinct or indistinct. Paratabulation may be suggested by periphragm folds or parasutural crests; however, it is sometimes indicated by the archaeopyle margin only or not discernible at all. When determinable: 3-?4`, 5ap, 6``, 6c, 5```, 1pv, 1````. Archaeopyle apical to (?) combination; the latter type might involve one or more paraplates of the postapical series. Operculum free or attached.
--------------------------------------------
Pourtoy, 1988
Diagnosis:
Cysts proximate to proximochorate, elongate ovoidal in shape, the hypocyst being more rounded than the epicyst, sometimes possessing an apical horn and/or two weakly developed antapical horns or protuberances. The wall consists of a distinct endophragm and a distinct periphragm. The tabulation is generally indicated only by the irregular archeopyle margin and its secondary parasutures. It is sometimes indistinctly marked by folds of the periphragm, even parasutural septa. The archeopyle is presumably apical of type (tA), its outline being longitudinally bisymmetrical, closer to the apex on the dorsal surface and deeply indented on the ventral surface. The operculum is free or in place. The position of the paracingulum, generally indiscernible, may sometimes be marked by folds or parasutural septa, or by fusion of the periphragm and endophragm, at the lower third of the cyst corresponding to its greatest width. The parasulcus is not discernible.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams 1987, p. 19-20:
Synopsis:
Cysts proximate, endocyst elongate-ovoidal and surrounded by a loosely fitting, variously folded periphragm. Archeopyle supposedly apical, but more likely combined apical and intercalary with a deep sulcal notch and a free operculum.
Description:
Shape: Elongate-ovoidal, apex more narrowly rounded than antapex.
Wall relationships: Endophragm and periphragm distinct; amount of cavation varies depending on the complexity and magnitude of the
periphragmal folding.
Wall features: No clearly delimited parasutural features. Periphragm simply to complexly folded, some folds may simulate parasutural features. Archeopyle: Reported as apical, but more likely a combined apical and intercalary type; principal archeopyle suture closer to apex dorsally than ventrally and longitudinally asymmetrical; left lateral margin with an anteriorly camerate paraplate (2``) separated from the deep sulcal notch by a narrow, anteriorly planate paraplate (1``).
Paratabulation: Partly indicated by archeopyle.
Paracingulum: Not indicated.
Parasulcus: Anterior position inferred by deep sulcal notch; other indications lacking.
Size: Intermediate, about 55 µm to 75 µm in length.
Affinities:
Aprobolocysta differs from Batioladinium Brideaux 1975 in possessing a thin, folded periphragm which is separated from the endophragm over a substantial part of the cyst. In Batioladinium the two wall layers, when discernible, are appressed. The two genera are otherwise similar in shape and have the same type of archeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Aprobolocysta Duxbury, 1977, emend. Pourtoy, 1988. According to Stover and Williams (1987, p.19) cysts are proximate, endocyst elongate-ovoidal and surrounded by a loosely fitting, variously folded periphragm. Archeopyle supposedly apical, but more likely combined apical and intercalary with a deep sulcal notch and a free operculum. In actuality, the archeopyle results from the loss of the two Kofoid apical plates, the operculum being federate. The first apical plate (1"), which is exerts, remains part of the loisthocyst.