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Andreedinium elongatum
Andreedinium elongatum (Beju, 1971) Feist-Burkhardt and Monteil, in Feist-Burkhardt, 1990
Originally Fromea, subsequently Fromea?, thirdly Wallodinium, fourthly Palaeostomocystis, fifthly (and now) Andreedinium.
Nomenclatural sr. synonym of Phallocysta minuta Prauss, 1989, since Prauss, 1989, included Andreedinium (as Fromea) elongatum in synonymy with Phallocysta minuta. Riding et al., 1991, considered the form described by Prauss, 1989, as Phallocysta minuta to have a distinctive morphology. Accordingly, Lentin and Williams, 1993, proposed the name Phallocysta subconica for it.
Tax. jr. synonym of Prismatocystis (now Wallodinium) cylindricum Habib, 1970, according to Duxbury, 1983. Feist-Burkhardt and Monteil in Feist-Burkhardt, 1990, retained Andreedinium elongatum as a separate species.
Holotype: Beju, 1971, pl.3, fig.7, text-fig.6A
Locus typicus: well at Plaviceni, Roumania
Stratum typicum: Bathonian-Bajocian
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Original description as Fromea elongata: [Beju, 1971, p. 289]:
Diagnosis:
Shell formed of two distinct parts: a subspherical or slightly elongated chamber prolonged by a subcylindrical or slightly conical neck, wide opened at its apical end. The transition from the chamber to the neck is gradual but always recognizable on the borders. Neck/chamber ratio 1/4 to 1/3, Shell wall relatively thin (0.5-1.5 µm) levigate to finely punctate. Opening wide, subcircular with smooth or slightly undulated margins.
Dimensions:
Overall length: 46-70 µm; overall width 24-36 µm.
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Emended description:
Feist-Burkhardt and Monteil 1994, 9-10:
Description:
Dinoflagellate cyst. Proximate, epicavate, with straight longitudinal axis. Pericyst elongate ovoidal, with tapered epicyst and a weak constriction in its anterior part at about the three-quarters cyst length; apex narrowly rounded or slightly pointed; antapex broadly rounded. Endocyst subspherical to ellipsoidal, occupying most of the hypocyst, closely appressed to the pericyst in the hypocystal region.
Periphragm and endophragm psilate to finely punctate: periphragm sometimes faintly longitudinally striped.
Periarchaeopyle intercalary, type 31a. Periopercular pieces posteriorly adnate to the pre-cingular paraplates. Endoarchaeopyle type undetermined, frequently developed.
Paratabulation expressed by archaeopyle only.
Paracingulum and parasulcus not indicated.
Dimensions:
Observed size range: Length of pericyst: 42-56 µm; width of pericyst: 24-32 µm; length of endocyst: 24-35 µm; width of endocyst: 24-32 µm.
Remarks:
The epicavate species elongatum resembles the likewise epicavate Phallocysta eumekes. This might suggest to combine it with the genus Phallocysta. The species elongatum is attributed to the genus Andreedinium and not to Phallocysta because in our view, and following Below (1987), the archaeopyle type and the fact whether the opercular pieces are free or adnate is a more important character than the presence or absence of cavations. Prauss (1989, p. 20, 21) erected the species Phallocysta minuta and included the holotype of Fromea elongata Beju 1970 in the synonymy. According to Lentin & Williams (1993, p.506), "P. minuta" is an illegitimate name (ICBN, article 63.1.) and a nomenclatural junior synonym of F. elon Rata Beju 1971. We do not agree with the contention of Riding et al. (1991, p.153) that the form described by Prauss as "P. minuta" has a distinctive morphology. We therefore consider the substitute name Phallocysta subconical proposed by Lentin & Williams (1993, p.507) as a nomenclatural junior synonym of Andreedinium elongatum (Beju 1971) Feist-Burkhardt & Monteil in Feist-Burkhardt 1990 emend.
In the original diagnosis, Beju (1971, p 289) described the cyst as ".. a subspherical or slightly elongated chamber prolonged by a subcylindrical or slightly conical neck... The transition from the chamber to the neck is gradual but always recognizable on the borders. Neck/chamber ratio lt4 to 113..." In most specimens observed the transition between "chamber" and "neck" is accentuated by a weak constriction. In the ornamented type species,A. arcticum Below (1987) a resembling weak constriction has been interpreted as the zone anterior to the paracingulum (Below, 1987, pl. 22, fig. 1). In one specimen of A. elongatum, the endoarchaeopyle appears as intercalary (pl. 3, figs. 1, 2).
Prauss (1989) erected the species Phallocysta minuta in order to accommodate small epicavate dinoflagellate cysts with an intercalary archaeopyle and smooth peri- and endophragm. In the synonymy, he included distinctly ornamented cysts ("dinoflagellate type 3" of Thusu, 1978, pl. 11, fig. 14; "Phallocysta eumekes" of Riding, 1984, Fig. 6 C-D) as well as the holotype of the psilate to finely punctate cyst Fromea elongata Beju 1971.
The illegitimate name "Phallocysta minuta" Prauss 1989 has later been used by Riding et al. (1991) and Riding & Thomas (1992) for distinctly ornamented dinoflagellate cysts, which do not correspond to the holotypes of Fromea elongata or "Phallocysta minuta". Both holotypes are smooth-walled and considered by us to belong to the same species, Andreedinium elongatum emend. The distinctly ornamented specimens figured by Riding et al. (1991, pl. 2, fig. 21 -25) and Riding & Thomas (1992, pl. 2.2, fig. 8), as "Phallocysta minuta", are considered to belong to a species close to, or conspecific with Andreedinium erregulense (Filatoff 1975) Stover & Helby 1987 or Andreedinium aff. elongatum.
Affinities/Comparisons:
Andreedinium elongatum emend. differs from Andreedinium erregulense (Filatoff 1975) Below 1987 in having the peri- and endophragm closely appressed to each other in the hypocystal region, rather than being in loose contact and, sometimes, forming wide hypopericoels (Stover & Helby, 1987, p. 111). In A. erregulense, the endocyst may occupy practically all of the hypocyst and a part of the epicyst. In A. elongatum, the endocyst is restricted to the hypocyst. A. arcticum Below (1987) is acavate and strongly ornamented. Stover & Helby (1987, p. 111) provided a revised description for the species erregulensis and, establishing that both archaeopyles would be type L, proposed the new combination Phallocysta erregulensis (Filatoff 1975) Stover & Helby 1987. However, Lentin & Williams (1989, p. 17; 1993, p. 28) followed Below 1987 and accepted the combination Andreedinium erregulense (Filatoff 1975) Below 1987.
Andreedinium aff. elongatum differs from Andreedinium elongatum in having a periphragm ornamented by granules, rather than a psilate to finely punctate periphragm.
Originally Fromea, subsequently Fromea?, thirdly Wallodinium, fourthly Palaeostomocystis, fifthly (and now) Andreedinium.
Nomenclatural sr. synonym of Phallocysta minuta Prauss, 1989, since Prauss, 1989, included Andreedinium (as Fromea) elongatum in synonymy with Phallocysta minuta. Riding et al., 1991, considered the form described by Prauss, 1989, as Phallocysta minuta to have a distinctive morphology. Accordingly, Lentin and Williams, 1993, proposed the name Phallocysta subconica for it.
Tax. jr. synonym of Prismatocystis (now Wallodinium) cylindricum Habib, 1970, according to Duxbury, 1983. Feist-Burkhardt and Monteil in Feist-Burkhardt, 1990, retained Andreedinium elongatum as a separate species.
Holotype: Beju, 1971, pl.3, fig.7, text-fig.6A
Locus typicus: well at Plaviceni, Roumania
Stratum typicum: Bathonian-Bajocian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Fromea elongata: [Beju, 1971, p. 289]:
Diagnosis:
Shell formed of two distinct parts: a subspherical or slightly elongated chamber prolonged by a subcylindrical or slightly conical neck, wide opened at its apical end. The transition from the chamber to the neck is gradual but always recognizable on the borders. Neck/chamber ratio 1/4 to 1/3, Shell wall relatively thin (0.5-1.5 µm) levigate to finely punctate. Opening wide, subcircular with smooth or slightly undulated margins.
Dimensions:
Overall length: 46-70 µm; overall width 24-36 µm.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Feist-Burkhardt and Monteil 1994, 9-10:
Description:
Dinoflagellate cyst. Proximate, epicavate, with straight longitudinal axis. Pericyst elongate ovoidal, with tapered epicyst and a weak constriction in its anterior part at about the three-quarters cyst length; apex narrowly rounded or slightly pointed; antapex broadly rounded. Endocyst subspherical to ellipsoidal, occupying most of the hypocyst, closely appressed to the pericyst in the hypocystal region.
Periphragm and endophragm psilate to finely punctate: periphragm sometimes faintly longitudinally striped.
Periarchaeopyle intercalary, type 31a. Periopercular pieces posteriorly adnate to the pre-cingular paraplates. Endoarchaeopyle type undetermined, frequently developed.
Paratabulation expressed by archaeopyle only.
Paracingulum and parasulcus not indicated.
Dimensions:
Observed size range: Length of pericyst: 42-56 µm; width of pericyst: 24-32 µm; length of endocyst: 24-35 µm; width of endocyst: 24-32 µm.
Remarks:
The epicavate species elongatum resembles the likewise epicavate Phallocysta eumekes. This might suggest to combine it with the genus Phallocysta. The species elongatum is attributed to the genus Andreedinium and not to Phallocysta because in our view, and following Below (1987), the archaeopyle type and the fact whether the opercular pieces are free or adnate is a more important character than the presence or absence of cavations. Prauss (1989, p. 20, 21) erected the species Phallocysta minuta and included the holotype of Fromea elongata Beju 1970 in the synonymy. According to Lentin & Williams (1993, p.506), "P. minuta" is an illegitimate name (ICBN, article 63.1.) and a nomenclatural junior synonym of F. elon Rata Beju 1971. We do not agree with the contention of Riding et al. (1991, p.153) that the form described by Prauss as "P. minuta" has a distinctive morphology. We therefore consider the substitute name Phallocysta subconical proposed by Lentin & Williams (1993, p.507) as a nomenclatural junior synonym of Andreedinium elongatum (Beju 1971) Feist-Burkhardt & Monteil in Feist-Burkhardt 1990 emend.
In the original diagnosis, Beju (1971, p 289) described the cyst as ".. a subspherical or slightly elongated chamber prolonged by a subcylindrical or slightly conical neck... The transition from the chamber to the neck is gradual but always recognizable on the borders. Neck/chamber ratio lt4 to 113..." In most specimens observed the transition between "chamber" and "neck" is accentuated by a weak constriction. In the ornamented type species,A. arcticum Below (1987) a resembling weak constriction has been interpreted as the zone anterior to the paracingulum (Below, 1987, pl. 22, fig. 1). In one specimen of A. elongatum, the endoarchaeopyle appears as intercalary (pl. 3, figs. 1, 2).
Prauss (1989) erected the species Phallocysta minuta in order to accommodate small epicavate dinoflagellate cysts with an intercalary archaeopyle and smooth peri- and endophragm. In the synonymy, he included distinctly ornamented cysts ("dinoflagellate type 3" of Thusu, 1978, pl. 11, fig. 14; "Phallocysta eumekes" of Riding, 1984, Fig. 6 C-D) as well as the holotype of the psilate to finely punctate cyst Fromea elongata Beju 1971.
The illegitimate name "Phallocysta minuta" Prauss 1989 has later been used by Riding et al. (1991) and Riding & Thomas (1992) for distinctly ornamented dinoflagellate cysts, which do not correspond to the holotypes of Fromea elongata or "Phallocysta minuta". Both holotypes are smooth-walled and considered by us to belong to the same species, Andreedinium elongatum emend. The distinctly ornamented specimens figured by Riding et al. (1991, pl. 2, fig. 21 -25) and Riding & Thomas (1992, pl. 2.2, fig. 8), as "Phallocysta minuta", are considered to belong to a species close to, or conspecific with Andreedinium erregulense (Filatoff 1975) Stover & Helby 1987 or Andreedinium aff. elongatum.
Affinities/Comparisons:
Andreedinium elongatum emend. differs from Andreedinium erregulense (Filatoff 1975) Below 1987 in having the peri- and endophragm closely appressed to each other in the hypocystal region, rather than being in loose contact and, sometimes, forming wide hypopericoels (Stover & Helby, 1987, p. 111). In A. erregulense, the endocyst may occupy practically all of the hypocyst and a part of the epicyst. In A. elongatum, the endocyst is restricted to the hypocyst. A. arcticum Below (1987) is acavate and strongly ornamented. Stover & Helby (1987, p. 111) provided a revised description for the species erregulensis and, establishing that both archaeopyles would be type L, proposed the new combination Phallocysta erregulensis (Filatoff 1975) Stover & Helby 1987. However, Lentin & Williams (1989, p. 17; 1993, p. 28) followed Below 1987 and accepted the combination Andreedinium erregulense (Filatoff 1975) Below 1987.
Andreedinium aff. elongatum differs from Andreedinium elongatum in having a periphragm ornamented by granules, rather than a psilate to finely punctate periphragm.