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Impagidinium spongianum
Impagidinium spongianum Sütő-Szentai, 1985, p.519, pl.81, fig.6 (non 5 — see below).
This name was not validly published in Sütő-Szentai (1982a, pl.5, fig.3), who did not give a description. Sütő-Szentai (1990, pl.2, fig.3 — p.860) also cited this species as new.
The nomenclatural status of this species is in question because Sütő-Szentai (1985, p.519 and caption to pl.81) indicated her pl.81, fig.5 as the holotype; however, as L. Londeix (pers. comm.) has pointed out, this specimen had been previously designated as a paratype of Millioudodinium (now Apteodinium?) foveolatum, and does not accord in morphology with the genus Impagidinium. It appears that the holotype was thus incorrectly indicated and should have been cited as pl.81, fig.6 in Sütő-Szentai (1985) (the same specimen as the single illustration labelled as Impagidinium spongiosum in Sütő-Szentai, 1982a, pl.5, fig.3). This is an unusual situation and it is unclear how ICN rules might apply, although generally typographic errors are not reasons for invalidating a name. We thus provisionally accept that Impagidinium spongianum was validly published in Sütő-Szentai (1985) despite the apparently incorrect indication of the holotype.
Holotype: Sütő-Szentai, 1982a, pl.5, fig.3; Sütő-Szentai, 1985, p.519, pl.81, fig.6 (non 5 — see below).
Age: late Miocene.
Original description (Sütõ-Szentai, 1985):
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Supplementary description Soliman and Riding 2017:
Impagidinium spongianum is ovoidal in shape. The epicyst has a rounded apex with a prominent apical boss ~ 3 to 5 μm in height (Plate I, 6). The cyst wall is relatively thick (~ 1.5 μm) and spongy; in some specimens, scattered gemmae are present. Using light microscopy, the cyst wall appears coarsely reticulate. The sutural crests are ~ 1.5 μm in height; they are undulate distally and are smooth to finely perforate proximally. The sutural crests delineate a standard S-type gonyaulacacean tabulation, however, the apical plate sutures may be faintly expressed (Plate I, 5). The sulcus is shallow, and some of the larger sulcal plates can be resolved in some specimens (Plate I, 4). The cingulum is offset by one cingulum width (Plate I, 4). The archaeopyle is precingular (type P) with a free operculum.
Dimensions. The maximum length of the cyst body, including the apical boss, is 42 (50) 60 μm and the maximum equatorial width is 34 (42) 51 μm. Nineteen specimens were measured.
Comparison. Impagidinium spongianum differs from other species of Impagidinium by its characteristic thick and spongy cyst wall and the presence of an apical boss. Leptodinium punctatum differs from I. spongianum based on the illustration and description Balteş (1971, p. 3; pl. 4; Figs. 2–3, 6–7) in having slender prominences and low sutural crests rather than a spongy cyst wall and high sutural crests. Impagidinium (?) sp. 1 of Corradini and Biffi (1988; pl. 3, figs. 7–11) and Forms 1 and 2 of Balteş (1971, pl. 4, 1, 3 respectively) resemble Impagidinium spongianum in surface ornamentation and in having high sutural crests. While the specimen illustrated in Balteş (1971, pl. 4, 2) is excluded because it has a smooth surface. However, Impagidinium (?) sp. 1 of Corradini and Biffi (1988) appears to lack the apical boss which is not clear in Form 1 of Balteş (1971, pl. 4, 1) because of its antapical oblique orientation. Impagidinium eugubinum Biffi and Manum, 1988 has dome-shaped to nipple-like prominences. Caspidinium rugosum Marret et al., 2004 is also similar to Impagidinium spongianum, but differs due to its dextral torsion and the absence of an apical boss. The irregular height of septa and the low intratabular relief differentiate I. caspienense Marret et al., 2004 from I. spongianum.
Distribution. Impagidinium spongianum was recorded from most of the samples studied herein.
Previous records. Impagidinium spongianum has been recorded from the Pannonian of Hungary (Sütőné-Szentai, 1985, Sütőné-Szentai, 1986, Sütőné-Szentai, 1990, Sütőné-Szentai, 1999, Sütőné-Szentai, 2000, Sütőné-Szentai, 2003). The only record outside the Pannonian Basin is from the Upper Miocene to Lower Pliocene of the Maccarone section, Marche, Italy (Popescu et al., 2007).
This name was not validly published in Sütő-Szentai (1982a, pl.5, fig.3), who did not give a description. Sütő-Szentai (1990, pl.2, fig.3 — p.860) also cited this species as new.
The nomenclatural status of this species is in question because Sütő-Szentai (1985, p.519 and caption to pl.81) indicated her pl.81, fig.5 as the holotype; however, as L. Londeix (pers. comm.) has pointed out, this specimen had been previously designated as a paratype of Millioudodinium (now Apteodinium?) foveolatum, and does not accord in morphology with the genus Impagidinium. It appears that the holotype was thus incorrectly indicated and should have been cited as pl.81, fig.6 in Sütő-Szentai (1985) (the same specimen as the single illustration labelled as Impagidinium spongiosum in Sütő-Szentai, 1982a, pl.5, fig.3). This is an unusual situation and it is unclear how ICN rules might apply, although generally typographic errors are not reasons for invalidating a name. We thus provisionally accept that Impagidinium spongianum was validly published in Sütő-Szentai (1985) despite the apparently incorrect indication of the holotype.
Holotype: Sütő-Szentai, 1982a, pl.5, fig.3; Sütő-Szentai, 1985, p.519, pl.81, fig.6 (non 5 — see below).
Age: late Miocene.
Original description (Sütõ-Szentai, 1985):
-------------------------------------------------------------------------------------------------------
Supplementary description Soliman and Riding 2017:
Impagidinium spongianum is ovoidal in shape. The epicyst has a rounded apex with a prominent apical boss ~ 3 to 5 μm in height (Plate I, 6). The cyst wall is relatively thick (~ 1.5 μm) and spongy; in some specimens, scattered gemmae are present. Using light microscopy, the cyst wall appears coarsely reticulate. The sutural crests are ~ 1.5 μm in height; they are undulate distally and are smooth to finely perforate proximally. The sutural crests delineate a standard S-type gonyaulacacean tabulation, however, the apical plate sutures may be faintly expressed (Plate I, 5). The sulcus is shallow, and some of the larger sulcal plates can be resolved in some specimens (Plate I, 4). The cingulum is offset by one cingulum width (Plate I, 4). The archaeopyle is precingular (type P) with a free operculum.
Dimensions. The maximum length of the cyst body, including the apical boss, is 42 (50) 60 μm and the maximum equatorial width is 34 (42) 51 μm. Nineteen specimens were measured.
Comparison. Impagidinium spongianum differs from other species of Impagidinium by its characteristic thick and spongy cyst wall and the presence of an apical boss. Leptodinium punctatum differs from I. spongianum based on the illustration and description Balteş (1971, p. 3; pl. 4; Figs. 2–3, 6–7) in having slender prominences and low sutural crests rather than a spongy cyst wall and high sutural crests. Impagidinium (?) sp. 1 of Corradini and Biffi (1988; pl. 3, figs. 7–11) and Forms 1 and 2 of Balteş (1971, pl. 4, 1, 3 respectively) resemble Impagidinium spongianum in surface ornamentation and in having high sutural crests. While the specimen illustrated in Balteş (1971, pl. 4, 2) is excluded because it has a smooth surface. However, Impagidinium (?) sp. 1 of Corradini and Biffi (1988) appears to lack the apical boss which is not clear in Form 1 of Balteş (1971, pl. 4, 1) because of its antapical oblique orientation. Impagidinium eugubinum Biffi and Manum, 1988 has dome-shaped to nipple-like prominences. Caspidinium rugosum Marret et al., 2004 is also similar to Impagidinium spongianum, but differs due to its dextral torsion and the absence of an apical boss. The irregular height of septa and the low intratabular relief differentiate I. caspienense Marret et al., 2004 from I. spongianum.
Distribution. Impagidinium spongianum was recorded from most of the samples studied herein.
Previous records. Impagidinium spongianum has been recorded from the Pannonian of Hungary (Sütőné-Szentai, 1985, Sütőné-Szentai, 1986, Sütőné-Szentai, 1990, Sütőné-Szentai, 1999, Sütőné-Szentai, 2000, Sütőné-Szentai, 2003). The only record outside the Pannonian Basin is from the Upper Miocene to Lower Pliocene of the Maccarone section, Marche, Italy (Popescu et al., 2007).