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Carpatella
From Williams et al., 2017:
[Carpatella, Grigorovich, 1969a, p. 74; Emendations: Fechner and Mohr, 1986, p. 183-184; Damassa, 1988, p. 167- 168, 170, 172, 174-175
Type species: Carpatella cornuta, Grigorovich, 1969a (pl.1, fig.1)]
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Original description: [Gregorovich, 1969]: (Translation: Stover and Evitt, 1978):
Description:
Cyst spherical, sometimes ovate, with one apical and one antapical horn. Transverse furrow circular. Apical aperture open, sometimes closed by a
small plate. Tabulation distinct. Formula of plates 3(?)`, 6", 3p, (5-6```), 1(?)````. Sutures joining plates convex. Surface of plates granular: from finely to coarsely granular, rarely smooth.
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Modified description:
Stover and Evitt, 1978, p. 142-144:
Description:
Shape: Subspherical to ellipsoidal with a short medial protrusion or horn at each pole.
Wall Relationships: Autophragm only.
Wall Features: Low smooth parasutural ridges evidently present on some specimens. Autophragm smooth to granular.
Paratabulation: Indicated by archeopyle and paracingulum and additionally on some individuals by parasutural features. Formula, when paraplates are discernible, given as 3`?, 6", 3c, 5-6```, 1````?.
Archeopyle: Precingular, Type P (3" only); operculum free.
Paracingulum: Indicated by low, parallel, transverse equatorial ridges that are apparently connected (dorsally?) by longitudinal ridges to account for the 3c designated in the paratabulation formula.
Parasulcus: Not indicated.
Size: Intermediate to large.
Affinities:
Carpatella differs from Apteodinium and Millioudodinium in having a short, medial, antapical horn or protrusion.
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Emended descriptions:
Fechner and Mohr, 1986: (Translation Fechner and Mohr, 1986: LPP):
Diagnosis:
Cyst acavate, proximate, sphaeroidal to oval in shape with one apical and one antapical horn. Paratabulation gonyaulacystoid. Epicyst and hypocyst approximately same size, separated by a spiral, hexatabulare paracingulum. Plate boundaries indicated by low ridges. Paratabulation scheme: 0-1pr, 4`, 6``, 6c, 6```, 1p, 1````, Xs. Archeopyle Type P(3``).
Description:
Cyst in shape round to slightly oval with a slim, outstanding apical horn and a usually shorter, sturdier antapical horn. While the apical horn, in gonal position, is build up by the four antapical parasutural ridges, the rounded antapical horn is in intratabular position.
The gonyaulacoid paratabulation is rarely developed completely.
Paratabulation on the hypocyst usually clearer reflected than on the epicyst. Plate boundaries marked by low to moderate high, smooth or denticulate ridges. The hexatabulare paracingulum is staggered at the parasulcus. In the parasulcal area, several partial developed paraplates are visible. Autopraghm only.
Size intermediate to large.
Affinities:
Carpatella differs from Cribroperidinium Neale and Sarjeant, 1962; emend. Davey 1969 in having an antapical horn and lacking accessory, subparallel to parasutures running ridges. Kenleya Cookson and Eisenack, 1965, a genus with two polar horns, too, has in contrast to Carpatella no defined paratabulation but high ridges.
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Damassa, 1988:
Synopsis:
Proximate cysts, subspherical to ellipsoidal in shape, having a short horn at apex and antapex. Sexiform gonyaulacacean paratabulation indicated by parasutural features. Ventral organization L-type. Apical paraplate A (4`) contacts B (2`) dorsal to preapical P; paraplate Q is absent; precingular li (6") contacts both A and lu (1`); Iu (1```) and II (2```) relatively small, ai (as) contacts Il (2```), Iu (1```) does not contact au (Ic); X (Ip) and Z (ps) elongate, arcuate; antapical Y (1````) slightly asymmetrical-oblong; postcingular parasuture IV/V (4```/ 5```) offset to the left of precingular parasuture 4/5 (3"/4"). Archeopyle precingular, Type P, precingular 4 (3") only, with rounded pentagonal margin; operculum free. Wall consists of autophragm only, outer part densely fibrous or spongy in appearance, inner surface of wall smooth. Porichnion visible between apical paraplates A and lu with SEM.
Description:
Shape: Cysts subspherical to ellipsoidal in ventro-dorsal or lateral view, with single short horns at apex and antapex; approximately circular in polar view; slight indentation in sulcal region. Horns are solid structures formed from densely fibrous, spongy wall material, not by protrusion of the entire wall, nor by coalescing parasutural features (Plate 1, figs. 5, 9).
Wall structure: Cysts proximate and acavate, wall consisting of autophragm only. Surface texture densely fibrous; in cross section wall appears spongy, having a smooth inner surface (Plate 3, fig. 3; see arrow). There is a discontinuity within the wall, but no obvious change in texture. Wall thickness approximately 5-8 µm.
Archeopyle: Precingular archeopyle, Type P, consisting of paraplate 4 (3") only; rounded pentagonal in shape and may be slightly enlarged. Operculum free. Wall is distinctly thinner at margins of archeopyle and operculum (Plate 1, figs. 2, 3).
Surface features: Paratabulation indicated by narrow parasutural "furrows" flanked by somewhat broader raised bands (Plate 1, fig. 6; Plate 3, fig. 4). Intratabular ornament consists of parallel rows of small "pits" visible with SEM on some specimens, generally restricted to larger paraplates (e.g., Plate 3, figs. 1, 2; compare with intratabular ridges of Cribroperidinium).
Paratabulation: A complete sexiform gonyaulacoid paratabulation, essentially equivalent to the Ventriosum pattern, Aptiana-Ventriosum complex, of Helenes (1986), is indicated by parasutural features (Text-Figure 3): I preapical (P = pr); 4 apicals (lu, A, B, C = 1`-4`); 6 precingulars (2, 3, 4, 5, 6, and li = 1"-6"); 6 cingulars (au, b, c, d, e, and fi = 1c-6c); 6 sulcals (ai, fu, Ii, Im, Iu and Z = as, ras, rs, ls, 1``` and ps); S postcingulars (II, III, IV, V, and VI = 2```-6```); 1 posterior intercalary (X = lp); and 1 antapical (Y = 1````). In Kofoidian terms the paratabulation formula is: lpr, 4`, 6", 6c, 6s, 5```, 1p, 1````. The paratabulation pattern is characterized by an L-type ventral configuration. Apical paraplates A and B (4` and 2`) are in contact dorsal to P; Q is not present. Paraplates lu and li (1` and 6") are in contact in the ventral region (li is camerate and also contacts A; ai is planate). Paraplates lu and A are elongate, and a porichnion can be observed with the SEM on the edge of lu adjacent to the lu/A parasuture (Plate 2, fig. 3). In the sulcal region, most specimens of Carpatella exhibit a configuration in which paraplate ai (as) contacts II (2```), but Iu (1```) does not contact au (1c); thus Iu is not a postcingular paraplate (in the strict Kofoidian sense) because it does not contact the paracingulum. The length of the ai/II (as/2"`) contact is variable (see Plate 1, figs. 1, 4; Plate 2, figs. 2, 6; Text-Figure 3A), and several specimens were observed with a four-way contact between paraplates ai, II, Iu and au. In contrast, most species having a Ventriosum pattern are characterized by a contact between paraplates Iu and au. In Carpatella, as in other species having the Ventriosum pattern, Iu and II are relatively small, the remaining postcingular paraplates (III-VI or 3```-6```) are distinctly larger. Postcingular parasuture IV/V is offset to the left of precingular parasuture 4/5, but does not attain a truly mid-dorsal position. Antapical paraplate Y (1````) is slightly asymmetrical-oblong, contacting paraplates X (1p), Z (ps) and III-VI (3```-6```). Antapical parasutures Y/X, Y/Z and Y/VI are relatively short, and may be nearly colinear. Parasuture Y/V is only slightly longer than Y/III (see Helenes, 1986, p. 78-79).
Size:
Intermediate to large. Length of cysts approximately 100-130 µm, including horns (length of horns approximately 10-18 µm); equatorial diameter approximately 90-100 µm.
Affinities:
Carpatella is not alone in having six sulcal and only five postcingular paraplates (speaking in the strict Kofoidian sense). The ai/II contact, which eliminates Iu from the ranks of the postcingular paraplates, also occurs in all species assigned to Ctenidodinium, Leptodinium, Occisucysta, Tehamadinium and Korystocysta, in Gonyaulacysta dualis (Helenes, 1986), and in several species of Hystrichokolpoma (Damassa et al., 1987). At present Carpatella is a monotypic genus. It has been distinguished from Apteodinium, which is similar in overall appearance (e.g. shape, wall texture, size), on the basis of the presence of both apical and antapical horns (Stover and Evitt, 1978, p. 144). In addition, species of Apteodinium tend to lack clear evidence of paratabulation (Stover and Evitt, 1978); however, see Lucas-Clark (1987) for a partial Aptiana-Ventriosum paratabulation scheme. It is apparent that Carpatella cornuta possesses features of paratabulation, archeopyle and wall structure nearly identical to species of Cribroperidinium (Helenes, 1984). The two genera may be distinguished on the basis of the development of a second (antapical) horn in Carpatella and in the morphologic details by which the paratabulation is expressed (parasutural furrows and intratabular "pits" in Carpatella, parasutural ridges and intratabular ridges in Cribroperidinium). The only difference in paratabulation observed between these genera is in the configuration of the ai/ II-Iu/au contacts (Iu/au in Cribroperidinium, ai/II in most specimens of C. cornuta).
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Discussion: Damassa, 1988:
Several recent studies of Maastrichtian and Danian dinoflagellate assemblages in southern Scandinavia have focused on biostratigraphy and paleoecology (Hansen, 1977, 1979; Kjellstrom and Hansen, 1981; Hultberg, 1985, 1986; Thomsen and Heilmann-Clausen, 1985). The strata in which these assemblages occur have gained further attention in the last few years due to the intense interest in the Cretaceous/Tertiary boundary and associated extinction events (e.g. Alvarez et al., 1980). Carpatella cornuta Grigorovich, 1969 is a form characteristic of basal Paleocene (Danian) deposits; indeed, Hansen (1977, p. 7) named a zonule for this species. Despite the recognition of C. cornuta as an important boundary marker, its morphologic details have received little attention, due in part to its large sizeand distinctive shape, which permit identification even at low magnifications. Grigorovich`s original illustrations and description (1969, p. 74-76) indicate gonyaulacacean affinities, but the paratabulation formula given is incomplete. Stover and Evitt (1978, p. 144- 145) modified the original description of Carpatella, but without the original material in hand, were unable to provide a complete analysis. Fechner and Mohr (1986) recently published a revised description based on specimens attributed to Carpatella from the Eocene of South Morocco; however, the identification of their specimens is uncertain.
Unusually well-preserved specimens from several localities in southwestern Sweden and southeastern Denmark (Text-Figure 1) are herein analyzed in detail with both light and scanning electron microscopy. The paratabulation pattern is clearly visible, and is identical in nearly all respects to that of forms included in the Aptiana-Ventriosum complex (Ventriosum pattern) by Helenes (1986). The reader also is referred to Helenes (1984) for detailed discussion of Cribroperidinium, and to Damassa (1984), Damassa et al. (1987) and Lucas-Clark (1987) for discussions of other forms belonging to the Aptiana -Ventriosum complex. The critical and characteristic features of dinoflagellates in this complex include: asymmetrical-oblong antapical Y (1````); postcingular parasuture IV/V (4```/5```) offset to the left of precingular parasuture 4/5 (3"/4"); apicals A/B (4`/2`) in contact dorsal to preapical P; precingular li (6") camerate, and in contact with apicals A and lu (4` and 1`); anterior sulcal ai (as) planate, in contact anteriorly only with lu; posterior intercalary X and posterior sulcal Z elongate, arcuate; lu (1```) and II(2```) relatively small, III-VI (3```-6```) distinctly larger.
Since Grigorovich`s original description of Carpatella cornuta in 1969, there have been relatively few occurrences reported in the literature. Specimens illustrated by Morgenroth (1968, p. 542544, pl. 44, figs. 1-3) and Evitt (1973, p. 34, pl. 1, figs. 12-14) were identified as "Danea mutabilis." Other occurrences reported as Carpatella cornuta include those by Hansen (1977, pl. 7, fig. 21 F; 1979, p. 137, fig 5), Hultberg (1985, p. 61, pl. 1, figs. 3, 4, p. 112,pl.2,fig.C; 1986,p.38,pl. 1,figs.3,4),and Firth (1987, pl. 3, fig. 6). I am certain that Hansen`s, Hultberg`s and Firth`s specimens are conspecific with my material, and am reasonably confident of the identification of Morgenroth`s and Evitt`s specimens as C. cornuta; however, I have serious doubts regarding the identity of those specimens described as C. cornuta by Fechner and Mohr (1986, p. 181188, figs. 2, 3). Although their description corresponds fairly well in general terms to my concept of Carpatella, there are several differences in details of morphology and paratabulation between their specimens and those described here (see Fechner and Mohr, 1986, fig. 3). The apical horn is described as having formed from four apical parasutural crests, in contrast to the simple structure illustrated here. Also, the denticulate crests ("Kamme") noted by Fechner and Mohr (1986, p. 184) have not been reported in other specimens assigned to Carpatella, and are certainly not evident in the material used in this study.
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Iakovleva, 2019
Emended diagnosis. Subspherical to ellispoidal proximate cysts, having a short horn at apex and antapex. Sexiform gonyaulacacean paratabulation is expressed to varying degrees in different species and indicated by parasutural features. Ventral organisation L-type. Archeopyle precingular, Type P, comprising precingular paraplate 3” only, with rounded pentagonal margin; operculum free or in place. Wall consisting of two layers: pedium, mostly invisible, extremely thin and smooth; luxuria solid, densely fibrous or spongy. Surface of outer layer may be smooth, with features of low relief or ornamented by intratabular processes and penitabular septa.
Emended description.
Shape. Cysts subspherical to ellipsoidal in ventro-dorsal or lateral view, with single and very short to intermediate horns at apex and antapex; approximately circular in polar view; slight indentation in sulcal region is observed in the type species. Horns are solid structures formed from densely fibrous, spongy wall material.
Size. Intermediate to large. Length of cysts ~69–130 μm, including horns (length of horns ~4–20 μm); equatorial diameter ~68–100 μm. Wall structure. Cyst proximate, acavate, wall consisting of two layers: pedium extremely thin and smooth, very rarely observed only in antapical area. Inner and outer layers so tightly compressed that the pedium is not visible in most cases. Inner surface smooth. Outer surface texture densely fibrous or spongy.
Archeopyle. Precingular archeopyle, Type P, comprising paraplate 3’’ only; rounded pentagonal in shape. Operculum free or in place. Wall thinner at margins of archeopyle and operculum.
Surface features. Surface features of various species appear to be quite different. Surface may be smooth or with features of low relief such as granula, rugae and fibrous ridges. Paratabulation of the type species is indicated by narrow parasutural “furrows” flanked by somewhat broader raised bands. Intratabular ornament of the type species consists of parallel rows of small “pits” visible only with SEM (see Damassa 1988: 170).
Surface of outer wall may contain numerous solid rods, forming a complex tegillum which is developed as simulate septal complexes indicating the paratabulation of the cyst (see Willumsen 2004: 121). Paratabulation may be also reflected by short fibrous processes rising from each paraplate (see Willumsen 2004: 124).
Paratabulation. Various species included in the genus Carpatella demonstrate different degrees of paratabulation development. Complete sexiform gonyaulacoid paratabulation of the “Aptiana–Ventriosum complex” of Helenes (1986), indicated by parasutural features, is
manifested in the type species Carpatella cornuta (see Damassa 1988: 170–173). Parasutural features define the following paraplates: 1 preapical (pr), 4 apical (1’–4’), 6 precingular (1’’–6’’), 6 cingulars (1c–6c), 6 sulcals (as, ras, rs, ls, 1’’’, ps), 5 postcingulars (2’’’–6’’’), 1 posterior intercalary (1p) and 1 antapical (1’’’’). The paratabulation formula is 1pr, 4’, 6’’, 6c, 6s, 5’’’, 1p, 1’’’’. The paratabulation pattern is characterised by an L-type ventral configuration.
Stratigraphic age. Latest Maastrichtian– mid Lutetian. R e m a r k s. Species in this genus significantly differ from one another by the degree of development of the paratabulation features, by manifestation of the parasutural and intratabular ornamentation, by the size of the body and apical and antapical horns, and by the visibility (presence?) of the pedium. Some species have no indication of paratabulation (visible under LM), except for the paraplate 3’’ (operculum) and a shallowly furrowed cingulum; their attribution to the genus Carpatella is based on the presence of single apical and antapical horns.
Type species. Carpatella cornuta (Grigorovich 1969) Damassa 1988
[Carpatella, Grigorovich, 1969a, p. 74; Emendations: Fechner and Mohr, 1986, p. 183-184; Damassa, 1988, p. 167- 168, 170, 172, 174-175
Type species: Carpatella cornuta, Grigorovich, 1969a (pl.1, fig.1)]
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Original description: [Gregorovich, 1969]: (Translation: Stover and Evitt, 1978):
Description:
Cyst spherical, sometimes ovate, with one apical and one antapical horn. Transverse furrow circular. Apical aperture open, sometimes closed by a
small plate. Tabulation distinct. Formula of plates 3(?)`, 6", 3p, (5-6```), 1(?)````. Sutures joining plates convex. Surface of plates granular: from finely to coarsely granular, rarely smooth.
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Modified description:
Stover and Evitt, 1978, p. 142-144:
Description:
Shape: Subspherical to ellipsoidal with a short medial protrusion or horn at each pole.
Wall Relationships: Autophragm only.
Wall Features: Low smooth parasutural ridges evidently present on some specimens. Autophragm smooth to granular.
Paratabulation: Indicated by archeopyle and paracingulum and additionally on some individuals by parasutural features. Formula, when paraplates are discernible, given as 3`?, 6", 3c, 5-6```, 1````?.
Archeopyle: Precingular, Type P (3" only); operculum free.
Paracingulum: Indicated by low, parallel, transverse equatorial ridges that are apparently connected (dorsally?) by longitudinal ridges to account for the 3c designated in the paratabulation formula.
Parasulcus: Not indicated.
Size: Intermediate to large.
Affinities:
Carpatella differs from Apteodinium and Millioudodinium in having a short, medial, antapical horn or protrusion.
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Emended descriptions:
Fechner and Mohr, 1986: (Translation Fechner and Mohr, 1986: LPP):
Diagnosis:
Cyst acavate, proximate, sphaeroidal to oval in shape with one apical and one antapical horn. Paratabulation gonyaulacystoid. Epicyst and hypocyst approximately same size, separated by a spiral, hexatabulare paracingulum. Plate boundaries indicated by low ridges. Paratabulation scheme: 0-1pr, 4`, 6``, 6c, 6```, 1p, 1````, Xs. Archeopyle Type P(3``).
Description:
Cyst in shape round to slightly oval with a slim, outstanding apical horn and a usually shorter, sturdier antapical horn. While the apical horn, in gonal position, is build up by the four antapical parasutural ridges, the rounded antapical horn is in intratabular position.
The gonyaulacoid paratabulation is rarely developed completely.
Paratabulation on the hypocyst usually clearer reflected than on the epicyst. Plate boundaries marked by low to moderate high, smooth or denticulate ridges. The hexatabulare paracingulum is staggered at the parasulcus. In the parasulcal area, several partial developed paraplates are visible. Autopraghm only.
Size intermediate to large.
Affinities:
Carpatella differs from Cribroperidinium Neale and Sarjeant, 1962; emend. Davey 1969 in having an antapical horn and lacking accessory, subparallel to parasutures running ridges. Kenleya Cookson and Eisenack, 1965, a genus with two polar horns, too, has in contrast to Carpatella no defined paratabulation but high ridges.
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Damassa, 1988:
Synopsis:
Proximate cysts, subspherical to ellipsoidal in shape, having a short horn at apex and antapex. Sexiform gonyaulacacean paratabulation indicated by parasutural features. Ventral organization L-type. Apical paraplate A (4`) contacts B (2`) dorsal to preapical P; paraplate Q is absent; precingular li (6") contacts both A and lu (1`); Iu (1```) and II (2```) relatively small, ai (as) contacts Il (2```), Iu (1```) does not contact au (Ic); X (Ip) and Z (ps) elongate, arcuate; antapical Y (1````) slightly asymmetrical-oblong; postcingular parasuture IV/V (4```/ 5```) offset to the left of precingular parasuture 4/5 (3"/4"). Archeopyle precingular, Type P, precingular 4 (3") only, with rounded pentagonal margin; operculum free. Wall consists of autophragm only, outer part densely fibrous or spongy in appearance, inner surface of wall smooth. Porichnion visible between apical paraplates A and lu with SEM.
Description:
Shape: Cysts subspherical to ellipsoidal in ventro-dorsal or lateral view, with single short horns at apex and antapex; approximately circular in polar view; slight indentation in sulcal region. Horns are solid structures formed from densely fibrous, spongy wall material, not by protrusion of the entire wall, nor by coalescing parasutural features (Plate 1, figs. 5, 9).
Wall structure: Cysts proximate and acavate, wall consisting of autophragm only. Surface texture densely fibrous; in cross section wall appears spongy, having a smooth inner surface (Plate 3, fig. 3; see arrow). There is a discontinuity within the wall, but no obvious change in texture. Wall thickness approximately 5-8 µm.
Archeopyle: Precingular archeopyle, Type P, consisting of paraplate 4 (3") only; rounded pentagonal in shape and may be slightly enlarged. Operculum free. Wall is distinctly thinner at margins of archeopyle and operculum (Plate 1, figs. 2, 3).
Surface features: Paratabulation indicated by narrow parasutural "furrows" flanked by somewhat broader raised bands (Plate 1, fig. 6; Plate 3, fig. 4). Intratabular ornament consists of parallel rows of small "pits" visible with SEM on some specimens, generally restricted to larger paraplates (e.g., Plate 3, figs. 1, 2; compare with intratabular ridges of Cribroperidinium).
Paratabulation: A complete sexiform gonyaulacoid paratabulation, essentially equivalent to the Ventriosum pattern, Aptiana-Ventriosum complex, of Helenes (1986), is indicated by parasutural features (Text-Figure 3): I preapical (P = pr); 4 apicals (lu, A, B, C = 1`-4`); 6 precingulars (2, 3, 4, 5, 6, and li = 1"-6"); 6 cingulars (au, b, c, d, e, and fi = 1c-6c); 6 sulcals (ai, fu, Ii, Im, Iu and Z = as, ras, rs, ls, 1``` and ps); S postcingulars (II, III, IV, V, and VI = 2```-6```); 1 posterior intercalary (X = lp); and 1 antapical (Y = 1````). In Kofoidian terms the paratabulation formula is: lpr, 4`, 6", 6c, 6s, 5```, 1p, 1````. The paratabulation pattern is characterized by an L-type ventral configuration. Apical paraplates A and B (4` and 2`) are in contact dorsal to P; Q is not present. Paraplates lu and li (1` and 6") are in contact in the ventral region (li is camerate and also contacts A; ai is planate). Paraplates lu and A are elongate, and a porichnion can be observed with the SEM on the edge of lu adjacent to the lu/A parasuture (Plate 2, fig. 3). In the sulcal region, most specimens of Carpatella exhibit a configuration in which paraplate ai (as) contacts II (2```), but Iu (1```) does not contact au (1c); thus Iu is not a postcingular paraplate (in the strict Kofoidian sense) because it does not contact the paracingulum. The length of the ai/II (as/2"`) contact is variable (see Plate 1, figs. 1, 4; Plate 2, figs. 2, 6; Text-Figure 3A), and several specimens were observed with a four-way contact between paraplates ai, II, Iu and au. In contrast, most species having a Ventriosum pattern are characterized by a contact between paraplates Iu and au. In Carpatella, as in other species having the Ventriosum pattern, Iu and II are relatively small, the remaining postcingular paraplates (III-VI or 3```-6```) are distinctly larger. Postcingular parasuture IV/V is offset to the left of precingular parasuture 4/5, but does not attain a truly mid-dorsal position. Antapical paraplate Y (1````) is slightly asymmetrical-oblong, contacting paraplates X (1p), Z (ps) and III-VI (3```-6```). Antapical parasutures Y/X, Y/Z and Y/VI are relatively short, and may be nearly colinear. Parasuture Y/V is only slightly longer than Y/III (see Helenes, 1986, p. 78-79).
Size:
Intermediate to large. Length of cysts approximately 100-130 µm, including horns (length of horns approximately 10-18 µm); equatorial diameter approximately 90-100 µm.
Affinities:
Carpatella is not alone in having six sulcal and only five postcingular paraplates (speaking in the strict Kofoidian sense). The ai/II contact, which eliminates Iu from the ranks of the postcingular paraplates, also occurs in all species assigned to Ctenidodinium, Leptodinium, Occisucysta, Tehamadinium and Korystocysta, in Gonyaulacysta dualis (Helenes, 1986), and in several species of Hystrichokolpoma (Damassa et al., 1987). At present Carpatella is a monotypic genus. It has been distinguished from Apteodinium, which is similar in overall appearance (e.g. shape, wall texture, size), on the basis of the presence of both apical and antapical horns (Stover and Evitt, 1978, p. 144). In addition, species of Apteodinium tend to lack clear evidence of paratabulation (Stover and Evitt, 1978); however, see Lucas-Clark (1987) for a partial Aptiana-Ventriosum paratabulation scheme. It is apparent that Carpatella cornuta possesses features of paratabulation, archeopyle and wall structure nearly identical to species of Cribroperidinium (Helenes, 1984). The two genera may be distinguished on the basis of the development of a second (antapical) horn in Carpatella and in the morphologic details by which the paratabulation is expressed (parasutural furrows and intratabular "pits" in Carpatella, parasutural ridges and intratabular ridges in Cribroperidinium). The only difference in paratabulation observed between these genera is in the configuration of the ai/ II-Iu/au contacts (Iu/au in Cribroperidinium, ai/II in most specimens of C. cornuta).
----------------------------------------
Discussion: Damassa, 1988:
Several recent studies of Maastrichtian and Danian dinoflagellate assemblages in southern Scandinavia have focused on biostratigraphy and paleoecology (Hansen, 1977, 1979; Kjellstrom and Hansen, 1981; Hultberg, 1985, 1986; Thomsen and Heilmann-Clausen, 1985). The strata in which these assemblages occur have gained further attention in the last few years due to the intense interest in the Cretaceous/Tertiary boundary and associated extinction events (e.g. Alvarez et al., 1980). Carpatella cornuta Grigorovich, 1969 is a form characteristic of basal Paleocene (Danian) deposits; indeed, Hansen (1977, p. 7) named a zonule for this species. Despite the recognition of C. cornuta as an important boundary marker, its morphologic details have received little attention, due in part to its large sizeand distinctive shape, which permit identification even at low magnifications. Grigorovich`s original illustrations and description (1969, p. 74-76) indicate gonyaulacacean affinities, but the paratabulation formula given is incomplete. Stover and Evitt (1978, p. 144- 145) modified the original description of Carpatella, but without the original material in hand, were unable to provide a complete analysis. Fechner and Mohr (1986) recently published a revised description based on specimens attributed to Carpatella from the Eocene of South Morocco; however, the identification of their specimens is uncertain.
Unusually well-preserved specimens from several localities in southwestern Sweden and southeastern Denmark (Text-Figure 1) are herein analyzed in detail with both light and scanning electron microscopy. The paratabulation pattern is clearly visible, and is identical in nearly all respects to that of forms included in the Aptiana-Ventriosum complex (Ventriosum pattern) by Helenes (1986). The reader also is referred to Helenes (1984) for detailed discussion of Cribroperidinium, and to Damassa (1984), Damassa et al. (1987) and Lucas-Clark (1987) for discussions of other forms belonging to the Aptiana -Ventriosum complex. The critical and characteristic features of dinoflagellates in this complex include: asymmetrical-oblong antapical Y (1````); postcingular parasuture IV/V (4```/5```) offset to the left of precingular parasuture 4/5 (3"/4"); apicals A/B (4`/2`) in contact dorsal to preapical P; precingular li (6") camerate, and in contact with apicals A and lu (4` and 1`); anterior sulcal ai (as) planate, in contact anteriorly only with lu; posterior intercalary X and posterior sulcal Z elongate, arcuate; lu (1```) and II(2```) relatively small, III-VI (3```-6```) distinctly larger.
Since Grigorovich`s original description of Carpatella cornuta in 1969, there have been relatively few occurrences reported in the literature. Specimens illustrated by Morgenroth (1968, p. 542544, pl. 44, figs. 1-3) and Evitt (1973, p. 34, pl. 1, figs. 12-14) were identified as "Danea mutabilis." Other occurrences reported as Carpatella cornuta include those by Hansen (1977, pl. 7, fig. 21 F; 1979, p. 137, fig 5), Hultberg (1985, p. 61, pl. 1, figs. 3, 4, p. 112,pl.2,fig.C; 1986,p.38,pl. 1,figs.3,4),and Firth (1987, pl. 3, fig. 6). I am certain that Hansen`s, Hultberg`s and Firth`s specimens are conspecific with my material, and am reasonably confident of the identification of Morgenroth`s and Evitt`s specimens as C. cornuta; however, I have serious doubts regarding the identity of those specimens described as C. cornuta by Fechner and Mohr (1986, p. 181188, figs. 2, 3). Although their description corresponds fairly well in general terms to my concept of Carpatella, there are several differences in details of morphology and paratabulation between their specimens and those described here (see Fechner and Mohr, 1986, fig. 3). The apical horn is described as having formed from four apical parasutural crests, in contrast to the simple structure illustrated here. Also, the denticulate crests ("Kamme") noted by Fechner and Mohr (1986, p. 184) have not been reported in other specimens assigned to Carpatella, and are certainly not evident in the material used in this study.
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Iakovleva, 2019
Emended diagnosis. Subspherical to ellispoidal proximate cysts, having a short horn at apex and antapex. Sexiform gonyaulacacean paratabulation is expressed to varying degrees in different species and indicated by parasutural features. Ventral organisation L-type. Archeopyle precingular, Type P, comprising precingular paraplate 3” only, with rounded pentagonal margin; operculum free or in place. Wall consisting of two layers: pedium, mostly invisible, extremely thin and smooth; luxuria solid, densely fibrous or spongy. Surface of outer layer may be smooth, with features of low relief or ornamented by intratabular processes and penitabular septa.
Emended description.
Shape. Cysts subspherical to ellipsoidal in ventro-dorsal or lateral view, with single and very short to intermediate horns at apex and antapex; approximately circular in polar view; slight indentation in sulcal region is observed in the type species. Horns are solid structures formed from densely fibrous, spongy wall material.
Size. Intermediate to large. Length of cysts ~69–130 μm, including horns (length of horns ~4–20 μm); equatorial diameter ~68–100 μm. Wall structure. Cyst proximate, acavate, wall consisting of two layers: pedium extremely thin and smooth, very rarely observed only in antapical area. Inner and outer layers so tightly compressed that the pedium is not visible in most cases. Inner surface smooth. Outer surface texture densely fibrous or spongy.
Archeopyle. Precingular archeopyle, Type P, comprising paraplate 3’’ only; rounded pentagonal in shape. Operculum free or in place. Wall thinner at margins of archeopyle and operculum.
Surface features. Surface features of various species appear to be quite different. Surface may be smooth or with features of low relief such as granula, rugae and fibrous ridges. Paratabulation of the type species is indicated by narrow parasutural “furrows” flanked by somewhat broader raised bands. Intratabular ornament of the type species consists of parallel rows of small “pits” visible only with SEM (see Damassa 1988: 170).
Surface of outer wall may contain numerous solid rods, forming a complex tegillum which is developed as simulate septal complexes indicating the paratabulation of the cyst (see Willumsen 2004: 121). Paratabulation may be also reflected by short fibrous processes rising from each paraplate (see Willumsen 2004: 124).
Paratabulation. Various species included in the genus Carpatella demonstrate different degrees of paratabulation development. Complete sexiform gonyaulacoid paratabulation of the “Aptiana–Ventriosum complex” of Helenes (1986), indicated by parasutural features, is
manifested in the type species Carpatella cornuta (see Damassa 1988: 170–173). Parasutural features define the following paraplates: 1 preapical (pr), 4 apical (1’–4’), 6 precingular (1’’–6’’), 6 cingulars (1c–6c), 6 sulcals (as, ras, rs, ls, 1’’’, ps), 5 postcingulars (2’’’–6’’’), 1 posterior intercalary (1p) and 1 antapical (1’’’’). The paratabulation formula is 1pr, 4’, 6’’, 6c, 6s, 5’’’, 1p, 1’’’’. The paratabulation pattern is characterised by an L-type ventral configuration.
Stratigraphic age. Latest Maastrichtian– mid Lutetian. R e m a r k s. Species in this genus significantly differ from one another by the degree of development of the paratabulation features, by manifestation of the parasutural and intratabular ornamentation, by the size of the body and apical and antapical horns, and by the visibility (presence?) of the pedium. Some species have no indication of paratabulation (visible under LM), except for the paraplate 3’’ (operculum) and a shallowly furrowed cingulum; their attribution to the genus Carpatella is based on the presence of single apical and antapical horns.
Type species. Carpatella cornuta (Grigorovich 1969) Damassa 1988