Back
Callaiosphaeridium bicoronatum
Figs. 11, 12, Pl. 4, figs. 13–19, Pl. 5, figs. 1–18.
? 2000 Callaiosphaeridium asymmetricum (Deflandre and Courteville 1939) Davey and Williams 1966b – Slimani: pl. 7, figs. 9, 10.
? 2001a Callaiosphaeridium asymmetricum (Deflandre and Courteville 1939) Davey and Williams 1966b – Slimani: pl. 3, fig. 11.
? 2011 Callaiosphaeridium asymmetricum (Deflandre and Courteville 1939) Davey and Williams 1966b – Slimani, Louwye, Dusar, Lagrou: fig. 5 m. 2018b Callaiosphaeridium sp. A – Niechwedowicz: p. 63.
Derivation of name: From the Latin bi = two and corona = crown, with reference to the two, apical and antapical crown- like structures, formed by slender gonal processes connected by high sutural septa with distal thickenings and crests.
Holotype: Fig. 11, Pl. 5, figs. 1–10; Piotrawin quarry, sample PN81; slide MWGUW ZI/90/PN81/0a; slide co-ordinates: 16/12.2, EF: M32/1; housed at the S. J. Thugutt Geological Museum, Faculty of Geology, University of Warsaw, Warsaw, Poland.
Type locality and horizon: Piotrawin quarry, central Poland (51° 05' 37" N, 21° 48' 06" E), topmost part of the outcrop; mid-upper Campanian (high “Inoceramus” inkermanensis Zone).
Diagnosis: Callaiosphaeridium species with distinct sutural septa of constant height, consistently connecting slender solid gonal processes occupying epi- and hypocyst. Each septum with distal thickening (transverse solid ridge parallel to plate suture), surmounted with numerous short spines incorporated into low crests. Network of slender processes connected by septa with distal thickenings and crests forming continuous rings around plates at apex and antapex, giving polar cyst ornament crown-like appearance. Tabulation well-expressed, indicated by sutural features (ridges and septa) and gonal processes. Operculum commonly attached (ventrally).
Description: Chorate cysts with subspheroidal to ovoidal central body, bearing gonal (processes) and sutural (ridges and high septa) features; suturocavate. Cyst fragile, central body wall very thin (c. 0.2–0.5 μm), homogeneous in structure, with indistinguishable layering. Internal wall surface smooth, rugulate ornament externally (appearance of wrinkled skin of withered fruit), covering most of the plate areas; plate margins smooth, commonly with lines of perforations parallel to plate boundaries; septa and tubular processes very thin-walled (c. 0.1–0.3 μm) and smooth. Processes of two types: (1) six equatorial tubular processes, and (2) slender, solid processes, occasionally furcate, located elsewhere on epi- and hypocyst excluding cingulum. Equatorial processes tubiform with oval to elliptical cross-sections (wider in equatorial plane), bearing three to four well- developed longitudinal striae extended from cingular and postcingular sutural ridges. Equatorial processes distally flared, and terminate with very fragile and low (c. 3 μm) crests with numerous incorporated short spines (not longer than crests); rarely with a few fragile moustache-like spines (c. 7 μm in length) arising from outer surface of process wall near its distal margin. Apex and antapex occupied by crown- like structures, formed from slender gonal processes connected by a constant height septa network, forming continuous rings outlining particular plates at apex (1', 2', 3', 4'), and at antapex (1'''', 1p); height of septa comparable with slender process length. Distally each septum supported by thickening (transverse solid ridge parallel to suture, connecting slender process tips), surmounted by low (c. 3 μm) crests with numerous incorporated short spines (crests with spines similar to those terminating equatorial processes). Apical and antapical crown-like structures often connected with equatorial processes by sutural septa of unequal height (height decreasing toward the equatorial processes), partially supported by distal thickenings; equatorial processes occasionally interconnected by low septa. Tabulation formula 4', 6'', 6c, 6''', 1p, 5s (ps, ls, rs, ras, as), 1'''', well-demonstrated by distribution of gonal processes, sutural ridges, and septa. Sutural ridges between plates 1' and 4' may be reduced; ridges outlining plate 1''' and sulcal plates may be reduced or absent. Cingulum relatively narrow, laevorotatory, shifted by one cingulum width. Archeopyle epicystal (formula A1–4' + P1–6''), operculum commonly attached.
Dimensions: Holotype: Central body length (operculum attached): 59 μm, central body width: 55 μm, equatorial process length: 25 μm, slender process length: 17 μm, septa height: 17 μm, height of crests crowning septa: 4 μm. Range: Central body length (operculum attached): 43 (53.8)64 μm, central body width: 39(49.6)61 μm, equatorial process length: 19(25.7)33 μm, slender process length: 12 (16.9)24 μm, septa height: 12(16.9)24 μm, height of crests crowning septa: 3(3.5)5 μm (33 specimens measured).
Discussion: Callaiosphaeridium bicoronatum sp. nov. is a thin-walled (see Pl. 4, fig. 19), very fragile species. Its fragility is particularly manifest under SEM: all specimens mounted in glycerin jelly and viewed under TLM show 3-D preservation, while those observed under SEM are collapsed and folded (Pl. 4, figs. 17–19, Pl. 5, figs. 13–18). The SEM study proves that the central body wall is externally rugulate (Pl. 5, figs. 14–16) (under TLM the ornament can appear to be granular, scabrate, or foveolate). As in C. asymmetricum, the rugulate ornament disappears near plate margins, where the wall surface is smooth and regularly perforate (lines of perforations parallel to the plate boundaries; Pl. 5, figs. 14–16). The presence of perforations, and the occasional breakage of the sutural ridges and septa to reveal hollow cavities, substantiates the suturocavate nature of the sutural features. The low crests with numerous spines that surmount septa (Pl. 5, figs. 4, 5, 12, 14, 15) and equatorial processes (Pl. 5, fig. 15) are prone to mechanical damage, and are not always preserved. The distal thickenings of septa (transverse ridges parallel to plate sutures; see Pl. 4, fig. 16, Pl. 5, figs. 2, 4–8, 11, 12, 14, 15) strengthen the construction of the apical and antapical crown-like structures. Consequently, this ornament can easily be identified, even in damaged specimens. A comparison with the slender processes in C. asymmetricum (namely, the presence of trifid process branches more or less perpendicular to process stem and parallel to sutures) suggests that the slender processes in C. bicoronatum sp. nov. may also be viewed as furcate processes. Then, the thickenings distally supporting septa could be interpreted as having formed from merged neighboring furcated process tips. The sutural ridges separating the first and fourth apical plates, and some of the ridges demarcating the plates in the sulcal region (plates 1''', ls, and ras), are commonly incompletely developed or absent. Rarely, the arrangement of ridges in the sulcus reveals the presence of the flagellar pore, surrounded by plates 1''', ls, ras, and as (Pl. 5, figs. 9, 10). The slender gonal processes typically occupy positions 6'''/ras/rs and 6'''/6c/ras and are accompanied by high septa, but are not connected to the antapical crown-like structure (see Fig. 11).
Remarks: Callaiosphaeridium asymmetricum in Slimani (2000, pl. 7, figs. 9, 10, 2001a, pl. 3, fig. 11) and Slimani et al. (2011, fig. 5m), with slender gonal processes connected by high septa that form crown-like structures at the cyst poles, closely resembles C. bicoronatum sp. nov. However, the actual relationship of those forms to C. bicoronatum sp. nov. requires further study. Callaiosphaeridium asymmetricum (Deflandre and Courteville 1939) Davey and Williams 1966b, differs from C. bicoronatum sp. nov. in having U-shaped, relatively low sutural septa in the spaces between the processes. In C. bicoronatum sp. nov., the septa are of constant height and supported by distal thickenings that bear low crests with numerous incorporated spines. Like C. asymmetricum, the equatorial processes in C. bicoronatum sp. nov. may also bear the “moustache-like” spines; however, in the new species these are more fragile and consequently rarely preserved. Furthermore, the equatorial processes in C. asymmetricum lack distal crests with incorporated spines, which is a characteristic feature of C. bicoronatum sp. nov. The operculum in C. bicoronatum sp. nov. is also more commonly attached than that in C. asymmetricum. Callaiosphaeridium trycherium Duxbury 1980 can be distinguished from C. bicoronatum sp. nov. through its irregular sutural septa and taeniate sutural processes. Callaiosphaeridium scabratum Khowaja-Ateequzzaman and Garg 2004 differs from C. bicoronatum sp. nov. in the form of its relatively short and broad equatorial processes (length ≈ width; see Khowaja-Ateequzzaman and Garg 2004, p. 100, 102). Furthermore, in C. scabratum the apical region is not subdivided by sutural ridges into separate plates, rather forming a “pentagon” (Khowaja-Ateequzzaman and Garg 2004, p. 100, pl. 1, fig. 7).
Recorded stratigraphic range: Middle upper Campanian–lowermost Maastrichtian, upper-third “Inoceramus” inkermanensis Zone – lower “Inoceramus” redbirdensis Zone (recorded from Kłudzie North, Kłudzie South, Piotrawin, Podole, Raj, and Raj North).
Other possible occurrences: Belgium: Turnhout borehole, sample –933 m (upper Campanian, Areoligera coronata Zone of Slimani 2001a) – as Callaiosphaeridium asymmetricum in Slimani (2000, pl. 7, figs. 9, 10, 2001a, pl. 3, fig. 11); Meer borehole, sample 1089 m (lower upper Campanian, Exochosphaeridium? masureae Zone of Slimani 2001a) – as Callaiosphaeridium asymmetricum in Slimani et al. (2011, fig. 5 m).
? 2000 Callaiosphaeridium asymmetricum (Deflandre and Courteville 1939) Davey and Williams 1966b – Slimani: pl. 7, figs. 9, 10.
? 2001a Callaiosphaeridium asymmetricum (Deflandre and Courteville 1939) Davey and Williams 1966b – Slimani: pl. 3, fig. 11.
? 2011 Callaiosphaeridium asymmetricum (Deflandre and Courteville 1939) Davey and Williams 1966b – Slimani, Louwye, Dusar, Lagrou: fig. 5 m. 2018b Callaiosphaeridium sp. A – Niechwedowicz: p. 63.
Derivation of name: From the Latin bi = two and corona = crown, with reference to the two, apical and antapical crown- like structures, formed by slender gonal processes connected by high sutural septa with distal thickenings and crests.
Holotype: Fig. 11, Pl. 5, figs. 1–10; Piotrawin quarry, sample PN81; slide MWGUW ZI/90/PN81/0a; slide co-ordinates: 16/12.2, EF: M32/1; housed at the S. J. Thugutt Geological Museum, Faculty of Geology, University of Warsaw, Warsaw, Poland.
Type locality and horizon: Piotrawin quarry, central Poland (51° 05' 37" N, 21° 48' 06" E), topmost part of the outcrop; mid-upper Campanian (high “Inoceramus” inkermanensis Zone).
Diagnosis: Callaiosphaeridium species with distinct sutural septa of constant height, consistently connecting slender solid gonal processes occupying epi- and hypocyst. Each septum with distal thickening (transverse solid ridge parallel to plate suture), surmounted with numerous short spines incorporated into low crests. Network of slender processes connected by septa with distal thickenings and crests forming continuous rings around plates at apex and antapex, giving polar cyst ornament crown-like appearance. Tabulation well-expressed, indicated by sutural features (ridges and septa) and gonal processes. Operculum commonly attached (ventrally).
Description: Chorate cysts with subspheroidal to ovoidal central body, bearing gonal (processes) and sutural (ridges and high septa) features; suturocavate. Cyst fragile, central body wall very thin (c. 0.2–0.5 μm), homogeneous in structure, with indistinguishable layering. Internal wall surface smooth, rugulate ornament externally (appearance of wrinkled skin of withered fruit), covering most of the plate areas; plate margins smooth, commonly with lines of perforations parallel to plate boundaries; septa and tubular processes very thin-walled (c. 0.1–0.3 μm) and smooth. Processes of two types: (1) six equatorial tubular processes, and (2) slender, solid processes, occasionally furcate, located elsewhere on epi- and hypocyst excluding cingulum. Equatorial processes tubiform with oval to elliptical cross-sections (wider in equatorial plane), bearing three to four well- developed longitudinal striae extended from cingular and postcingular sutural ridges. Equatorial processes distally flared, and terminate with very fragile and low (c. 3 μm) crests with numerous incorporated short spines (not longer than crests); rarely with a few fragile moustache-like spines (c. 7 μm in length) arising from outer surface of process wall near its distal margin. Apex and antapex occupied by crown- like structures, formed from slender gonal processes connected by a constant height septa network, forming continuous rings outlining particular plates at apex (1', 2', 3', 4'), and at antapex (1'''', 1p); height of septa comparable with slender process length. Distally each septum supported by thickening (transverse solid ridge parallel to suture, connecting slender process tips), surmounted by low (c. 3 μm) crests with numerous incorporated short spines (crests with spines similar to those terminating equatorial processes). Apical and antapical crown-like structures often connected with equatorial processes by sutural septa of unequal height (height decreasing toward the equatorial processes), partially supported by distal thickenings; equatorial processes occasionally interconnected by low septa. Tabulation formula 4', 6'', 6c, 6''', 1p, 5s (ps, ls, rs, ras, as), 1'''', well-demonstrated by distribution of gonal processes, sutural ridges, and septa. Sutural ridges between plates 1' and 4' may be reduced; ridges outlining plate 1''' and sulcal plates may be reduced or absent. Cingulum relatively narrow, laevorotatory, shifted by one cingulum width. Archeopyle epicystal (formula A1–4' + P1–6''), operculum commonly attached.
Dimensions: Holotype: Central body length (operculum attached): 59 μm, central body width: 55 μm, equatorial process length: 25 μm, slender process length: 17 μm, septa height: 17 μm, height of crests crowning septa: 4 μm. Range: Central body length (operculum attached): 43 (53.8)64 μm, central body width: 39(49.6)61 μm, equatorial process length: 19(25.7)33 μm, slender process length: 12 (16.9)24 μm, septa height: 12(16.9)24 μm, height of crests crowning septa: 3(3.5)5 μm (33 specimens measured).
Discussion: Callaiosphaeridium bicoronatum sp. nov. is a thin-walled (see Pl. 4, fig. 19), very fragile species. Its fragility is particularly manifest under SEM: all specimens mounted in glycerin jelly and viewed under TLM show 3-D preservation, while those observed under SEM are collapsed and folded (Pl. 4, figs. 17–19, Pl. 5, figs. 13–18). The SEM study proves that the central body wall is externally rugulate (Pl. 5, figs. 14–16) (under TLM the ornament can appear to be granular, scabrate, or foveolate). As in C. asymmetricum, the rugulate ornament disappears near plate margins, where the wall surface is smooth and regularly perforate (lines of perforations parallel to the plate boundaries; Pl. 5, figs. 14–16). The presence of perforations, and the occasional breakage of the sutural ridges and septa to reveal hollow cavities, substantiates the suturocavate nature of the sutural features. The low crests with numerous spines that surmount septa (Pl. 5, figs. 4, 5, 12, 14, 15) and equatorial processes (Pl. 5, fig. 15) are prone to mechanical damage, and are not always preserved. The distal thickenings of septa (transverse ridges parallel to plate sutures; see Pl. 4, fig. 16, Pl. 5, figs. 2, 4–8, 11, 12, 14, 15) strengthen the construction of the apical and antapical crown-like structures. Consequently, this ornament can easily be identified, even in damaged specimens. A comparison with the slender processes in C. asymmetricum (namely, the presence of trifid process branches more or less perpendicular to process stem and parallel to sutures) suggests that the slender processes in C. bicoronatum sp. nov. may also be viewed as furcate processes. Then, the thickenings distally supporting septa could be interpreted as having formed from merged neighboring furcated process tips. The sutural ridges separating the first and fourth apical plates, and some of the ridges demarcating the plates in the sulcal region (plates 1''', ls, and ras), are commonly incompletely developed or absent. Rarely, the arrangement of ridges in the sulcus reveals the presence of the flagellar pore, surrounded by plates 1''', ls, ras, and as (Pl. 5, figs. 9, 10). The slender gonal processes typically occupy positions 6'''/ras/rs and 6'''/6c/ras and are accompanied by high septa, but are not connected to the antapical crown-like structure (see Fig. 11).
Remarks: Callaiosphaeridium asymmetricum in Slimani (2000, pl. 7, figs. 9, 10, 2001a, pl. 3, fig. 11) and Slimani et al. (2011, fig. 5m), with slender gonal processes connected by high septa that form crown-like structures at the cyst poles, closely resembles C. bicoronatum sp. nov. However, the actual relationship of those forms to C. bicoronatum sp. nov. requires further study. Callaiosphaeridium asymmetricum (Deflandre and Courteville 1939) Davey and Williams 1966b, differs from C. bicoronatum sp. nov. in having U-shaped, relatively low sutural septa in the spaces between the processes. In C. bicoronatum sp. nov., the septa are of constant height and supported by distal thickenings that bear low crests with numerous incorporated spines. Like C. asymmetricum, the equatorial processes in C. bicoronatum sp. nov. may also bear the “moustache-like” spines; however, in the new species these are more fragile and consequently rarely preserved. Furthermore, the equatorial processes in C. asymmetricum lack distal crests with incorporated spines, which is a characteristic feature of C. bicoronatum sp. nov. The operculum in C. bicoronatum sp. nov. is also more commonly attached than that in C. asymmetricum. Callaiosphaeridium trycherium Duxbury 1980 can be distinguished from C. bicoronatum sp. nov. through its irregular sutural septa and taeniate sutural processes. Callaiosphaeridium scabratum Khowaja-Ateequzzaman and Garg 2004 differs from C. bicoronatum sp. nov. in the form of its relatively short and broad equatorial processes (length ≈ width; see Khowaja-Ateequzzaman and Garg 2004, p. 100, 102). Furthermore, in C. scabratum the apical region is not subdivided by sutural ridges into separate plates, rather forming a “pentagon” (Khowaja-Ateequzzaman and Garg 2004, p. 100, pl. 1, fig. 7).
Recorded stratigraphic range: Middle upper Campanian–lowermost Maastrichtian, upper-third “Inoceramus” inkermanensis Zone – lower “Inoceramus” redbirdensis Zone (recorded from Kłudzie North, Kłudzie South, Piotrawin, Podole, Raj, and Raj North).
Other possible occurrences: Belgium: Turnhout borehole, sample –933 m (upper Campanian, Areoligera coronata Zone of Slimani 2001a) – as Callaiosphaeridium asymmetricum in Slimani (2000, pl. 7, figs. 9, 10, 2001a, pl. 3, fig. 11); Meer borehole, sample 1089 m (lower upper Campanian, Exochosphaeridium? masureae Zone of Slimani 2001a) – as Callaiosphaeridium asymmetricum in Slimani et al. (2011, fig. 5 m).