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Willeidinium baiocassinum
Willeidinium baiocassinum Feist-Burkhardt 1995a
Holotype: Feist-Burkhardt 1995a: Plate 1, figs. 1-3; Text-Figure 5, fig. 1).
Locus typicus: Upper part of Calcaire a Spongiaires Formation, Port-en-Bessin (West), Normandy, France
Stratum typicum: late Bajocian, Parkinsoni Zone, Bomfordi Subzone.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Willeidinium baiocassinum Feist-Burkhardt, 1995a. From the diagnosis by Feist-Burkhardt (1995a), cysts proximate, subspherical, suturocavate. Endophragm and periphragm closely appressed except for parasutural areas where the raised periphragm forms tunnel-like septa following the paraplate boundaries. Surface between parasutural septa smooth or with randomly distributed grana or verrucae. Parasutures marked by hollow septa, only occasionally perforated, with entire distal rim. Transverse paracingular septa regularly perforated between insertion points of longitudinal paracingular septa. Archeopyle epicystal, type E@, operculum adnate, the epicyst remains generally attached to the hypocyst by an isthmus consisting of the anterior sulcal . Principal archeopyle suture anterior to paracingulum. Sometimes accessory sutures in peri- and endophragm formed between precingular paraplates. Paratabulation entirely indicated by parasutural septa; derived gonyaulacacean as for genus. Distalmost apical paraplate (3') very large and in contact with the anterior sulcal paraplate (A/ai arrangement of Helenes, 1986), probably formed by fusion of 3' and 4'. Anterior intercalary homolog *2a large, reaching the apex. distalmost precingular paraplate(5") subplanate, very large and narrowing towards the parasulcus; probably formed by fusion of standard gonyaulacalean 5" and 6". Paraplate 4" camerate. Precingular paraplates with a “stalk-like” tip at their adcingular border except for 3". Hypocystal paratabulation symmetrical sexiform. Boundary between 4"’ and 5"’ distal in location relative to the boundary between 3" and 4" (sinistral torsion). Paracingulum levorotatory, indicated by parasutural septa, clearly subdivided. Parasulcus subdivided by parasutural septa and marked additionally by a distinct longitudinal parasulcal depression. A flagellar scar is sometimes visible. L- type ventral organization with A/ai arrangement. Size: length 52-62 µm, width 54-65 µm.
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Description: Feist-Burkhardt 1995a, p. 171-174
Cysts proximate, subspherical, suturocavate. Endophragm and periphragm closely appressed except for parasutural areas where the raised periphragm forms tunnel-like septa following the paraplate boundaries. Surface between parasutural septa smooth or with randomly distributed grana or verrucae. Parasutures marked by hollow septa, only occasionally perforated, with entire distal rim. Transverse paracingular septa regularly perforated between insertion points of longitudinal paracingular septa. Archeopyle epicystal, type Ea [= (tAt1tP)a], operculum adnate; the epicyst remains generally attached to the hypocyst by an isthmus consisting of the anterior sulcal paraplate (as); principal archeopyle suture anterior to paracingulum. Sometimes accessory sutures in peri- and endophragm formed between precingular paraplates. Paratabulation entirely indicated by parasutural septa; derived gonyaulacacean, formula: ?2 pr, 3' [1', 2', 3'*(3'+4.')], 2a, 5" [1", 2", 3", 4", 5"*(5"+6")]' 6c, 6"', I p, I "", 6s (see Text-Figure ] ). Distalmost apical paraplate (3') very large and in contact with the anterior sulcal paraplate (as) (A/ai-arrangement of Helenes, 1986), probably formed by fusion of standard gonyaulacalean 3' and 4'. Anterior intercalary homologue *2a large, reaching the apex. Distalmost precingular paraplate (5') subplanate, very large and narrowing towards the parasulcus; probably formed by fusion of standard gonyaulacalean 5" and 6". Paraplate 4" camerate. Precingular paraplates with a "stalk-like" tip at their adcingular border, except for 3" (see Text-Figure 5.2). Hypocystal paratabulation symmetrical sexiform. Boundary between 4"' and 5"' distal in ]ocation re]ative to the boundary between 3 " and 4" (= sinistral torsion of Fensome et a]., 1993). Paracingu]um levorotatory, indicated by parasutural septa, clearly subdivided. Parasulcus subdivided by parasutural septa and marked additionally by a distinct longitudinal parasulcal depression. A flagellar scar is sometimes visible. L- type ventral organization with A/ai-arrangement.
Size. Holotype: length: 52 µm, width: 55 µm Size Range. Length: 52 µm to 62 µm, width: 54 µm to 65 µm (8 specimens measured).
Remarks. The unusual paratabulation of W. baiocassinum is described in detail below.
Comparison. The paratabulation of Willeidinium baiocassinum differs from that of species belonging to other genera in having five precingular paraplatcs, two anterior intercalary homologues, three apical paraplates and an A/ai ventral arrangement (after Helenes,1986). An undescribed species of Willeidinium from the Bajocian - Bathonian of southwest Germany differs from W. baiocassinum in having septa with denticulate rather than smooth crcsts (W. Wille, pers. commun., 1992). Willeidinium baiocassinum may superficially resemble other suturocavate species such as Conyaulacysta centriconnata Riding 1983, Leptoclinium subtile Klement 1960, or species of Impagidinium, but they differ in paratabulation and in archeopyle type. Conyaulacysta, Leptodinium and Impagidinium have a precingular archeopyle, type IP (3").
Occurrence. Late Bajocian (Parkinsoni Zone, Bomfordi Subzone) to early Bathonian (Zigzag Zone, Yeovilensis Subzone) at the Bajocian stratotype, Normandy, France (Feist-Burkhardt,1992), and the late Bajocian Parkinsoni Zone) to early Bathonian (Zigzag Zone) of southwest Germany (W. Wille, pers. commun., 1992). baiocassinum seems to be a good marker species for the latest Bajocian to early Bathonian of Europe.
Paratubulation pattern of Willeidinium Baiocassinum: Feist-Burkhardt 1995a, p. 171-174
The most striking feature in the epicystal paratabulation of W. baiocassinum is the presence of only five precingular paraplates (Text-Figure I ). The precingular paraplates I ", 2", 3" and 4" are of almost equal size. Paraplate 4" is camerate. Paraplate 5" is much larger exceeding half the cyst width in lateral view (Plate 3, fig. 3). It is subplanate, has a straight, non-gabled contact to the adjacent apical paraplate 3" and becomes very narrow towards the ventral side before reaching the parasulcus (as) (Plate I, figs. l, 2; Plate ], figs. 5, 6; Plate 2, fig. 3). Paraplate 5" is presumed to be the result of fusion of the standard gonyaulacalean paraplates 5" and 6" (Text-Figure 1). Towards the apex the cyst shows four well developed paraplates (here labeled 1', 2', *2a and 3') and one very small anterior intercalary paraplate ( I a), anterior to the left-dorsal 3" (Plate 4, fig. 6). Paraplate *2a is equidimensional and only slightly smaller than 2'. Although paraplate *2a reaches the morphological apex, it is here considered to be an anterior intercalary homologue because of its topology, causing a camerate paraplate 4" (see discussion below). The apical paraplates 1', 2' and 3' reach the morphological apex. Paraplate I ' is narrow and elongate. Paraplate 2' is equidimensional and only slightly larger than *2a. Paraplate 3' is the largest paraplate in the apical series. It reaches almost to the paracingulum and has a long contact with the anterior sulcal paraplate (as) (A/ai-arrangement of Helenes, 1986; see Plate l, fig. 1, 2, and Plate 2, fig. 3). Paraplate 3' is presumed to be the result of fusion of the standard gonyaulacalean paraplates 3' and 4' (Text-Figure 1). The apex is formed by a round structure, subdivided by a septum. It corresponds to the first and second preapical paraplates (I and 2pr) (Plate 1, figs. 2, 5, 6, Plate 2, fig. 3). Exact shape, size relationship and contacts to neighboring paraplates has not been determined. Six more or less rectangular paraplates subdivide the paracingulum (Plate l, fig. I; Plate 2, figs. 4, 6). The parasulcal area is straight and clearly subdivided (as, ras, rs, ls, ps). Additionally it shows a distinct longitudinal parasulcal depression (Plate I, figs. I, 2, Plate 2, figs. 4, 5). A flagellar scar is sometimes visible. The ventral organization is of L- type (Evitt, 1985) in the rare combination with an A/ai-arrangement (Helenes, 1986). The hypocystal paratabulation pattern is symmetrical sexiform (Plate 1, figs, I, 3-5, Plate 2, figs. 1, 3, 4, 6; Plate 3, figs. 1, 3; Plate 4, figs. 4, 5). Paraplate 4"' lies in mid-dorsal position. The cyst shows a sinistrally contorted paraplate configuration (Fensome et al ., 1993) . Due to the very large paraplates 3' and 5", the plate boundary between 3" and 4" lies in mid-dorsal position and to the left relative to the plate boundary 4"'/5 "' (See Text-Figure I ) .
Holotype: Feist-Burkhardt 1995a: Plate 1, figs. 1-3; Text-Figure 5, fig. 1).
Locus typicus: Upper part of Calcaire a Spongiaires Formation, Port-en-Bessin (West), Normandy, France
Stratum typicum: late Bajocian, Parkinsoni Zone, Bomfordi Subzone.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Willeidinium baiocassinum Feist-Burkhardt, 1995a. From the diagnosis by Feist-Burkhardt (1995a), cysts proximate, subspherical, suturocavate. Endophragm and periphragm closely appressed except for parasutural areas where the raised periphragm forms tunnel-like septa following the paraplate boundaries. Surface between parasutural septa smooth or with randomly distributed grana or verrucae. Parasutures marked by hollow septa, only occasionally perforated, with entire distal rim. Transverse paracingular septa regularly perforated between insertion points of longitudinal paracingular septa. Archeopyle epicystal, type E@, operculum adnate, the epicyst remains generally attached to the hypocyst by an isthmus consisting of the anterior sulcal . Principal archeopyle suture anterior to paracingulum. Sometimes accessory sutures in peri- and endophragm formed between precingular paraplates. Paratabulation entirely indicated by parasutural septa; derived gonyaulacacean as for genus. Distalmost apical paraplate (3') very large and in contact with the anterior sulcal paraplate (A/ai arrangement of Helenes, 1986), probably formed by fusion of 3' and 4'. Anterior intercalary homolog *2a large, reaching the apex. distalmost precingular paraplate(5") subplanate, very large and narrowing towards the parasulcus; probably formed by fusion of standard gonyaulacalean 5" and 6". Paraplate 4" camerate. Precingular paraplates with a “stalk-like” tip at their adcingular border except for 3". Hypocystal paratabulation symmetrical sexiform. Boundary between 4"’ and 5"’ distal in location relative to the boundary between 3" and 4" (sinistral torsion). Paracingulum levorotatory, indicated by parasutural septa, clearly subdivided. Parasulcus subdivided by parasutural septa and marked additionally by a distinct longitudinal parasulcal depression. A flagellar scar is sometimes visible. L- type ventral organization with A/ai arrangement. Size: length 52-62 µm, width 54-65 µm.
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Description: Feist-Burkhardt 1995a, p. 171-174
Cysts proximate, subspherical, suturocavate. Endophragm and periphragm closely appressed except for parasutural areas where the raised periphragm forms tunnel-like septa following the paraplate boundaries. Surface between parasutural septa smooth or with randomly distributed grana or verrucae. Parasutures marked by hollow septa, only occasionally perforated, with entire distal rim. Transverse paracingular septa regularly perforated between insertion points of longitudinal paracingular septa. Archeopyle epicystal, type Ea [= (tAt1tP)a], operculum adnate; the epicyst remains generally attached to the hypocyst by an isthmus consisting of the anterior sulcal paraplate (as); principal archeopyle suture anterior to paracingulum. Sometimes accessory sutures in peri- and endophragm formed between precingular paraplates. Paratabulation entirely indicated by parasutural septa; derived gonyaulacacean, formula: ?2 pr, 3' [1', 2', 3'*(3'+4.')], 2a, 5" [1", 2", 3", 4", 5"*(5"+6")]' 6c, 6"', I p, I "", 6s (see Text-Figure ] ). Distalmost apical paraplate (3') very large and in contact with the anterior sulcal paraplate (as) (A/ai-arrangement of Helenes, 1986), probably formed by fusion of standard gonyaulacalean 3' and 4'. Anterior intercalary homologue *2a large, reaching the apex. Distalmost precingular paraplate (5') subplanate, very large and narrowing towards the parasulcus; probably formed by fusion of standard gonyaulacalean 5" and 6". Paraplate 4" camerate. Precingular paraplates with a "stalk-like" tip at their adcingular border, except for 3" (see Text-Figure 5.2). Hypocystal paratabulation symmetrical sexiform. Boundary between 4"' and 5"' distal in ]ocation re]ative to the boundary between 3 " and 4" (= sinistral torsion of Fensome et a]., 1993). Paracingu]um levorotatory, indicated by parasutural septa, clearly subdivided. Parasulcus subdivided by parasutural septa and marked additionally by a distinct longitudinal parasulcal depression. A flagellar scar is sometimes visible. L- type ventral organization with A/ai-arrangement.
Size. Holotype: length: 52 µm, width: 55 µm Size Range. Length: 52 µm to 62 µm, width: 54 µm to 65 µm (8 specimens measured).
Remarks. The unusual paratabulation of W. baiocassinum is described in detail below.
Comparison. The paratabulation of Willeidinium baiocassinum differs from that of species belonging to other genera in having five precingular paraplatcs, two anterior intercalary homologues, three apical paraplates and an A/ai ventral arrangement (after Helenes,1986). An undescribed species of Willeidinium from the Bajocian - Bathonian of southwest Germany differs from W. baiocassinum in having septa with denticulate rather than smooth crcsts (W. Wille, pers. commun., 1992). Willeidinium baiocassinum may superficially resemble other suturocavate species such as Conyaulacysta centriconnata Riding 1983, Leptoclinium subtile Klement 1960, or species of Impagidinium, but they differ in paratabulation and in archeopyle type. Conyaulacysta, Leptodinium and Impagidinium have a precingular archeopyle, type IP (3").
Occurrence. Late Bajocian (Parkinsoni Zone, Bomfordi Subzone) to early Bathonian (Zigzag Zone, Yeovilensis Subzone) at the Bajocian stratotype, Normandy, France (Feist-Burkhardt,1992), and the late Bajocian Parkinsoni Zone) to early Bathonian (Zigzag Zone) of southwest Germany (W. Wille, pers. commun., 1992). baiocassinum seems to be a good marker species for the latest Bajocian to early Bathonian of Europe.
Paratubulation pattern of Willeidinium Baiocassinum: Feist-Burkhardt 1995a, p. 171-174
The most striking feature in the epicystal paratabulation of W. baiocassinum is the presence of only five precingular paraplates (Text-Figure I ). The precingular paraplates I ", 2", 3" and 4" are of almost equal size. Paraplate 4" is camerate. Paraplate 5" is much larger exceeding half the cyst width in lateral view (Plate 3, fig. 3). It is subplanate, has a straight, non-gabled contact to the adjacent apical paraplate 3" and becomes very narrow towards the ventral side before reaching the parasulcus (as) (Plate I, figs. l, 2; Plate ], figs. 5, 6; Plate 2, fig. 3). Paraplate 5" is presumed to be the result of fusion of the standard gonyaulacalean paraplates 5" and 6" (Text-Figure 1). Towards the apex the cyst shows four well developed paraplates (here labeled 1', 2', *2a and 3') and one very small anterior intercalary paraplate ( I a), anterior to the left-dorsal 3" (Plate 4, fig. 6). Paraplate *2a is equidimensional and only slightly smaller than 2'. Although paraplate *2a reaches the morphological apex, it is here considered to be an anterior intercalary homologue because of its topology, causing a camerate paraplate 4" (see discussion below). The apical paraplates 1', 2' and 3' reach the morphological apex. Paraplate I ' is narrow and elongate. Paraplate 2' is equidimensional and only slightly larger than *2a. Paraplate 3' is the largest paraplate in the apical series. It reaches almost to the paracingulum and has a long contact with the anterior sulcal paraplate (as) (A/ai-arrangement of Helenes, 1986; see Plate l, fig. 1, 2, and Plate 2, fig. 3). Paraplate 3' is presumed to be the result of fusion of the standard gonyaulacalean paraplates 3' and 4' (Text-Figure 1). The apex is formed by a round structure, subdivided by a septum. It corresponds to the first and second preapical paraplates (I and 2pr) (Plate 1, figs. 2, 5, 6, Plate 2, fig. 3). Exact shape, size relationship and contacts to neighboring paraplates has not been determined. Six more or less rectangular paraplates subdivide the paracingulum (Plate l, fig. I; Plate 2, figs. 4, 6). The parasulcal area is straight and clearly subdivided (as, ras, rs, ls, ps). Additionally it shows a distinct longitudinal parasulcal depression (Plate I, figs. I, 2, Plate 2, figs. 4, 5). A flagellar scar is sometimes visible. The ventral organization is of L- type (Evitt, 1985) in the rare combination with an A/ai-arrangement (Helenes, 1986). The hypocystal paratabulation pattern is symmetrical sexiform (Plate 1, figs, I, 3-5, Plate 2, figs. 1, 3, 4, 6; Plate 3, figs. 1, 3; Plate 4, figs. 4, 5). Paraplate 4"' lies in mid-dorsal position. The cyst shows a sinistrally contorted paraplate configuration (Fensome et al ., 1993) . Due to the very large paraplates 3' and 5", the plate boundary between 3" and 4" lies in mid-dorsal position and to the left relative to the plate boundary 4"'/5 "' (See Text-Figure I ) .