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Wanaea cornucavata
Wanaea cornucavata Feist-Burkhardt and Pross, 1998, p.109–110, pl.3, figs.1–6; pl.4, figs.1–7; pl.8, figs.1–6; pl.13, figs.1–5; pl.14, figs.1–5; pl.16, figs.3–4.
Holotype: Feist-Burkhardt and Pross, 1998, pl.3, figs.1–6; pl.8, figs.1–3; pl.13, figs.1–5.
Age: early Bathonian.
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Original description (Feist-Burkhardt and Pross, 1998):
Wanaea cornucavata sp. nov. (Pl. 3, fig. 1-6, Pl. 4, fig. 1-7, Pl. 8, fig. 1-6, Pl. 13, fig. 1-5, Pl. 14, fig. 1-5, Pl. 16, fig. 3, 4)
?1978 Wanaea acollaris DODEKOVA 1975 - DRUGG, pl. 8, fig. 10.
pars 1985 Energlynia acollaris (DODEKOVA 1975) SARJEANT 1978 - RIDING, PENN & WOOLLAM, pl. 2, fig. 7.
1992 Wanaea sp. - FEIST-BURKHARDT & WILLE, pl. 2, fig. 15.
1998 Wanaea sp. 1 - FEIST-BURKHARDT & MONTEil, pl. 13, figs. 3, 4.
Derivation of name. The specific epithet refers to the prominent cavate antapical horn.
Types:
- Holotype: Slide Porto 5-8, England Finder reference: K24/4 (Pl. 3, fig. 1-6, Pl. 8, fig. 1-3, Pl. 13, fig. 1-5).
- Paratype 1: Slide Porto 5-8, E.F. ref.: H13 (Pl. 4, fig. 1-7, Pl. 8, fig. 4- 6, Pl. 14, fig. 1-5).
- Paratype 2: Slide Porto 5-8, E.F. ref. : L30 (Pl. 16, fig . 3, 4).
Holotype locality and age. Couches de Passage (c), Marnes de Port-en-Bessin Formation, Port-en-Bessin (West), Normandy, France, Early Bathonian, Zigzag Zone, Yeovilensis Subzone. For more information see FEIST-BURKHARDT & MONTEil (1998).
Description. Cysts proximate, cornucavate to holocavate. Hypocyst broadly conical with a short rounded, cavate antapical horn, epicyst lidlike, flat to gently vaulted. Cyst wall composed of two layers, a thin autophragm and a thinner ectophragm. Ectophragm may be irregularly perforated and/or closely pressed to the autophragm. Ectophragm supported by irregularly formed processes of different height and spacing unevenly distributed over the cyst. Ectocoel largest at the antapical horn. Processes supporting the ectophragm near and at the parasutures are higher than in the centre of the paraplates, forming a trabeculate flange at the paracingulum. Archaeopyle epicystal, type Ea. Operculum formed by the entire epicyst, adnate to the hypocyst in the parasulcal area. Paratabulation gonyaulacacean, indistinctly indicated by the alignment of processes along the parasutures. Paracingulum indicated by the archaeopyle margin and a trabeculate, probably posterior, paracingular flange. Parasulcus not indicated or indicated by a parasulcal depression.
Size. Holotype: hypocyst, laterally compressed, including antapical horn, length x breadth: 78 x 83 μm. Breadth of flange: = 4 μm. Size range. Hypocyst, laterally compressed, including antapical horn, length: 68 to 78 μm, breadth: 83 to 90 μm. Breadth of flange: = 3 to 5 μm.
Remarks. The main characteristic features of Wanaea cornucavata sp. nov. are the presence of a cavate antapical horn and the trabeculate paracingular flange. Both features are easily recognized in conventional light microscopy. CLSM of the same specimens revealed the exact nature of the cyst wall, in fact being composed of two wall layers here interpreted as autophragm and ectophragm.
Unfortunately the expression of paratabulation in the examined specimens is too weak and indistinct to allow the determination of the complete paratabulation formula and pattern. Only a few large paraplates on the hypocyst and some precingular paraplates could be determined, indicating a gonyaulacacean paratabulation pattern. A right lateral precingular paraplate, probably paraplate 5", is clearly "stalked", i.e. shows a small elongation at its adcingular border directed to the dorsal side. This is a typical feature for gonyaulacacean cysts observed in genera such as Oissi/iodinium, Ourotrigia, Korystocysta and Willeidinium (FEIST-BURKHARDT, 1995). Wanaea cornucavata sp. nov. is the first species described in the genus Wanaea exhibiting cavation. The paracingular flange is formed by an alignment of stout, about 1 μm broad and up to 4 μm high processes which are connected distally to form a quite regular flange of trabeculae. The thin ectophragm covers these processes. A similar arrangement of aligned processes and covering ectophragm is observed at the parasutures on the hypocyst, although the processes are lower than at the paracingular flange. The specimen figured by DRUGG (1978, pl. 8, fig. 10) in a SEM photomicrograph as Wanaea acollaris DODEKOVA 1975 most probably also belongs to Wanaea cornucavata sp. nov .. The specimen comes from the same sample locality and lithological unit as the material studied herein. In the SEM photomicrograph the cavation is not readily visible, but perforations on the cyst surface, especially near the parasutures and at the antapical horn, indicate the presence of an incomplete ectophragm. The trabeculate paracingular flange is visible on the right lateral face of the cyst in the photo background.
Comparison. Wanaea cornucavata sp. nov. differs from all other species described in the genus Wanaea in being cavate and showing a trabeculate paracingular flange. Wanaea spectabilis (DEFLANDRE & COOKSON 1955) COOKSON & EISENACK 1958 is also described having a narrow cingular flange with radiating processes which are distally connected (FENSOME, 1981, p. 54). After the drawing of WOOLLAM (1982, p. 46, Fig. 1, B iii), who studied topotype material of W spectabilis, the flange is better described as a continuous lace with small round proximal perforations and larger elongate distal perforations rather than trabeculae as in W. cornucavata sp. nov.. W. clathrata COOKSON &.EISENACK 1958, W. digitata COOKSON & EISENACK 1958, W. fimbriata SARJEANT 1961 and W. thysanota WOOLLAM 1982 differ from W cornucavata sp. nov. in having a broader, more distinct and more elaborate lace-like paracingular flange and, if present, an acavate antapical horn. W indotata DRUGG 1978 differs in showing very little ornamentation (" ... smooth with sparsely scattered grana or spinulae", DRUGG, 1978, p. 51), in being acavate and showing none or only a fuzzy rim-like structure at the paracingulum. The original description of W. acollaris DODEKOVA 1975 (DODEKOVA 1975, p. 20, 21) matches quite well with the morphology of W cornucavata sp. nov.. DODEKOVA's description of the ornament at the paracingulum ("Neighbouring spines may join in the proximal and distal ends") may correspond to the trabeculate ornament in W cornucavata which is here called a paracingular flange. However, W acollaris differs in being acavate.
Occurrence. Wanaea cornucavata sp. nov. has so far been reported from France, Germany and England from the Early Bathonian only. Early Bathonian, Zigzag Zone, Yeovilensis Subzone to Tenuiplicatus Zone of the Bajocian stratotype section, Normandy, Western France (FEISTBURKHARDT & MONTEil, 1998; DRUGG, 1978). Early Bathonian (Zigzag Zone) of Southwest Germany (FEIST-BURKHARDT & WILLE, 1992). Early Bathonian, Lower Fuller's Earth Formation, England (RIDING et al. 1985). The species is considered a useful stratigraphic marker for the basal Bathonian with a first appearance datum (FAD) in the Zigzag Zone.
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Holotype: Feist-Burkhardt and Pross, 1998, pl.3, figs.1–6; pl.8, figs.1–3; pl.13, figs.1–5.
Age: early Bathonian.
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Original description (Feist-Burkhardt and Pross, 1998):
Wanaea cornucavata sp. nov. (Pl. 3, fig. 1-6, Pl. 4, fig. 1-7, Pl. 8, fig. 1-6, Pl. 13, fig. 1-5, Pl. 14, fig. 1-5, Pl. 16, fig. 3, 4)
?1978 Wanaea acollaris DODEKOVA 1975 - DRUGG, pl. 8, fig. 10.
pars 1985 Energlynia acollaris (DODEKOVA 1975) SARJEANT 1978 - RIDING, PENN & WOOLLAM, pl. 2, fig. 7.
1992 Wanaea sp. - FEIST-BURKHARDT & WILLE, pl. 2, fig. 15.
1998 Wanaea sp. 1 - FEIST-BURKHARDT & MONTEil, pl. 13, figs. 3, 4.
Derivation of name. The specific epithet refers to the prominent cavate antapical horn.
Types:
- Holotype: Slide Porto 5-8, England Finder reference: K24/4 (Pl. 3, fig. 1-6, Pl. 8, fig. 1-3, Pl. 13, fig. 1-5).
- Paratype 1: Slide Porto 5-8, E.F. ref.: H13 (Pl. 4, fig. 1-7, Pl. 8, fig. 4- 6, Pl. 14, fig. 1-5).
- Paratype 2: Slide Porto 5-8, E.F. ref. : L30 (Pl. 16, fig . 3, 4).
Holotype locality and age. Couches de Passage (c), Marnes de Port-en-Bessin Formation, Port-en-Bessin (West), Normandy, France, Early Bathonian, Zigzag Zone, Yeovilensis Subzone. For more information see FEIST-BURKHARDT & MONTEil (1998).
Description. Cysts proximate, cornucavate to holocavate. Hypocyst broadly conical with a short rounded, cavate antapical horn, epicyst lidlike, flat to gently vaulted. Cyst wall composed of two layers, a thin autophragm and a thinner ectophragm. Ectophragm may be irregularly perforated and/or closely pressed to the autophragm. Ectophragm supported by irregularly formed processes of different height and spacing unevenly distributed over the cyst. Ectocoel largest at the antapical horn. Processes supporting the ectophragm near and at the parasutures are higher than in the centre of the paraplates, forming a trabeculate flange at the paracingulum. Archaeopyle epicystal, type Ea. Operculum formed by the entire epicyst, adnate to the hypocyst in the parasulcal area. Paratabulation gonyaulacacean, indistinctly indicated by the alignment of processes along the parasutures. Paracingulum indicated by the archaeopyle margin and a trabeculate, probably posterior, paracingular flange. Parasulcus not indicated or indicated by a parasulcal depression.
Size. Holotype: hypocyst, laterally compressed, including antapical horn, length x breadth: 78 x 83 μm. Breadth of flange: = 4 μm. Size range. Hypocyst, laterally compressed, including antapical horn, length: 68 to 78 μm, breadth: 83 to 90 μm. Breadth of flange: = 3 to 5 μm.
Remarks. The main characteristic features of Wanaea cornucavata sp. nov. are the presence of a cavate antapical horn and the trabeculate paracingular flange. Both features are easily recognized in conventional light microscopy. CLSM of the same specimens revealed the exact nature of the cyst wall, in fact being composed of two wall layers here interpreted as autophragm and ectophragm.
Unfortunately the expression of paratabulation in the examined specimens is too weak and indistinct to allow the determination of the complete paratabulation formula and pattern. Only a few large paraplates on the hypocyst and some precingular paraplates could be determined, indicating a gonyaulacacean paratabulation pattern. A right lateral precingular paraplate, probably paraplate 5", is clearly "stalked", i.e. shows a small elongation at its adcingular border directed to the dorsal side. This is a typical feature for gonyaulacacean cysts observed in genera such as Oissi/iodinium, Ourotrigia, Korystocysta and Willeidinium (FEIST-BURKHARDT, 1995). Wanaea cornucavata sp. nov. is the first species described in the genus Wanaea exhibiting cavation. The paracingular flange is formed by an alignment of stout, about 1 μm broad and up to 4 μm high processes which are connected distally to form a quite regular flange of trabeculae. The thin ectophragm covers these processes. A similar arrangement of aligned processes and covering ectophragm is observed at the parasutures on the hypocyst, although the processes are lower than at the paracingular flange. The specimen figured by DRUGG (1978, pl. 8, fig. 10) in a SEM photomicrograph as Wanaea acollaris DODEKOVA 1975 most probably also belongs to Wanaea cornucavata sp. nov .. The specimen comes from the same sample locality and lithological unit as the material studied herein. In the SEM photomicrograph the cavation is not readily visible, but perforations on the cyst surface, especially near the parasutures and at the antapical horn, indicate the presence of an incomplete ectophragm. The trabeculate paracingular flange is visible on the right lateral face of the cyst in the photo background.
Comparison. Wanaea cornucavata sp. nov. differs from all other species described in the genus Wanaea in being cavate and showing a trabeculate paracingular flange. Wanaea spectabilis (DEFLANDRE & COOKSON 1955) COOKSON & EISENACK 1958 is also described having a narrow cingular flange with radiating processes which are distally connected (FENSOME, 1981, p. 54). After the drawing of WOOLLAM (1982, p. 46, Fig. 1, B iii), who studied topotype material of W spectabilis, the flange is better described as a continuous lace with small round proximal perforations and larger elongate distal perforations rather than trabeculae as in W. cornucavata sp. nov.. W. clathrata COOKSON &.EISENACK 1958, W. digitata COOKSON & EISENACK 1958, W. fimbriata SARJEANT 1961 and W. thysanota WOOLLAM 1982 differ from W cornucavata sp. nov. in having a broader, more distinct and more elaborate lace-like paracingular flange and, if present, an acavate antapical horn. W indotata DRUGG 1978 differs in showing very little ornamentation (" ... smooth with sparsely scattered grana or spinulae", DRUGG, 1978, p. 51), in being acavate and showing none or only a fuzzy rim-like structure at the paracingulum. The original description of W. acollaris DODEKOVA 1975 (DODEKOVA 1975, p. 20, 21) matches quite well with the morphology of W cornucavata sp. nov.. DODEKOVA's description of the ornament at the paracingulum ("Neighbouring spines may join in the proximal and distal ends") may correspond to the trabeculate ornament in W cornucavata which is here called a paracingular flange. However, W acollaris differs in being acavate.
Occurrence. Wanaea cornucavata sp. nov. has so far been reported from France, Germany and England from the Early Bathonian only. Early Bathonian, Zigzag Zone, Yeovilensis Subzone to Tenuiplicatus Zone of the Bajocian stratotype section, Normandy, Western France (FEISTBURKHARDT & MONTEil, 1998; DRUGG, 1978). Early Bathonian (Zigzag Zone) of Southwest Germany (FEIST-BURKHARDT & WILLE, 1992). Early Bathonian, Lower Fuller's Earth Formation, England (RIDING et al. 1985). The species is considered a useful stratigraphic marker for the basal Bathonian with a first appearance datum (FAD) in the Zigzag Zone.
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