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Mendicodinium mataschenense
Mendicodinium mataschenense Soliman and Feist-Burkhardt in Soliman et al., 2013, p.37,41,43, pl.1, figs.1–9; pl.2, figs.1–9; pl.3, figs.1–12; text-fig.2.
Holotype: Soliman et al., 2013, pl.1, figs.1–3.
Age: Tortonian.
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Original description (Soliman et al., 2013):
Mendicodinium mataschenensis Soliman & Feist-Burkhardt n. sp. Plate 1, figures 1–9; Plate 2, figures 1–9; Plate 3, figures 1–12; Figure 2
Holotype. Plate 1, figures 1–3; England Finder H47/2; sample 20 of core 7, slide B, Mataschen clay pit, Styrian Basin, Austria.
Paratypes. Plate 1, figures 4–6; England Finder H48/3; sample 20 of core 7, slide B, Mataschen clay pit, Styria Basin, Austria.
Repository. The holotype and the type material (residue, rock sample and SEM stubs) are deposited in the Joanneum Museum, Graz, Austria under number UMJ G&P 210901 and UMJ G&P 210902, respectively.
Type locality. Mataschen clay pit near Kapfenstein (Styria, Austria), 158570 3300E/468540 1800N (2.3 km NW of Kapfenstein, 7.7 km SE of Feldbach, Styria, Austria).
Type horizon. Lower part of the Mataschen clay pit (Feldbach Formation, Sieglegg Member; Gross et al. 2008); samples of cores 6 and 7.
Stratigraphic horizon. Early Tortonian (early Pannonian).
Derivation of name. From the type locality near the village of Mataschen, Styria, Austria.
Diagnosis. A small species of Mendicodinium with an autophragm densely ornamented with rugulae of low relief.
Description. A subspherical, proximate and small species of Mendicodinium. The cyst is pale yellow or pale brown and sometimes colorless. The autophragm is thin (less than 0.3 mm) and densely ornamented with non-tabular rugulae of a maximum height of c. 0.5 mm. Three morphologies of the rugulae are observed: closely adjacent short, high and sinuous ridges (Plate 3, figures 1–4); wide ridges of moderate height (Plate 3, figures 5, 8), or partly fused ridges into granules (Plate 3, figure 6). The cyst is dorso-ventrally compressed and some specimens are partially folded or crumpled. The cyst broadens at the cingulum, and the hypocyst is slightly larger than the epicyst. The ‘split’ above the cingulum is spirally arranged, and causes an offset of the ends of the cingulum on the ventral side. The epicyst is slightly pointed at the apex and the hypocyst is flattened at the antapex. There is no indication of horns or bosses. The cingulum may be indicated by a narrow strip of low ornamentation (Plate 3, figure 5) which is, however, rarely observed. The archeopyle is of epicystal type (tEa) with smooth sutures. The operculum is adnate ventrally. Tabulation is indicated only by the archeopyle and, sometimes, by a faintly indicated cingulum (Plate 3, figure 5).
Dimensions. Holotype length 35 µm; width 36 µm. Minimum cyst length: 26.0 µm; maximum cyst length 37.0 µm; mean: 30.5 µm. Minimum cyst width at cingulum: 27 µm; maximum cyst width at cingulum: 41.0 µm; mean: 32.0 µm (Figure 2). 52 specimens measured.
Comparison. Mendicodinium reticulatum Morgenroth 1970, described from the Lower Jurassic (Lias delta) of Germany, is morphologically very close to Mendicodinium mataschenensis. However, Mendicodinium reticulatum is slightly larger (length 45.0– 46.0 µm, 3 specimens; width 41.0–48.0 µm, four specimens; Morgenroth 1970, p. 348) and has a reticulate surface ornamentation. In terms of surface ornamentation, it is similar to Mendicodinium sp. A of Wrenn and Kokinos (1986) from the Middle Miocene, De Soto Canyon, Gulf of Mexico; Mendicodinium mataschenensis is however smaller in size and characterized by an adnate operculum rather than by a free operculum (based on the specimens illustrated in Wrenn and Kokinos 1986; plate 4, figure 3 and plate 10, figure 4). ‘Mendicodinium robustum’ Zevenboom and Santarelli 1995 ex Fensome et al. 2009 from the late Serravallian–early Tortonian, Giammoia-Falconara sections (Caltanissetta Basin), Italy, has a scabrate wall (Zevenboom 1995, p. 159). The wall of Mendicodinium groenlandicum (Pocock & Sarjeant 1972) Davey 1979 from the Middle Jurassic of Greenland is smooth or slightly punctate. Mendicodinium mataschenensis differs from Mendicodinium kemperi Heilmann-Clausen & Thomsen 1995, from the Barremian of Ahlum-1 borehole and Gott clay pit at Sarstedt, Lower Saxony Basin, Germany, by its small cyst width (32.0 mm versus 67.0 mm), in having a uniform type of surface ornamentation, a slightly pointed apex and the absence of sutures (Heilmann-Clausen and Thomsen 1995). With regard to cyst size, Mendicodinium mataschenensis is similar to the Mendicodinium species (Mendicodinium umbriense, Mendicodinium spinosum, Mendicodinium microscabratum and Mendicodinium brunneum) described form the Lower Jurassic of Italy by Bucefalo Palliani et al. (1997). However, it is characterized by its unique rugulate surface ornamentation, and accessory archeopyle sutures have never been observed. Mendicodinium mataschenensis is distinguished form the majority of Mendicodinium species by its small size and the rugulate surface ornamentation. Table 1 illustrates the characteristic morphologic features of Mendicodinium species.
Remarks. Like many dinoflagellate cysts with an epicystal archeopyle, Mendicodinium is also characterized by the separation of the epicyst and hypocyst caused by mechanical fragmentation or degradation. This is not the case for Mendicodinium mataschenensis, where both halves of the cysts are usually still connected ventrally. This may be the result of the more or less parautochthonous sedimentation without major transport and the high sedimentation rate of approximately one centimetre per decade (Gross et al. 2011).
Discussion. Doubts about the systematic affiliation of Mendicodinium species as dinoflagellate cysts have been raised several times. Due to their relatively simple morphology, in particular the proximate cyst shape, low-relief surface ornamentation and the absence of clear tabulation, identification of their dinoflagellate nature is not always certain. Mendicodinium groenlandicum (Pocock & Sarjeant 1972) Davey 1979 was originally described as an acritarch in the genus Thuledinium, before Davey (1979) recognized its dinoflagellate nature and transferred it to the genus Mendicodinium. The simple morphological features of Mendicodinium may have caused confusion, e.g. with some pollen grains such as Inaperturopollenites, especially in case of deformation and/or fragmentation. For example, Schrank (2004) studied specimens of the alleged dinoflagellate cyst Mendicodinium? quadratum Kumar 1987 from the Jurassic Tendaguru Beds in Tanzania. Based on SEM images, he demonstrated clearly that it is actually a monosulcate pollen grain. He emended and transferred the species to the gymnosperm pollen genus Shanbeipollenites Qian Lijun & Wu Jingyun in Qian et al. (1987), emend. Schrank 2004. Mendicodinium is also quite similar in its morphology to the zygospores of zygnematacean green algae, such as the extant species Spirogyra (Chlorophyta). Such zygospores with a fossil record in the Mesozoic and Cenozoic are e.g. Schizophacus (see Ensom et al. 2009). In the case of Mendicodinium mataschenensis n. sp., the cingulum (although occasionally faintly indicated) and the helicoidal, equatorial suture causing an offset of the cingulum on the ventral face are evidence of an epicystal archeopyle with a ventrally adnate operculum, and dispel any doubts of its dinoflagellate affinity.
Comments. Mendicodinium is a widespread genus during the Jurassic and Early Cretaceous. Only few records are known from the Neogene: Mendicodinium robustum Zevenboom & Santarelli in Zevenboom 1995 ex Fensome et al. 2009 is documented from the Miocene of Italy (Zevenboom 1995) and the Scotian Margin (Fensome et al. 2009). Mendicodinium sp. A of Wrenn and Kokinos (1986) is abundant in the Middle Miocene of the Gulf of Mexico, but only rarely found in the Pliocene (Wrenn & Kokinos 1986). Further occurrences are known from the Burdigalian of France (Londeix & Jan du Chêne 1988), the Miocene of the Netherlands (Donders et al. 2009) and the Miocene of ODP Site 1168, off western Tasmania (Brinkhuis et al. 2003). Mendicodinium sp. A of Krijgsman et al. (1995) was described from the Late Miocene of the Gibliscemi Section in Sicily.
Occurrence. The occurrence of Mendicodinium mataschenensis is restricted to only c. 1 m (cores 6, 7) at the base of the Mataschen clay pit outcrop. Interestingly, its occurrence is contemporaneous with the occurrence of the ostracod species Cyprides mataschensis Gross 2008 (see Gross et al. 2008, figure 3). Investigation of samples above and below this horizon revealed the absence of this taxon.
Paleoecology. Most of the Mendicodinium species are described from restricted marine environments. Sarjeant (1972) reported Mendicodinium groenlandicum from a shelf environment of the Callovian in East Greenland, where it comprised 21% of the assemblage. Poulsen (1992) recorded an assemblage dominated by Mendicodinium groenlandicum from Horsens-I borehole (Jurassic, Denmark) and attributed its occurrence to ecological control. He proposed a calm and shallow bay environment with periodic anoxic conditions. High abundance of Mendicodinium reticulatum associated with frequent Chasmatosporites was found by Koppelhus and Nielsen (1994) in the Lower Jurassic of Denmark. As Chasmatosporites is a good indicator for warm to hot, sub-humid environments (Fu et al. 2009), a climatic link may be responsible for the Mendicodinium-dominated assemblages. Unusual dinoflagellate cyst assemblages including Mendicodinium echinatum and Mendicodinium scabratum are typical for the Lower Jurassic Plover Formation in the Timor Sea (north of Australia) which was deposited in a strongly fluvially influenced environment passing upsection into deltaic and shallow marine settings (Riding & Helby 2001). Brackish and shallow water Barremian sediments of Siberia also proved to be rich in Mendicodinium (Pestchevitskaya 2008). More records of abundant Mendicodinium from very shallow, marginal marine environments have been reported (e.g. Feist-Burkhardt & Pittet 1996). Characteristic mass occurrences were even termed ‘Mendicodinium events’ by Poulsen (1996) who considered these events to be indicative for restricted marine conditions. A somewhat comparable Jurassic counterpart to the Miocene section at Mataschen is represented by the Sorthat Beds, Baga˚ Formation from Bornholm, Denmark. These beds are characterized by bioturbated, laminated and crossbedded sands topped by a thin coal seam with rootlets that formed in a brackish lagoon with tidal channels (Koppelhus and Nielsen 1994). Interestingly, both sections yield morphologically very similar specimens of Mendicodinium. In contrast to these findings, Bucefalo Palliani et al. (1997) described Mendicodinium taxa with ammonites and calcareous nannofossils: rich sediments, suggesting normal marine conditions.contrast to these findings, Bucefalo Palliani et al. (1997) described Mendicodinium taxa with ammonites and calcareous nannofossils: rich sediments, suggesting normal marine conditions.
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Holotype: Soliman et al., 2013, pl.1, figs.1–3.
Age: Tortonian.
-------------------------------------------------
Original description (Soliman et al., 2013):
Mendicodinium mataschenensis Soliman & Feist-Burkhardt n. sp. Plate 1, figures 1–9; Plate 2, figures 1–9; Plate 3, figures 1–12; Figure 2
Holotype. Plate 1, figures 1–3; England Finder H47/2; sample 20 of core 7, slide B, Mataschen clay pit, Styrian Basin, Austria.
Paratypes. Plate 1, figures 4–6; England Finder H48/3; sample 20 of core 7, slide B, Mataschen clay pit, Styria Basin, Austria.
Repository. The holotype and the type material (residue, rock sample and SEM stubs) are deposited in the Joanneum Museum, Graz, Austria under number UMJ G&P 210901 and UMJ G&P 210902, respectively.
Type locality. Mataschen clay pit near Kapfenstein (Styria, Austria), 158570 3300E/468540 1800N (2.3 km NW of Kapfenstein, 7.7 km SE of Feldbach, Styria, Austria).
Type horizon. Lower part of the Mataschen clay pit (Feldbach Formation, Sieglegg Member; Gross et al. 2008); samples of cores 6 and 7.
Stratigraphic horizon. Early Tortonian (early Pannonian).
Derivation of name. From the type locality near the village of Mataschen, Styria, Austria.
Diagnosis. A small species of Mendicodinium with an autophragm densely ornamented with rugulae of low relief.
Description. A subspherical, proximate and small species of Mendicodinium. The cyst is pale yellow or pale brown and sometimes colorless. The autophragm is thin (less than 0.3 mm) and densely ornamented with non-tabular rugulae of a maximum height of c. 0.5 mm. Three morphologies of the rugulae are observed: closely adjacent short, high and sinuous ridges (Plate 3, figures 1–4); wide ridges of moderate height (Plate 3, figures 5, 8), or partly fused ridges into granules (Plate 3, figure 6). The cyst is dorso-ventrally compressed and some specimens are partially folded or crumpled. The cyst broadens at the cingulum, and the hypocyst is slightly larger than the epicyst. The ‘split’ above the cingulum is spirally arranged, and causes an offset of the ends of the cingulum on the ventral side. The epicyst is slightly pointed at the apex and the hypocyst is flattened at the antapex. There is no indication of horns or bosses. The cingulum may be indicated by a narrow strip of low ornamentation (Plate 3, figure 5) which is, however, rarely observed. The archeopyle is of epicystal type (tEa) with smooth sutures. The operculum is adnate ventrally. Tabulation is indicated only by the archeopyle and, sometimes, by a faintly indicated cingulum (Plate 3, figure 5).
Dimensions. Holotype length 35 µm; width 36 µm. Minimum cyst length: 26.0 µm; maximum cyst length 37.0 µm; mean: 30.5 µm. Minimum cyst width at cingulum: 27 µm; maximum cyst width at cingulum: 41.0 µm; mean: 32.0 µm (Figure 2). 52 specimens measured.
Comparison. Mendicodinium reticulatum Morgenroth 1970, described from the Lower Jurassic (Lias delta) of Germany, is morphologically very close to Mendicodinium mataschenensis. However, Mendicodinium reticulatum is slightly larger (length 45.0– 46.0 µm, 3 specimens; width 41.0–48.0 µm, four specimens; Morgenroth 1970, p. 348) and has a reticulate surface ornamentation. In terms of surface ornamentation, it is similar to Mendicodinium sp. A of Wrenn and Kokinos (1986) from the Middle Miocene, De Soto Canyon, Gulf of Mexico; Mendicodinium mataschenensis is however smaller in size and characterized by an adnate operculum rather than by a free operculum (based on the specimens illustrated in Wrenn and Kokinos 1986; plate 4, figure 3 and plate 10, figure 4). ‘Mendicodinium robustum’ Zevenboom and Santarelli 1995 ex Fensome et al. 2009 from the late Serravallian–early Tortonian, Giammoia-Falconara sections (Caltanissetta Basin), Italy, has a scabrate wall (Zevenboom 1995, p. 159). The wall of Mendicodinium groenlandicum (Pocock & Sarjeant 1972) Davey 1979 from the Middle Jurassic of Greenland is smooth or slightly punctate. Mendicodinium mataschenensis differs from Mendicodinium kemperi Heilmann-Clausen & Thomsen 1995, from the Barremian of Ahlum-1 borehole and Gott clay pit at Sarstedt, Lower Saxony Basin, Germany, by its small cyst width (32.0 mm versus 67.0 mm), in having a uniform type of surface ornamentation, a slightly pointed apex and the absence of sutures (Heilmann-Clausen and Thomsen 1995). With regard to cyst size, Mendicodinium mataschenensis is similar to the Mendicodinium species (Mendicodinium umbriense, Mendicodinium spinosum, Mendicodinium microscabratum and Mendicodinium brunneum) described form the Lower Jurassic of Italy by Bucefalo Palliani et al. (1997). However, it is characterized by its unique rugulate surface ornamentation, and accessory archeopyle sutures have never been observed. Mendicodinium mataschenensis is distinguished form the majority of Mendicodinium species by its small size and the rugulate surface ornamentation. Table 1 illustrates the characteristic morphologic features of Mendicodinium species.
Remarks. Like many dinoflagellate cysts with an epicystal archeopyle, Mendicodinium is also characterized by the separation of the epicyst and hypocyst caused by mechanical fragmentation or degradation. This is not the case for Mendicodinium mataschenensis, where both halves of the cysts are usually still connected ventrally. This may be the result of the more or less parautochthonous sedimentation without major transport and the high sedimentation rate of approximately one centimetre per decade (Gross et al. 2011).
Discussion. Doubts about the systematic affiliation of Mendicodinium species as dinoflagellate cysts have been raised several times. Due to their relatively simple morphology, in particular the proximate cyst shape, low-relief surface ornamentation and the absence of clear tabulation, identification of their dinoflagellate nature is not always certain. Mendicodinium groenlandicum (Pocock & Sarjeant 1972) Davey 1979 was originally described as an acritarch in the genus Thuledinium, before Davey (1979) recognized its dinoflagellate nature and transferred it to the genus Mendicodinium. The simple morphological features of Mendicodinium may have caused confusion, e.g. with some pollen grains such as Inaperturopollenites, especially in case of deformation and/or fragmentation. For example, Schrank (2004) studied specimens of the alleged dinoflagellate cyst Mendicodinium? quadratum Kumar 1987 from the Jurassic Tendaguru Beds in Tanzania. Based on SEM images, he demonstrated clearly that it is actually a monosulcate pollen grain. He emended and transferred the species to the gymnosperm pollen genus Shanbeipollenites Qian Lijun & Wu Jingyun in Qian et al. (1987), emend. Schrank 2004. Mendicodinium is also quite similar in its morphology to the zygospores of zygnematacean green algae, such as the extant species Spirogyra (Chlorophyta). Such zygospores with a fossil record in the Mesozoic and Cenozoic are e.g. Schizophacus (see Ensom et al. 2009). In the case of Mendicodinium mataschenensis n. sp., the cingulum (although occasionally faintly indicated) and the helicoidal, equatorial suture causing an offset of the cingulum on the ventral face are evidence of an epicystal archeopyle with a ventrally adnate operculum, and dispel any doubts of its dinoflagellate affinity.
Comments. Mendicodinium is a widespread genus during the Jurassic and Early Cretaceous. Only few records are known from the Neogene: Mendicodinium robustum Zevenboom & Santarelli in Zevenboom 1995 ex Fensome et al. 2009 is documented from the Miocene of Italy (Zevenboom 1995) and the Scotian Margin (Fensome et al. 2009). Mendicodinium sp. A of Wrenn and Kokinos (1986) is abundant in the Middle Miocene of the Gulf of Mexico, but only rarely found in the Pliocene (Wrenn & Kokinos 1986). Further occurrences are known from the Burdigalian of France (Londeix & Jan du Chêne 1988), the Miocene of the Netherlands (Donders et al. 2009) and the Miocene of ODP Site 1168, off western Tasmania (Brinkhuis et al. 2003). Mendicodinium sp. A of Krijgsman et al. (1995) was described from the Late Miocene of the Gibliscemi Section in Sicily.
Occurrence. The occurrence of Mendicodinium mataschenensis is restricted to only c. 1 m (cores 6, 7) at the base of the Mataschen clay pit outcrop. Interestingly, its occurrence is contemporaneous with the occurrence of the ostracod species Cyprides mataschensis Gross 2008 (see Gross et al. 2008, figure 3). Investigation of samples above and below this horizon revealed the absence of this taxon.
Paleoecology. Most of the Mendicodinium species are described from restricted marine environments. Sarjeant (1972) reported Mendicodinium groenlandicum from a shelf environment of the Callovian in East Greenland, where it comprised 21% of the assemblage. Poulsen (1992) recorded an assemblage dominated by Mendicodinium groenlandicum from Horsens-I borehole (Jurassic, Denmark) and attributed its occurrence to ecological control. He proposed a calm and shallow bay environment with periodic anoxic conditions. High abundance of Mendicodinium reticulatum associated with frequent Chasmatosporites was found by Koppelhus and Nielsen (1994) in the Lower Jurassic of Denmark. As Chasmatosporites is a good indicator for warm to hot, sub-humid environments (Fu et al. 2009), a climatic link may be responsible for the Mendicodinium-dominated assemblages. Unusual dinoflagellate cyst assemblages including Mendicodinium echinatum and Mendicodinium scabratum are typical for the Lower Jurassic Plover Formation in the Timor Sea (north of Australia) which was deposited in a strongly fluvially influenced environment passing upsection into deltaic and shallow marine settings (Riding & Helby 2001). Brackish and shallow water Barremian sediments of Siberia also proved to be rich in Mendicodinium (Pestchevitskaya 2008). More records of abundant Mendicodinium from very shallow, marginal marine environments have been reported (e.g. Feist-Burkhardt & Pittet 1996). Characteristic mass occurrences were even termed ‘Mendicodinium events’ by Poulsen (1996) who considered these events to be indicative for restricted marine conditions. A somewhat comparable Jurassic counterpart to the Miocene section at Mataschen is represented by the Sorthat Beds, Baga˚ Formation from Bornholm, Denmark. These beds are characterized by bioturbated, laminated and crossbedded sands topped by a thin coal seam with rootlets that formed in a brackish lagoon with tidal channels (Koppelhus and Nielsen 1994). Interestingly, both sections yield morphologically very similar specimens of Mendicodinium. In contrast to these findings, Bucefalo Palliani et al. (1997) described Mendicodinium taxa with ammonites and calcareous nannofossils: rich sediments, suggesting normal marine conditions.contrast to these findings, Bucefalo Palliani et al. (1997) described Mendicodinium taxa with ammonites and calcareous nannofossils: rich sediments, suggesting normal marine conditions.
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