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Pentadinium alabamense
Pentadinium alabamense Quaijtaal and Brinkhuis, 2012, p.50,52–53, pl.1, figs.1A–L; pl.2, figs.A–F; text-figs.3A–B.
Holotype: Quaijtaal and Brinkhuis, 2012, pl.1, figs.A–D.
Age: early Oligocene.
Original description (Quaijtaal & Brinkhuis, 2012):
Pentadinium alabamensis, sp. nov., Plate 1, A–D
1999 Pentadinium sp. A, Jaramillo and Oboh-Ikuenobe, plate 2, fig. 9
Etymology: Named after the state of Alabama (USA), home of the type species.
Holotype: Sample SSQ 17 (42.56 m core depth), slide 1, England Finder (EF) coordinates N33/2, Plate 1, A–D
Paratype 1: Sample SSQ 17(42.56 m core depth), slide 2, EF G31/1, Plate 1, E–G
Paratype 2: Sample SSQ 17(42.56 m core depth), slide 2, EF H30/4, Plate 1, H–J
Type locality: St. Stephens Quarry, Alabama, USA
Type stratum: Red Bluff Clay
Geographic and stratigraphic distribution: Pentadinium alabamensis sp. nov. has so far been reported from four localities; Jaramillo and Oboh-Ikuenobe (1999) recorded it in two cores in Mississippi State (Mobil Exploration and Production Services #1 Young and #1 Wayne cores), as well as from the SSQ outcrop (see Fig. 1). We found P. alabamensis sp. nov. in the SSQ core, taken ca 1.6 km from the SSQ outcrop analyzed by Jaramillo and Oboh-Ikuenobe (1999). The species has never been mentioned or shown in other regions.
Repository: Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584CD Utrecht, The Netherlands.
Diagnosis:
A species of Pentadinium displaying a gonyaulacoid tabulation (3–4′, 6″, 6c, 6‴, 1p, 1⁗; Evitt, 1985) with a 1P (3″) archeopyle, operculum free. The species shows several characteristics typical for Pentadinium: two walls that appear as a single layer at the plate interior and show separation at the plate margins. The endophragm is thicker than the periphragm. Furthermore, it shows cavation around the cingulum. Plates 1′ and 4′ are more or less fused and plate 6″ is poorly delimited (see Plate 2A,E). The endophragm is subsphaerical, scabrate or microgranulate. The periphragm is thin, perforate and widely extends outwards. The tabulation is expressed by these extreme outgrowths of the periphragm, considered to principally reflect extreme suturocavation. Outgrowths form septa at the apical plates and a fenestrate membrane on the rest of the cyst. The sulcal plates are not reflected.
Description:
A medium sized (60–70 μm), subsphaerical to elliptical species of Pentadinium, showing extreme suturocavation.
Wall: The cyst possesses two wall layers. The endophragm is thick and scabrate to microgranulate (see Plate 2D). The periphragm is thin, perforate and closely appressed to the endophragm at the central areas of the plates. At these appressed areas the periphragm is not perforate. At the plate boundaries the periphragm is detached and extends outwards exceptionally (suturocavation). This aspect in Pentadinium alabamensis sp. nov. is so extreme that it appears to bear large distal crest-like structures, a fenestrate periphragm supported by slender processes (see Fig. 3; Plate 2B, F). We consider these to be exceptional outfolds of the suturocavate nature of the periphragm. The sulcal region is not reflected by the periphragm (see Fig. 3B).
Tabulation: It does not show any tabulation, except for the archaeopyle; displays a gonyaulacoid tabulation: 3–4′, 6″, 6c, 6‴, 1p, 1⁗ with a 1P(3″) archeopyle. The crest-like structures on the cyst are mostly found to represent the apical plates series (plates 1–4′, see Plate 2A), while from the precingular plates downward the periphragm is almost completely detached, reflecting the precingular, cingular, postcingular and antapical plates. The cingular plates may be difficult to see under the light microscope (see Fig. 3).
Archaeopyle: precingular, 1P (3″) archeopyle, operculum free.
Dimensions:
Average diameter of the endocyst was 55 μm, average diameter of the pericyst 91 μm (n= 15).
Holotype: diameter of endocyst 53 μm, diameter of pericyst 95 μm; paratype 1: endocyst 54 μm, pericyst 95 μm; paratype 2: endocyst 50 μm, pericyst 87 μm.
Comparison:
Pentadinium alabamensis sp. nov. can be distinguished from all species of Pentadinium in showing extreme separation of the perforate periphragm from the endophragm. Although Pentadinium favatum also might show extreme separation of these layers, this is not a consistent feature as in P. alabamensis. More importantly, P. favatum has its characteristic honeycomb texture. Pentadinium? circumsutum, P. corium Schiøler (2005), P. goniferum, P. granulatum (Gocht, 1969) Fensome et al. (2009), P. imaginatum, P. membranaceum, P. sabulum Fensome et al. (2009) and P. taenagrium can all be distinguished from the new species P. alabamensis in having a granular to vermiculate endocyst surface structure, whereas P. lophophorum can be separated based on its typical surface ornamentation. P. alabamensis can be distinguished from P. netangei based on its size and having a perforate rather than a microgranulate periphragm. The camocavate P. omasum has, unlike P. alabamensis, a pseudopunctate endocyst structure and cavation is restricted to the dorsal part of the cyst. P. laticinctum s.s., P. polypodum, P. spinulum and P. galileoi Sancay et al. (2006) share the relatively smooth surface of the endocyst. However, the last three species possess processes of different sorts and can therefore not be confused with P. alabamensis. The periphragm of P. laticinctum s.s. is not as extremely detached as in P. alabamensis and is, where detached, not perforate.
Holotype: Quaijtaal and Brinkhuis, 2012, pl.1, figs.A–D.
Age: early Oligocene.
Original description (Quaijtaal & Brinkhuis, 2012):
Pentadinium alabamensis, sp. nov., Plate 1, A–D
1999 Pentadinium sp. A, Jaramillo and Oboh-Ikuenobe, plate 2, fig. 9
Etymology: Named after the state of Alabama (USA), home of the type species.
Holotype: Sample SSQ 17 (42.56 m core depth), slide 1, England Finder (EF) coordinates N33/2, Plate 1, A–D
Paratype 1: Sample SSQ 17(42.56 m core depth), slide 2, EF G31/1, Plate 1, E–G
Paratype 2: Sample SSQ 17(42.56 m core depth), slide 2, EF H30/4, Plate 1, H–J
Type locality: St. Stephens Quarry, Alabama, USA
Type stratum: Red Bluff Clay
Geographic and stratigraphic distribution: Pentadinium alabamensis sp. nov. has so far been reported from four localities; Jaramillo and Oboh-Ikuenobe (1999) recorded it in two cores in Mississippi State (Mobil Exploration and Production Services #1 Young and #1 Wayne cores), as well as from the SSQ outcrop (see Fig. 1). We found P. alabamensis sp. nov. in the SSQ core, taken ca 1.6 km from the SSQ outcrop analyzed by Jaramillo and Oboh-Ikuenobe (1999). The species has never been mentioned or shown in other regions.
Repository: Laboratory of Palaeobotany and Palynology, Utrecht University, Budapestlaan 4, 3584CD Utrecht, The Netherlands.
Diagnosis:
A species of Pentadinium displaying a gonyaulacoid tabulation (3–4′, 6″, 6c, 6‴, 1p, 1⁗; Evitt, 1985) with a 1P (3″) archeopyle, operculum free. The species shows several characteristics typical for Pentadinium: two walls that appear as a single layer at the plate interior and show separation at the plate margins. The endophragm is thicker than the periphragm. Furthermore, it shows cavation around the cingulum. Plates 1′ and 4′ are more or less fused and plate 6″ is poorly delimited (see Plate 2A,E). The endophragm is subsphaerical, scabrate or microgranulate. The periphragm is thin, perforate and widely extends outwards. The tabulation is expressed by these extreme outgrowths of the periphragm, considered to principally reflect extreme suturocavation. Outgrowths form septa at the apical plates and a fenestrate membrane on the rest of the cyst. The sulcal plates are not reflected.
Description:
A medium sized (60–70 μm), subsphaerical to elliptical species of Pentadinium, showing extreme suturocavation.
Wall: The cyst possesses two wall layers. The endophragm is thick and scabrate to microgranulate (see Plate 2D). The periphragm is thin, perforate and closely appressed to the endophragm at the central areas of the plates. At these appressed areas the periphragm is not perforate. At the plate boundaries the periphragm is detached and extends outwards exceptionally (suturocavation). This aspect in Pentadinium alabamensis sp. nov. is so extreme that it appears to bear large distal crest-like structures, a fenestrate periphragm supported by slender processes (see Fig. 3; Plate 2B, F). We consider these to be exceptional outfolds of the suturocavate nature of the periphragm. The sulcal region is not reflected by the periphragm (see Fig. 3B).
Tabulation: It does not show any tabulation, except for the archaeopyle; displays a gonyaulacoid tabulation: 3–4′, 6″, 6c, 6‴, 1p, 1⁗ with a 1P(3″) archeopyle. The crest-like structures on the cyst are mostly found to represent the apical plates series (plates 1–4′, see Plate 2A), while from the precingular plates downward the periphragm is almost completely detached, reflecting the precingular, cingular, postcingular and antapical plates. The cingular plates may be difficult to see under the light microscope (see Fig. 3).
Archaeopyle: precingular, 1P (3″) archeopyle, operculum free.
Dimensions:
Average diameter of the endocyst was 55 μm, average diameter of the pericyst 91 μm (n= 15).
Holotype: diameter of endocyst 53 μm, diameter of pericyst 95 μm; paratype 1: endocyst 54 μm, pericyst 95 μm; paratype 2: endocyst 50 μm, pericyst 87 μm.
Comparison:
Pentadinium alabamensis sp. nov. can be distinguished from all species of Pentadinium in showing extreme separation of the perforate periphragm from the endophragm. Although Pentadinium favatum also might show extreme separation of these layers, this is not a consistent feature as in P. alabamensis. More importantly, P. favatum has its characteristic honeycomb texture. Pentadinium? circumsutum, P. corium Schiøler (2005), P. goniferum, P. granulatum (Gocht, 1969) Fensome et al. (2009), P. imaginatum, P. membranaceum, P. sabulum Fensome et al. (2009) and P. taenagrium can all be distinguished from the new species P. alabamensis in having a granular to vermiculate endocyst surface structure, whereas P. lophophorum can be separated based on its typical surface ornamentation. P. alabamensis can be distinguished from P. netangei based on its size and having a perforate rather than a microgranulate periphragm. The camocavate P. omasum has, unlike P. alabamensis, a pseudopunctate endocyst structure and cavation is restricted to the dorsal part of the cyst. P. laticinctum s.s., P. polypodum, P. spinulum and P. galileoi Sancay et al. (2006) share the relatively smooth surface of the endocyst. However, the last three species possess processes of different sorts and can therefore not be confused with P. alabamensis. The periphragm of P. laticinctum s.s. is not as extremely detached as in P. alabamensis and is, where detached, not perforate.