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Aldorfia sibirica
From Fensome et al., 2019:
Aldorfia sibirica, Pestchevitskaya, 2009, p.108–110, pl.1, figs.1a–c,2a–b; text-fig.2B.
Holotype: Pestchevitskaya, 2009, pl.1, figs.1a–c.
Age: early Valanginian.
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Original description: [Pestchevitskaya, 2009, p. 108-110] (translation from Google):
Aldorfia sibirica Pestchevitskaya sp. n.
Table, figs. 1, 2; Fig. 2, B
Origin of name. From the name of the region (Siberia) of the first finds.
Holotype. Specimen No. 842/31.1-8 CSGM, table, figs. 1a–c; eastern shore of Anabar Bay, outcrop 1A, layer 20, sample 31, prep. 31.1, lower Valanginian, Sibirites ramulicosta Zone, Beani Subzone.
Diagnosis [in English].
Cyst proximate by-layered cribro-peridinioid; outline rounded, oval or irregular rhombic with wide rounded angles; apical horn wide, short; auto-phragm thick, smooth or roughened, forms projections or septa, supported ectophragm; ectophragm thiner, smooth, continuous, forms prominences, folds and wrinkles of various configuration; ectocoel filled by reticulate and spongious structures with cavities of different size and shape; paratabulation fileny expressed by unclear parasutural features, often by archeopyle only; formula: 1pr (Q), 4’, 6’’, 6c, 5s, 6’’’, 1p, 1’’’’; paracingulum slightly laevoratatory or straight; parasulcus rather wide; archeopyle precingular, type 1P (3’’).
Material. 7 specimens of good and fair preservation.
Description. The cyst is proximate, two-layered, cribroperidinoid. The shape is round, oval or irregular rounded-rhombic. In the apical region there is a wide, short apical horn of a columnar shape, dome-shaped with a pointed distal end. Usually straight, sometimes it slightly tapers towards the end. The autophragm is dense, smooth or rough, forms low (0.7-2 µm) outgrowths and septa that support the ectophragm. The ectophragm is thinner, smooth, transparent, solid. It forms bulges, folds and wrinkles of various configurations on the surface of the cyst, as well as the apical horn. The ectocelus has a reticular and spongy structure, with caverns of varying size (0.5–2.5 µm) and shape; the apical horn is hollow. Usually the ectocelus is quite narrow, developed uniformly around the circumference of the cyst, although sometimes its width increases near the apical region. Paratabulation is weakly manifested, expressed by unclear parasutural lines, more often only by the archeopil, formula 1pr (Q), 4’, 6’’, 6c, 5s, 6’’’, 1p, 1’’’’. The last precingular paraplate is narrow, the first postcingular is strongly reduced. The paracingulate is weakly twisted or straight. The parasulcus is sufficiently wide and straight. Paraplates 1p and ps are located on the sides of the right or left sulcal, forming a U-shaped structure characteristic of the subfamily Cribroperidinioideae. Archaeopilprecingular, type 1P (3’’). The operculum is either attached or absent.
Dimensions (µm). Length – 81–103; width – 56–79; pericoel width – 0.5–10; apical horn length – 9–16; base width – 10–14; distal end width – 4–8. Variability. The shape of the cyst and the width of the pericoel, as well as the length of the apical horn, vary.
Comparison. The type species A. aldorfensis (Gocht) Stover et Evitt [Gocht, 1970] has a similar structure of the ectocoel. However, the outgrowths of the autophragm are longer, as a result of which the ectocoel is wider, especially in the apical and antapical regions, where it forms characteristic bulges. The paracingulum is marked by a fold of the ectophragm, the apical horn is shorter, the shape of the cyst is rhombic. Species that are now transferred to the genus Apteodinium (corticatum, defl andrei, spongiosum, vectense, warringtonii) are distinguished by the absence of the Q-paraplate in the apical region (see Notes) and some other morphological features. Species A. warringtonii (Poulsen) Riding et Fensome [Poulsen, 1996] is similar in cyst shape, apical horn structure and pericoel, but differs in smaller size (52–66 µm in length), narrower sulcus and coarser outgrowths of the autophragms, which form a reticular-fibrous structure. The species A. corticatum (Norris et Jux) Lucas-Clark [Lucas-Clark, 1987] has a rhombic cyst with a fairly long apical horn. The species A. defl andrei (Clarke et Verdier) Lucas-Clark [Ibid.] has a wider ectocoel, especially in the apical and antapical regions, and the apical horn is practically absent. The species A.vectense (Duxbury) Lucas-Clark [Duxbury, 1983] is distinguished by a branched, labyrinth-like structure of the ectocoel, which has a significant width in the apical part. The apical horn of the species A. spongiosum McIntyre et Brideaux [McIntyre, Brideaux, 1980] also has a structure of the ectocoel that forms characteristic patterns similar to frost. Notes. The study of the new species Aldorfia sibirica made it possible to establish an almost complete form of paratabulation. In the apical region there is a Q-paraplate, which is also observed in the type species A. aldorfensis [Helenes, 1986]. This feature is considered characteristic of Aldorfia and distinguishes it from the genus Apteodinium [Lucas-Clark, 1987]. Dinocysts of the genus Aldorfia have a two-layer wall structure with a characteristic spongy and liquorous filling of the ectocoel. For a long time, this feature was considered an important diagnostic feature that distinguishes Aldorfia from other genera of the subfamily Cribroperidinioideae, including the morphologically close Apteodinium. A study of the type species Apteodinium granulatum Eisenack using an electron scanning microscope and a detailed analysis of the morphological structure of some other species of this genus showed that they can also have a two-layer wall of a similar structure [Ibid.]. In this case, the spongy layer has a smaller thickness and smaller caverns compared to Aldorfia [Ibid.]. These features of the wall structure, as well as the absence of distinctive features of the paratabulation of the apical region (Q-paraplates and sometimes very small intercalary K-paraplates), allowed many species of Aldorfia to be transferred to the genus Apteodinium [Ibid.]. Among other characters of the genus Apteodinium, distinguishing it from Aldorfia, are the less angular general appearance of the cyst and the more elongated shape of the paraplates 1p and ps. However, the modified diagnosis of the genus Apteodinium notes that the paratabulation of many regions, including the apical (which is important for distinguishing from the genus Aldorfia), is not always manifested [Ibid.]. Thus, the generic affiliation of cribroperidinoid dinocysts with a two-layered spongy wall structure of the Aldorfi type remains unclear. Location. Eastern shore of the Anabar Bay, outcrop 1A, layers 16–20, lower Valanginian, Siberites ramulicosta zone, ramulicosta and beani subzones.
Aldorfia sibirica, Pestchevitskaya, 2009, p.108–110, pl.1, figs.1a–c,2a–b; text-fig.2B.
Holotype: Pestchevitskaya, 2009, pl.1, figs.1a–c.
Age: early Valanginian.
---------------------------------------------------------------------------------------------------
Original description: [Pestchevitskaya, 2009, p. 108-110] (translation from Google):
Aldorfia sibirica Pestchevitskaya sp. n.
Table, figs. 1, 2; Fig. 2, B
Origin of name. From the name of the region (Siberia) of the first finds.
Holotype. Specimen No. 842/31.1-8 CSGM, table, figs. 1a–c; eastern shore of Anabar Bay, outcrop 1A, layer 20, sample 31, prep. 31.1, lower Valanginian, Sibirites ramulicosta Zone, Beani Subzone.
Diagnosis [in English].
Cyst proximate by-layered cribro-peridinioid; outline rounded, oval or irregular rhombic with wide rounded angles; apical horn wide, short; auto-phragm thick, smooth or roughened, forms projections or septa, supported ectophragm; ectophragm thiner, smooth, continuous, forms prominences, folds and wrinkles of various configuration; ectocoel filled by reticulate and spongious structures with cavities of different size and shape; paratabulation fileny expressed by unclear parasutural features, often by archeopyle only; formula: 1pr (Q), 4’, 6’’, 6c, 5s, 6’’’, 1p, 1’’’’; paracingulum slightly laevoratatory or straight; parasulcus rather wide; archeopyle precingular, type 1P (3’’).
Material. 7 specimens of good and fair preservation.
Description. The cyst is proximate, two-layered, cribroperidinoid. The shape is round, oval or irregular rounded-rhombic. In the apical region there is a wide, short apical horn of a columnar shape, dome-shaped with a pointed distal end. Usually straight, sometimes it slightly tapers towards the end. The autophragm is dense, smooth or rough, forms low (0.7-2 µm) outgrowths and septa that support the ectophragm. The ectophragm is thinner, smooth, transparent, solid. It forms bulges, folds and wrinkles of various configurations on the surface of the cyst, as well as the apical horn. The ectocelus has a reticular and spongy structure, with caverns of varying size (0.5–2.5 µm) and shape; the apical horn is hollow. Usually the ectocelus is quite narrow, developed uniformly around the circumference of the cyst, although sometimes its width increases near the apical region. Paratabulation is weakly manifested, expressed by unclear parasutural lines, more often only by the archeopil, formula 1pr (Q), 4’, 6’’, 6c, 5s, 6’’’, 1p, 1’’’’. The last precingular paraplate is narrow, the first postcingular is strongly reduced. The paracingulate is weakly twisted or straight. The parasulcus is sufficiently wide and straight. Paraplates 1p and ps are located on the sides of the right or left sulcal, forming a U-shaped structure characteristic of the subfamily Cribroperidinioideae. Archaeopilprecingular, type 1P (3’’). The operculum is either attached or absent.
Dimensions (µm). Length – 81–103; width – 56–79; pericoel width – 0.5–10; apical horn length – 9–16; base width – 10–14; distal end width – 4–8. Variability. The shape of the cyst and the width of the pericoel, as well as the length of the apical horn, vary.
Comparison. The type species A. aldorfensis (Gocht) Stover et Evitt [Gocht, 1970] has a similar structure of the ectocoel. However, the outgrowths of the autophragm are longer, as a result of which the ectocoel is wider, especially in the apical and antapical regions, where it forms characteristic bulges. The paracingulum is marked by a fold of the ectophragm, the apical horn is shorter, the shape of the cyst is rhombic. Species that are now transferred to the genus Apteodinium (corticatum, defl andrei, spongiosum, vectense, warringtonii) are distinguished by the absence of the Q-paraplate in the apical region (see Notes) and some other morphological features. Species A. warringtonii (Poulsen) Riding et Fensome [Poulsen, 1996] is similar in cyst shape, apical horn structure and pericoel, but differs in smaller size (52–66 µm in length), narrower sulcus and coarser outgrowths of the autophragms, which form a reticular-fibrous structure. The species A. corticatum (Norris et Jux) Lucas-Clark [Lucas-Clark, 1987] has a rhombic cyst with a fairly long apical horn. The species A. defl andrei (Clarke et Verdier) Lucas-Clark [Ibid.] has a wider ectocoel, especially in the apical and antapical regions, and the apical horn is practically absent. The species A.vectense (Duxbury) Lucas-Clark [Duxbury, 1983] is distinguished by a branched, labyrinth-like structure of the ectocoel, which has a significant width in the apical part. The apical horn of the species A. spongiosum McIntyre et Brideaux [McIntyre, Brideaux, 1980] also has a structure of the ectocoel that forms characteristic patterns similar to frost. Notes. The study of the new species Aldorfia sibirica made it possible to establish an almost complete form of paratabulation. In the apical region there is a Q-paraplate, which is also observed in the type species A. aldorfensis [Helenes, 1986]. This feature is considered characteristic of Aldorfia and distinguishes it from the genus Apteodinium [Lucas-Clark, 1987]. Dinocysts of the genus Aldorfia have a two-layer wall structure with a characteristic spongy and liquorous filling of the ectocoel. For a long time, this feature was considered an important diagnostic feature that distinguishes Aldorfia from other genera of the subfamily Cribroperidinioideae, including the morphologically close Apteodinium. A study of the type species Apteodinium granulatum Eisenack using an electron scanning microscope and a detailed analysis of the morphological structure of some other species of this genus showed that they can also have a two-layer wall of a similar structure [Ibid.]. In this case, the spongy layer has a smaller thickness and smaller caverns compared to Aldorfia [Ibid.]. These features of the wall structure, as well as the absence of distinctive features of the paratabulation of the apical region (Q-paraplates and sometimes very small intercalary K-paraplates), allowed many species of Aldorfia to be transferred to the genus Apteodinium [Ibid.]. Among other characters of the genus Apteodinium, distinguishing it from Aldorfia, are the less angular general appearance of the cyst and the more elongated shape of the paraplates 1p and ps. However, the modified diagnosis of the genus Apteodinium notes that the paratabulation of many regions, including the apical (which is important for distinguishing from the genus Aldorfia), is not always manifested [Ibid.]. Thus, the generic affiliation of cribroperidinoid dinocysts with a two-layered spongy wall structure of the Aldorfi type remains unclear. Location. Eastern shore of the Anabar Bay, outcrop 1A, layers 16–20, lower Valanginian, Siberites ramulicosta zone, ramulicosta and beani subzones.