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Acanthaulax areolata
From Fensome et al., 2019:
Acanthaulax areolata, (Sarjeant, 1961a, p.95-96, pl.13, fig.13; text-fig.5), Riley and Fenton, 1982, p.199.
Holotype: Sarjeant, 1961a, pl.13, fig.13; text-fig.5; Jan du Chêne et al., 1986a, pl.3, figs.1–2.
Combination illegitimate — nomenclatural senior synonym: Gonyaulacysta scarburghensis.
NOW Trichodinium scarburghense.
Originally Gonyaulax areolata (name illegitimate; Appendix B), subsequently Gonyaulacysta scarburghensis, thirdly Gonyaulacysta areolata (combination illegitimate), fourthly Acanthaulax areolata (combination illegitimate), fifthly Acanthaulax scarburghensis, sixthly Liesbergia scarburghensis, seventhly (and now) Trichodinium scarburghense. Taxonomic junior synonym: Acanthaulax senta, according to Berger (1986, p.343). This combination was not validly published in Riley and Fenton (1980, p.340), since these authors did not reference the basionym.
Age: late Callovian–early Oxfordian.
Locus typicus: Scarborough Castle Cliff, England.
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Original description as Gonyaulax areolata: [Sarjeant, 1961, p.95-96]:
Diagnosis: :
A species of fossil Gonyaulax with an ovoid theca having the tabulation ?', 1a, 6", 6''', ?1p, 1'''' and with a strong, tapering apical horn rounded at its extremity. The whole thecal surface except the longitudinal and transverse furrows is covered by low ridges forming an irregular reticulate patterning; the thecal wall is very thin but consists of two layers, the outer bearing the ridges. The boundaries of plates and the furrow margins bear low alveolate crests. The longitudinal furrow extends from apex to antapex; it is narrow, as the transverse furrow.
Description:
Theca yellowish. Tabulation not easily discerned and a composite text-figure therefore given. Apical tabulation obscure. An anterior intercalary plate clearly present, plus six pre-equatorial plates, of which the first (1") is reduced. Transverse furrow extends around theca in a strong laevo-rotatory spiral such that its two ends differ in antero-posterior position by approximately three times the furrow's width. Six postequatorial plates certainly present; a posterior intercalary plate appears present but could not be definitely confirmed. No posterior ventral plates present, longitudinal furrow extending to polygonal antapical plate. Surface reticulation of ridges dense; fields delimited by these ridges always small, not regularly polygonal but varying considerably in relative size and shape. Reticulation extending on to apical horn but absent from furrows. Crests consist of linked processes (links sometimes broken) arising from sutures, their points of origin corresponding with junctions of ridges with sutures.
Dimensions:
Holotype: Overall length 155 µm, length of horn 25 µm, overall breadth 125 µm; transverse furrow c. 10 µm wide, longitudinal furrow c. 5 µm wide. Range: overall length 120 - 170 µm, relative proportions being fairly constant.
Acanthaulax areolata, (Sarjeant, 1961a, p.95-96, pl.13, fig.13; text-fig.5), Riley and Fenton, 1982, p.199.
Holotype: Sarjeant, 1961a, pl.13, fig.13; text-fig.5; Jan du Chêne et al., 1986a, pl.3, figs.1–2.
Combination illegitimate — nomenclatural senior synonym: Gonyaulacysta scarburghensis.
NOW Trichodinium scarburghense.
Originally Gonyaulax areolata (name illegitimate; Appendix B), subsequently Gonyaulacysta scarburghensis, thirdly Gonyaulacysta areolata (combination illegitimate), fourthly Acanthaulax areolata (combination illegitimate), fifthly Acanthaulax scarburghensis, sixthly Liesbergia scarburghensis, seventhly (and now) Trichodinium scarburghense. Taxonomic junior synonym: Acanthaulax senta, according to Berger (1986, p.343). This combination was not validly published in Riley and Fenton (1980, p.340), since these authors did not reference the basionym.
Age: late Callovian–early Oxfordian.
Locus typicus: Scarborough Castle Cliff, England.
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Original description as Gonyaulax areolata: [Sarjeant, 1961, p.95-96]:
Diagnosis: :
A species of fossil Gonyaulax with an ovoid theca having the tabulation ?', 1a, 6", 6''', ?1p, 1'''' and with a strong, tapering apical horn rounded at its extremity. The whole thecal surface except the longitudinal and transverse furrows is covered by low ridges forming an irregular reticulate patterning; the thecal wall is very thin but consists of two layers, the outer bearing the ridges. The boundaries of plates and the furrow margins bear low alveolate crests. The longitudinal furrow extends from apex to antapex; it is narrow, as the transverse furrow.
Description:
Theca yellowish. Tabulation not easily discerned and a composite text-figure therefore given. Apical tabulation obscure. An anterior intercalary plate clearly present, plus six pre-equatorial plates, of which the first (1") is reduced. Transverse furrow extends around theca in a strong laevo-rotatory spiral such that its two ends differ in antero-posterior position by approximately three times the furrow's width. Six postequatorial plates certainly present; a posterior intercalary plate appears present but could not be definitely confirmed. No posterior ventral plates present, longitudinal furrow extending to polygonal antapical plate. Surface reticulation of ridges dense; fields delimited by these ridges always small, not regularly polygonal but varying considerably in relative size and shape. Reticulation extending on to apical horn but absent from furrows. Crests consist of linked processes (links sometimes broken) arising from sutures, their points of origin corresponding with junctions of ridges with sutures.
Dimensions:
Holotype: Overall length 155 µm, length of horn 25 µm, overall breadth 125 µm; transverse furrow c. 10 µm wide, longitudinal furrow c. 5 µm wide. Range: overall length 120 - 170 µm, relative proportions being fairly constant.