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Tubotuberella apatela

From Fensome et al., 2019:
Tubotuberella apatela (Cookson and Eisenack, 1960b, p.249, pl.37, figs.12–13) Ioannides et al., 1977, p.464. Emendation: Sarjeant, 1982b, p.42, as Tubotuberella apatela.
Holotype: Cookson and Eisenack, 1960b, pl.37, fig.12; Jan du Chêne et al., 1986a, pl.124, figs.1–2; Fensome et al., 1993a, fig.1 — p.921.
Originally Scriniodinium, subsequently Psaligonyaulax, thirdly (and now) Tubotuberella, fourthly Glabridinium. Sarjeant (1982b, p.41) retained this species in Tubotuberella. This combination was not validly published in Fisher and Riley (1976, p.52), since these authors did not fully reference the basionym.

Locus typicus: Wapet's Wallal Corehole, NW Australia
Stratum typicum: Late Jurassic

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Translation Courtinat, 1989: LPP

Original description: Cookson and Eisenack 1960, p. 249: Scriniodinium apatelum
Diagnosis: Shell flat, the main portion ovoidal to somewhat rhomboidal; epitheca with a small, thin-walled, cylindrical and truncate horn; hypotheca narrowing distally towards a square opening with a smooth or serrated edge and sometimes with a short spine-like projection at each angle. The girdle is circular, occasionally well marked but usually only indicated by narrow ledges on the two sides. Membrane of shell thin, smooth, perforate or serrate at the sides. The capsule, which fills the shell laterally and follows its outline in the middle region, terminates in a short apical prominence. A relatively large, hoof-shaped pylome extends from just beneath the apex to the level of the girdle.
Dimensions: Range: length: 70-145 µm; breadth: 42-72 µm.

Ioannides et al., 1977, p. 464: Tubotuberella apatela
Description: Cavate cysts; inner body ovoidal to nearly rhomboidal; epitract ending in small, cylindrical truncate horn; hypotract narrowing distally toward cylindrical to subpolygonal opening with smooth to serrate edge, and occasionally a short projection at each angle formed by folds running along hypotract portion. Tabulation not observed. Cingulum indicated by narrow ledges on two sides. Capsule large, filling pericoel in middle region, may bear short apical prominence. Precingular archaeopyle always present.
Dimensions: Range: overall length: 70-115 µm; overall breadth 32-55 µm; capsule length: 45-70 µm; capsule breadth: 32-49 µm (16 specimens measured).

Supplemental diagnosis: Brideaux, 1977, p. 35: Glabridinium apatelum
As for the genus with these particular features: pericyst length/width ratio approximately two to one, pericyst tapering gently at the apex; endocyst ovoid to subrhombic, the epiendocyst slightly longer than the hypoendocyst; peri- and endoperculum elongate, hoof-shaped; pericingulum indistinct, marked by narrow, thin cingular parasutures slightly below the mid-latitude of the pericyst; and perisulcus absent.

Emended diagnosis: Sarjeant, 1982, p. 42
Cyst proximate, bicavate, elongate ellipsoidal to compressed rhomboidal in ambitus, with epitract and hypotract of similar length but sharply dissimilar in form. Epipericoel in the form of a semi-ellipsoid, either tapering smoothly or suddenly at about two-thirds length to form a distinct, blunt-tipped horn.
Hypotract having the form of a steepsided cone, inverted and truncated, its flanks inbent at the position of divergence of periphragm from endophragm (i.e. at about one-third its length). The hypopericoel is as long as, or slightly longer than, its breadth at the position of the antapex of the endoblast. Parasutures poorly indicated by lines of low ridges on the periphragm; these forms marked gonal protrusions where the boundaries between postcingulars intersect the antapex, but gonal spinules per se are lacking. Paratabulation visible in detail only in favourable specimens: 0-?2pa, ?0a, 6'', 6-?7c, 6''', 1p, 1pv, 1''''. Paraplate 4' elongate, but shorter than 1'; its contact with 6'' is small. The latter paraplate is triangular, with one long side, or both, somewhat concave. (In many specimens, the paratabulation can only be partially elucidated, if at all). Antapex of periblast occupied by a large opisthopyle. Archaeopyle single-plate precingular, formed by the loss of paraplate 3''.

Affinities:
Cookson and Eisenack 1960, p. 249: Scriniodinium apatelum has some features of Gonyaulax jurassica (Deflandre) and G. eisenacki (Deflandre), but none of the specimens have shown any sign of tabulation.
Brideaux, 1977, p. 35: The species is distinguished from Tubtuberella rhomkiformis Vozzhennikova by the absence of paratabulation and development of an apical horn.
Sarjeant 1982, p. 42: Tubotuberella apatela differs from T. dangeardii in its more elongate outline and in having a hypopericoel whose length is equal to, or slightly greater than, its breadth. In T. rhombiformis, the apical horn is absent and the hypopericoel yet longer; in T. egemenii, the epipericoel is feebly developed and the hypopericoel very much smaller in proportion to the size of the hypotract.
Courtinat, 1989, p.219: T. apatela possesses an apical horn on the periphragm and a mamelon on the endophragm, which distinguishes it from T. rhombiformis, which does not possess a mamelon on the endophragm, and a a weakly developed apical horn on the periphragm.

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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.

Tubotuberella apatela (Cookson and Eisenack, 1960) Ioannides et al., 1977. This species differs from T. dangeardii in its more elongate outline and in having a hypopericoel whose length is equal to, or slightly greater than, its breadth. The apical horn is distinct and blunt. Parasutures poorly indicated by lines or low ridges on the periphragm. These form marked gonal protrusions where the boundaries between the postcingulars intersect the antapex. The archeopyle is precingular resulting from the loss of 3". Size: pericyst length 83.7-94.5 µm, width 40.5-51.3, endocyst length 43.2-54 µm, width 37.8-48.6 µm. Holotype pericyst length 121.51 µm, width 64.8 µm, endocyst length 62.4 µm, width 59.5 µm.
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