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Gonyaulacysta deflandrei
Gonyaulacysta deflandrei Riley in Fisher and Riley, 1980
NOW Leptodinium. Originally Gonyaulacysta, subsequently (and now) Leptodinium, thirdly Millioudodinium.
Junior homonym: Gonyaulacysta deflandrei (Sarjeant, 1966b) Below, 1981a.
This name was not validly published in Fisher and Riley (1976, p.52) since no description or illustration was provided (nomen nudum).
Holotype: Fisher and Riley, 1980, pl.1, figs.1-2; Jan du Chêne et al., 1986, pl.75, fig.7.
Age: Volgian
Original diagnosis: Riley in Fisher and Riley, 1980, p. 321
A species of Gonyaulacysta with an elongate cyst bearing a long, tapering apical horn; antapex rounded. Plate boundaries indicated by low, membranous crests from which arise short spiney outgrowths, which are irregularly distributed and isolate, or more often distally confluent forming a loosely constructed sutural network. Reflected tabulation 4", 5"", 5c, 5""", 5p, 1p, 1pv, 1"""". Cingulum helicoid, dividing the cyst unequally, epitract longer than hypotract. Sulcus broad, largely confined to the hypotract. Cyst wall composed of two layers, a thin granulate endophragm and a thick granulate periphragm. Endophragm and periphragm in contact except in the apicular region, anterior of apical horn formed from periphragm only.
Dimensions: Holotype: overall length 89 µm, breadth 45 µm, length of apical horn 16 µm. Range: overall length 89-98 µm, breadth 45-53 µm, length of apical horn 16-26 µm.
Affinities: Riley in Fisher and Riley, 1980, p. 321
The apical horn of this species is very distinctive, its anterior is formed from the periphragm only so that there is a cavity between the two wall layers into which the endophragm bulges.
A comparison may be drawn between G. deflandrei and G. perforans (Cookson and Esienack) Sarjeant in that both have a similar elongate cyst, a long apical horn and comparable reflected tabulations. G. perforans is, however, consistentlv larger and possesses an apical horn forrned from both wall layer and well developed, porate membraneous crests. G. cristata differs primarily by the shape of the cyst and forms of sutural ornamentation.
Gonyaulacysta sp. F. Gitmez and Sarjeant may be conspecifi with G. deflandrei but it appears to lack the elaborate sutural orn ornamentation.
NOW Leptodinium. Originally Gonyaulacysta, subsequently (and now) Leptodinium, thirdly Millioudodinium.
Junior homonym: Gonyaulacysta deflandrei (Sarjeant, 1966b) Below, 1981a.
This name was not validly published in Fisher and Riley (1976, p.52) since no description or illustration was provided (nomen nudum).
Holotype: Fisher and Riley, 1980, pl.1, figs.1-2; Jan du Chêne et al., 1986, pl.75, fig.7.
Age: Volgian
Original diagnosis: Riley in Fisher and Riley, 1980, p. 321
A species of Gonyaulacysta with an elongate cyst bearing a long, tapering apical horn; antapex rounded. Plate boundaries indicated by low, membranous crests from which arise short spiney outgrowths, which are irregularly distributed and isolate, or more often distally confluent forming a loosely constructed sutural network. Reflected tabulation 4", 5"", 5c, 5""", 5p, 1p, 1pv, 1"""". Cingulum helicoid, dividing the cyst unequally, epitract longer than hypotract. Sulcus broad, largely confined to the hypotract. Cyst wall composed of two layers, a thin granulate endophragm and a thick granulate periphragm. Endophragm and periphragm in contact except in the apicular region, anterior of apical horn formed from periphragm only.
Dimensions: Holotype: overall length 89 µm, breadth 45 µm, length of apical horn 16 µm. Range: overall length 89-98 µm, breadth 45-53 µm, length of apical horn 16-26 µm.
Affinities: Riley in Fisher and Riley, 1980, p. 321
The apical horn of this species is very distinctive, its anterior is formed from the periphragm only so that there is a cavity between the two wall layers into which the endophragm bulges.
A comparison may be drawn between G. deflandrei and G. perforans (Cookson and Esienack) Sarjeant in that both have a similar elongate cyst, a long apical horn and comparable reflected tabulations. G. perforans is, however, consistentlv larger and possesses an apical horn forrned from both wall layer and well developed, porate membraneous crests. G. cristata differs primarily by the shape of the cyst and forms of sutural ornamentation.
Gonyaulacysta sp. F. Gitmez and Sarjeant may be conspecifi with G. deflandrei but it appears to lack the elaborate sutural orn ornamentation.