Back
Costacysta
From Williams et al., 2017:
[Costacysta, Heilmann-Clausen and Van Simaeys, 2005, p. 158
("Costacysta" in Waagstein and Heilmann-Clausen, 1995, p.190, Name not validly published: no description. )
Type species: Costacysta bucina, Heilmann-Clausen and Van Simaeys, 2005 (pl.2, fig.15)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Heilmann-Clausen and Van Simaeys, 2005]:
Description:
A gonyaulacacean, holocavate dinoflagellate cyst with an ellipsoidal endocyst enclosed in a larger, thinner walled pericyst. The two phragma are connected by a prominent process or columella arising from the antapex of the endocyst. The columella is narrow and massive at the base, and situated on top of a minute horn of the endocyst. The main part of the columella is hollow and the columella expands strongly towards the distal end, attaining the shape of a funnel. The distal end of the columella is continuous with the periphragm. The two phragma are furthermore connected by a crater-like or funnel-shaped ring structure situated on the midventral surface, and probably representing a flagellar scar. The archeopyle is precingular (Type P, 3″ only). Apart from the archeopyle, no paratabulation is clearly indicated, although folds and wrinkles of the periphragm may be present and loosely form a partial paracingulum and a few other parasutures.
Derivation of name. For the palynologist Lucy I. Costa.
Affinities:
No previously described genera are morphologically close to Costacysta gen. nov. Two cavate gonyaulacoid genera with a prominent columella are known, Amiculosphaera Harland 1979 and Wilsonisphaera Slimani 1994. In Amiculosphaera the columella is at the apex, and furthermore no cavity is present in the hypocyst where the phragma are appressed. According to Schiøler and Wilson (1994), who described Wilsonisphaera as its junior synonym Glaphyrosphaera, this taxon has a prominent columella in the parasulcal area. It further differs from Costacysta by the presence of parasutural ridges on the periphragm.
[Costacysta, Heilmann-Clausen and Van Simaeys, 2005, p. 158
("Costacysta" in Waagstein and Heilmann-Clausen, 1995, p.190, Name not validly published: no description. )
Type species: Costacysta bucina, Heilmann-Clausen and Van Simaeys, 2005 (pl.2, fig.15)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Heilmann-Clausen and Van Simaeys, 2005]:
Description:
A gonyaulacacean, holocavate dinoflagellate cyst with an ellipsoidal endocyst enclosed in a larger, thinner walled pericyst. The two phragma are connected by a prominent process or columella arising from the antapex of the endocyst. The columella is narrow and massive at the base, and situated on top of a minute horn of the endocyst. The main part of the columella is hollow and the columella expands strongly towards the distal end, attaining the shape of a funnel. The distal end of the columella is continuous with the periphragm. The two phragma are furthermore connected by a crater-like or funnel-shaped ring structure situated on the midventral surface, and probably representing a flagellar scar. The archeopyle is precingular (Type P, 3″ only). Apart from the archeopyle, no paratabulation is clearly indicated, although folds and wrinkles of the periphragm may be present and loosely form a partial paracingulum and a few other parasutures.
Derivation of name. For the palynologist Lucy I. Costa.
Affinities:
No previously described genera are morphologically close to Costacysta gen. nov. Two cavate gonyaulacoid genera with a prominent columella are known, Amiculosphaera Harland 1979 and Wilsonisphaera Slimani 1994. In Amiculosphaera the columella is at the apex, and furthermore no cavity is present in the hypocyst where the phragma are appressed. According to Schiøler and Wilson (1994), who described Wilsonisphaera as its junior synonym Glaphyrosphaera, this taxon has a prominent columella in the parasulcal area. It further differs from Costacysta by the presence of parasutural ridges on the periphragm.