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Aquadulcum serpens
Aquadulcum serpens, Harland and Sarjeant, 1970
Holotype: Harland and Sarjeant, 1970, pl.21, fig.7-8, text-fig.5
Locus typicus: Cobrico Swamp, Victoria, Australia
Stratum typicum: Holocene
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Original description: [Harland and Sarjeant, 1970, p. 221]:
Diagnosis:
Peridinoid to sub-spherical central body bearing a dense ornamentation of vermiculae. Sulcus and cingulum clearly defined by lack of ornament. The cingulum is offset by an amount equal to half its own width. The archaeopyle was not seen.
Description:
The central body is peridinoid to sub-spherical in shape, the epitract being slightly more conical than hypotract. Over the surface of the cyst there is a dense, irregular ornamentation of vermiculae, i.e. upraised ridges that appear "worm-like" in plan view. (This is the sense as used by the authors.) At low magnifications, this ornamentation appears to exhibit a separation into discrete areas, forming a faint pattern on the surface of the cyst. This pattern does not suggest a reflected tabulation. The sulcus extends to at least three-quarters of the length of the epitract and approximately one-half the length of the hypotract. An offset equal to half the width of the cingulum may be seen across the sulcus. The cyst surface between the vermiculae is smooth and no other form of ornamentation was seen.
The presence of a slight break at the apex of the holotype may be an indication of the development of a transapical archaeopyle, but this remains to be confirmed.
Dimensions:
Holotype: Length 45 µm, breadth 37 µm, height of vermiculae above central body approximately 1 µm.
Range: Length 45 µm, breadth 34-37 µm, height of vermiculae above cyst, less than 1 µm to 1 µm. Two specimens were measured, the total available material.
Affinities:
The only species of dinoflagellate cyst yet described which possesses an ornament comparable to that of A. serpens is Tenua verrucosa Sarjeant 1968; however, the "verrucae" of the latter species are seen, at high magnification, to be very broad, very short spines with brief branches, thus quite dissimilar to the ornament of A. serpens; moreover, an apical (A) archaeopyle is consistently developed.
This species was first described from the Holocene (Sub-Boreal Stage, 3000-500 B.C.) of Myalup Swamp, near Harvey, Western Australia. It has an ellipsoidal shell, with conical epitract and rounded hypotract, bearing an irregular scatter of short spines, simple or with two unequally developed branches Spines are absent from cingulum and sulcus; the cingulum is extremely broad, planar, the sulcus somewhat less broad.
A re-examination of the holotype disclosed no recognizable archaeopyle. A faint marginal slit was present at the level of the cingulum, but this probably resulted simply from compression.
This species is transferred to the genus Aquadulcum on the basis of general form and the absence of an endoblast (inner body). It is a proximate cyst, apparently composed of two wall layers in continuous contact, with the spines arising from the outermost layer only.
Holotype: Harland and Sarjeant, 1970, pl.21, fig.7-8, text-fig.5
Locus typicus: Cobrico Swamp, Victoria, Australia
Stratum typicum: Holocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Harland and Sarjeant, 1970, p. 221]:
Diagnosis:
Peridinoid to sub-spherical central body bearing a dense ornamentation of vermiculae. Sulcus and cingulum clearly defined by lack of ornament. The cingulum is offset by an amount equal to half its own width. The archaeopyle was not seen.
Description:
The central body is peridinoid to sub-spherical in shape, the epitract being slightly more conical than hypotract. Over the surface of the cyst there is a dense, irregular ornamentation of vermiculae, i.e. upraised ridges that appear "worm-like" in plan view. (This is the sense as used by the authors.) At low magnifications, this ornamentation appears to exhibit a separation into discrete areas, forming a faint pattern on the surface of the cyst. This pattern does not suggest a reflected tabulation. The sulcus extends to at least three-quarters of the length of the epitract and approximately one-half the length of the hypotract. An offset equal to half the width of the cingulum may be seen across the sulcus. The cyst surface between the vermiculae is smooth and no other form of ornamentation was seen.
The presence of a slight break at the apex of the holotype may be an indication of the development of a transapical archaeopyle, but this remains to be confirmed.
Dimensions:
Holotype: Length 45 µm, breadth 37 µm, height of vermiculae above central body approximately 1 µm.
Range: Length 45 µm, breadth 34-37 µm, height of vermiculae above cyst, less than 1 µm to 1 µm. Two specimens were measured, the total available material.
Affinities:
The only species of dinoflagellate cyst yet described which possesses an ornament comparable to that of A. serpens is Tenua verrucosa Sarjeant 1968; however, the "verrucae" of the latter species are seen, at high magnification, to be very broad, very short spines with brief branches, thus quite dissimilar to the ornament of A. serpens; moreover, an apical (A) archaeopyle is consistently developed.
This species was first described from the Holocene (Sub-Boreal Stage, 3000-500 B.C.) of Myalup Swamp, near Harvey, Western Australia. It has an ellipsoidal shell, with conical epitract and rounded hypotract, bearing an irregular scatter of short spines, simple or with two unequally developed branches Spines are absent from cingulum and sulcus; the cingulum is extremely broad, planar, the sulcus somewhat less broad.
A re-examination of the holotype disclosed no recognizable archaeopyle. A faint marginal slit was present at the level of the cingulum, but this probably resulted simply from compression.
This species is transferred to the genus Aquadulcum on the basis of general form and the absence of an endoblast (inner body). It is a proximate cyst, apparently composed of two wall layers in continuous contact, with the spines arising from the outermost layer only.