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Aprobolocysta pustulosa
Aprobolocysta pustulosa, Smith and Harding, 2004, p. 359, 361, 363, pl.1, figs.1-2,9-11; pl.6, figs.1-3.
Holotype: Smith and Harding, 2004, pl.1, figs.1-2.
Age: Early Valanginian
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Original description: [Smith and Harding, 2004, p. 359, 361, 363]:
Diagnosis:
small elongate ovoidal cysts with an apical archeopyle, probably type (2A), the archeopyle margin descending strongly from dorsal to ventral surfaces, with a pronounced sulcal notch on the ventral surface. The periphragm is developed into numerous non-tabular, subspherical to polygonal pustules which frequently deflate to leave concave distal surfaces. Such pustules may be discrete, compound, or be surmounted by one or more micro-pustules. The antapex is rounded to bilobed.
Description:
small, elongate ovoidal cysts, maximum cyst width mid-way between antapex and apex. Apex dome-shaped or slightly conical, antapex rounded to strongly asymmetrically bilobed.
Periphragm folded into variable numbers of non-tabular, generally subspherical (‘inflated’) pustules of variable size and position. Between 2 and 15 pustules have been recorded on the ventral surfaces, and 4–18 on dorsal surfaces of the specimens examined (e.g. Plate I, 3–6). The pustules may be discrete or fused laterally to form compound clusters, and are restricted basally, close to the endophragm, so that maximum circumference of the pustule is attained a short distance distally from the endophragm. In certain specimens, pustules may appear sub-polygonal when densely packed on the cyst surface (Plate I, 5,6). Occasionally smaller subspherical micro-pustules are developed individually or in small clusters on the distal or lateral surfaces of the larger pustules.
Endophragm and periphragm are adpressed between pustules (Plate I, 11). Periphragm is smooth to shagrinate over the pustules, and shagrinate and punctate in adpressed areas. The restricted basal region of many pustules (between the point of maximum circumference and adpression with the endophragm) bears numerous tiny claustra (Plate VI, 3). Pustules frequently deflate (particularly in SEM preparations) to form concave distal surfaces (Plate I, 5,6; Plate VI, 2). Endophragm is smooth.
Tabulation is only indicated at the archeopyle margin which descends strongly from the dorsal to ventral surfaces (Plate VI, 1).
Archeopyle is apical, type probably (2A) with a pronounced sulcal notch which is slightly displaced to the right of mid-ventral. The shape of the archeopyle is consistent with the tabulation of the apical region of this genus as suggested by Fensome et al. (1993, pp. 77–78).
Dimensions:
antapex-archeopyle margin: (39) 41 (51) μm; maximum width: (21) 26 (31) μm; pustule diameter: (2.6) 10 (16.9) μm. 13 specimens measured, all from sample K17.
Affinities/Remarks:
this species differs from other representatives of Aprobolocysta by the distinctive subspherical ‘inflated’ pustules formed from the periphragm. A. alata Backhouse 1988 is similar in having an ‘inflated’ periphragm, with prominent cavation in certain areas of the cyst, but markedly differs in the broad, distinctive cingular adpression of the wall layers. It differs from Riasanodinium federovae Iosifova 1992 which does not possess the extensive adpression of the wall layers between pustules (‘plate centred processes’ as described by Iosifova, 1996, p. 231). More importantly, this new species differs from R. federovae in the nature of the steeply inclined archeopyle margin, the strongly developed ‘sulcal notch’, and that broomeoid rather than gonyaulacoid tabulation is suggested (see Iosifova, 1996, p. 231).
Holotype: Smith and Harding, 2004, pl.1, figs.1-2.
Age: Early Valanginian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Smith and Harding, 2004, p. 359, 361, 363]:
Diagnosis:
small elongate ovoidal cysts with an apical archeopyle, probably type (2A), the archeopyle margin descending strongly from dorsal to ventral surfaces, with a pronounced sulcal notch on the ventral surface. The periphragm is developed into numerous non-tabular, subspherical to polygonal pustules which frequently deflate to leave concave distal surfaces. Such pustules may be discrete, compound, or be surmounted by one or more micro-pustules. The antapex is rounded to bilobed.
Description:
small, elongate ovoidal cysts, maximum cyst width mid-way between antapex and apex. Apex dome-shaped or slightly conical, antapex rounded to strongly asymmetrically bilobed.
Periphragm folded into variable numbers of non-tabular, generally subspherical (‘inflated’) pustules of variable size and position. Between 2 and 15 pustules have been recorded on the ventral surfaces, and 4–18 on dorsal surfaces of the specimens examined (e.g. Plate I, 3–6). The pustules may be discrete or fused laterally to form compound clusters, and are restricted basally, close to the endophragm, so that maximum circumference of the pustule is attained a short distance distally from the endophragm. In certain specimens, pustules may appear sub-polygonal when densely packed on the cyst surface (Plate I, 5,6). Occasionally smaller subspherical micro-pustules are developed individually or in small clusters on the distal or lateral surfaces of the larger pustules.
Endophragm and periphragm are adpressed between pustules (Plate I, 11). Periphragm is smooth to shagrinate over the pustules, and shagrinate and punctate in adpressed areas. The restricted basal region of many pustules (between the point of maximum circumference and adpression with the endophragm) bears numerous tiny claustra (Plate VI, 3). Pustules frequently deflate (particularly in SEM preparations) to form concave distal surfaces (Plate I, 5,6; Plate VI, 2). Endophragm is smooth.
Tabulation is only indicated at the archeopyle margin which descends strongly from the dorsal to ventral surfaces (Plate VI, 1).
Archeopyle is apical, type probably (2A) with a pronounced sulcal notch which is slightly displaced to the right of mid-ventral. The shape of the archeopyle is consistent with the tabulation of the apical region of this genus as suggested by Fensome et al. (1993, pp. 77–78).
Dimensions:
antapex-archeopyle margin: (39) 41 (51) μm; maximum width: (21) 26 (31) μm; pustule diameter: (2.6) 10 (16.9) μm. 13 specimens measured, all from sample K17.
Affinities/Remarks:
this species differs from other representatives of Aprobolocysta by the distinctive subspherical ‘inflated’ pustules formed from the periphragm. A. alata Backhouse 1988 is similar in having an ‘inflated’ periphragm, with prominent cavation in certain areas of the cyst, but markedly differs in the broad, distinctive cingular adpression of the wall layers. It differs from Riasanodinium federovae Iosifova 1992 which does not possess the extensive adpression of the wall layers between pustules (‘plate centred processes’ as described by Iosifova, 1996, p. 231). More importantly, this new species differs from R. federovae in the nature of the steeply inclined archeopyle margin, the strongly developed ‘sulcal notch’, and that broomeoid rather than gonyaulacoid tabulation is suggested (see Iosifova, 1996, p. 231).