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Aprobolocysta bipartita
From Fensome et al., 2019:
Aprobolacysta bipartita, Backhouse, 1987, p.212, figs.9E–H.
Holotype: Backhouse, 1987, figs.9E–F; Fensome et al., 1996, figs.1–2 — p.2067.
Originally (and now) Aprobolocysta, subsequently Necrobroomea. Lentin and Williams (1993, p.31) retained this species in Aprobolocysta.
Age: middle Hauterivian.
Locus typicus: Perth basin, Australia
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Original description: [Backhouse, 1987, p. 212]:
Description:
Cyst small, proximate, elongate and ovoidal.
Apex rounded without an apical horn; 2 short antapical horns developed by the endophragm; left horn slightly longer than the right.
Endophragm finely granular, approximately 0.5 µm thick; periphragm thinner, appressed to the endophragm in the apical, cingular, anterior sulcal, and antapical areas, slightly raised and tightly folded or wrinkled elsewhere.
Archeopyle apical, probably type [tA]; operculum usually missing. Principal archeopyle suture with a deep sulcal notch and a short gabled paraplate to the left of the sulcal notch.
Accessory sutures and the morphology of the periphragm not delineating a precise paratabulation.
Dimensions:
Total length of holotype 62 µm, width across the hypocyst 34 µm.
Range of length with operculum missing (11 specimens) 39(51)61 µm, width 31(35)43 µm.
Affinities:
Aprobolocysta bipartita is similar in overall shape and structure to A. galeata. It is distinguished from A. galeata by possessing longer antapical horns and a tightly folded periphragm only in the precingular and postcingular areas. The absence of high, rounded, periphragmal folds distinguishes A. bipartita from A . alata. From the stratigraphic distribution of A. galeata, A. bipartita and A. alata it is concluded that these species form a morphocline. The transition from A. bipartita to A. alata takes place at, or just below the base of the A. alata Zone.
Aprobolacysta bipartita, Backhouse, 1987, p.212, figs.9E–H.
Holotype: Backhouse, 1987, figs.9E–F; Fensome et al., 1996, figs.1–2 — p.2067.
Originally (and now) Aprobolocysta, subsequently Necrobroomea. Lentin and Williams (1993, p.31) retained this species in Aprobolocysta.
Age: middle Hauterivian.
Locus typicus: Perth basin, Australia
---------------------------------------------------------------------------------------------------
Original description: [Backhouse, 1987, p. 212]:
Description:
Cyst small, proximate, elongate and ovoidal.
Apex rounded without an apical horn; 2 short antapical horns developed by the endophragm; left horn slightly longer than the right.
Endophragm finely granular, approximately 0.5 µm thick; periphragm thinner, appressed to the endophragm in the apical, cingular, anterior sulcal, and antapical areas, slightly raised and tightly folded or wrinkled elsewhere.
Archeopyle apical, probably type [tA]; operculum usually missing. Principal archeopyle suture with a deep sulcal notch and a short gabled paraplate to the left of the sulcal notch.
Accessory sutures and the morphology of the periphragm not delineating a precise paratabulation.
Dimensions:
Total length of holotype 62 µm, width across the hypocyst 34 µm.
Range of length with operculum missing (11 specimens) 39(51)61 µm, width 31(35)43 µm.
Affinities:
Aprobolocysta bipartita is similar in overall shape and structure to A. galeata. It is distinguished from A. galeata by possessing longer antapical horns and a tightly folded periphragm only in the precingular and postcingular areas. The absence of high, rounded, periphragmal folds distinguishes A. bipartita from A . alata. From the stratigraphic distribution of A. galeata, A. bipartita and A. alata it is concluded that these species form a morphocline. The transition from A. bipartita to A. alata takes place at, or just below the base of the A. alata Zone.