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Achomosphaera heterostyla
From Fensome et al., 2019:
Achomosphaera heterostyla, (Heisecke, 1970, p.238,240, pl.5, figs.1–4; pl.6, figs.4–5) Stover and Evitt, 1978, p.138.
Holotype: Heisecke, 1970, pl.5, figs.3–4; pl.6, fig.4.
Originally Hystrichosphaera, subsequently Spiniferites, thirdly (and now) Achomosphaera.
Age: Danian.
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Original description; [Heisecke, 1970] translation PKB 2024:
DIAGNOSIS. Ovoid corate cyst with smooth wall carrying two types of processes, 1) infundibuliform
with the distal end denticulated to aculeate and 2) thinner processes with the distal end tri- or tetrafurcated. Adjacent processes may be joined by partitions. The reflected tabulation could not be determined with certainty but due to the distribution of the processes it would appear to be that of Hystrichosphaera. It generally presents a typical precingulate archaeopil, but in isolated cases it can extend to cover the entire apical area, so that it constitutes a combined archaeopyle of type Aa + P of Evitt (1967).
HOLOTYPE. Preparation 429(2), coordinates 41.4/100.8.
DIMENSIONS. Diameter of the central body 35.5 x 34 μ, total diameter 61 x 54 μ, length of the processes up to 14 μ.
DESCRIPTION. Ovoid corated cyst composed of a smooth and delicate endophragm and a smooth periphragm that gives rise to the processes. Both layers are largely united on the surface, but in the antiapical and sulcal zone they generally separate, forming a continuous cavity beneath the bases of the adjacent processes. The processes are mostly gonal, occasionally sutural, hollow, they do not communicate with the interior of the central body and their shapes are varied; Basically they can be grouped into two types: 1) infundibuliform, with the distal end denticulate to aculeate with more or less fenestrate walls and frequently with bifurcations in the middle of their length, sometimes with a triangular section; 2) thinner processes with the distal end tri- or tetranfurcated. The processes of the first type and of larger size are found in the antiapical region, but they are also observed in less obvious forina in the apical area. Some processes are joined by ridges or membranous septa. In general, the specimens have precingular archaeopyle, however specimen 429
(2)-32.5/104.8 presents an archaeopyle of the type Aa + P of Evitt (1967), encompassing a precingular plate and the apical plates. Based on the distribution of the processes in the holotype specimen, the reflected tabulation of 4', 6", 6c, 5"', lp, 1"" was estimated, with the plate being 6" reduced.
DIMENSIONS. Diameter of the central body 42.5-32 μ, total diameter 66.5-50 μ, length of
the processes until 19 11-. NumberQ of specimens measured: 7. ·
MAIN MATERIAL STUDiED. Preparation 429(1), coordinates 31.7/113.2; preparation 429(2), coordinates 41.4/108.8; 32.5/104.8; preparation 429(9), coordinates 51.9/101.4. Discusion. Due to the presence of the combined archaeopyle Aa + P, this form could not be assigned to the genus Hystrichosphaera.
However, because it coincides in all the other characteristics with said genus and because it presents this type of combined archaeopyle only in very isolated cases, I consider that they are not sufficient elements.
to separate these specimens into a new genus, therefore this species is provisionally attributed to the genus Hystrichosphaera until a more in-depth study allows it to be classified more accurately.
COMPARISONS. The new species coincides considerably with Hystrichosphaera perforata Davey and Williams, 1966, mainly due to the two types of processes, the similar size and the fenestration.
which usually present the processes distally, however it differs from said species in that the two types of processes are not related to their gonal or sutural position, as occurs in H. perforata; Furthermore, the sutural membranes or septa are better defined in H. perforata. The specimens studied here differ from Hystrichosphaera buccina Davey and Williams, 1966, by being considerably larger in size.
smaller, because it has a more delicate and smooth wall and because of the type of processes; and differ from Hystrichosphaera
tertiary Eisenack ·and Gocht, 1960, the latter does not present a clear differentiation between the processes, but presents the limits between the plates clearly defined and possibly has different tabulation
reflected.
HORIZON. Sample MH2.
DERIVATIO NOMINIS. From the Greek heteros, distinct and stylos, column, punch.
Achomosphaera heterostyla, (Heisecke, 1970, p.238,240, pl.5, figs.1–4; pl.6, figs.4–5) Stover and Evitt, 1978, p.138.
Holotype: Heisecke, 1970, pl.5, figs.3–4; pl.6, fig.4.
Originally Hystrichosphaera, subsequently Spiniferites, thirdly (and now) Achomosphaera.
Age: Danian.
---------------------------------------------------------------------------------------------------
Original description; [Heisecke, 1970] translation PKB 2024:
DIAGNOSIS. Ovoid corate cyst with smooth wall carrying two types of processes, 1) infundibuliform
with the distal end denticulated to aculeate and 2) thinner processes with the distal end tri- or tetrafurcated. Adjacent processes may be joined by partitions. The reflected tabulation could not be determined with certainty but due to the distribution of the processes it would appear to be that of Hystrichosphaera. It generally presents a typical precingulate archaeopil, but in isolated cases it can extend to cover the entire apical area, so that it constitutes a combined archaeopyle of type Aa + P of Evitt (1967).
HOLOTYPE. Preparation 429(2), coordinates 41.4/100.8.
DIMENSIONS. Diameter of the central body 35.5 x 34 μ, total diameter 61 x 54 μ, length of the processes up to 14 μ.
DESCRIPTION. Ovoid corated cyst composed of a smooth and delicate endophragm and a smooth periphragm that gives rise to the processes. Both layers are largely united on the surface, but in the antiapical and sulcal zone they generally separate, forming a continuous cavity beneath the bases of the adjacent processes. The processes are mostly gonal, occasionally sutural, hollow, they do not communicate with the interior of the central body and their shapes are varied; Basically they can be grouped into two types: 1) infundibuliform, with the distal end denticulate to aculeate with more or less fenestrate walls and frequently with bifurcations in the middle of their length, sometimes with a triangular section; 2) thinner processes with the distal end tri- or tetranfurcated. The processes of the first type and of larger size are found in the antiapical region, but they are also observed in less obvious forina in the apical area. Some processes are joined by ridges or membranous septa. In general, the specimens have precingular archaeopyle, however specimen 429
(2)-32.5/104.8 presents an archaeopyle of the type Aa + P of Evitt (1967), encompassing a precingular plate and the apical plates. Based on the distribution of the processes in the holotype specimen, the reflected tabulation of 4', 6", 6c, 5"', lp, 1"" was estimated, with the plate being 6" reduced.
DIMENSIONS. Diameter of the central body 42.5-32 μ, total diameter 66.5-50 μ, length of
the processes until 19 11-. NumberQ of specimens measured: 7. ·
MAIN MATERIAL STUDiED. Preparation 429(1), coordinates 31.7/113.2; preparation 429(2), coordinates 41.4/108.8; 32.5/104.8; preparation 429(9), coordinates 51.9/101.4. Discusion. Due to the presence of the combined archaeopyle Aa + P, this form could not be assigned to the genus Hystrichosphaera.
However, because it coincides in all the other characteristics with said genus and because it presents this type of combined archaeopyle only in very isolated cases, I consider that they are not sufficient elements.
to separate these specimens into a new genus, therefore this species is provisionally attributed to the genus Hystrichosphaera until a more in-depth study allows it to be classified more accurately.
COMPARISONS. The new species coincides considerably with Hystrichosphaera perforata Davey and Williams, 1966, mainly due to the two types of processes, the similar size and the fenestration.
which usually present the processes distally, however it differs from said species in that the two types of processes are not related to their gonal or sutural position, as occurs in H. perforata; Furthermore, the sutural membranes or septa are better defined in H. perforata. The specimens studied here differ from Hystrichosphaera buccina Davey and Williams, 1966, by being considerably larger in size.
smaller, because it has a more delicate and smooth wall and because of the type of processes; and differ from Hystrichosphaera
tertiary Eisenack ·and Gocht, 1960, the latter does not present a clear differentiation between the processes, but presents the limits between the plates clearly defined and possibly has different tabulation
reflected.
HORIZON. Sample MH2.
DERIVATIO NOMINIS. From the Greek heteros, distinct and stylos, column, punch.