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Achomosphaera brevis
From Fensome et al., 2019:
Achomosphaera brevis Soliman and Riding, 2017, p.327–328,330, pl.3, figs.7–8; pl.5, figs.13–16; text-fig.3.
Holotype: Soliman and Riding, 2017, pl.5, figs.13–14.
Age: Late Miocene.
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Original description Soliman and Riding, 2017:
Holotype. Sample HC1-16, slide A, England-Finder coordinate K39 (Plate V, 13, 14). Specimen number UMJ G and P 211335 of the Joanneum Museum, Graz, Austria.
Paratype. Sample HC1-16, slide A, England-Finder coordinate O32 (Plate V, 15, 16).
Etymology. From the Latin brevis, meaning short, with reference to the short processes.
Type locality. Hennersdorf Clay Pit, Vienna Basin, Austria.
Lithostratigraphy of the type material. The Záhorie Member of the Bzenec Formation, Upper Miocene (Pannonian).
Diagnosis. A small ovoidal species of Achomosphaera. The cyst wall is thin and smooth. The processes are exclusively gonal and relatively short, straight, wide proximally and multifurcate distally. Adjacent cingular processes are occasionally merged together. Usually there is a large quadrangular shaped process in the sulcal area. No sutures are present. The archaeopyle is precingular (type P), and the operculum is free.
Description. A small species of Achomosphaera with an ovoidal cyst body. The cyst wall is thin (~ 1.0 μm) with a smooth or shagreenate surface. The processes are gonal only and relatively short (up to ~ 25% of the cyst length), hollow, smooth and normally closed distally. Occasionally some processes are open distally (Plate III, 7). The width of the processes is variable although their length is fairly constant. They are bulbous proximally, where they are expanded to twice the width at the mid shaft; typically they are cylindrical in cross section. Fenestrations are rarely present at the process bases. Distally, the processes are expanded, branching and multifurcate; they may have serrate margins and have recurved tips. Closely adjacent processes in the cingular area may have merged bases (Fig. 3). If they are not merged, the cingular processes are arranged in two parallel rows. The sulcus is delineated by high parasutural crests at the contacts between post and pre-cingular plates in the form of a large quadrangular shaped process (Plate III, 8). No intrasutural tabulation is developed. The archaeopyle is precingular, type P, formed by the loss of plate 3″ and the operculum is free.
Comparison. Achomosphaera brevis sp. nov. is significantly smaller than most other species of this genus. It differs from Achomosphaera ramulifera (Deflandre, 1937) Evitt, 1963 in that the processes are exclusively gonal, hollow and multifurcate rather than trifurcate. It is also similar to Achomosphaera andalousiensis Jan du Chêne, 1977 but Achomosphaera brevis sp. nov. differs in that the distal ends of the processes lack large fenestrae, and the sulcus delineated by high parasutural crests (Plate III, 8). Achomosphaera brevis sp. nov. differs from Achomosphaera argesensis Demetresçu, 1989 by the lack of an apical boss and A. argesensis has ‘a flat process developed on the apical area or on both apical and antapical areas’ (Demetresçu, 1989) which is lacking in Achomosphaera brevis described herein. It can be distinguished from Achomosphaera bulla Cookson and Eisenack, 1974 by its oval shape and hollow processes, and differs from Achomosphaera fenestra Kirsch, 1991 by lacking fenestrae in the processes shafts. Achomosphaera improcera Islam, 1983 is similar in size, but has gonal processes with trifurcate distal ends and intergonal processes with bifurcate ends.
Dimensions. The maximum overall length is 29 (37) 44 μm; the maximum overall width is 22 (87) 34 μm; and the maximum length of the processes is 3 (7) 10 μm. Thirty-four specimens were measured.
Distribution. This species was recorded sporadically in the current study.
Achomosphaera brevis Soliman and Riding, 2017, p.327–328,330, pl.3, figs.7–8; pl.5, figs.13–16; text-fig.3.
Holotype: Soliman and Riding, 2017, pl.5, figs.13–14.
Age: Late Miocene.
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Original description Soliman and Riding, 2017:
Holotype. Sample HC1-16, slide A, England-Finder coordinate K39 (Plate V, 13, 14). Specimen number UMJ G and P 211335 of the Joanneum Museum, Graz, Austria.
Paratype. Sample HC1-16, slide A, England-Finder coordinate O32 (Plate V, 15, 16).
Etymology. From the Latin brevis, meaning short, with reference to the short processes.
Type locality. Hennersdorf Clay Pit, Vienna Basin, Austria.
Lithostratigraphy of the type material. The Záhorie Member of the Bzenec Formation, Upper Miocene (Pannonian).
Diagnosis. A small ovoidal species of Achomosphaera. The cyst wall is thin and smooth. The processes are exclusively gonal and relatively short, straight, wide proximally and multifurcate distally. Adjacent cingular processes are occasionally merged together. Usually there is a large quadrangular shaped process in the sulcal area. No sutures are present. The archaeopyle is precingular (type P), and the operculum is free.
Description. A small species of Achomosphaera with an ovoidal cyst body. The cyst wall is thin (~ 1.0 μm) with a smooth or shagreenate surface. The processes are gonal only and relatively short (up to ~ 25% of the cyst length), hollow, smooth and normally closed distally. Occasionally some processes are open distally (Plate III, 7). The width of the processes is variable although their length is fairly constant. They are bulbous proximally, where they are expanded to twice the width at the mid shaft; typically they are cylindrical in cross section. Fenestrations are rarely present at the process bases. Distally, the processes are expanded, branching and multifurcate; they may have serrate margins and have recurved tips. Closely adjacent processes in the cingular area may have merged bases (Fig. 3). If they are not merged, the cingular processes are arranged in two parallel rows. The sulcus is delineated by high parasutural crests at the contacts between post and pre-cingular plates in the form of a large quadrangular shaped process (Plate III, 8). No intrasutural tabulation is developed. The archaeopyle is precingular, type P, formed by the loss of plate 3″ and the operculum is free.
Comparison. Achomosphaera brevis sp. nov. is significantly smaller than most other species of this genus. It differs from Achomosphaera ramulifera (Deflandre, 1937) Evitt, 1963 in that the processes are exclusively gonal, hollow and multifurcate rather than trifurcate. It is also similar to Achomosphaera andalousiensis Jan du Chêne, 1977 but Achomosphaera brevis sp. nov. differs in that the distal ends of the processes lack large fenestrae, and the sulcus delineated by high parasutural crests (Plate III, 8). Achomosphaera brevis sp. nov. differs from Achomosphaera argesensis Demetresçu, 1989 by the lack of an apical boss and A. argesensis has ‘a flat process developed on the apical area or on both apical and antapical areas’ (Demetresçu, 1989) which is lacking in Achomosphaera brevis described herein. It can be distinguished from Achomosphaera bulla Cookson and Eisenack, 1974 by its oval shape and hollow processes, and differs from Achomosphaera fenestra Kirsch, 1991 by lacking fenestrae in the processes shafts. Achomosphaera improcera Islam, 1983 is similar in size, but has gonal processes with trifurcate distal ends and intergonal processes with bifurcate ends.
Dimensions. The maximum overall length is 29 (37) 44 μm; the maximum overall width is 22 (87) 34 μm; and the maximum length of the processes is 3 (7) 10 μm. Thirty-four specimens were measured.
Distribution. This species was recorded sporadically in the current study.