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Areosphaeridium dictyostilum
Areosphaeridium dictyostilum, (Menéndez, 1965); Emendation: Sarjeant, 1981
Originally Hystrichosphaeridium, subsequently Oligosphaeridium?, thirdly Areosphaeridium.
Tax. jr. synonym of Areosphaeridium diktyoplokus (Klumpp, 1953) Eaton, 1971, according to Eaton, 1971. Sarjeant, 1981, retained Areosphaeridium dictyostilum as a separate species.
Tax. sr. synonym of Areosphaeridium arcuatum Eaton, 1971, according to Sarjeant, 1981. Lentin and Williams, 1985, retained Areosphaeridium arcuatum as a separate species.
Tax. sr. synonym of Areosphaeridium capricornum (Cookson and Eisenack, 1965) Stover and Evitt, 1978, according to Sarjeant, 1981. Lentin and Williams, 1985, retained Areosphaeridium capricornum as a separate species.
Holotype: Menéndez, 1965, pl.2, fig.6; pl.3, figs.18-20.
Locus typicus: Tierra del Fuego, well LSX 4 (La Sara) of Tennessee, Argentinia
Stratum typicum: Eocene-Oligocene
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Original description as Hystrichosphaeridium dictyostilum: [Menéndez, 1965, p.11-12]: (Translation: Sarjant, 1981, p. 115):
Diagnosis:
Body ellipsoidal or ovoidal, membrane without protuberances, with tubular processes (17 or 18) disposed more or less radially, wide at the base, free end infundibuliform with irregular ramifications or forming a reticulum.
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Emended description:
Sarjeant, 1981, p. 115:
Diagnosis:
Cyst subspherical to subovoidal or subpolygonal, skolochorate.
Processes intratabular, with solid fibrous stems of length varying in the range one third to one-half the short diameter of the cyst. Each process is distally expanded and bifurcate (licrate); the attitude of the bifurcations varies from patulate to recurved. The two branches are of variable relative and absolute length; they vary in breadth from slender, with a denticulate distal margin, to broad, with an irregular distal margin and sometimes a net-like structure. Fenestration may be developed in the process stems, producing stem branches which are sometimes distally free. Paratabulation: 4", 6"", 0c, 6""", 1p, 1"""" (not always fully reflected, since the processes representing paraplates 6"", 6""" and 1p may be lacking). The cingular zone is typically devoid of processes; the antapex, with its single process, is typically offset to the right of the midventral line. Between the postcingular processes and the antapical process there may be one or occasionally two additional processes.
Archaeopyle apical (type tA), tetratabular: operculum free.
Dimensions:
Holotype: Length of cyst (apex lacking) 45 µm, breadth 56 µm, length of processes 15-19 µm, breadth of processes 1-2.9 µm, thickness of phragma 1.5 µm.
Originally Hystrichosphaeridium, subsequently Oligosphaeridium?, thirdly Areosphaeridium.
Tax. jr. synonym of Areosphaeridium diktyoplokus (Klumpp, 1953) Eaton, 1971, according to Eaton, 1971. Sarjeant, 1981, retained Areosphaeridium dictyostilum as a separate species.
Tax. sr. synonym of Areosphaeridium arcuatum Eaton, 1971, according to Sarjeant, 1981. Lentin and Williams, 1985, retained Areosphaeridium arcuatum as a separate species.
Tax. sr. synonym of Areosphaeridium capricornum (Cookson and Eisenack, 1965) Stover and Evitt, 1978, according to Sarjeant, 1981. Lentin and Williams, 1985, retained Areosphaeridium capricornum as a separate species.
Holotype: Menéndez, 1965, pl.2, fig.6; pl.3, figs.18-20.
Locus typicus: Tierra del Fuego, well LSX 4 (La Sara) of Tennessee, Argentinia
Stratum typicum: Eocene-Oligocene
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Original description as Hystrichosphaeridium dictyostilum: [Menéndez, 1965, p.11-12]: (Translation: Sarjant, 1981, p. 115):
Diagnosis:
Body ellipsoidal or ovoidal, membrane without protuberances, with tubular processes (17 or 18) disposed more or less radially, wide at the base, free end infundibuliform with irregular ramifications or forming a reticulum.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Sarjeant, 1981, p. 115:
Diagnosis:
Cyst subspherical to subovoidal or subpolygonal, skolochorate.
Processes intratabular, with solid fibrous stems of length varying in the range one third to one-half the short diameter of the cyst. Each process is distally expanded and bifurcate (licrate); the attitude of the bifurcations varies from patulate to recurved. The two branches are of variable relative and absolute length; they vary in breadth from slender, with a denticulate distal margin, to broad, with an irregular distal margin and sometimes a net-like structure. Fenestration may be developed in the process stems, producing stem branches which are sometimes distally free. Paratabulation: 4", 6"", 0c, 6""", 1p, 1"""" (not always fully reflected, since the processes representing paraplates 6"", 6""" and 1p may be lacking). The cingular zone is typically devoid of processes; the antapex, with its single process, is typically offset to the right of the midventral line. Between the postcingular processes and the antapical process there may be one or occasionally two additional processes.
Archaeopyle apical (type tA), tetratabular: operculum free.
Dimensions:
Holotype: Length of cyst (apex lacking) 45 µm, breadth 56 µm, length of processes 15-19 µm, breadth of processes 1-2.9 µm, thickness of phragma 1.5 µm.