Hystrichosphaeridium dictyostilum Menéndez, 1965, p.11–12, pl.2, fig.6; pl.3, figs.18–22. Emendations: Sarjeant, 1981, p.115, as Areosphaeridium dictyostilum; Fensome et al., 2007, p.396–397, as Enneadocysta dictyostila.

NOW Enneadocysta. Originally Hystrichosphaeridium, subsequently Oligosphaeridium?, thirdly Areosphaeridium, fourthly Enneadocysta?, fifthly (and now) Enneadocysta.
Taxonomic senior synonym: Hystrichosphaeridium (now Areosphaeridium) diktyoplokum, according to Eaton (1971, p.359) — however, Sarjeant (1981, p.115) retained Areosphaeridium (now Enneadocysta) dictyostilum.
Taxonomic junior synonyms: Enneadocysta partridgei, according to Fensome et al. (2007, p.396), Areosphaeridium (now Enneadocysta) arcuatum and Cordosphaeridium (now Cooksonidium) capricornum, both according to Sarjeant (1981, p.115–116) — however, Lentin and Williams (1985, p.26) retained Areosphaeridium (now Enneadocysta) arcuatum and Cordosphaeridium (now Cooksonidium) capricornum.

Holotype: Menéndez, 1965, pl.2, fig.6; pl.3, figs.18–20.
Locus typicus: Tierra del Fuego, well cuttings from well LSX 4 (La Sara) of Tennessee, in 1121 1301 m, Argentinia
Stratum typicum: Tertiary

Original diagnosis: MenÚndez, 1965, p.11-12
The body is ellipsoidal or oval with a nearly smooth membrane having tubular processes (17 or 18) positioned more or less radially, and broadening at the base; the free end is broadly infundibuliform with irregular ramification or forming a reticulum.
Dimensions: Central body 56 by 45 µm; 1.5 µm thick; appendages 15 to 19 µm long and 1 to 2.9 µm wide.