From Fensome et al., 2019:
Hystrichophaeridium? breviatum Morgenroth, 1966a, p.29, pl.7, figs.11–12. Holotype: Morgenroth, 1966a, pl.7, figs.11–12; Fauconnier and Masure, 2004, pl.43, figs.5–7. Taxonomic senior synonym (at subspecific rank): Hystrichosphaeridium zoharyi subsp. ktana (as Polysphaeridium subtile subsp. ktana), according to Islam (1983b, p.343) — however, Masure and Foucher in Fauconnier and Masure (2004, p.309–310) retained this taxon as a questionable species of Hystrichosphaeridium. Questionable assignment: Stover and Evitt (1978, p.56). Age: Early Eocene.

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Original description: [Morgenroth, 1966a] (translated from German):

Hystrichosphaeridium breviatum n, sp.
Plate 7 Fig. 11-12

Derivatio nominis: breviatum lat: The shortened (cf. process length).
Holotype: The specimen preserved in specimen H92 and illustrated in Plate 7 Fig. 11-12.
Paratypoid: H 105.
Locus typicus: Fehmarn, Katharinenhof.
Stratum typicum: Lower Eocene (?2),
Diagnosis: A species of the genus Hystrichosphaeridium with a relatively thick capsule wall and numerous, very short, cylindrical processes.
Description: The surface of the slightly ellipsoidal to spherical capsule is granular. Numerous short, cylindrical, hollow processes, which are open distally, protrude from the relatively thick (21') capsule wall. The maximum process length corresponds to approximately 1/3 of the capsule radius.
Note: No pylomas were observed in the two specimens presented.
Dimensions: Holotype: Capsule Ø 42μ x 45μ, process length 6μ; Paratypoid: Capsule Ø 60μ, process length 8μ.
Number of specimens examined: 2.