From Fensome et al., 2019:
Hystrichostrogylon digitus Fensome et al., 2016b, p.51, pl.9, figs.1–3. Holotype: Fensome et al., 2016b, pl.9, fig.3. Age: last occurrence, Bartonian–Priabonian.
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Original description Fensome et al., 2016b:

Holotype. Plate 9, fig. 3, from a cuttings sample at 2435‒2445 m in Rut H-11, GSC type collection no. 137952, sample P39375, slide 01, co-ordinates 15.8 × 105.0, England Finder Q48/1. Length of central body (excluding cavation) 45 μm, width of central body (excluding cavation) 38 μm; overall length of cyst 73 μm, overall width of cyst 72 μm. The age determined for the sample from which the holotype was recovered is Lutetian Priabonian.

Etymology. From the Latin digitus (finger), in reference to the long extensions at the process endings. The epithet is a noun in apposition.

Diagnosis. A species of Hystrichostrogylon in which the bi- and trifurcations of the processes constitute long, fine, cylindrical distal branches generally one-third to one half the length of the process stem. The distal branches tend to be perpendicular to the process stem.

Size. Length of central body (excluding cavation) 40‒45 μm, width of central body (excluding cavation) 33‒40 μm; overall length of cyst 73‒82 μm, overall width of cyst 66‒79 μm; 3 specimens measured.

Age. LO: Bartonian‒Priabonian. Not plotted.

Remarks. This species differs from other species of Hystrichostrogylon in having remarkably long, fine branches at the ends of the processes.