From Fensome et al., 2019:
Gresslyodinium mirabile Below, 1990, p.51–52, pl.11, figs.1–16; text-fig.14. Holotype: Below, 1990, pl.11, figs.2,4–7,10–11,14. Contrary to the opinion of Lentin and Williams (1993, p.269), this name is validly published. Below (1987a, p.6) stated that, unless otherwise indicated, all the material is in his personal collection. Since Below (1987a, 1987b, 1990) are parts I to III of a single study, we agree with J. Jansonius (personal communication) that Below's (1987a) repository statement refers to all three publications, fulfilling the requirement of ICN Article 40.7 (see also the discussion on Article 40.7 in the Introduction). Age: Bajocian. Age: Bajocian.

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Original description (Below, 1990) (translated from German):

Gresslyodinium mirabile n. gen. n. sp.
Plate 11, Figs. 1-16; Fig. 14

Derivio nominis: mirabilis (Latin, adv.) = wonderful.
Holotype: Specimen S7-1104(K7)3/1 (Plate 11, Figs. 2, 4-7, 10-11, 14).
Typical location: Sengenthal, Neumarkt id.Obf.

Description:
Typical stratum: lower gravel layer; Dogger Gamma, Bajocian.
Vesicle/plate arrangement of the dinoflagellate Amphiesma cop, pop, cap, 3', 2a, 6'', 7c, 6"', 2"", as, FM, Is, rs, ps; 1' exsert with adelopore on the suture 1'/6'', 1a quadragonal, 2a hexagonal; tegulation 4*, 2**, 4***, 2****, 7c, 4(*), 4(**), 3(***); growth of thecal plates in a gonyaulacoid manner;
Zygote cyst habitus proximal, equatorially finicavate, fusiform, tentoriate epicyst and somewhat shorter, elongated tentoriate hypocyst, extended to form the long apical horn and shorter anta-pical horn, respectively, circular in equatorial section; wall consisting of a thin pedium and overlying Reticulate/spongiform luxuria, fusing intraareat distal to the tegillum, hypocystal finate and forming reticulated septa especially along the cingulate margins, epicystal finate ornamentation strongly reduced, mostly resolved into rows of granules or completely absent;
Arrangement scheme XPR/cop, pop, cap, NR'/3', NRa/1a(arch)-2a(arch)/2a, 6', Xc, 6'", 2"", Xs; cop tiny as oval tip of the apical horn, horseshoe-shaped enclosed by pop, tiny cap adjoining ventrally; 3 apicals: very small planate 1' (V) exsert with porichnion on the finis 1'/6'', VIII2' (LVL), IX3' (VVR); 2 anterior intercalaries: small caroid 1a (DL) and linteloid 2a (D); 6 precingulate: anterior bigeniculate VI-nE 1'' (VVR), anterior geniculate V-nE 2'' (LVL), anterior geniculate V-nE 3'" (DDL), anterior linear IV-nE 4'' (DDR), Finis 3"/4'' dorsal, anterior geniculate V-nE 5" (RVR), anterior geniculate V-nE 6'' (VVR); cingulum left-handed spiral, heptapartite, 6 postcingulates: posterior linear VI-nE 1'" (VVL), posterior linear IV-nE 2'" (VL), posterior geniculate V-nE3'" (DL), posterior linear IV-nE 4'" (D), posterior linear IV-nE 5'" (R), posterior linear VI-nE 6''' (VVR); 2 antapics: V1''" to VL, VI2''" to V; sulcus areate or sulcal areas towards FM nonfinate: small Vlas, steno vFM, small V1s and IVrs, as well as large omega-shaped Vip's bulged between 1''" and 2''"; archaeopyle anteriorly intercalary/apical, PR + 2' + 3' + 1a + 2a; operculum foederate, opercular plate secate, general opercular formula (PR + 2' + 3')(s), + 1a(s) + 2a(s).

Dimensions of the holotype:
Length 75 μm, width 37 μm, thickness 37 μm.

Reference:
Specimen 1104.