Plate 12, Figures 1-7, 9
Holotype: Plate 12, Figure 2, 3.
Paratype: Plate 12, Figures 1, 6.

Type Locality: Speeton Bed C9D, early Hauterivian, regale ammonite Zone. Holotype: Slide C9D(2), E.F. U44.3. Paratype: Slide C9D(1), E.F. K40.0.

Derivation of Name: From the Latin dentatus, toothed - in reference to the denticulate sutural crests.

Diagnosis: A thick-walled, dorso-ventrally flattened species, subcircular in outline, with a fibro-perforate texture and a short, broad-based apical horn. Tabulation of the formula 4', 6'', ?c, 6''', 1p, 1p.v., 1'''' is marked by delicate, regularly denticulate crests marginally and on the dorsal surface, but these are reduced to low ridges ventrally. A narrow cingulum is clearly defined and a prominent sulcal groove is invariably present. The archeopyle is tetratabular apical with the operculum usually lost. The zig-zag archeopyle margin displays a distinct but shallow sulcal notch.

Dimensions: Holotype: Length - 63 μm. Width - 63 μm.
Paratype: Length: 71 μm. Width - 76 μm.
Complete specimen (paratype): 71 × 76 μm.
Overall (operculum lost): 66 (59) 51 μm × 73 (63) 53 μm.
Specimens Measured: 9.

Remarks: The possession of regularly denticulate sutural crests separates this species from all others of this genus. Its possession of an apical horn also distinguishes it from Meiourogonyaulax pertusa (Duxbury 1977) Below 1981 and Meiourogonyaulax stoveri Millioud 1969.
This species has a very restricted range, being recorded only in Speeton Beds C10 and C9D, early Hauterivian, lower regale ammonite Zone.