Types, Locality and Age. Holotype: Slide GIS-W2, England
Finder reference: M60/3 (Plate 3A; Fig. 7A). Paratype
1: Slide GIS-W2, E.F. reference: M58/1 (Plate 3B;
Fig. 7B. Paratype 2: Slide GIS-W2, E.F. reference: E51/3 (Plate 3C; Fig. 7C). Paratype 3: Slide GIS-W2, E.F. reference:
O54/2 (Plate 3D; Fig. 7D). All types are from
the bioclastic limestone in the lower part of the «Gisliflue
Reef», Gisliflue West section (WGS84 coordinates:
47.425237° N, 8.107563° E), Aargau, Switzerland. Sample
GIS-W2. Middle Jurassic, Early Bajocian, Humphriesianum
Zone.
Derivation of Name. From the Greek ‘hypo’ meaning
‘under’, and ‘lyein’ meaning ‘to dissolve’ or ‘to separate’, in
reference to the fact that not only the epicyst but also the
hypocyst is involved in archaeopyle formation. The specific
epithet ‘argoviense’ is derived from Latin and means
‘coming from Aargau’, in reference to the type locality in
this canton in Switzerland.
Diagnosis generico-specifica. Gonyaulacacean (leptodinioidean)
cysts that are proximate, with subspherical
body. Acavate. Surface almost smooth to ornamented
with features of low relief. Tabulation gonyaulacacean
with neutral torsion, either indicated by archaeopyle
only, or partially expressed by negative structures such
as reduction of ornamentation. Archaeopyle holocystal,
where the epicyst, the cingulum and the hypocyst dissociate
into constituent plates.