Ian J. Slipper
Cythereis reticulata (Jones and Hinde)
Gault Clay Bed VIII; left valve
Description. Large (1·1 mm long) well-calcified, inflated carapace, displaying well developed reticulation. Larger left valve with distinct hinge ear; dorsal and median ribs continuous, the ventral rib is divided into a series of spines, subcentral tubercle smooth, or with a number of tubercles; spines developed at some intersections of reticulation meshes and along longitudinal
ribs; amphidont hinge. Strong sexual dimorphism displayed by male valves being higher, longer and more rectangular than females. Juveniles lack the reticulation but retain the strong ventral rib.
Age. Albian.
Distribution. Found commonly throughout the Gault Clay at Folkestone, maximum occurrence in the upper part of Bed IX where it comprises11 per cent of the ostracod fauna; in younger beds it tends to be replaced by Cythereis folkestonensis. This species is routinely found in lower to middle Albian sediments in northern and north-western Germany, northern France, southern and eastern England.
NOTE - I have reason to believe that the concept of Cythereis reticulata is flawed. Looking at the original Jones and Hinde descriptions this does not fit - However, it has become so entrenched in the literature that for the sake of stability this be retained.
Cythereis reticulata (Jones and Hinde)
Gault Clay Bed VIII; left valve
Description. Large (1·1 mm long) well-calcified, inflated carapace, displaying well developed reticulation. Larger left valve with distinct hinge ear; dorsal and median ribs continuous, the ventral rib is divided into a series of spines, subcentral tubercle smooth, or with a number of tubercles; spines developed at some intersections of reticulation meshes and along longitudinal
ribs; amphidont hinge. Strong sexual dimorphism displayed by male valves being higher, longer and more rectangular than females. Juveniles lack the reticulation but retain the strong ventral rib.
Age. Albian.
Distribution. Found commonly throughout the Gault Clay at Folkestone, maximum occurrence in the upper part of Bed IX where it comprises11 per cent of the ostracod fauna; in younger beds it tends to be replaced by Cythereis folkestonensis. This species is routinely found in lower to middle Albian sediments in northern and north-western Germany, northern France, southern and eastern England.
NOTE - I have reason to believe that the concept of Cythereis reticulata is flawed. Looking at the original Jones and Hinde descriptions this does not fit - However, it has become so entrenched in the literature that for the sake of stability this be retained.