Zygolithus diplogrammus Deflandre in Deflandre & Fert, 1954
Rectapontis Varol & Jakubowski, 1989
Loxoliths are characterised by a single wall, commonly with a proto inner wall, and a transverse bar lacking a distal process. Species are distinguished primarily by the morphology, structural organisation, and optical behaviour of the transverse bar.
In plan view under cross-polarised light, the single wall and proto inner wall remain in constant extinction. The optical behaviour of the transverse bar depends on its morphology and structural organisation.
Glaukolithus is frequently regarded as synonymous with Zeugrhabdotus but differs in lacking a distal process. Species concepts within Glaukolithus vary considerably among authors, indicating that a comprehensive revision of the genus is required.
Reinhardt, P. 1964. Einige Kalkflagellaten-Gattungen (Coccolithophoriden, Coccolithineen) aus dem Mesozoikum Deutschlands. - Monatsberichteder Deutschen Akademieder Wissenschaftenzu Berlin. 6: 749-759.
Deflandre, G. & Fert, C. 1954. Observations on current and fossil coccolithophorids in ordinary and electron microscopy. Annales de Paléontologie 40: 115-176.
Varol, O. & Jakubowski, M. (1989). Some new nannofossil taxa. INA Newsletter. 11(1): 24-29.