Published online by Cambridge University Press: 20 May 2016
The discovery of domatial dimorphism in the leperditellid ostracode Loculocavata n. gen. and the monotiopleurid Primitiella minima (Harris), and the possibility that Leperditella Ulrich exhibits domatial dimorphism, requires a revision of the concept and/or diagnosis of the Platycopina. Domatial dimorphism is manifested by a special domiciliar space for egg/brood care in females. Domatia are represented by a loculate domiciliar wall or by a more generalized space bounded anteriorly by an interior partition caused by thickening or folding (sulcation) of the shell wall. Domatial dimorphism occurs in morphologically diverse ostracodes as shown by the podocopine Mesocyprideis, kloedenellids, cytherellids, monotiopleurids, the leperditellid Loculocavata n. gen., and by its possible occurrence in Hypotetragona and Leperditella. Changes in the present concept and/or diagnosis of the Platycopina are required to account for the above. Possible classifications range from restricting the Platycopina to holosolenic ostracodes with R/L overlap and domatial dimorphism to including within the Platycopina all groups that exhibit domatial dimorphism. The position of adductor muscle attachment in Loculocavata n. gen. and Primitiella minima (Harris) suggests that L2 may be the external expression of the position of adductor muscle attachment in some ostracodes.