The Upper Bathonian and Lower Callovian ostracod species Fastigatocythere juglandica (Jones, 1884) is shown to comprise a total of five subspecies. Of these, F. juglandica juglandica, F. juglandica major (Jones & Sherborn, 1888) and F. juglandica postrotunda subsp. nov., described as new herein, are all confined to the Upper Bathonian. Lophocythere fulgurata (Jones & Sherborn, 1888) is demonstrated to be an instar of F. juglandica major. Fastigatocythere juglandica degenerata subsp. nov., described as new herein and F. juglandica rugosa Weinholz comb. nov., both confined to the Lower Callovian, extend the known range of the species into that stage for the first time.