Microstellaria juliae – a remarkable new subfamily, new genus and new species in the Pyramidellidae (Gastropoda)

A new genus and species within the Pyramidellidae are described from offshore coral reefs at various localities in Indonesia and from the Royal Charlotte atoll in the South China Sea: Microstellaria juliae gen. et spec. nov. Thus far only dead specimens have been found. The remarkable discoidal, planispiral shells with regularly placed projecting spines appear to be miniature versions of Stellaria Möller, 1832 (family Xenophoridae) or juvenile Astraea Röding, 1798 (Turbinidae). The heterostrophic protoconch at an almost 90^o angle to the teleoconch demonstrates its placement within the Pyramidelloidea, however, the shells have some unique features. The internal septa in the early part of the teleoconch have not been recorded before from the Pyramidelloidea. They are interpreted as preventive measure in case the protoconch is damaged. The planispiral shape is exceptional within the Pyramidellidae, albeit not unique. The projecting spines along the periphery and on the aperture are unique within the superfamily. Therefore the genus is placed within a new subfamily Microstellariinae subfam. nov., currently within the Pyramidellidae, but it could constitute a separate family within the Pyramidelloidea.