A new species of centrohelid heliozoans Pterocystis infundibula sp. n. from the Gulf of Aqaba (Israel) was studied with light and electron microscopy. The cell diameter is 10.53–19.03 (average 13.73) μm. P. infundibula has scales of two distinct types. Plate scales are 1.99–3.02 (av. 2.53) × 1.10–1.54 (av. 1.35) μm in size, flat, oval or slightly ovoid with an axial thickening. Spine scales are 1.39–5.22 (av. 2.88) μm long, with a funnel-shaped base, which is indistinctly continuous with a shaft, demonstrating gradual levels of reduction to the extent of the complete absence. Spine scales are fenestrated with holes of irregular shape and have a thin marginal border. The cells are floating or attached to the substratum, sometimes in aggregates of 2–5 cells. The similarities with and differences from other Pterocystis spp. as well as other centrohelids are discussed.