Platonea dilatata was named by Gordon and Taylor (2015) [Colony encrusting, ramose, comprising narrow branches of subtriangular cross section detached from their original substrates. Branches 0.8 to 1.5 mm in width. Colony origin unknown. Autozooids arranged in transverse to slightly distally divergent rows alternating on either side of branch, 6 or 7 connate apertures in each row, rows from opposite sides of branches typically touching at branch midline in infertile branches but separated in fertile branches; frontal walls slightly convex; apertures rounded rectangular, transversely elongate, about 110-130 mm long by 140-160 mm wide; peristomes short, stout; pseudopores subcircular. Gonozooids large, extending across full width of branch, coincident with conspicuous increase in branch width and depth, filling valleys between autozooidal rows and occupying branch crests; frontal walls densely pseudoporous; ooeciopore not identified with certainty, although a hole on the midline of a fertile branch and adjacent to one of the innermost apertures of a row of autozooidal apertures may be a broken ooeciopore (Fig. 8C), in which case the ooeciopore is non-terminal and probably adnate to an autozooidal aperture.]. It is not extant. Its type specimen is IGNS BZ245.