Aphananthe tenuicostata was named by Dorofeev (1982) [Endocarp small, ovoid to pyriform, length 3–4 mm, width 3 mm (n = 3), distorted (slightly crumpled and folded), thin-walled; with a prominent rounded, peglike, asymmetrically placed subapical protrusion of dense amorphous content [not crushed like the rest of the fruit]. Seed coat overlaps and thins at protrusion edge. Surface not shiny; texture minutely scabrate. Surface with weakly defined isodiametric polygonal cells up to 50 μm. Wall thickness c. 70 μm. Where visible in two specimens (pl. 7j, l), the wall is lined with a firmly attached thin, papery shiny cuticle.]. It is not extant.