Rhyticaryum

Rio, Cédric Del, Stull, Gregory W. & Franceschi, Dario De, 2020, Survey of the fruits and endocarps of Icacinaceae (Lamiids, Icacinales), European Journal of Taxonomy 645, pp. 1-130 : 98

Key to the genus Rhyticaryum

1. Endocarp 28.8–36.3 mm in length, endocarp wall 800–950 µm thick .......... R. macrocarpum Becc. – Endocarp less than 23.6 mm in length, endocarp wall less than 600 µm thick ................................ 2

2. Endocarp primary vascular bundle in a channel ......................... R. novoguineense (Warb.) Sleumer – Endocarp primary vascular bundle outside the endocarp wall ......................................................... 3

3. Endocarp ridging reticulate ............................................................................................................... 4 – Endocarp ridging not reticulate .......................................................................... R. oleraceum Becc.

4. Subapical pores present, endocarp wall less than 250 µm thick ................... R. elegans G.Schellenb. – Subapical pores absent, endocarp wall more than 300 µm thick ...................................................... 5

5. Areoles 15–21 on each face, endocarp wall 514–575 µm thick ..................... R. fasciculatum Becc. – Fewer than 15 areoles on each face, endocarp wall less than 500 µm thick .................................... 6

6. Fruit strigose, endocarp width ca 10 mm ................................. R. longifolium K.Schum. & Lauterb. – Fruit glabrous, endocarp width ca 13 mm ......................................................... R. racemosum Becc .