Rhyticaryum Becc.

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

Genus Rhyticaryum Becc.

Figs 31.10–31.25, 32, 33.1–33.18

Description

FRUIT. Elliptical, asymmetrical at the apex, laterally compressed, red when mature. Epicarp strigose, with simple hairs with granular ornamentation or glabrous, shriveled when dry, revealing the underlying reticulum of endocarp ridges. Calyx persistent.

ENDOCARP. Brown-cream, elliptical in lateral view, lenticular in transverse section. Keel surrounding the endocarp in the plane of symmetry. Apex asymmetrical in lateral view, with pair of subapical pores, occasionally absent; base symmetrical. Outer surface of the endocarp ridged, rarely rugose; ridges diffuse or delimiting a reticulate pattern enclosing polygonal areoles with freely ending ridgelets. Ridges rounded, occasionally sharp. Vasculatures of the endocarp resting on the ridges. Endocarp primary vascular bundle outside the endocarp wall or in a channel on the keel. Endocarp wall at least with one layer with rows of periclinally oriented cells and another with rows of anticlinally oriented cells. Locule surface covered with large to rounded and regularly spaced papillae. Locule lacunate.

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 .