Osodendron altissimum subsp. busiraensis (G.C.C. Gilbert & Boutique) E.J.M. Koenen, stat. nov. et, 2022

Koenen, Erik J. M., 2022, Osodendron gen. nov. (Leguminosae, Caesalpinioideae), a new genus of mimosoid legumes of tropical Africa, PhytoKeys 205, pp. 453-470 : 453

1.2. Osodendron altissimum subsp. busiraensis (G.C.C. Gilbert & Boutique) E.J.M. Koenen, stat. nov. et comb. nov.

Basionym.

Arthrosamanea altissima var. busiraensis G.C.C. Gilbert & Boutique, Fl. Congo Belge 3: 183. 1952.

Type material.

Democratic Republic of Congo, Eala surroundings, Wangata-Watsiko, October 1943, Germain 1604 (holotype: BR! [BR0000015846686], isotype: P [P00418269] digital image!).

Note.

This subspecies was originally described as an infraspecific variety. I have considered treating it as a distinct species, but after studying material held at BR, I concluded it cannot be reliably separated from the typical subspecies across its entire range. The material stands out in its combination of slightly different leaf shape and smaller pods, but material outside the Busira river catchment in the Democratic Republic of Congo, as well as in other parts of Africa, is rather variable in leaf shape and pod size. Given that both these differences are consistently present in most of the material from that region, i.e. the variation is geographically structured within this variable and widespread species, subspecies is more appropriate than varietal rank and I treat it here as such.

Distribution.

Local to the Busira river catchment in the western Democratic Republic of Congo (Fig. 2A ).

Ecology.

As the typical subspecies.

Representative specimens studied.

Democratic Republic of Congo: Boyekoli Ebale Congo Expedition 2010 104 (fls, BR); J. Louis 2052 (BR) & 13196 (BR); Robyns 653 (BR); Ghesquiere 2787 (BR); G. Hulstaert 607 (BR).

Figures

Figure 2. Osodendron altissimum A distribution of the two subspecies as per the legend, based on data from Gbif. org with the addition of occurrence records for O. altissimum subsp. busiraensis from specimens at BR B trunk on riverbank C bipinnate leaf D close-up of leaflets E close-up of rachis apex showing nectary F inflorescences G unripe pod H mature pod. Images: B, F, H William Hawthorne (FHO) C-E, G David Harris (E), from www. africanplants. senckenberg. de.