Euphorbia otjipembana subsp. fluvialis (L.C.Leach) Bruyns, 2020

Bruyns, Peter V., Klak, Cornelia & Hanáček, Pavel, 2020, A review of the Euphorbia schinzii-complex (Euphorbiaceae) in southern Africa, Phytotaxa 436 (3), pp. 201-221 : 210

6b. Euphorbia otjipembana subsp. fluvialis (L.C.Leach) Bruyns , comb. nov.

Euphorbia subsalsa subsp. fluvialis Leach (1976: 29) . Type:— ANGOLA. Kunene: Ruacana Falls, 28 September 1970, Leach & Cannell 14509 (holotype LISC, isotypes BM!, K!, LUAI, M!, MO, PRE!, SRGH).

Discussion: — Leach (1976) did not state why subsp. fluvialis was placed under E. subsalsa .

From E. subsalsa (see below) it is separated by its more robust habit, with plants branching from the base and freely above the base, 4-angled branches that are erect, uniformly greyish green (unstriped) and 15–30 mm thick, the spines are 7–15 mm long, with the stipular prickles 1.5–6 mm long. The quite robust spine-shields are parallel-sided below the spines with a rounded base and initially they have a slight gap (± 1 mm long) above the next axillary bud, but they later may fuse to form a ± continuous margin along the angles. The cyathial glands are erect, concave above and are suffused with pink, while the female floret is raised on a short pedicel around 0.5 mm long. Most of these features of subsp. fluvialis differ from those in subsp. subsalsa and are more closely matched in E. kaokoensis and E. otjipembana . With E. otjipembana , it shares the thicker branches, longer and more robust spine-shields, the erect concave cyathial glands and the raised female floret. Consequently, it is now placed as a subspecies of E. otjipembana .

Additional specimens examined: — ANGOLA. Mountains above Iona (1612DC), ± 1200 m, Bruyns 10387 (BOL). 21 km south of Otjinjau (1613DB), 1200 m, Bruyns 10786 (BOL). 22 km west of Oncocua (1613DC), 900 m, Bruyns 10366 (WIND). 22 km towards Oncocua from Ruacana (1613DB), 1150 m, Bruyns 10358 (BOL). Sera Techamalinda (1712BA), 650 m, Bruyns 10695 (BOL). Ruacana Falls (1714AC), Leach & Cannell 14509 (BM, etc). NAMIBIA. Epupa Falls (1713AA), Leach & Cannell 15036 (WIND). Near Otjombana (1713BA), 700 m, Bartsch 1354 (WIND). Swartbooisdrift (1713BD), Hall sub NBG 254/51 (NBG). 15 km west of Ruacana Falls (1714AC), 800 m, Bruyns 10657 (BOL). 5 km west of Ruacana Falls (1714AC), Rodin 9262 (WIND). 7 km SW of Ruacana Falls (1714AC), 750 m, Leistner et al. 74 (PRE). Kunene River, Great Falls to Little Falls, Barnard (SAM).