Euphorbia clivicola subsp. calcritica 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 : 207-208

2b. Euphorbia clivicola subsp. calcritica Bruyns , subsp. nov.

This new subspecies differs from subsp. clivicola by the slightly rhizomatous habit, the longer spines, the pale stripe along the middle of the branches and the brownish yellow cyathial glands.

Type:— SOUTH AFRICA. Limpopo. 20 km from Zebediela towards Roedtan (2429AD), 1030 m, 31 October 2011, Bruyns 12045 (holotype BOL!).

Slightly rhizomatous succulent forming small clusters of branches to 150 mm in diam. Branches 40–60(–150) × 6−10 mm, subcylindrical, grey-green to brownish green with pale stripe between rows of tubercles; tubercles with spine-shields 5–10 × 1–3 mm, ± 3 mm broad above spines and 4–8 mm long slender and finely acute below spines, bearing 2 spreading initially reddish brown (later grey) spines 5–12 mm long; leaf-rudiments ± 0.5 × 0.7–1.2 mm, erect, fleeting, ovate, with irregular tiny stipular prickles ± 0.25 mm long. Cyathia and glands slightly brownish yellow with reddish bracts.

Distribution & Habitat: — Subsp. calcritica has only been recorded between Zebediela and Roedtan ( Fig. 2 ), though it is likely to occur more widely in this area. At the type locality it grows in flat patches with much calcritic rubble on and beneath the surface, among short bushes (mostly <20 cm tall) between larger and scattered clumps of trees.

Discussion: —This new subspecies has been known since a record made by Frank Bayer in 1942 at PRE (photo only), but there are no specimens other than the type. It shares with subsp. clivicola the prominent tubercles which are not joined into angles, differing from subsp. clivicola by the slightly rhizomatous habit, the paler markings on the branches and the brownish yellow cyathial glands.

Figures

FIGURE 2. Distribution of Euphorbia clivicola (circle = subsp. clivicola, triangle = subsp. calcritica).