Euphorbia acanthoclada Pahlevani, 2017

Pahlevani, Amir H., 2017, Four new species of Euphorbia sect. Pithyusa (subg. Esula, Euphorbiaceae) from SW Asia, Phytotaxa 312 (1), pp. 83-93 : 84

Euphorbia acanthoclada Pahlevani , sp. nov. ( Fig. 1 ; Breckle & Rafiqpoor, 2010: Fig. Eu-03)

Most closely related to E. acanthodes , but differing by pilose (not glabrous) bark and stem, a less intricate thorny branching system, the abaxial leaf surface, especially margins, sparsely pilose, leaves without any conspicuous veins or only obscure midrib (instead of 1–3 prominent palmate veins); glands of cyathia with two long horns (instead of two short ones or no horns), glands reddish-brown.

Type:— AFGHANISTAN. Herat: between Shindand and Farah Rud , 1150 m, 23 April 1967, Rechinger 33383 (holotype B100846959 !; isotypes M0224496 !, WU!) .

Perennial, caespitose, spinescent and pubescent subshrubs, 15–20 cm high, woody last year branches becoming whitish. Cauline leaves sessile, lanceolate, oblong to oblanceolate, 10–15 × 3–5 mm, truncate to rounded at the base, entire to subentire and cartilaginous at margin, acute to subacute at apex, glaucous, occasionally sparsely pilose beneath, especially at margin, glabrous above, without prominent veins or only with obscure midrib. Terminal rays 2–3, once dichotomously branched; with 0–3 axillary rays; rays and axillary rays later becoming rigid spinescent. Ray leaves similar to cauline leaves in shape and size; raylet leaves mostly ovate to rather rhombic, rounded at base, acute and mucronulate at apex, entire to subentire and cartilaginous at margin. Cyathial involucre campanulate, 3–3.5 mm in diameter, internally pilose and externally glabrous; lobes lanceolate and acute, glands 4, gland appendages lunate, with two long horns, reddish-brown. Ovary smooth, style and stigma unknown. Capsules seen only immature, trilobate, 5.5–7 mm in diameter, glabrous, smooth. Seeds unknown.

Additional specimen examined (paratype): — AFGHANISTAN. Farah: Gija [Gijam], 900 m, 10 April 1949, KØie 4227 ( W).

Etymology: —The epithet ‘ acanthoclada ’ refers to its thorny shoots.

Affinity and plant geography: —Morphological characters of the newly discovered species indicate that it belongs to section Pithyusa . No DNA could be extracted from the rather old herbarium specimens. This species, like many other members of section Pithyusa , is an Irano-Turanian element. Euphorbia acanthoclada has been collected only from the type locality in W Afghanistan, Herat province and once from another place [Gijam] in SW Afghanistan by K Ø ie ( Fig. 2 ). This species was misidentified and reported as E. acanthodes Akhani (2004: 108) , an endemic and rare species from SW Iran, by Breckle et al. (2013). There is no ecological information of its habitat, it is found at elevations between 900 and 1150 m.

Conservation status: —Based on conservation analysis and IUCN threatened categories, it is suggested to evaluate its conservation status as ‘critically endangered’ (CR) (IUCN 2017).

Figures

FIGURE 1. Photograph of holotype specimen of Euphorbia acanthoclada.

FIGURE 2. Geographical distribution of Euphorbia acanthoclada and E. boreo-baluchestanica.