Euphorbia kavirensis 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 : 88

Euphorbia kavirensis Pahlevani , sp. nov. ( Fig. 4 )

Euphorbia kavirensis is closely related to E. gedrosiaca but differs in its obovate to cuneate cauline leaves (instead of linear-lanceolate to oblong ones) with 3 conspicuous to rather inconspicuous palmate nerves (instead of the midrib visible only), terminal rays 1–2(–3) (instead of 3–4), branching once dichotomous (instead of twice dichotomous), raylet-leaves sparsely pilose at the base (instead of glabrous), and smaller seeds (2.5–2.8 × 1–1.5 mm instead of 3–3.3 × 1.5–2.2 mm).

Type:— IRAN. Esfahan: Kashan, Deh-abad , near Abuzeyd-abad , 1000 m, 3 June 1975, Moussavi & Tehrani 30689 E (holotype W!; isotype IRAN 55498!) .

Perennial erect, glabrous herbs, 18–50 cm high, with several branches from base. Cauline leaves rather sparse, sessile, obovate to cuneate, 6–11 × 3–5 mm, cuneate to rounded at the base, margin entire, apex acute, mucronulate or obtuse, glabrous, glaucous, 3-conspicuous to rather inconspicuous palmate nerves. Terminal rays 1–2(–3), up to once dichotomous, axillary rays 0–2, mostly longer than terminal ones. Ray-leaves similar to the cauline leaves but smaller, 2–3; raylet-leaves ovate to suborbicular, sparsely pilose at the base, 3–4 × 3–3.5 mm. Cyathial involucre campanulate, 2.5–3 mm in diameter; lobes lanceolate, lacerate; glands 4, gland appendages trapeziform, hornless or with two short horns. Ovary smooth, glabrous, style free at the base, shortly bifid, 1 mm long, the stigma thickened. Capsules smooth, conical, shallowly trilobate, glabrous, immature or opened. Seeds conical, irregularly pitted, 2.5–2.8 × 1–1.5 mm, dark brown, caruncle conical, 1 × 0.5 mm.

Additional specimens examined (paratypes): — IRAN. Esfahan: Kavir Protected region, in desert 50–54 km from Chashmeh-ye Safid Ab [Cheshme Sefid Ab] towards Haji Ali Abbas , 950 m, 26 May 1974, Rechinger 46480 ( IRAN!, M!, W!) ; Esfahan, Nain, Anarak, 14 km on the road to Chopanan , 1400 m, 13 October 1974, Foroughi & Assadi 15140 ( W!) ; between Tehran and Tabas, south of Dasht-e Kavir , 950 m, 33º32’N, 54º59’E, 6 April 1972, Léonard 5413 ( IRAN!, K!) ; between Tehran and Tabas, east of Dasht-e Kavir , 900 m, 34º05’N, 52º27’E, 3 April 1972, Léonard 5332 ( IRAN!, K!) ; Yazd: on the desert margin between Nain and Aghda , 1000 m, 21 April 1948, Rechinger et al. 2695 ( K!) .

Etymology: —The epithet ‘ kavirensis ’ refers to Dasht-e Kavir, Persian name for the temperate desert of the interior Iran.

Ecology and conservation: — Euphorbia kavirensis occurs in the large Iranian interior desert “Dashte Kavir” in steppes of Artemisia Linneaus (1753: 845) and on gypsum hillsides at 950–1400 m elevation. So far this species is known from six localities, however, because of homogenous conditions in interior steppes it is expected to be found in further locations in the future. For more precise assessment of conservation status of the species, some more excursions in its habitat will be needed. Based on IUCN threatened categories and existing data of E. kavirensis , it is suggested to evaluate its conservation status as ‘vulnerable’ (VU) (IUCN 2017).

Affinity and plant geography: — Euphorbia kavirensis belongs to section Pithyusa and is sister to E. gedrosiaca (Pahlevani, unpubl. data). It has been misidentified as E. gedrosiaca or E. erythradenia on herbarium sheets. All three mentioned species comprise (1–)2–3(–4) terminal rays, but with the exception of morphological and phylogenetical differences, their distributional pattern is also different. Euphorbia erythradenia is limited to the south-eastern part of Zagros Mountains, E. gedrosiaca is distributed to SE and E Iran to W Afghanistan, whereas, E. kavirensis occurs in deserts of central Iran ( Fig. 5 ).

Figures

FIGURE 4. Photograph of holotype specimen of Euphorbia kavirensis.

FIGURE 5. Geographical distribution of Euphorbia kavirensis and E. ziaratensis.