Euphorbia akmanii İ.Genç & Kültür, 2016

Genç, İlker & Kültür, Şükran, 2016, Euphorbia akmanii (Euphorbiaceae), a new species from Turkey, Phytotaxa 265 (2), pp. 112-120 : 113-117

Euphorbia akmanii İ.Genç & Kültür , sp. nov. ( Figs. 1 , 2 , 4 )

Euphorbia akmanii differs from E. erubescens by its longer flowering stems, elliptic to oblanceolate (not obovate-oblong), subacute or acute (not obtuse or subacute) first year cauline leaves, petiolate-subsessile (not sessile) second year cauline leaves, unicellular (not multicellular) hairs, laciniate (not two-horned) and greenish to white (not yellow with reddish horns) cyathial gland appendages and hairy (not glabrous) capsules.

Type:— TURKEY. Osmaniye: Zorkun Yaylası, Gürgen orman altı , Amanos Dağ , ca. 850 m, 4 June 1968, Y. Akman 22 (holotype ANK! , isotype ISTE! ).

Pubescent robust perennial to 105 cm tall, flowering stems biennial.Indumentum simple, hairs unicellular.Cauline leaves of first year’s growth petiolate, elliptic to oblanceolate, 2–9 × (0.7–) 1–2.2 cm, apex subacute or acute, mucronulate, margin entire, base attenuate; second year’s cauline leaves petiolate-subsessile, elliptic, 6–12.5 × (1.8–) 2–3.5 cm, apex subacute or acute, mucronulate, margin entire, base attenuate; ray-leaves sessile, lanceolate to ovate, 3.5–9.5 × 1.5–4 cm, apex subacute or subobtuse, mucronulate, base tapered or rounded. Raylet-leaves (cups) 4–9 cm across. Rays (2–)3–5, once or twice dichotomous; axillary rays absent. Cyathial lobes oblong, densely pubescent, glands 4, gland appendages deeply laciniate, greenish to white. Ovary densely pubescent, 3-locular; styles 3, connate at the base, stigmas bifid. Fruit pedicellate, 6 × 7 mm, ovoid, strongly trilobed, granulose, evenly to densely pubescent. Seeds ovoid, carunculate, (2.8–)3 × 2.3–2.5 mm (excluding the caruncle), testa smooth, greyish; caruncle small. conical, yellowish.

Additional specimen examined (paratype): — TURKEY. Osmaniye: between Osmaniye to Zorkun , 980 m, 16 June 2015, İ. Genç 2339 & Ş. Kültür ( ISTE 109084 !) .

Etymology:— Euphorbia akmanii is named in honour of Prof. Dr. Yıldırım Akman, a Turkish botanist who made the first collection of the new species.

Habitat and ecology:— The new species grows in open deciduous forests at an elevation of 850– 980 m. Flowering and fruiting time May–July.

Distribution:— It is only known from the type locality in the north-west part of the Amanus Mountains in the southern part of Turkey ( Fig. 1 ).

Conservation status:— According to the IUCN criteria ver. 3.1 ( IUCN 2012), the conservation status of E. akmanii is classified as Critically Endangered [CR: B2ab(ii, iii, iv)] because of the new species’ limited area of occupancy (less than 10 km 2) and occurrence in a single location.Additionally, the type locality is rather near settlements. Therefore, the area is under pressure of human impact because of building construction for upland travel and tourism. This pressure will eventually reduce the area of occupancy, decrease habitat quality and lower the number of mature individuals of the new species.

Discussion:— The new species belongs to sect. Patellares (Prokhanov in Komarov 1949: 453) Frajman in Frajman & Schönswetter (2011: 422) of subg. Esula . The section is characterized by the perennial herbaceous habit, the raylet leaves partly to considerably connate, linear to elliptic or ovate stem leaves with pinnate venation, and four semilunate, falcate or trapezoid cyathial glands with entire margin and two hornlike appendages ( Riina et al. 2013). Prokhanov (1949) and Radcliffe-Smith (1982) included Patellares in sect. Esula as a subsection, but Frajman & Schönswetter (2011) elevated this group to sectional level, considering its clear morphological distinction from sect. Esula , as well as its monophyly. Additionally, molecular evidence does not show a close affinity between sect. Patellares and sect. Esula ( Frajman & Schönswetter 2011, Riina et al. 2013).

Sect. Patellares includes 14 species worldwide ( Riina et al. 2013), and eight of these are distributed naturally in Turkey ( Fig. 1 ; Öztekin 2012) [ E. oblongifolia ( Koch 1847: 17) Koch (1848: 726) ; E. macroceras Fisch. & C.A.Mey. in Fischer et al. (1837: 36); E. amygdaloides Linneaus (1753: 463) ; E. davisii Khan (1964: 140) ; E. erubescens ; E. kotschyana Fenzl (1842: 7) ; E. characias Linneaus (1753: 463) subsp. wulfenii (Hoppe ex Koch 1844: 727) Radcliffe-Smith (1968: 55) ; and E. thompsonii Holmboe (1914: 121) ].

The laciniate cyathial gland appendages of the new species make it readily distinguishable from the other species of sect. Patellares ( Fig. 2a ). The cyathial glands of the section are characterized by semilunate, falcate or trapezoid shape, entire margins, and two horn-like appendages ( Fig. 3a ). Such laciniate or pectinate gland appendages may also occur in some species of other sections [e.g. E. denticulata Lam. in Lamarck & Poiret (1788: 431), E. craspedia Boissier (1846: 95) , E. cheiradenia Boiss. & Hohen. in Boissier (1853: 112)], which are distributed in Turkey, but other morphological characters of these taxa are certainly different from the new species.

The seeds of sect. Patellares are uniform, generally ovoid with smooth surface, grayish colour and a conical caruncle. Fruits are trilobate. Seeds and fruits of E. akmanii do not differ in these characters, although the granulate surface of the fruits is not shared by other species.

Because of its robust and long stems, petiolate and pubescent leaves, E. akmanii can also be compared with E. oblongifolia and E. macroceras , but the leaves of these two species are rounded truncate or shallowly cordate at the base.

According to Frajman & Schönswetter (2011), species of sect. Patellares are characterized by a pubescent-villose indumentum, composed of elongated, multicellular hairs. Euphorbia akmani has unicellular hairs, which distinguishes it from the other species in the section ( Figs. 4a, c, d ).

First-year cauline leaves of the new species are not larger than second-year leaves, whereas the opposite is true in E. amygdaloides , E. davisii , E. erubescens and E. thompsonii . Also E. akmanii differs from these species by its granulate (not smooth) fruit surface.

The most important diagnostic characters distinguishing the new species from the rest of taxa of sect. Patellares distributed in Turkey are given in the Table 1 .

The type specimen (Akman 22) lacks the lower part of the stem with first-year cauline leaves, mature fruits and seeds. It was examined by Radcliffe-Smith during the preparation of the treatment of Euphorbia for the Flora of Turkey and the East Aegean Islands. The author mentioned the sample at the end of the description of E. macrostegia (= E. erubescens ) ( Radcliffe-Smith 1982). Despite the fact that it is different in many ways, it was identified as E. erubescens by him. However, as a result of our detailed investigations, the new species is considered to differ from E. erubescens in several features that are shown in Figures 2–4 and Table 1 .

Figures

FIGURE 1. Distribution of the species of the sect. Patellares in Turkey.

FIGURE 2. E. akmanii. a. Raylet-leaves and cyathia showing the laciniate cyathial gland appendages. b. Fertile branches. c. pubescent capsule. d. ventral and dorsal views of seed and caruncle. Photos by İ. Genç.

FIGURE 3. E. erubescens. a. Raylet-leaves and cyathia showing horn-like gland appendages and smooth capsule. b. Fertile branches. c. ventral and dorsal views of seed and caruncle. Photos by İ. Genç.

FIGURE 4. SEM photos of E. akmanii (a–d); E. erubescens (e–h). Fruit surface (a, b, e, f). Leaf surface (c, d, g, h). Vouchers specimens ISTE 109084 (a–d), ISTE 109085 (e–h).