Onosma ghahremanii Attar & Naqinezhad, 2016

Naqinezhad, Alireza & Attar, Farideh, 2016, Onosma ghahremanii sp. nov. (Boraginaceae), a new species from Alborz Mts., Iran, Phytotaxa 268 (4), pp. 286-290 : 286-289

Onosma ghahremanii Attar & Naqinezhad sp. nov. ( Fig. 1 ).

Perenne, rhizome in surculos longos subterraneo. Caules subsimplices. Folia basalia petiolata, linearia-spathulata, pilis longiusculis appressis tuberculis glabris insidentibus, pilis brevibus sparse supra subtusque obsita. Inflorescentia dense scorpioideo-capitata. Bracteae ad 15 mm longae. Pedicelli 4–8 mm longi. Calyces floriferi 10–22 mm longi, fructiferi accrescentes, liberi. Corolla 12–24 mm longa, clavato-campanulata, glabra. Annulus nectarifer glaber.

Type:— IRAN. Tehran province: Damavand mountain, near to Tar lake, 2700 m a.s.l., 35º43’16.75” N, 52º14’37.4” E, 12 June 1992, Attar, Ghahreman & Khatamsaz 38000 (holotype TUH!, isotype K!).

Caespitose perennial with lignified subhorizontal thick rootstocks, stem one or few, branched from the base, 20–40 cm long, with dried petioles of old leaves and sterile shoots at the base, usually ascending, covered with white appressed setae, 1–1.5 mm long, setae tuberculate at the base, tubercles glabrous, mixed with 0.1–0.3 mm long spreading to spreading-appressed haplotrichous, white hairs. Basal and lower cauline leaves 70–140 × 7–16 mm, lanceolate or narrowly lanceolate to narrowly spathulate, acute, attenuate towards the base into more or less long petiole (20–50 mm long); middle and upper leaves few, similar to the lower but smaller, subsessile, 40–55 x 3–5 mm, narrowly spathulate, with tubercle-based appressed setae on both surfaces, tubercles glabrous, with short dense appressed hairs between the tubercles, setae ca. 0.3 mm long; midrib prominent and appressed-setose on the abaxial leaf surface and glabrous on the adaxial leaf surface. Petiole 2–4 cm long. Inflorescence of 1–5 terminal or subterminal many-flowered scorpioidcapitate cymes, 2–4 cm diameter. Bracts narrowly linear, 6–8 mm long. Pedicels 4–8 mm long with spreading setae. Calyx 10–22 mm long, poorly accrescent in fruit; calyx lobes 5, divided to the base, linear or linear-lanceolate, acute, 1–2 mm wide, outside covered with pale yellow dense appressed-ascending antrorse setae and mixed with short hairs inside. Corolla 12–24 mm long, clavate-campanulate to cylindrical, in vivo white and whitish or crème-colored in dry specimens; lobes triangular, obtuse, 2 mm wide and 1.2 mm long, pubescent at apex, glabrous inside. Nectar disk 1 × 2 mm, glabrous, lobulate, crescent, rounded to obtuse at the lobe apex. Anthers sagittate, included, 7–8 mm long, connate at the base, connective protracted, apical sterile portion 0.5–0.7 mm long. Filaments ca. 5 mm long, arising from approximately the middle of corolla tube. Nutlets 4 × 2.5–3 mm, ovoid, apiculate, keeled above.

Distribution and ecology:— Onosma ghahremanii grows in the dry mountain steppe on steep, gravelly slopes around Tar Lake, at an elevation of 2700 m a.s.l. This site is conserved by the “Department of Environment”, Iran ( Fig. 2 ). It is an endemic species to the Irano-Turanian region.

Etymology: —The specific epithet honors the late Prof. Dr. Ahmad Ghahreman, Professor of Botany at the

University of Tehran and innovator of the Central Herbarium of Tehran University, TUH. Phenology: —Flowering and fruiting in June and July. Taxonomical remarks: — Onosma ghahremanii is most closely related to O. microcarpum de Candolle (1846: 62) ,

O. gaubae Bornmüller (1937: 893) and O. borragoidinum Ponert (1973: 140) , all of which belong to the Haplotrichousgroup of Onosma ( Riedl 1967, Khatamsaz 2002, Mehrabian et al. 2014). Onosma microcarpum is a common species in most mountainous regions of Iran, Iraq, Armenia and Transcaucasia ( Riedl 1967). O. gaubae is endemic to the Qazvin province in the north of Iran. O. borragoidinum is confined to gravelly slopes of Central Alborz Mts ( Ponert 1973). There are clear morphological differences between O. ghahremanii and these related species, summarized in Table 1. The stems, leaves and calices of O. ghahremanii are covered with appressed setae, while having a dense spreading indumentum in O. microcarpum and O. borragoidinum . Calyx lobes are free at the base in O. ghahremanii , while they are slightly coherent in O. gaubae . The corolla in the new species is distinctly white (in vivo) and crème-coloured (in sicco), whereas pale yellow (in vivo and sicco) in O. microcarpum and O. borragoidinum and yellowish (in sicco) in O. gaubae . Stamen filaments have a different length and are attached at different heights of the corolla tube (see Table 1).

According to the taxonomic treatment by Riedl (1967) in Flora Iranica , O. ghahremanii should be placed in the section Onosma , subsection Onosma and series O. dichroanthi Boissier (1843: 107) .

Conservation status:— Onosma ghahremanii should be evaluated as critically endangered (CR) based on IUCN (2012), according to criteria B1 (extent of occurrence, less than 100 km 2) and B2 (area of occupancy, less than 10 km 2). Furthermore, the estimated total number of individuals does not exceed 100 (criterion C).

In addition, human activities especially overgrazing and tourism (particularly around Tar lake) are threatening this species.

Figures

FIGURE 1. Onosma ghahremanii (holotype);A. Habit, B. Calyx, C. Corolla,Appressed setae and hairs on leaf, stem and corolla apex are shown with magnification. Line drawing by R. Farahdoost.

FIGURE 2. Distribution of Onosma ghahremanii (●) and two closest species, O. borragoidinum (■), and O. gaubae (▲) in Iran.