Onosma ligniclada Attar & Mirtadzadini, 2025

Attar, Farideh, Mirtadzadini, Mansour, Binzet, Rıza & Sotoodeh, Arash, 2025, New taxa of Onosma L. (Boraginaceae, Lithospermeae) from Iran, Adansonia (3) 47 (16), pp. 299-310 : 302-303

Onosma ligniclada Attar & Mirtadzadini , sp. nov.

( Figs 2; 3)

TYPE MATERIAL. — Iran • W, Kermanshah, c. 11 km to the crossroad of Gilan-e Gharb and Sumar; 1050 m alt.; 34°16’30”N, 46°32’12”E; 28.V.2016; Attar, Mirtadzadini & Raie Niaki 46689; holotype: TUH!; isotype: MIR ! • same location; 2.V.2019; Attar & Habibi 48901; paratype: TUH !.

DIAGNOSIS. — Differt ab Onosma albo-rosea Fisch. & C. A. Mey. : Caules usque 50 cm (nec 10-20 cm); folia basalia late elliptica, 20-45 × 7-17 mm (nec obovato-spathulato lanceolata, 20-60 × 6-12[-15] mm); pedicellus 2-4 mm longus (nec 1-3 mm longus); corolla alba (nec alba, rosea); filament ± 2.5 mm longa (nec 8-9 mm longa); nuculae 8 mm longae (nec 6-7 [-8] mm longae).

RECOGNITION. — Onosma ligniclada sp. nov. is related to Onosma albo-rosea , which belongs to the sect. Onosma subsect. Asterotricha ( Riedl 1967; Khatamsaz 2002). Onosma albo-rosea is distributed in Iran, Turkey, Iraq and Syria. These two species have some morphological differences such as the height of the plant, the size and color of the corolla, and size of leaves of sterile shoots. Further differences are outlined in Table 2.

DISTRIBUTION, HABITAT AND PHENOLOGY. — Onosma ligniclada sp. nov. grows on the dry hillside steppes, at elevation of 1050 m. It is an endemic species of Iran. The species that are associated with this species in the area include: Avena sp. , Chardinia orientalis (L.) Kuntze, Echinops kermanshahensis Mozaff. , Hirschfeldia incana (L.) Lagrèze, Oliveria decumbens Vent. , Onopordum acanthium L., Zoegea sp. Flowering in April to June, fruiting in May to July.

ETYMOLOGY. — The specific epithet is derived from the woody base of the plant, referring to the lignified structure present either at the base of the stem or at the lower parts of the branches.

CONSERVATION STATUS. — Onosma ligniclada sp. nov. is currently known from a single locality with a small population. Considering its very restricted area of occupancy (AOO), occurrence at one location, and an inferred continuing decline in habitat quality, we assess it as Endangered (EN) under criterion B2ab(iii) (IUCN 2012).

DESCRIPTION

Perennial, woody at base, up to 50 cm high. Stem branched, white or sometimes brownish with sterile shoots at the base,erect, covered with white and ±patent setae. Leaves of sterile shoots broad ovate-elliptic,acute,10-20× 3-8 mm (including a c. 5mm long petiole); basal leaves of flowering shoots ovate-elliptic, acute, 20-45 × 7-17mm; middle and upper leaves similar to the lower ones, subsessile; indumentum consists of white tubercle-based adpressed dense setae on the upper surface and lax on the lower surface; tubercles stellate hairy, rays long and numerous, regular; midrib prominent, adpressed-setose on the abaxial leaf surface. Petiole 2-4 cm long. Cymes few-flowered, 5-8 cm long. Bracts linear-lanceolate, 20 × 3-4 mm. Pedicels 5 mm long in flower, to 7 mm long in fruit, with spreading setae. Calyx ± 20 mm long in flower, 3-5 mm wide, accrescent, 30-32 mm long in fruit, 7-8 mm wide in the fruiting state; calyx lobes 5, divided to near the base, united for 5 mm, outside covered with sparse white patent setae, tubercles stellate hairy, pubescent between them, inside similar outside but fewer. Corolla cream at first, turning bluish towards upper, 26-29 mm long, campanulatecylindrical; lobes triangular, obtuse, 2.5 mm wide and 2 mm long, pubescent outside, glabrous inside.Annulus 0.5 mm wide, glabrous, lobulate, crescent.Anthers sagittate, included, c. 8 mm long. Filaments c. 3 mm long, arising from approximately the middle of the corolla tube. Nutlets 8 × 7 mm, often solitary, cream, smooth, shiny, ovate-three-faced, with dorsal keel, with a middle vein on the adaxial surface, gradually beaked ( Figs 2; 8).