Onosma sanninensis Maalouf & Binzet, 2025

Maalouf, Ramy & Binzet, Riza, 2025, Onosma sanninensis (Boraginaceae), a new species from the Mount Sannine Central Lebanon, Phytotaxa 702 (1), pp. 72-82 : 73-79

Onosma sanninensis Maalouf & Binzet sp. nov. (Sect. Onosma , subsect. Asterotricha ) ( Figures 1 and 2 )

Type. LEBANON: Mount Sannine , El Bahsa slope, 25.v.2024, 33°56′42.5′′N 35°50′52.6′′E, 1840 m, Maalouf 1 (holotype: BEI; isotype: MERA: paratype: BEI Maalouf 2) .

Diagnosis:— Onosma sanninensis is related to O. caerulescens Boiss. and O. inexspectata Teppner. It differs from O. caerulescens by the leaves 15–50 × 2–12(–15) mm (not 35-50 × – 18 mm); bracts 12 mm, linear-oblong (not 3–7 mm, linear lanceolate to narrowly linear); pedicels very short (not 1–3 mm in flower – 6 mm in fruit); corolla whitish or deep pink at first, becoming white, reddish or dark blue (not bright yellow at first, turning orange-red-brown at end of anthesis, maturing to dark purple-blue). Moreover, the new species resembles O. inexspectata , but it differs by its leaves 10–30(–45) × (2–)3–6(–11) mm (not 35–50 × – 18 mm); bracts 15–20 mm, cordate (not 3–7 mm, linear lanceolate to narrowly linear); pedicels 1–2 mm (not 1–3 mm in flower – 6 mm in fruit); corolla 18 –20 mm (not 22–24 mm); nutlets 2.7–3.1 × 2.3–2.6 mm, attenuate-acuminate (not 5 × 3 mm, acute).

Description: —Perennial herb, loosely woody at base. Stems, erect, multiple from base, 15–25 cm tall, brownishred in color, the stem indumentum exhibits both white, patent, short fine hairs and longer, more conspicuous hairs. Basal leaves form a rosette, the largest reaching 4–5 cm long, up to – 1.8 cm at the widest point, spathulate or oblanceolate, obtuse or subobtuse; cauline leaves alternate, up to 3.5 × 1.6 cm, oblanceolate, smaller when closer to the inflorescence. The leaves on the lower part of the plant, being the oldest, show signs of senescence. They desiccate over time, taking on a silver, white, or canescent appearance as they dry. Inflorescence a terminal cyme, uniparous but more often biparous, 5–15 flowers each; in the dichasial cyme, a solitary flower typically occupies the median position at the bifurcation point of the primary axes, forming a characteristic V-shape. This central floral element is a constant feature, though in some instances, this position is occupied by a pair of flowers. Pedicels 1–3 mm in flower, – 6 mm long in fruit; bracts linear-lanceolate to narrowly linear, 3–7 mm long, as long as or longer than pedicels. Calyx divided into 5 linear lobes, acute, 17 mm long at flowering, accrescent to 22 mm long in fruit, densely covered with white appressed bristly hairs. Corolla tubular-campanulate, 22 –24 x 5 mm, papillate exterior with minor pilosity under lobes; lobes acuminate and revolute, bright yellow at first, turning orange-red-brown at end of anthesis, maturing to dark purple-blue. Filaments c. 4 mm long, anthers linear, – 7 mm long, basifixed. Style c. 3 – 4 mm protruding outside the corolla limb, stigma small, distinctly bilobed; Nutlets 5 × 3 mm, ovoid with acute beaked, ventral keeled, papillate, shiny, pale greenish.

Additional specimens examined: — O. caerulescens : Syria, inter Rascheya and Damas, 0 m, 0.5.1846, Boissier , P. E. 237222/5-8 ( G), C6 Kahramanmaras: Pazarcık-Gölbaşı 20 km, roadside, open Quercus forest, 930 m, 27.05.2004, Binzet 2 ( MERA) ; ibid. open Quercus forest, 927 m, 27.05.2009, Binzet 200901 ( MERA) ; ibid. 930 m, 23.05.2018, MB Kekil 201817 ( MERA). O. inexspectata : C6 Adana, Amanus Mts , 1 km E. of Hasanbeyli below, Nurdağı Pass, 900 m. 14.V.1966 No: 973 ( KEW), C6 Osmaniye, Hasanbeyli-Fevzipaşa 2 km, 1150 m, slopes, forest clearings, 25.V.2004, Binzet 3 ( MERA). C6 Osmaniye, Hasanbeyli, E 800–900 m, slopes and forest clearings, 23.05.2018, MB Kekil 201816 ( MERA) ; C6 Osmaniye, Hasanbeyli, Eastern of Türkmenpınarı , 1100–1150 m, slopes, forest clearings, 27. V.2021, Binzet 202145 ( MERA) .

Phenology:— Flowering from May to August and fruiting from July to August.

Distribution and habitat:— Onosma sanninensis is endemic to the central part of the western slopes of Mount Sannine, in the central Mount Lebanon range, within the Oro-Mediterranean vegetation level, sensu Abi Saleh and Safi, 1988. This new species thrives in rocky substrates with limestone bedrocks, at altitudes ranging between 1750 and 2100 meters ( Figure 3 ). The habitat is above the tree line, and the vegetation formation is characterized by dwarf shrubs and thorn-cushion communities named phryganas or traganthic formations ( Blondel et al. 2010) corresponding to the EUNIS habitat R1K_LB1 (Oro-Mediterranean hedgehog-heaths of Lebanon, sensu El-Zein et al. 2022). The associated species include: Amelanchier parviflora Boiss. , Cotoneaster nummularius Fisch. & C.A.Mey. , Rosa pulverulenta M.Bieb. , Acantholimon ulicinum (Willd. ex Schult.) Boiss. , Allium pseudostamineum Kollmann & Shmida , Anchonium billardieri DC. , Anthemis cretica L. subsp. cassia (Boiss.) Grierson , Cherleria rupestris (Labill.) A.J. Moore & Dillenb. , Cicer incisum (Willd.) K.Malý , Cynoglossum nebrodense Guss. , Fritillaria crassifolia Boiss. & A. Huet , Leontodon libanoticus Boiss. , Silene libanotica Boiss. , Onosma caerulescens , Scrophularia libanotica Boiss. subsp. libanotica var. nevshehirensis R.R Mill. , Lathyrus formosus (Steven) Kenicer and Stachys ehrenbergii Boiss.

Etymology: —The species epithet is derived from Mount Sannine, Baskinta where the new species was discovered on the 14th of August 2019.

Conservation:— Onosma sanninensis meets the thresholds for Endangered under Criterion D1, with a total global population estimated to number fewer than 250 mature individuals within an area approximately 1.6 km in perimeter ( Figure 3 ). However, the species faces additional vulnerabilities that further elevate its extinction risk. The entire population exists as one subpopulation across the limited occupied range. This restriction to one undivided unit makes O. sanninensis especially susceptible to extirpation from a single stochastic or catastrophic event. With an estimated total population size less than 250 mature individuals confined to a single subpopulation, O. sanninensis qualifies for listing as Critically Endangered under Criterion C2a(i). While the species meets Endangered Criterion D1 based solely on population size, the additional risk factors captured under C2a(i) mean it meets the threshold and conditions for the higher category of Critically Endangered. Therefore, O. sanninensis is assessed as Critically Endangered under Criterion C2a(i) based on its extremely limited population and occupancy of habitat.

Palynology: —Pollen grains are heteropolar, trisyncolporate, and prolate-spheroidal P/E (Polar axis/Equatorial axis) ratio 1.12. The exine ornementation is scabrate. Exine surface of the grains is insular. The insulae have free scabrae and the scabrae are widely spaced. The average means of the number of scabrae in each insulae range from 8 to 15. The main palynological characters, SEM and LM micrographs of O. sanninensis are presented in Table 2 and Figure 4 . revised according to O. sanninensis .

Nutlet morphology: — O. sanninensis : Nutlets 5 × 3 mm, ovoid with acute beaked, ventral and dorsal keeled, papillate, shiny, pale greenish. Nutlets gradually narrow towards the beak and are acute in shape.

The epidermal cells on the surface of the nutlet appear in various sizes and shapes. These cells are ± long and rectangular-polygonal in shape, characterized by their large size, with clear, thin cell walls that are not straight (see Figure 5a–c ).

O. caerulescens : The nutlets measure 4–5 mm in length, featuring sharp ventral keels and less prominent dorsal keels. They have short beaks, are greyish, and narrow abruptly towards the beak, ending in an acuminate shape.

Epidermis cells are generally elongated, rectangular-polygonal and small-narrow. Cell walls are clear, thick, and generally straight ( Figure 5d–f ).

O. inexspectata : 2.7–3.1 × 2.3–2.6 mm, obovate-triquetra, attenuate-acuminate, ventral keeled. The nutlets gradually narrow towards the beak and terminate in an acute apex. Nutlet ornamentation is rugose, characterized by small or fine wrinkles on the epidermal cells of the nutlet surface. The epidermal cells are not clear (see Figure 5g –i ).

Figures

FIGURE 1. Onosma sanninensis in situ: a.—Habit in flowering. b.,c.—Inflorescences. d.—leaf indumentum e.—Basal leaves in rosette.

FIGURE 2. Distribution map of O. caerulescens (filled triangle), O. inexspectata (filled star) and O. sanninensis (filled rectangle).

FIGURE 3. AOO of O. sanninensis (Photo acquired from Google Earth).

FIGURE 4. SEM microphotographs of pollen: O. sanninensis a–f; O. caerulescens g–j; O. inexspectata k–n; and LM microphotographs of pollen: O. sanninensis o–q.

FIGURE 5. SEM microphotographs of nutlets of O. sanninensis a: ventral view, b: dorsal view, c: ornamentation; O. caerulescens d: ventral view, e: dorsal view, f: ornamentation; O. inexspectata g: ventral view, h: dorsal view, i: ornamentation.