Alkanna assadii Khajoei Nasab & Zeraatkar

Zeraatkar, Amin, Nasab, Farzaneh Khajoei & Shirmardi, Hamzeh Ali, 2024, A new endemic species of Alkanna (Lithospermeae: Boraginaceae) from hilly environments of west Iran, Phytotaxa 653 (3), pp. 273-280 : 274-279

Alkanna assadii Khajoei Nasab & Zeraatkar sp. nov. ( Figures 2–4 )

Description:—Perennial, 20–35 cm height, stem multi-branched, branched from base, densely covered with short trichomes (up to 0.2 mm long), with stiff, unicellular, scabrid trichomes (up to 1.8 mm long, absent at lower part of the stem), and moderately short glands (up to 0.2 mm long). Roots reddish. Basal leaves ovate-lanceolate, 50–120 × 4–12 mm, tapering into the petiole, acute at apex, margins undulate, with a prominent midrib, ciliate at the margins, lower and upper surfaces densely covered with short trichomes, sparsely with stiff, unicellular, scabrid trichomes, and moderately short glands. Cauline leaves ovate-lanceolate or oblanceolate, 30–50 × 4–15 mm, acute, sessile, subauriculate or truncate at base, margins undulate, with a prominent midrib, indumentum like in basal leaves. Inflorescence with 1–2 scorpioid cymes, each cyme with 6–10 flowers. Calyx 10–12 × 1–3 mm; lobes narrowly lanceolate, entire at the margin, acute at apex, lower and upper surfaces densely with stiff, unicellular, scabrid trichomes (up to 1.8 mm long), short trichomes (up to 0.2 mm long), and sparsely short glands (up to 0.2 mm long). Corolla orange-pale yellow (orange in bud), the intercostal parts orange, veins yellow, becoming violet-blue when dried, 13–18 mm long, outside glabrous, pubescent inside, densely-moderately covered with short glands (up to 0.1 mm long or subsessile) below the junction of the corolla lobes to the lower surface of the filament of two lower stamens; lobes ca. 4 × 5 mm, finely undulate margins. Pedicels 3–4 mm long, pilose. Bracts lanceolate, 12–21 × 4–6 mm, undulate margins, acute at apex, cuneate at base, lower and upper surfaces covered with densely short trichomes (up to 0.2 mm long), sparsely with stiff, unicellular, scabrid trichomes (up to 1.8 mm long), and moderately short glands (up to 0.2 mm long). Stamens inserted irregularly at two different levels; three higher at the throat and two lower in the tube; filaments 0.2–0.4 mm long; anthers ca. 0.8 mm long. Style ca. 3.5 mm long. Stigma shallowly bilobed; lobes ca. 0.2 mm long. Annulus glabrous. Nutlets not seen.

Type:— Iran. Chaharmahal and Bakhtiari province, Ben , near Karsang village, 32.52° N, 50.46° E, 2525 m, 30 April 2022, A. Zeraatkar 7192 (Holotype: D!).

Diagnosis:— Alkanna assadii can be distinguished from other Iranian Alkanna species by several morphological characters. It is distinguished from A. bracteosa by basal leaf length (50–120 vs. 100–200 mm), basal leaf shape (ovate-lanceolate vs. lanceolate), cauline leaf shape (ovate-lanceolate or oblanceolate vs. oblong or ovate-oblong), indumentum type (densely covered with short trichomes, with stiff, unicellular, scabrid trichomes, and moderately short glands vs. sparsely covered with stiff, unicellular, scabrid trichomes, sometimes also glandular-pubescent), corolla color (orange-pale yellow becoming violet-blue when dried vs. yellow), inside of corolla (with short glands below the junction of the corolla lobes to the lower surface of the filament of two lower stamens vs. glabrous), corolla length (13–18 vs. ± 10 mm), calyx length in flower (10–12 vs. 7–9 mm), and bract shape (lanceolate vs. ovate). Our new species also differs from A. trichophila , specifically by: ovate-lanceolate basal leaf (vs. broadly oblong or spathulate-lanceolate), basal leaf apex (acute vs. subacute), cauline leaf shape (ovate-lanceolate or oblanceolate vs. oblong, linear-lanceolate), corolla color (orange-pale yellow becoming violet-blue when dried vs. yellow), corolla shape (salver-shaped vs. tubular or funnel-shaped), outside of corolla (glabrous vs. usually pubescent and sometimes glandular), and bract shape (lanceolate vs. linear-lanceolate). Alkanna assadii differs from A. leptophylla in having ovate-lanceolate or oblanceolate, truncate at base, undulate margins cauline leaf (vs. elliptic-lanceolate, cordate at the base, with sinuate-crispate margin, in the dried state papyrus), corolla color (orange-pale yellow becoming violet-blue when dried vs. golden yellow (in vivo), brunescens (in sicco)), calyx length (10–12 vs. 8 mm), and bracts with undulate margins (vs. sinuate-crispate margin). It differs from A. orientalis in longer basal leaves (50–120 vs. 30–60 mm), indumentum type (with densely stiff, unicellular, scabrid trichomes, and moderately short glands vs. short glands), corolla color (orange-pale yellow becoming violet-blue when dried vs. golden yellow), corolla length (13–18 vs. ± 12 mm), calyx length (10–12 vs. 6–7 mm), and bract shape (lanceolate vs. oblong-ovate, semi-amplexicaul).

Alkanna assadii is similar to Alkanna frigida Boiss. in basal leaves width, indumentum type, corolla shape, anther length, and style length. However, it sufficiently differs from A. frigida in its habit, height, basal leaves length and shape, cauline leaves size and shape, setae size, gland size, corolla color and size, the status of the trichomes and glands in corolla, arrangement of the stamens in the corolla, pedicel length, calyx length, and bract shape and size. More detailed list of morphological differences among these species are presented in Table 1 . In addition to, the morphological differences mentioned above for these two species, they are distributed in very different habitats. A. frigida is found in mountainous habitats at altitudes between 1950 and 3500 m, while A. assadii is found in hills at altitudes between 2500 and 2550 m.

Distribution, ecology, and conservational status:— Alkanna assadii is currently known only from its type locality in the highlands of west Iran in Chaharmahal and Bakhtiari provinces, where the climate is cold and semihumid. Large parts of the area are composed of reddish sandstone and shale hills with thin intercalations of argillaceous limestone, conglomerate, and conglomeratic sandstones ( Figures 1 , 3 & 5 ). The area has been poorly investigated botanically compared to many other parts of the province and needs to be explored in detail. However, the area has been superficially visited by V. Mozaffarian during the preparation of “Flora of Chaharmahal and Bakhtiari” ( Mozaffarian 2017). Floristically and vegetation wise, the area is best characterized as semi-steppe, mostly composed of communities of Astragalus and grasses, often rich in perennial herbaceous Astragalus .

The most commonly associated species are Rindera lanata (Lam.) Bunge , Stachys koelzii Rech.f. , S. lavandulifolia Vahl , Teucrium orientale L., Thymus daenensis Čelak. , Eremurus persicus (Jaub. & Spach) Boiss. , E. spectabilis M.Bieb. , Fritillaria persica L., Oxytropis kotschyana Boiss. & Hohen. , Leontice armeniaca Boivin , Rumex ponticus E.H.L.Krause , Ranunculus kochii Ledeb. , R. straussii Bornm. , Scrophularia nervosa Benth. , Salvia aristata Aucher ex Benth. , Astragalus holopsilus Bunge , A. caraganae Fisch. & C.A.Mey. , A. cyclophyllos Beck , A. griseus Boiss. , A. angustiflorus K.Koch , A. effusus Bunge , A. compactus Lam. , A. trachyacanthos Fisch. , Astragalus sp. , Solenanthus circinnatus Ledeb. , Gypsophila polyclada Fenzl ex Boiss. , Centaurea leuzeoides Walp. , Scorzonera calyculata Boiss. , Serratula latifolia Boiss. , Klasea viciifolia (Boiss. & Hausskn.) L.Martins , Phlomis olivieri Benth. , Onobrychis melanotricha Boiss. , Euphorbia heteradena Jaub. & Spach , Bufonia kotschyana Boiss. , Lepidium draba L., Eryngium billardierei F.Delaroche , Allium stipitatum Regel , Lactuca orientalis (Boiss.) Boiss. , Bromus tomentellus Boiss. , Psathyrostachys fragilis (Boiss.) Nevski , Melica persica Kunth , Silene aucheriana Boiss. , S. latifolia Poir. , S. gynodioica Ghaz. S. longipetala Vent.

Less than ten plants were observed in the type locality that is not protected. We categorize the new species as Data Deficient (DD) according to IUCN criteria ( IUCN 2022). Further studies are needed for a more accurate classification. However, it is necessary to note that this area is subject to human pressure, and land-use change is considered the greatest threat to the ecosystems ( Figure 5 ). Therefore, the environments should be assigned to a priority list of research. Additionally, livestock traffic and overgrazing are serious threats to the species’ long-term survival.

Phenology:—Flowering: late April to late May.

Eponymy:—The species is named in honor of the prominent Iranian botanist, Prof. Dr. Mostafa Assadi (Research Institute of Forests and Rangelands, TARI), who, for more than five decades, directed and supported the study of the flora of Iran.

Figures

FIGURE 1. Distribution of Alkanna assadii sp. nov. Map by Farzaneh Khajoei Nasab.

FIGURE 2. Holotype of Alkanna assadii sp. nov. Photograph by Amin Zeraatkar.

FIGURE 3. Habit and habitat of Alkanna assadii sp. nov. Photograph by Amin Zeraatkar.

FIGURE 4. Alkanna assadii sp. nov. Corolla (A & B). Ovary (C). Median view of stigma. Indumentum on the upper surface of basal leaves. Scale bars:A, B= 3.5 mm; C= 1 mm; D= 0.2 mm; E= 1 mm. Drawn by Amin Zeraatkar.

FIGURE 5. Habitat of Alkanna assadii sp. nov. Photograph by Amin Zeraatkar.