Bupleurum iranicum Bidarlord & Lyskov, 2023

Bidarlord, Mahmoud, Kljuykov, Eugene & Lyskov, Dmitry, 2023, Bupleurum iranicum (Apiaceae), a new species from Talesh Mountains, northwestern Iran, Phytotaxa 583 (2), pp. 183-190 : 184-185

Bupleurum iranicum Bidarlord & Lyskov sp. nova ( Figs. 1 , 2 )

Type: — IRAN. Ardabil province , Khalkhal, Hashjin to Khalkhal, 5 km from Hashjin, marl hill, 37°25'1.50"N, 48°20'20.25"E, 1150 m a.s.l., 18 August 2021, M. Bidarlord 10016 (holotype: TARI; isotype: T, GILAN) .

Bupleurum iranicum is similar to Bupleurum brachiatum Koch in Boissier (1844: 844) and B. anatolicum Huber-Morath & Reese (1945: 150) in having narrow, linear cauline leaves, herbaceous bracts similar to the bracteoles, bracteoles shorter than the flowers, fruit surface smooth, petals smooth, and number of umbel rays 2–3. At the same time the new species differs from the above-mentioned taxa in the stem branching (non-branched or slightly branched vs. diffusely or dichotomously branched), umbel rays (subequal vs. unequal), bract length and number of bracts (equal, 1–2 vs. subequal, 2–5), and bract shape (elliptic to ovate vs. lanceolate) ( Table 1 ).

Annual; green or glaucescent-green plant, 20–40 (50) cm high, with erect, thin, round, stems with purple ribs at base, mainly simple or sparsely branching from base or middle, pseudodichotomous, with branches more or less spreading or simple. Lower leaves close to each other, lanceolate, tapering to rather wide petiole, more or less attenuate-acute, 5–7 cm long, 3–4 mm wide, with 4–7 (often 5) nerves at abaxial surface; median leaves not tapering as much at base, more acute, upper leaves and leaves on branches much smaller, narrower, uninerved, nearly subulate. Umbels with 2–3 rays; number of bracts 2–3 (often 3), bracts 1.5–2 mm long, subequal, narrowly elliptic to ovate, trinerved; peduncles 1.5–2 cm long; more or less erect, subequal; number of bracteoles 5, bracteoles elliptic to ovate, 1.4–1.6 mm long, nearly equal to flowering umbellets, with 3 ribs; number of flowers 4–7 per umbellet, pedicels about 1mm long; flower 1.2–1.5 mm long; Petals 0.6 mm long, inflexed lobe bifid. Anthers about 0.4 mm long. Stylopodium 0.6–0.7 mm broad, styles 0.3 mm long. Fruit 2–3× 1–1.5 mm, smooth, brown; mericarp more or less cylindrical, pentagonal in cross-section, compressed laterally, glabrous, vallecular secretory ducts solitary, commissural secretory ducts paired.

Paratype: — IRAN. Ardabil Province, 4 km N of Hashjin , marl hill, 1150 m, 10 August 2019, D. Lyskov 165-IR-19 ( MW) .

Etymology:— The specific epithet “ iranicum ” refers to Iran, where the type specimen was collected.

Phenology:— Bupleurum iranicum has been collected in the flowering and fruiting stage from late July to September

Distribution and ecology:— The species is only known from the type locality in Ardabil Province. Bupleurum iranicum is apparently an Irano-Turanian element endemic to type locality, northwest Iran. It was found on open dry slopes of marl hills, with average annual precipitation ca. 300 mm. A randomly distributed population of B. iranicum might consist of 200–500 individuals in one revealed population. It is worth mentioning that two new species, Lepidium khalkhalicum Bidarlord & D.A.German (2021: 2) (Bidarlord et al. 2021) and Sideritis khalkhalica Bidarlord & Jamzad (2021: 505) (Bidarlord & Jamzad 2021), have recently been described from this habitat. The species was found growing in association with Actinolema macrolema Boiss. (1872: 831) , Meniocus meniocoides (Boiss.) Hadač & Chrtek (1973: 260) , Anthemis schizostephana Boiss. & Hausskn. (1875: 314) , Avena byzantina K. Koch (1848: 392) , Bromus danthoniae Trin. (1831: 24) , Eremopyrum bonaepartis (Spreng.) Nevski (1933: 18) , Chardinia orientalis (L.) Kuntze (1887: 18), Galium tricornutum Dandy (1957: 47) , Halothamnus auriculus (Moq.) Botsch. (1981: 134) , Malvella sherardiana (L.) Jaub. & Spach (1854: 46), Ranunculus arvensis L. (1753: 555), Trigonella monantha C. A. Mey. (1831: 137) , and Ziziphora persica Bunge (1873: 39) .

International Union for Conservation of Nature (IUCN) red list category:— Bupleurum iranicum is known only from one sub-populations (criterion B2ab (iii)), the area of occupancy (AOO) is less than 10 km 2 (criteria B1 and B2b (i, ii)). Its extent of occurrence (EOO) cannot be calculated since it is known only from one population. It is also estimated that the total number of individuals of this endemic species does not exceed 500 individuals (criterion C). Its localities are nearby villages and not well protected at present. In addition, human activities, especially road constructing and overgrazing, are threatening the species. Therefore, according to the IUCN (2019) Red List categories and criteria, conservation status of B. iranicum is defined as critically endangered (CR).

Figures

FIGURE 1 Bupleurum iranicum: A—habitus, B—annual root, C—basal leaves, D—lower part of stem (ribbed), E—stem leaves

FIGURE 2 Bupleurum iranicum: A—inflorescence, B—immature infructescence, C—mature infructescence, D—bracts, E—bracteoles and umbellet, F—flower, G—petal, H—fruit, I—cross sections of mericarp (scale bars 0.5 mm)