Pilosella bulgarica Szeląg & Vladimirov, 2020

Szeląg, Zbigniew & Vladimirov, Vladimir, 2020, Pilosella bulgarica (Asteraceae) a new hybridogenous species from Bulgaria, Phytotaxa 428 (3), pp. 290-294 : 290-292

Pilosella bulgarica Szeląg & Vladimirov , sp. nov. ( Figs. 1–3 )

Type: ― BULGARIA. Central Stara Planina Mountains , Triglav massif, Kurudere gorge, subalpine grasslands and pastures on calcareous slopes, along a tourist path to Mt. Triglav, 1620 m a.s.l., 21 July 2018, Z. Szeląg & V. Vladimirov (holotype SOM; isotypes SOM, KRAM, Herb. Hierac. Z. Szeląg) .

Description: ―Phyllopodous. Stem 7–15 cm high, in the lower third glabrous or with few pale simple hairs 3 mm long; in middle part with scattered microglands and few stellate hairs; within synflorescence with scattered dark-based simple hairs 2–3 mm long, sparse to numerous microglands and numerous stellate hairs. Synflorescence with 3–5 erect capitula (and usually 1–2 capitula aborted). Synflorescence branches 1–3, grouped on top of the stem, up to 2 cm long, with 1–2 capitula. Acladium up to 1 cm long. Rosette leaves 5–12, up to 4 cm long and up to 0.5 cm wide, sessile, lanceolate to oblanceolate, entire, acute at apex (the outer leaves shorter and rounded at apex); on upper surface glabrous or with sparse pale brown-based simple hairs 4–6 mm long; on lower surface with protruding white midrib, glabrous, only on midrib and on margins with scattered to numerous pale brown-based simple hairs 4–6(–8) mm long; on margins also with few microglands and occasionally with stellate hairs. Cauline leaves 1–2, up to 2 cm long, lanceolate or subulate, sessile, rapidly reduced in size upwards, acute at apex, covered by indumentum like the rosette leaves. Peduncles with scattered to numerous pale, black in the lower third, simple hairs 1–3(–4) mm long, scattered to numerous stellate hairs, and few to numerous blackish glandular hairs 0.2–0.3 mm long. Bracteoles 1–2, blackish green, 1–2 mm long, with dark-based simple hairs and stellate hairs. Involucres 6–7 mm long, globose at base, with quite dense indumentum. Involucral bracts in two rows, acute at apex, up to 0.7 mm wide at base, blackish-green (the inner bracts with pale margins and far less dense indumentum), with numerous to dense pale dark-based simple hairs 2.5–4 mm long, scattered dark glandular hairs 0.2–0.5 mm long (ratio of simple hairs to glandular hairs 3:1), and sparse stellate hairs (more numerous at base of outer bracts). Ligules yellow, a little bit blackish at apex. Styles pure yellow. Achenes black, 1.6–1.9 mm long. Pappus white. Pollen in anthers quite numerous, spherical and of varying size. Flowering: July.

Ploidy level and mode of reproduction: ―2n ~ 5x ~ 45, probably apomictic.

Distribution and habitats: ―Endemic to the Triglav massif in the Central Stara Planina Mountains, Bulgaria; additional localities in the Kaloferska Planina Mountains are expected. The populations of Pilosella bulgarica comprised hundreds of plants spread along a tourist path from the Tazha (Тъжа) village to Mt. Triglav in the upper part of the Kurudere gorge, at 1520–1650 m a.s.l. They were growing in subalpine grasslands and pastures on southeastfacing calcareous slopes together with P. rhodopea , which is frequent in the Kurudere gorge.

Affinity: ― Pilosella bulgarica shows a combination of morphological characters of P. rhodopea and P. pavichii . The characters from P. rhodopea , its supposed maternal parent, are (1) the few-headed synflorescence with capitula grouped at the top of the stem, (2) the reduced cauline leaves, (3) the numerous long simple hairs on the involucral bracts, and (4) the stellate hairs on the stem. The characters from P. pavichii are (1) the smaller capitula with the turbinate involucres, (2) the rosette leaves acute at apex, on lower surface with protruding white midrib, and (3) the sparse indumentum of the stem.

Pilosella rhodopea is a common species in the subalpine habitats of the Central Stara Planina Mountains; its population above the Tazha hut (хижа Тъжа), separated by ca 10 km from the Kurudere gorge, is composed of diploid, triploid and tetraploid plants ( Šingliarová et al. 2011). Cytogenetic studies of P. rhodopea in the Kurudere gorge are in progress.

Pilosella pavichii , the second putative parental species of P. bulgarica , grows in the subalpine belt and in clearings in the mountain forest; it is known as diploid in Bulgaria, Greece, Montenegro, North Macedonia, Romania and Serbia ( Christov & Popov 1933; Strid & Frazén 1981; Vladimirov 2000; Mráz & Szeląg 2004; Yurukova-Grancharova et al. 2006; Szeląg et al. 2007; Szeląg & Ilnicki 2011). Recent studies have revealed also a tetraploid cytotype of P. pavichii growing together with diploid plants in the Pirin Mountains in Bulgaria ( Krahulcová et al. 2009, 2016). The pentaploid and hexaploid cytotypes of P. pavichii published by Krahulcová et al. (2016) are a bit surprising and may have been based on misidentified specimens of hybrids between P. pavichii and P. piloselloides s. lat., which are quite frequent in the anthropogenic disturbed habitats at lower altitudes in the Bulgarian mountains.

Note: ― Pilosella pavichii , originally described as Hieracium pavichii Heuffel (1853: 618) , was transferred to the genus Pilosella Vaillant (1754: 703) by Holub (1977: 306) (see Szeląg 2011), and not by Arvet-Touvet (1880) as considered by Krahulcová et al. (2009, 2016, 2018).

Figures

FIGURE 1. Holotype of Pilosella bulgarica (SOM).

FIGURE 2. Details of the holotype of Pilosella bulgarica: rosette leaves (left) and involucres (right).

FIGURE 3. Pilosella bulgarica in the locus classicus, on July 21, 2018.