Hieracium gussevii Szeląg, 2018

Szeląg, Zbigniew, 2018, Hieracia balcanica XIV. Two new species in Hieracium sect. Cernua (Asteraceae) from Bulgaria, Phytotaxa 348 (2), pp. 125-132 : 125-126

Hieracium gussevii Szeląg , sp. nov. ( Figs. 1‒2)

Type: ― Specimens from plants cultivated in the author’s garden, pressed on July 20, 2017, from the seeds collected in BULGARIA. Vitosha Mountains , SE slope of Mt. Goli Vrah , open places in Picea abies forest, along tourist route leading to the Aleko ski centre, 1800 m a.s.l., 20 July 2008, Z. Szeląg (holotype SOM 175982 ; isotypes SOM 175983 & 175984, KRAM, Herb. Hierac. Z. Szeląg) .

Description: ―Aphyllopodous. Stem 50–90 cm high, purplish at base, in lower half with dense, stiff, pale, 4–6 mm long simple hairs, and few stellate hairs; in upper half with sparse, pale, 3–4 mm long simple hairs and sparse stellate hairs; within synflorescence with numerous stellate hairs. Synflorescence branches 5–15 in axils of upper cauline leaves, up to 4–6 cm long, with 2–4 capitula (and usually 1–3 capitula aborted), covered by numerous to rather dense stellate hairs. Acladium 1–2 cm long. Rosette leaves (withering at anthesis) 8–12, up to 15 cm long and up to 1.5 cm wide, in shape and indumentum similar to lowest cauline leaves. Cauline leaves 15–30, somewhat coriaceous and glaucescent, sessile, ±semi-amplexicaul, gradually reduced in size upwards, lanceolate, acute at apex, sharply, remotely denticulate, with ±reticulate and protruding veins on lower surface. Lower cauline leaves up to 18 cm long, at base and along midrib with dense, stiff, pale, 4–6 mm long simple hairs, on margins with numerous 2–3 mm long, simple hairs mixed with a few microglands and sparse stellate hairs; on lower surface with ±numerous stellate hairs and scattered simple hairs. Upper cauline leaves on both surfaces glabrous or almost so, on margins and along midrib with a few 1–2 mm long, simple hairs, sparse stellate hairs and ±numerous microglands. Synflorescence with 20–40(–50), erect capitula. Peduncles thin, green, with dense stellate hairs. Bracteoles 2–4, green with scattered stellate hairs. Involucres 9–10 mm long, campanulate, with very sparse indumentum. Involucral bracts in two rows, obtuse at apex, up to 2 mm wide at base, dark green (in nature to blackish green), with a few, patent, dark glandular hairs 0.2–0.4 mm long, a few stellate hairs, and a tuft at apex. Ligules yellow, glabrous at apex. Styles yellow with dense, dark microtrichomes. Achenes dark brown to blackish, 3.7–4.0 mm long. Pappus pale-grey. Pollen in anthers numerous, spherical and of varying size. Flowering: August.

Affinity: ― Hieracium gussevii is similar to H. werneri from the Rhodopes in southern Bulgaria, but differs in its dense, simple hairs of the lower half of stem and the lower-cauline leaves, more numerous and glaucous cauline leaves, numerous stellate hairs on the stem within synflorescence, peduncles without microglands, involucral bracts with glandular hairs, and longer, dark brown to blackish achenes. The morphological differences between both species are stable in garden-cultivated plants.

The following morphologic features of H. gussevii seem to suggest a relationship with H. umbellatum Linnaeus (1753: 804) : (1) the lack of the rosette leaves by anthesis, (2) the unbranched stem up to 90 cm high, with 20–30 cauline leaves, (3) short synflorescence branches confined to the upper part of the stem, (4) few, patent glandular hairs on the involucral bracts, and (5) numerous stellate hairs in the upper part of the stem and especially on the peduncles.

However, (1) overwintering rosette leaves, (2) the stem purplish at the base, (3) the lower part of stem and lower cauline leaves covered by rough, dense, simple, hairs (4) short involucral bracts (5) capitula spherical in bud, and (6) glaucous leaves, resemble H. virosum Pallas (1771: 501) .

In southeastern Europe, H. virosum reaches the western limit of its geographical range and is represented by H. foliosum Willdenow (1803: 1589) , currently treated as conspecific with H. virosum ( Sennikov 2008) . In Bulgaria, H. virosum is a rare species and has been classified as ‘Endangered’ ( Vladimirov 2015: 521); it was also recorded from the Vitosha region ( Stojanov et al 1967). In my opinion, H. gussevii may have originated as the result of hybridization between H. sparsum and H. robustum Fries (1848: 193) , a hybridogenous species of the morphological formula H. virosum — H. umbellatum (cf. Sennikov 2012, see also Tupitsyna 2004).

Distribution and habitats: —Endemic to the Vitosha Mountains in western Bulgaria. Hieracium gussevii is quite frequent in the area between the Aleko chalet and Mt. Goli Vrah, at 1800–1830 m a.s.l., but it has been overlooked due to the morphological similarity with ubiquitous H. velenovskyi Freyn in Velenovský (1891: 346), growing side by side. The populations consisted of numerous plants growing in small clusters on the Picea abies forest margin, both in sunny and in partly overshadowed places, on silicate bedrock.

Chromosome number and mode of reproduction: —2n = 3x = 27, agamospermous ( Ilnicki & Szeląg 2011: 107, as Hieracium sp. ‘Aleko’).

Etymology: ―The new species is named in honour of my colleague Dr. Chavdar Gussev (Чавдар Гусев), Institute of Biodiversity and Ecosystem Research Bulgarian Academy of Sciences, Sofia, for his contribution to knowledge of the flora and vegetation in Bulgaria.