Taraxacum amoenulum Štěpánek & Kirschner, 2022

Štěpánek, Jan & Kirschner, Jan, 2022, A hotspot of endemism: Oreophytic Taraxacum species (Compositae, Crepidinae) in the mountains of Bulgaria, Phytotaxa 569 (1), pp. 1-139 : 47

0. Taraxacum amoenulum Štěpánek & Kirschner , sp. nov.

Type:— Bulgaria, Pirin Planina, N of the bottom of Sarchalijtsa valley ( N of the bottom of Sandanska Bistritsa valley), ca. 5 km N of Jane Sandanski , in the valley formed by the streem from Goljamo Slano Pole , wet meadows with Alchemilla spp. , Geum spp. , Ranunculus spp. , Carex spp. , Juncus spp. , etc., ca. 1700 m, 6 Jul 1980, P. Frost-Olsen ( PRA, no. det. 36098, holotype; isotype: PRA, no. det. 36100) .

Etymology:—Charming, graceful (derived from Latin amoenus).

Exsiccates:— Taraxaca Exs., no. 1270.

Diagnosis:—Plantae inter sectiones Croceorum et Alpestriorum intermediae, insignes phyllariis exterioribus pallidis, pallide viridescentibus, marginibus albidis latis fere translucentibus, et acheniis pallide ferrugineo-brunnescentibus, corpore superne spinulis brevibus latis, saepe coalescentibus obsito.

Plants medium-sized to small, relatively slender, 15–20 cm tall, leaves not numerous. Plant base without tunic, without indumentum among petiole bases or with sparse hairs. Petiole usually medium broadly to narrowly winged, light purplish to pale, darker coloured on mid-vein, 2.5–4.5 cm long. Leaves variously erect-patent, light green, not spotted, sparsely arachnoid (on mid-vein) or glabrous, narrowly lanceolate to linear-lanceolate in outline, usually 7–12 × 1.5– 2.5 cm, pinnatisect; terminal segment helmet-shaped to broadly so, or triangular or broadly so, not dominant, usually 1–1.5 (–2.5) × 1.0– 1.5 cm, obtusely acute to ± obtuse, distal margin convex to subsigmoid, entire or with a single tooth, in bigger segments with 1–2 obtuse teeth and a single acute one, basal lobules subrecurved to patent, acute, proximal margin ± straight, entire; lateral segments in 3–4 (–5) pairs, relatively small, subrecurved to ± patent, sometimes pointing forwards (then the opposite segment recurved), deltoid-triangular or abruptly narrowed in a lingulate distal part, usually 6–10 mm long, 6–9 mm wide at base, distal margin subconvex to sigmoid, rarely concave, entire or with 1 (–3) little acute teeth, proximal margin ± straight, usually entire; interlobes usually 5–10 × 2.5–6 mm, green, usually not bordered, rarely indistinctly so, sometimes ± raised, entire or with 1–3 filiform teeth of variable length; mid-vein pale greenish, basally sometimes purplish. Scapes pale green, sparsely arachnoid, more densely below capitulum, later glabrous, overtopping leaves. Capitulum yellow, ca. 3 cm wide, ± flat. Involucre not pruinose, 7–8 mm wide and narrowly rounded to subobconical at base. Outer phyllaries 16–20, light coloured, with contrasting colours, loosely appressed, apex often arcuate, later arcuate-patent, lanceolate to narrowly lanceolate, the outermost ones to linearlanceolate, usually 5–7 × (1–) 2–2.5 mm, pale coloured (almost translucent) before anthesis, with a pale green middle zone and a broad whitish border, later, at and after full anthesis, with a narrow, ca. 1 mm wide, deep olivaceous-green middle part and a pale greenish zone bordered by a membranous border 0.2–0.4 mm wide, margin minutely ciliate, with 1–2 filiform teeth near the base, apex flat; inner phyllaries ca. 11 mm long, of equal width. Outer ligules flat, striped dark grey outside, apical teeth grey, inner ligules canaliculate, their apical teeth light greyish pink. Stigmas not long, pale, dirty yellow or honey-yellow, with ± hyaline pubescence outside. Pollen present, pollen grains irregular in size. Achenes pale rusty-brown, 3.8–4.4 × 0.9–1.1 mm, body with ± distinct longitudinal ridges, with numerous short and broad spinules, sometimes coalescing in comb-like squamules in upper 2/5–1/3, with a ± abrupt transition into a relatively thick, subconical to subcylindrical cone 0.8–0.9 mm long; beak 7.5–9.5 mm long; pappus 5–5.5 mm long, white. – Agamosperm. – Fig. 21.

Relationships:— Taraxacum amoenulum deviates from the most common pattern of T. sect. Crocea in the rustybrown achenes, very pale, almost translucent and distinctly bordered outer phyllaries, less broadly winged petioles and frequently dentate interlobes. It seems to be intermediate between T. sect. Crocea and T. sect. Rhodocarpa (= T. sect. Alpestria), closer to the former.

Distribution and habitat:—Known from the Pirin, from the type gathering only. It grows in wet, mossy meadows in the montane belt. The IUCN conservation status is estimated as DD.

Note:—There is a similar form differring from T. amoenulum by a more robust growth, lower number of lateral segments, and longer achenes; we leave it for further study: The Rila, Samokov, village of Borovec, a path between the chalets Jastrebec and Musala, 2200–2350 m, 9 Aug 1990, J. Štěpánek & B. Kuzmanov, cultivated as JŠ 4504 (PRA, no. det. 35785).