Taraxacum vitellicolor 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 : 61-63

5. Taraxacum vitellicolor Štěpánek & Kirschner , sp. nov.

Type:— Bulgaria, montes Pirin , opp. Bansko , mons Vichren , ad ripam lacus parvi (superioris) borealis in valle lacuum Vlachinski ezera ad pedem orientalem dorsi Gredaro, ca. 1.5 km situ occidenali a monte Chvojnati vrch (2635 m), ca. 2250–2300 m, ca. 41° 45’ N, 23° 23’ E, 9 Aug 1997, J. Štěpánek, cultivated as JŠ 6535, collected in 1999 ( PRA, no. det. 36050, holotype; isotype: PRA, no. det. 36052, and duplicates) .

Etymology:—Yolk yellow (derived from Latin vitellus, egg yolk, and color, colour).

Diagnosis:—Plantae insignes foliis saepe indivisis vel lobo terminali magno, acheniis pallide fulvidis vel pallide cinnamomeo-brunneis, phyllariis exterioribus arcte adpressis, brevibus, variegatis, stria mediana obscure viridi, in zonam marginalem pallide virescentem et limbum angustissimum scariosum gradatim transiens.

Plants small, ± compact, 4–7 cm tall. Plant base without tunic, almost without hairs among petiole bases. Petiole broadly winged, pale to pale greenish, 1–2 cm long. Leaf rosettes medium rich, leaves appressed to the ground, deep green, slightly greyish, not spotted, glabrous, spatulate to broadly so to oblanceolate in outline, usually 3–5.5 × 1.5–2 cm, most often undivided, some leaves shallowly pinnatilobed to pinnatipartite, undivided leaves remotely shallowly sinuate-dentate, with 2–5 tooth pairs and apex rounded to obtusely acute, the pinnatilobed leaves with terminal segment dominant, helmet-shaped to oblong-pentagonal, usually 1.5–3 × 1.8–2.5 cm, obtusely acute, distal margin convex, entire or remotely shallowly sinuate-dentate, with teeth short and broad, ± obtuse, basal lobules patent to ± recurved, proximal margin concave to ± straight, entire; lateral segments in 1–2 pairs, recurved to patent, small, broad, broadly triangular, usually 3–5 mm long, 3–6 mm wide at base, distally convex to subsigmoid, entire, proximally usually concave; interlobes often not developed, if so, then broad, usually entire, green; mid-vein pale or suffused pinkish. Scapes pale greenish, glabrous, usually equalling leaf length. Capitulum 2.5–3 cm wide, flat to subconcave, deep yolk-coloured. Involucre not pruinose, 8–10 mm wide and broadly rounded at base. Outer phyllaries 14–17, tightly appressed, subimbricate, short, reaching 1/3 of the inner, ovate to lanceolate, usually 3.5–4.5 × 2–3 mm, ± acuminate with a narrow lingulate tip, with contrasting colours, ± light green, with a narrow, ± dark green middle strip and a gradual transition in a greyish light green part, and another gradual transition in a scarious border 0.1–0.2 mm wide, margin irregularly ciliate, apex flat, darker green and suffused purplish; inner phyllaries ca. 11 mm long, of ± equal width. Outer ligules flat, relatively broad, striped dark brownish grey-purple outside, apical teeth grey-black, inner ligules from flat to canaliculate to subcucullate towards the centre of capitulum, apical teeth black or grey-green. Stigmas discoloured, yellow-green, with black pubescence outside. Pollen present, pollen grains irregular in size. Achenes light beige to very pale cinnamon-brown, without distinct longitudinal ridges, 3.7–4.4 × 0.9–1.1 mm, body with subdense, variously long (short) erect to erect-patent broad spinules and squamules in upper 1/3–1/5, with a subabrupt to ± abrupt transition into a subcylindrical cone 0.7–0.8 mm long; beak 4.5–5 (–6) mm long, pappus dirty white, ca. 5 mm long. – Agamosperm. – Fig. 31, 32A.

Diagnostic notes:— T. vitellicolor is characterized by a dominant terminal segment representing 1/2–2/5 of leaf length, or leaves undivided, and by the peculiar achene colour (from light beige to very pale cinnamon-brown). In its general habit it might be considered as similar to T. mattmarkense van Soest but the latter has subprostrate to erectpatent leaves, outer phyllaries usually 4.5–6 mm long, blackish green with a distinct whitish border 0.3–0.7 mm wide, outer ligules not striped or faintly striped purplish, and greyish olivaceous-brown achenes with the body usually 1.2–1.3 mm thick.

Distribution and habitat:—Up to now, known from a single macrolocality in the Vichren Massif in the Pirin, at about 2300 m. It grows in a sparse wet grassland along a shore of an alpine lake. Its IUCN conservation status is estimated as VU.