Taraxacum chionomelas Kirschner & Štěpánek, 2017

Kirschner, Jan & Štěpánek, Jan, 2017, A revision of Taraxacum sect. Atrata, a dandelion group centred in the Middle Asia, and the problem of Taraxacum brevirostre, Phytotaxa 305 (4), pp. 225-261 : 238

5. Taraxacum chionomelas Kirschner & Štěpánek , sp. nova.

Type: — KYRGYZSTAN. Asia Media , Pamiro-Alaj , decl. boreal. partis orient. montium Turkestanskij chrebet, opp. Voruch , pagus Kšemiš: in saltu montano (sella montana) Kurgaktyr (3252 m) supra lacum Karakul Katta, 14 Aug 1988, J. Štěpánek, cultivated as JŠ 3835, collected 1990 ( PRA, no. det. 28134, holotype; isotypes: PRA, no. det. 28135, 28136 et dupl.)

Diagnosis: — Plantae graciles glabrae, foliis profunde pinnatilobatis vel pinnatipartitis, segmentis lateralibus numero 2–4, lobo terminali elongato, lineari-triangulari, phyllariis involucralibus exterioribus numerosis, ligulis pallide luteis subtubulosis, antheris polline carentibus, acheniis longissimis laevibus.

Description: —Plants slender, usually 6–13 cm tall. Petioles purplish, long, narrow, unwinged; leaves mid-green with purplish midvein, glabrous, narrowly oblanceolate in outline, usually 5–8 × (0.5–) 0.8–1.5 cm, pinnatilobed to pinnatipartite, with (2) 3 (4) pairs of linear-triangular to triangular subrecurved lateral segments to 0.8 cm long, usually entire (rarely with a single little tooth on distal margin), distal margin straight to subsigmoid, proximal margin ± straight, apex acute; interlobes narrow, to 2–3 mm wide, entire; terminal segment elongated, linear-triangular, to ca. 1.5–2 cm long, apex acute. Scapes brownish green, glabrous, overtopping leaves. Capitulum not fully opening, usually ca. 2 cm wide. Involucre dark grey-green and suffused pinkish, ± rounded at base. Outer phyllaries dark grey-green and suffused pink, usually 12–15, ± not imbricate, appressed, the outermost ones often ± linear, the other outer ones lanceolate, rarely to ovate-lanceolate, usually 5.5–7.5 × (1.8–) 2.2–3.0 mm, border whitish-membranous, (0.2–) 0.3– 0.5 (–0.7) mm wide, margins glabrous, often proximally with a few irregular teeth, with a sharp transition into grey-green middle part suffused pink, apex with small blackish cornicles; inner phyllaries usually 11–14 mm long, ± flat to corniculate. Ligules pale yellow, outer ligules canaliculate to subtubular, faintly striped greyish pink outside, inner ligule teeth short, greyish pink. Stigmas grey-yellow with dark pubescence outside. Anthers without pollen. Achenes (slightly greyish) stramineous-brown, ± fusiform, 5.4–6.0 × 1.1–1.2 mm, body smooth ( Fig. 12 ), sometimes with a few almost invisible little tubercles, cone not developed, body gradually narrowing into beak; beak easily breaking off, thickened (0.3 mm at base, otherwise ca. 0.2 mm), 4–5 mm long; pappus white, ca. 6 mm long.—Agamospermous.— Fig. 12 , 13A .

Taxonomic notes: — Taraxacum chionomelas is one of the southernmost species of sect. Atrata and is characterized by numerous outer phyllaries, subtubular pale yellow ligules, absence of pollen, deeply divided leaves with acute lateral and terminal segments, and large, ± smooth achenes. In particular, the leaf shape is unique in the section, and in combination with the absence of pollen, it gives a good tool for the safe identification. So far, T. chionomelas is known to occur in the northern slopes of the Turkestan Range (within the Pamiro-Alai system, Fig. 5 ). Achene surface structures were studied by means of SEM, and the pattern observed at high magnification is similar to that of T. subsect. Epyramidata.

Figures

FIGURE 5. Distribution ranges of Taraxacum chionomelas (square), T. corvinum (triangle), T. lilacinum (circle), T. pseudoatratum (pentagon), and T. sublilacinum (hexagon).

FIGURE 12. SEM photographs of an achene of T. chionomelas (beak is broken off). Scale bars:A, 1 mm; B, 0.3 mm; C, 50 μm.

FIGURE 13. A, T. chionomelas (PRA, no. det. 28134). B, T. corvinum (PRA, no. det. 28130). Scale bar equals 3 cm.