Taraxacum desolatum Kirschner & Štěpánek, 2025

Kirschner, Jan, Štěpánek, Jan & Buryy, Vladimir V., 2025, Towards a revision of Taraxacum sect. Borealia (Compositae, Crepidinae) in Siberia and the continental Far East, with special reference to the dandelions of the Altai and Kamchatka, Phytotaxa 679 (1), pp. 1-147 : 127-130

55. Taraxacum desolatum Kirschner & Štěpánek , sp. nov.

Type:— RUSSIA. Altai Republic, Kosh-Agach District, Aktru Valley , ca. 50.047°N, 87.658°E, 2700–2800 m, 31 Jul 1997, A. Aitchinson, cultivated under no JK 4705 ( PRA, no. det. 37812, holotype; isotype: PRA, no. det. 37814) .

Etymology:—Lonely, desolate.

Diagnosis:—Species insignis foliis mediocriter laete viridibus, saepissime pinnatipartitis, segmentis lateralibus deltoidei-triangularibus, ligulis estriatis, stigmatibus obscuris, acheniis stramineis vel ochraceo-stramineis, sublaevibus, corpore superne spinulis parvulis sparsissimis praedito, in pyramidem breviter conicam subabrupte transeunte.

Plants relatively small, with a ± compact growth, usually 6–12 cm tall. Plant base without tunic, with ± dense arachnoid indumentum among petiole bases. Petiole broadly winged in outer leaves, narrowly winged in inner ones, light green or slightly suffused pinkish beneath, with scattered arachnoid hairs. Leaves ± light mid-green, initially arachnoid, later sparsely so along mid-vein, ± oblanceolate in outline, ca. 5–10 (–12) × 1.3–2.7 cm, pinnatilobed to pinnatipartite; terminal segment broadly triangular to ± triangular, margins entire, ± straight, basal lobules patent, apex acute; lateral segments in 2–4 pairs, deltoid to triangular, patent to (more often) recurved, distal margin straight to subconvex, entire or with 1–3 minute teeth in the most proximal segments, proximal margin entire, usually subconcave; interlobes broad and short, usually 1–3 mm long, usually entire; mid-vein light greenish, sometimes pinkish. Scapes growing from outside the leaf rosette, brownish green, arachnoid (initially densely so), usually subequalling leaves. Capitulum seep yellow, ca. 3–3.5 cm wide. Involucre ± not pruinose, blackish green, usually 8–9 mm wide and rounded at base. Outer phyllaries (12) 14–15 (19), appressed, ± not imbricate (but some innermost of them markedly longer, as if seemingly intermediate between outer and inner phyllaries), lanceolate to broadly lanceolate, usually (6.5–) 7.0–7.5 (–9.0) × (2.2–) 2.5–3.0 (–3.5) mm, surface ± black-green, border sharply delimited, whitish, 0.1–0.2 mm wide, with a grey-green zone 0.5–0.8 mm wide and a central blackish band ca. 0.5 mm wide; margins ciliate (hairs relatively long), apex with ± black horns 1–1.5 mm long, projecting in the same direction as its phyllary (not perpendicular); inner phyllaries ca. 13–15 mm long, of unequal width, blackish olivaceous, with horns to 1 mm long. Outer ligules not very numerous, flat, ± not striped outside or striped faintly pinkish, all ligule teeth dirty yellow. Stigmas medium deep discoloured, yellow-grey, with blackish pubescence outside. Pollen abundant, pollen grains irregular in size. Achenes light pinkish ochraceous-stramineous to light stramineous, 4.0–4.3 × 1.1–1.3 mm, body very sparsely spinulose in upper 1/5 (–1/4), with spinules short, often curved upwards, body subabruptly narrowing into a broadly conical cone 0.4–0.6 mm long, ca. 0.5 mm thick at base, ca. 0.4 mm distally; beak 8.5–9.5 mm long, pappus ± white, ca. 5.5 mm long. – Agamospermous. – Fig. 89 , 90 .

Diagnostic notes:—Morphologically, T. desolatum stands close to T. peschkovae but is distinct from the latter in having mid-green (vs. dark green) leaves, mid-vein green or ± pinkish (vs. brown-purple), leaves divided, ligules ± not striped outside, and achenes with very sparse, minute spinules.

Distribution and habitat:— Taraxacum desolatum is known from a single macrolocality in Aktru Valley in the northern part of Kosh-Agach District, Altai Republic.

Figures

FIGURE 89. Taraxacum desolatum. The holotype. Photo M. Hladík.

FIGURE 90. Taraxacum desolatum. A, general habit (PRA, no. det. 37812, holotype); B, achenes (PRA, from cultivation JK 4705). Scale bars:A = 2 cm; B = 1 mm.