Taraxacum (sect. Rhodocarpa) van Soest 1954
Creators: name: Štěpánek, Jan
name: Kirschner, Jan
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Asterales
Asteraceae
Taraxacum

description: D. Taraxacum sect. Rhodocarpa van Soest (1954: 15)   
 Type:— Taraxacum rhodocarpum Dahlst.   
 = Taraxacum sect. Alpestria (van Soest 1966a: 35) van Soest (1966b: 459)   
 ≡ Taraxacum subgroup Alpestria van Soest (1966a: 35)   
 Type:— Taraxacum reophilum van Soest (1959: 132, as “reopliclum”)    Introduction   
 Taraxacum sect. Rhodocarpa is a name recently found to be an older synonym of T. sect. Alpestria that was introduced to accommodate Alpine dandelions, morphologically intermediate between T. sect. Alpina G. E. Haglund or T. sect. Fontana van Soest and T. sect. Taraxacum (Štěpánek & Kirschner 2021). When the early publications of van Soest (1966, 1966a, 1969) are considered, it is evident that his T. sect. Alpestria is a heterogeneous group encompassing morphologically mutually remote taxa (Uhlemann 2015), such as T. rhaeticum van Soest (1959: 134), or a group with ochraceous or reddish achenes (T. ochrospermum van Soest 1969: 122, T. rufocarpoides van Soest 1969: 122) or T. perfissum van Soest (1959: 129). A quite separate position is occupied by T. reophilum, the type of T. sect. Alpestria. Another group within the original T. sect. Alpestria includes T. alpestre (Tausch 1821: 564) Candolle (1838: 148), T. nigricans (Kitaibel in Schultes 1814: 405) Reichenbach (1831: 270) and allied taxa (Štěpánek et al. 2011), with the only known sexual member of this section, T. carpaticum Štěpánek & Kirschner (2011: 550), a species confined to the southernmost Carpathians. Taraxacum rhodocarpum is another distinctive, rather marginal taxon of this section.   
 Relationships among various groups of dandelions in the higher elevations of the Alps are difficult to outline because of the absence of Taraxacum sexuality there (sexual members of T. sect. Taraxacum occur at lower elevations in several regions of the Alps in Austria and Switzerland). On the other hand, there are several alpine sections of Taraxacum in the mountains of northern Greece, Bulgaria and Romania, with sexuality involved: T. paludosiforme of T. sect. Crocea (Rila, Pirin), T. pyrenaicum subsp. balcanicum of T. sect. Obliqua (Pirin), T. bulgaricum of T. sect. Bulgarica (Rila, Pirin, Belasica) and T. carpaticum (the Bucegi Mts., the Piatra Craiului Mts., Romania); we should also mention the widespread sexual T. linearisquameum van Soest (1966: 471) of T. sect. Taraxacum in the lowlands of Bulgaria and Romania.   
 The Bulgarian Taraxacum species included in T. sect. Rhodocarpa (= T. sect. Alpestria) in the present paper mostly exhibit certain relationships with the above sexual taxa: T. fragile and T. musteum are close to the group of T. alpestre and T. nigricans (and therefore to T. carpaticum); T. rhodopaeum, T. pictum and T. incantatum are similar to the experimental hybrids between T. linearisquameum and T. paludosiforme (J. Štěpánek, unpublished), and may have originated in a similar way. No clear links were found between the group of T. serenum, T. tetricum and T. radmilae and other taxa, perhaps with the exception of T. salutator. The remaining species, T. recognitum, T. pseudorecognitum and T. pandum, having relatively stiff leaves with narrow lateral segments, may be related to T. erzincanense, a species of unknown sectional position. Last, we should mention T. hamosius as an isolated taxon with distinctive features of achenes and leaves, similar to the group of T. rhaeticum van Soest (1959: 134) and T. hercynicum Kirschner & Štěpánek (1997a: 51). There is a morphological evidence of oligo- or multiclonality in several Bulgarian species of T. sect. Rhodocarpa (T. rhodopaeum, T. pictum and T. incantatum), and it is possible that (not only) the latter are relatively young hybridogenous apomicts.   
 It follows from the above considerations that we accept the traditional, broad circumscription of T. sect. Rhodocarpa (= T. sect. Alpestria) under the absence of a more detailed study of the Alpine dandelions and their relationships. The following description includes characters of the T. alpestre group, the Bulgarian species of T. sect. Rhodocarpa, and the core members of this section in the Alps.   
 Note:—The possible occurrence of T. sect. Rhodocarpa in upper montane and montane belts of the Bulgarian mountains may be underestimated because of a lower density of collection sites, as compared with the higher alpine localities.    Description   
 Plants medium-sized to ± robust; plant base without tunic. Leaves erect, erect-patent to patent-prostrate, most often subglabrous to glabrous, usually deeply dissected, often having a shape of those of T. officinale s. lat., petiole often winged, mid-vein without the longitudinally striate pattern. Capitulum yellow, deep yellow or golden yellow, often large; stigmas discoloured, pollen usually present. Involucre medium broad, rounded to obconical at base, pruinose or not so. Outer phyllaries most often 12–19, loosely appressed, erect-patent, arcuate-patent to arcuate recurved, not tightly appressed, nor reflexed, usually from narrowly lanceolate to ovate-lanceolate, relatively short, most frequently (5–) 6–9 × 2–3.5 mm, surface usually ± evenly olivaceous-green, dark olivaceous-green, deep grey-green, often blackishgreen when dry, most often with an abrupt transition in an inconspicuous, membranous or whitish-membranous border 0.1–0.3 mm wide, sometimes border absent or broader, margin glabrous or sparsely minutely ciliate, apex flat.Achenes light stramineous-brown, light yellowish brown, light greyish stramineous-brown, sometimes light brown to medium brown, 3.5–5 × ca. 0.9–1.1 mm, achene body usually ± densely spinulose above, most often abruptly or subabruptly, seldom to gradually narrowing in a short subcylindrical to subconical, sometimes conical, cone usually 0.5–0.9 mm long, rarely longer; beak thin, persistent, (4.5–) 6–8 (–9) mm long, pappus ± white.    An identification key to the Bulgarian members of T. sect. Rhodocarpa   
1 Petioles unwinged or very narrowly winged.................................................................................................................................... 2  
– Petioles broadly winged or winged in all leaves, or broadly winged in the earlier, outer leaves and narrowly so or unwinged in the late, inner leaves............................................................................................................................................................................... 4  
 2 Outer phyllaries abaxially with a dark middle part bordered pale greenish, with a gradual transition in a narrow border; distal part of achene body covered with large, coarse, ± appressed squamules; stigmas dark discoloured, almost black when dry.......................................................................................................................................................................................... 40. T. pictum, sp. nov.   
– Outer phyllaries abaxially ± evenly coloured, with an abrupt transition into a narrow border; distal part of achene body with ± dense, short suberect to erect-patent spinules and squamules; stigmas medium discoloured.......................................................... 3  
 3 Achene cone conical to subconical; leaves with conspicuously remote, patent lateral segments, interlobes 5–12 mm long.................................................................................................................................................................................... 38. T. pandum, sp. nov.   
 – Achene cone cylindrical to subcylindrical; lateral segments usually subrecurved, not remote, interlobes usually 2–6 mm long........................................................................................................................................................................... 34. T. radmilae, sp. nov.   
4 Petiole light greenish or pale green.................................................................................................................................................. 5  
– Petiole suffused light to deep pink-purple, brown-purple or purple................................................................................................. 9  
 5 Achenes medium brown with a dark cinnamon hue............................................................................... 36. T. recognitum, sp. nov.   
– Achenes light stramineous-brown, or light to pale yellowish brown............................................................................................... 6  
6 Cone (0.3–) 0.5–0.8 mm long........................................................................................................................................................... 7  
– Cone usually 0.8–1.3 mm long......................................................................................................................................................... 8  
 7 Outer phyllary surface colour with a gradual transition in a border 0.2–0.5 mm wide; leaves mostly with ± patent lateral segments...................................................................................................................................................... 32. T. serenum, sp. nov.   
 – Outer phyllary surface evenly blackish green, almost unbordered, the almost invisible border to 0.1 mm wide; leaves mostly with hamate-recurved lateral segments................................................................................................................... 42. T. pseudoalpestre   
 8 Outer phyllaries narrowly lanceolate to lanceolate, 1.5–2 mm wide......................................................... 29. T. musteum, sp. nov.   
 – Outer phyllaries ovate to lanceolate, 2–3 mm wide........................................................................................ 30. T. fragile, sp. nov.   
 9 Leaves subdensely arachnoid along mid-vein and subsparsely arachnoid on both surfaces, hairs coarse; distal leaf segments usually with sparse brown-purple spots; interlobes inconspicuously blotched; leaf segments approximated....... 31. T. hamosius, sp. nov.   
– Leaves glabrous, subglabrous or sparsely arachnoid along mid-vein and glabrous to subglabrous on both surfaces, hairs soft; leaf segments not spotted; interlobes not blotched; leaf segments not approximated........................................................................... 10  
 10 Outer phyllaries regularly loosely appressed, with a gradual transition in a narrow membranous border; cone 0.5–0.7 mm long..................................................................................................................................................................... 41. T. incantatum, sp. nov.   
– Outer phyllaries usually erect-patent, arcuate, arcuate-patent or arcuate-recurved, some of them may be loosely appressed, with an abrupt transition in a narrow, whitish, whitish-membranous or membranous border; cone usually 0.7–1.2 mm long................. 11  
 11 Beak 8–11 mm long; leaves with lateral segments clearly recurved..................................................... 39. T. rhodopaeum, sp. nov.   
– Beak 6–8 mm long; leaves with lateral segments predominantly patent....................................................................................... 12  
 12 Leaves light yellowish green; outer phyllaries 10–13................................................................. 37. T. pseudorecognitum, sp. nov.   
– Leaves mid-green to slightly greyish mid-green; outer phyllaries 14–20...................................................................................... 13  
 13 Achene body ± abruptly narrowing in the cone; longitudinal ridges on the achene body not distinct........ 33. T. tetricum, sp. nov.   
 – Achene body gradually narrowing in the cone; both lateral and dorsiventral longitudinal ridges on the achene body prominent.......................................................................................................................................................................... 35. T. salutator, sp. nov.
description: Published as part of Štěpánek, Jan & Kirschner, Jan, 2022, A hotspot of endemism: Oreophytic Taraxacum species (Compositae, Crepidinae) in the mountains of Bulgaria, pp. 1-139 in Phytotaxa 569 (1) on pages 96-98, DOI: 10.11646/phytotaxa.569.1.1, http://zenodo.org/record/7235182