Taraxacum sect. Palustria (Compositae, Cichorieae) in Bulgaria revised, with three new species

Abstract: Three new species of Taraxacum sect. Palustria (Compositae, Cichorieae) are described from Bulgaria, viz. T. abruptilobum, T. basilicum and T. rumelicum. The new species, on the basis of detailed, standardized descriptions and illustrations, are compared with similar species of this section. All the seventeen species of T. sect. Palustria in Bulgaria are agamospermous. An identification key to the members of T. sect. Palustria in Bulgaria is given. Citation: Štěpánek J. & Kirschner J. 2017: Taraxacum sect. Palustria (Compositae, Cichorieae) in Bulgaria revised, with three new species. — Willdenowia 47: 155–165. doi: https://doi.org/10.3372/wi.47.47207 Version of record first published online on 13 July 2017 ahead of inclusion in August 2017 issue.


Introduction
the Taraxacum flora of Bulgaria and adjacent regions has been dealt with by the present authors since the late 1980s (kirschner & Štěpánek 1993a, 1999b, 1999aŠtěpánek & kirschner 2014;Zeisek & al. 2015), with an ultimate goal of a critical, reasonably complete treatment of Taraxacum F. h. Wigg. in the series of Flora of Bulgaria. in particular, we focused our study on marsh dandelions, T. sect. Palustria (h. Lindb.) Dahlst. Our first expeditions to Bulgaria revealed eight species of this section (four newly described, kirschner & Štěpánek 1993a). Later on, we monographed T. sect. Palustria (kirschner & Štěpánek 1998) and revealed another six new species in the Bulgarian material. the present contribution completes our knowledge of T. sect. Palustria in Bulgaria on the basis of additional and/or newly cultivated material. another three new species are described so that 17 taxa referred to T. sect. Palustria are now known from Bulgaria, all with agamospermous reproduction (see Material and methods).
any taxonomic treatment of Taraxacum comparable to modern standards should follow several principles. they were summarized by richards (1973), kirschner & Štěpánek (1996) and Ge & al. (2011), and reflect the peculiar features and processes known in dandelions, particularly the coexistence of agamospermy and sexuality, complex hybridity and polyploidy, the low level of structural morphological differentiation and the high number of mutually similar and mostly hybridogenous species. the principles derived from the above features include (1) different kinds of species are to be recognized on the basis of the extent of variation and modes of reproduction, (2) distribution of sexuality is to be explored, (3) variation within a family of siblings should be studied for each taxon (to Štěpánek & kirschner: Taraxacum sect. Palustria in Bulgaria revised detect autonomous aberrants or facultative sexuality), and (4) the study should be started at the lowest variation level (within and among populations). We attempted to follow the above principles in the present paper.

Material and methods
the material for the present study comes from our expeditions to Bulgaria and from achene samples of other collectors. We would like to acknowledge the enormous help of the late Bogdan kuzmanov during our field and herbarium studies. the material is preserved in the herbarium pra, of the institute of Botany, academy of sciences, průhonice, czech republic. it represents one of the largest Taraxacum collections in the world; duplicates will be deposited in sOM (see index herbariorum at http:// sweetgum.nybg.org/science/ih/). Most of the material was also cultivated at the experimental garden of the institute of Botany, academy of sciences, průhonice, czech republic, following the methods published in kirschner & Štěpánek (1993b).
all the plants included in the present study have agamospermous reproduction. the mode of reproduction was studied in cultivation using methods described in kirschner & al. (2006). as a rule, more than one species grow side by side, up to five species according to our observations. it is therefore important that plants are collected and/or otherwise documented taking this diversity into account. Only well-developed plants are suitable for identification. ideally, plants in full flower should be evaluated, and their achenes obtained in cultivation. alternatively, the oldest capitulum in a plant may be collected with its scape and kept in water in a small vessel for up to ten days to get ripe achenes.

Results and Discussion
Taraxacum sect. Palustria in Bulgaria standard descriptions were published for all the Bulgarian species of Taraxacum sect. Palustria (kirschner & Štěpánek 1993a, 1998), with the exception of T. abrupti lobum, T. basilicum and T. rumelicum, the three species that are described here as new. We therefore provide a dichotomous identification key for all species, and full descriptions are published for the new species only.
the character diversity of the Bulgarian members of Taraxacum sect. Palustria is relatively low, and some important character states are missing from that territory (e.g., yellow stigmas, absence of pollen, outer phyllaries all patent). they belong to five species groups only, and T. sect. Palustria exhibits a relatively low diversity near its southern limit. the majority of species, according to the monograph of the section (kirschner & Štěpánek 1998), belong to the groups centred in Greece and Bulgaria, only rarely extending to other regions: the T. subalpinum group (seven species) and the T. apicula toides group (four species). the T. scaturiginosum group (represented by two species in Bulgaria) is widespread in the e Mediterranean and the Black sea region, reaching iran in the east. Taraxacum scaturiginosum is a taxon with one of the largest distribution ranges in this section; it extends from albania in the west through the Balkan pen insula, crimea and turkey to armenia, iraq and iran in the east. there is another group with higher diversity in the central Mediterranean and extending to the alps and farther north to central europe, the T. tenuifolium group, with two species in Bulgaria. the only species with a large geographical range reaching its southern limit in Bulgaria is the variable and widespread (Battjes & al. 1992) T. vindobonense s. lat. belonging to the group bearing the same name and diverse in the pannonian region and the narrower central europe.
Ecology and distribution -Wet grasslands and pastures. thracian plain (polyanovo). known from a single macrolocality in Bulgaria only.
Affinities -Taraxacum abruptilobum belongs to the group of T. subalpinum hudziok and T. noterophilum kirschner & al. (kirschner & Štěpánek 1998) and is quite close to T. ambitiosum, particularly in outer phyllary features, but the latter has a different character of achenes: much less densely spinulose, with a subgradual transition of body into a longer, usually 1.3 -1.5 mm-long cone. also the leaf shape is useful to tell the two taxa apart. another taxon similar to T. abruptilobum is the turkish  Štěpánek 1998). again, T. pseudopulchrum differs from T. abruptilobum in its achenes with a very short cone (0.5 -0.7 mm long) and shorter beak; its outer phyllaries are indistinctly bordered, and its leaf lateral lobes are much more densely dentate.
Ecology and distribution -at most of its sites, Tara xacum basilicum grows in temporarily wet meadows (vernal spring patches in meadows); the only known exception is the Vitosha locality with a slope permanently soaked with spring water. it is apparently, so far as the material goes, quite common in mountain ranges s of sofia (from Vitosha to Golo Bardo).
Affinities -Taraxacum basilicum, when compared with the other members of T. sect. Palustria in Bulgaria, apparently approaches the group of T. subalpinum (represented by seven species), and T. obuncum in particular.
Ecology and distribution -Taraxacum rumelicum grows in wet meadows around mountain springs. it is known from a rich population at the type locality only.
Affinities -Taraxacum rumelicum is a quite robust plant, relatively close to T. subudum, but differing from it primarily in darker, more numerous outer phyllaries and longer achenes with much longer pappus. also the group of T. paucilobum hudziok and T. vindobonense soest (as defined in kirschner & Štěpánek 1998) is to be compared with T. rumelicum. if we disregard the small, slender plants of T. paucilobum and its allies, T. vindobonense and a few taxa closely related to it have much shorter Willdenowia 47 -2017 achenes and cones, substantially shorter pappus, and a narrower shape of middle outer phyllaries.
Etymology -the epithet derives from eastern rumelia, the historical Balkan region where the species occurs.