Flowers of dicotyledonous plants host communities of arthropod species. We studied the community associated with dandelion (Taraxacum section Ruderalia), a complex of apomictic micro-species abundant in central Europe. Identification of microspecies in the field was impracticable. These plants produce an abundance of flowers that host arthropod communities that are not yet fully documented. We investigated species occurrence, its diurnal and seasonal variation and some of the factors that determine the abundance of the dominant species. Insect and spiders were collected from 2010 to 2012 at a locality in Prague. Whole capitula were harvested at weekly intervals and resident arthropods were identified. Diurnal variation in insect presence and the effect of pollen and microclimate on some of the species were also examined. The insect community (> 200 species) consisted mainly of species of Hymenoptera (86 spp.), Coleoptera (56 spp.), Diptera (46 spp.) and Heteroptera (23 spp.). The most abundant were Thysanoptera (2 spp.). Pollen eaters/collectors and nectar feeders dominated over predators and occasional visitors. From April to mid-August, the insect community was dominated by Coleoptera, and later by Diptera and Hymenoptera. Except for Meligethes spp. and species breeding in the capitula, the insects occupied flowers during the daytime when the flowers were open (10-12 h in spring and only 2-4 h in late summer). The presence of Meligethes spp. in particular flowers was associated with the presence of pollen; the occurrence of Byturus ochraceus with pollen and flower temperature. Although pollination is not necessary, dandelion plants produce both nectar and pollen. The community of arthropods that visit dandelion flowers is rich despite their being ephemeral.The composition of local faunas of flower visitors, presence of floral rewards and flower microclimate are important factors determining the composition of the flower community., Alois Honěk, Zdenka Martinková, Jiří Skuhrovec, Miroslav Barták, Jan Bezděk, Petr Bogusch, Jiří Hadrava, Jiří Hájek, Petr Janšta, Josef Jelínek, Jan Kirschner, Vítězslav Kubáň, Stano Pekár, Pavel Průdek, Pavel Štys, Jan Šumpich., and Obsahuje bibliografii
A taxonomic revision of Taraxacum sect. Leucantha Soest is presented. Species in this section are mainly characterized by the pale bordered and appressed outer involucral bracts, achenes covered with subsparse coarse spinules, thick cylindrical cone and a relatively short, thicker rostrum, and often white or pale yellowish flowers. They occur in subsaline wet meadows and steppe depressions over a large area including Mongolia, South Siberia, NE, N and W China, Tibet, the Western Himalayas, Tadzhikistan, Kyrgyzstan and E and NE Kazakhstan. Eighteen species are recognized, seven of them described as new: Taraxacum niveum from the Altai and Dzhungaria, T. candidatum centred in Ladakh, Tadzhikistan and Kyrgyzstan, T. album from Kyrgyzstan, T. flavidum from Mongolia and Transbaikalia, T. occultum from East Mongolia, T. virgineum from Ladakh, India, and T. inimitabile from Gobi-Altai, Mongolia. An analysis of syntypes of the names T. dealbatum Hand.-Mazz. and T. sinense Dahlstedt is given. For the safe interpretation of the name T. luridum, epitype was designated. All the species are agamospermous but sexuality and diploidy is documented for a few Transbaikalian plants of the section Leucantha.
On the basis of rich material from Asia, a recently described group of dandelions, Taraxacum sect. Stenoloba Kirschner et Štěpánek, is revised taxonomically. Four previously described species are recognized: T. sinomongolicum, newly typified, T. mongoliforme, with a lectotype replacing the original holotype now not extant, and a new epitype, T. scariosum, a new combination of Leontodon scariosus Tausch, replacing the frequently confused names, T. asiaticum, newly typified, and T. stenolobum, and T. multisectum, a taxon for the first time compared with other members of the section. Three new species are described: T. abax occupies a large range from S Siberia and Mongolia to NE China, T. abalienatum and T. odibile are known from Mongolia and SE Siberia. Taraxacum abax and T. abalienatum represent core species of the section Stenoloba, whilst T. odibile exhibits a mixture of characters of sections Stenoloba and Leucantha. All the known members of the section Stenoloba are agamosperms. Taraxacum mongoliforme, T. abax and T. scariosum proved to be triploid with 2n = 24. This account includes detailed descriptions and an identification key.
On the basis of the authors’ collections and cultivated material from Asia, a recently described group of dandelions, Taraxacum sect. Suavia, is revised. In addition to three species described previously (T. haneltii, T. sumneviczii and T. formosissimum), six new species from Mongolia and Kyrgyzstan are recognized. Three of them, T. suave, T. stupendum and T. margaritarium, possess most of the features characterizing the section Suavia, one, T. suasorium, is regarded as intermediate between sections Suavia and Leucantha, whilst the remaining two, T. nobile and T. venustius, exhibit some characters of another related section (T. sect. Stenoloba). The members of the section Suavia are agamospermous. Detailed descriptions, drawings and an identification key are given.
A detailed study of Taraxacum sect. Ruderalia for the 8th volume of the Flora of the Czech Republic revealed five new agamospermous species, viz. T. atroviride Štěpánek et Trávníček, T. clarum Kirschner, Štěpánek et Trávníček, T. moldavicum Chán, H. Ollgaard, Štěpánek, Trávníček et Žíla, T. urbicola Kirschner, Štěpánek et Trávníček and T. violaceifrons Trávníček. These species are formally described, thoroughly characterized morphologically and compared with similar taxa. They are known from numerous localities in Central Europe; T. moldavicum, in addition to the Central European distribution, is known to occur in two regions in Denmark. All these species are also documented by photographs of their general habit and important features.
A long-standing problem with the taxonomic status and synonymy of the names Taraxacum nigricans (Kit.) Reichenb. and T. alpestre (Tausch) DC. is resolved. These two names, the oldest ones referable to high mountain dandelions in Central Europe, are typified, and a detailed comparison of these species’ morphology, genotype make-up, karyotypes and distribution is provided, together with a discussion of other cases of similar and probably closely related agamospermous taxa of Taraxacum and Hieracium. Taraxacum nigricans (2n = 32) and T. alpestre (2n = 32) are endemic to the Nízke Tatry Mts, Slovakia, and the Krkonoše/Karkonosze Mts, Czech Republic/ Poland, respectively. These are shown to differ in a series of minor but constant morphological, allozyme and karyotype features, and their treatment as separate agamospermous species is supported. A detailed analysis of cultivated and wild material from the Carpathians revealed the existence of a sexual taxon very close to the above two species and endemic to the region of the Bucegi Mts, Romania. It is described as a new species, T. carpaticum Štěpánek et Kirschner. Two new agamospermous species, apparently allied to T. nigricans, are described: T. rupicaprae Štěpánek et Kirschner, a species characterized by orange-ochraceous achenes and confined to the High Tatra Mts, and T. elegantissimum Štěpánek et Kirschner (2n = 24), which has substantially broader outer bracts and is known from the Rodna, Retezat and Fagaras Mts, Romania. Another three species are described that are morphological similar to T. carpaticum: T. pastorum (the Fagaras Mts, Romania), T. iucundum (the Retezat Mts, Romania) and T. pseudoalpestre (the Fagaras Mts, Romania).