Chromosome numbers are given for 16 taxa (and one interspecific hybrid) of Hieracium subgen. Pilosella originating from Central Europe: H. apatelium Nägeli et Peter (2n = 45), H. aurantiacum L. (2n = 36), H. bauhini Besser (2n = 36, 45, 54), H. brachiatum Bertol. ex DC. (2n = 45, 48, 63, 72), H. densiflorum Tausch (2n = 36), H. echioides Lumn. (2n = 18, 27, 36), H. floribundum Wimm. et Grab. (2n = 36, 45), H. glomeratum Froel. (2n = 36, 45), H. guthnickianum Hegetschw. (2n = 54), H. lactucella Wallr. (2n = 18), H. onegense (Norrl.) Norrl. (2n = 18), H. pilosella L. (2n = 36, 45, 54), H. piloselliflorum Nägeli et Peter (2n = 36, 45), H. piloselloides Vill. (2n = 36), H. rothianum Wallr. (2n = 36), H. schultesii F. W. Schultz (2n = 45), and the hybrid H. floribundum × H. aurantiacum (2n = 36). New chromosome numbers are reported for H. brachiatum and H. floribundum. The octoploid cytotype (2n = 72), recorded in H. brachiatum, is the highest ploidy level ever found in plants from the subgen. Pilosella originating from the field. Aneuploidy, rare in this subgenus in Europe, occurs in this hybridogenous species as well: it was recorded in one plant (2n = 48) collected in a hybrid swarm H. pilosella × H. bauhini. The breeding system in H. bauhini, H. brachiatum, H. densiflorum, H. echioides, H. pilosella, H. piloselloides, and H. rothianum was studied. The sexual reproduction of pentaploid H. pilosella is a new observation: it means an increase of diversity in possible reproduction modes of those cytotypes having odd chromosome numbers.
Chromosome numbers (ploidy levels) were recorded in the following 25 taxa of Hieracium subgen. Pilosella: H. arvicola Nägeli et Peter (2n = 45), H. aurantiacum L. (2n = 36, 45), H. bauhini Besser (2n = 36, 45), H. bifurcum M. Bieb. (2n = 45), H. brachiatum Bertol. ex DC. (2n = 36, 45), H. caespitosum Dumort. (2n = 36), H. cymosum L. (2n ~ 4x), H. densiflorum Tausch (2n = 36, ~ 4x), H. echioides Lumn. (2n = 18, 45), H. fallacinum F. W. Schultz (2n = 36, 45), H. floribundum Wimm. et Grab. (2n = 36, ~ 4x, 45,), H. glomeratum Froel. in DC. (2n = 45), H. iseranum Uechtr. (2n = 36), H. kalksburgense Wiesb. (2n ~ 5x), H. lactucella Wallr. (2n = 18), H. macranthum (Ten.) Ten. (2n = 18), H. onegense (Norrl.) Norrl. (2n = 18), H. pilosella L. (2n = 36, 45, 54), H. piloselliflorum Nägeli et Peter (2n = 45), H. pilosellinum F. W. Schultz (2n = 36, 45), H. piloselloides Vill. (2n = 27, 36, ~ 4x, 45, ~ 5x), H. pistoriense Nägeli et Peter (2n = 27), H. rothianum Wallr. (2n ~ 3x), H. schultesii F. W. Schultz (2n = 36, 45, ~ 5x), H. zizianum Tausch (2n = 27, 36, 54), and one hybrid, H. onegense × H. pilosella (2n = 36). Besides chromosome counts in root-tip meristems, flow cytometry was used to determine the DNA ploidy level in 83 samples of 9 species. The presence of a long marker chromosome was confirmed in tetraploid H. caespitosum and H. iseranum, in pentaploid H. glomeratum, and in both tetraploid and pentaploid H. floribundum. The documented mode of reproduction is sexual (H. densiflorum, H. echioides, H. piloselloides) and apomictic (H. brachiatum, H. floribundum, H. pilosellinum, H. piloselloides, H. rothianum, H. zizianum). Hieracium bifurcum and H. pistoriense are sterile. The chromosome number and/or mode of reproduction of H. bifurcum (almost sterile pentaploid), H. pilosellinum (apomictic pentaploid), H. piloselloides (apomictic triploid), H. pistoriense (sterile triploid), H. rothianum (apomictic triploid) and H. zizianum (apomictic triploid) are presented here for the first time. The sexual reproduction recorded in the pentaploid H. echioides is the second recorded case of this mode of reproduction in a pentaploid cytotype of Hieracium subgenus Pilosella. A previously unknown occurrence of H. pistoriense (H. macranthum – H. bauhini) in Slovakia is reported.
Chromosome numbers for 239 plants from 84 localities in the Czech Republic, Slovakia, Hungary, Germany and Poland are given. Most of the populations were pentaploid (2n = 45), while hexaploid (2n = 54) and tetraploid (2n = 36) populations were rarer. A long marker chromosome was observed in plants from 8 pentaploid populations. Tetraploid plants occurred mainly in Slovakia and Hungary. In the Czech Republic and Germany, most populations were pentaploid. Hexaploid populations (2n = 54) were rare but scattered over the entire study area. The co-occurrence of two different cytotypes was documented at 7 sites. Most tetraploids were fully sexual and only a few tetraploid plants from Poland were apomictic; pentaploid and hexaploid plants were apomictic. Two morphotypes of H. bauhini were distinguished: tetraploid and hexaploid plants from Slovakia and Hungary, and some hexaploid plants from the Czech Republic were assigned to the H. magyaricum group, while tetraploids and hexaploids from the Czech Republic and Poland plus all pentaploids belong to the H. bauhini group.
A new apomictic triploid (2n = 3x = 51) species belonging to the Sorbus latifolia group, S. milensis M. Lepší, K. Boublík, P. Lepší et P. Vít, putatively of hybridogenous origin between sexual Sorbus aria s.l. and S. torminalis, is described from the České středohoří Mts (northwestern Bohemia, Czech Republic). Several biosystematic techniques, including molecular (nuclear microsatellite markers), karyological (chromosome counts, genome size) and multivariate morphometrics were used to assess the variation in this species and justify its independent taxonomic status. The only known population of S. milensis consists of 38 adult and 19 juvenile individuals, is phenotypically homogenous and distinct from other Bohemian hybridogenous Sorbus species. All sampled individuals were karyologically uniform and showed little genetic variation. Sorbus milensis is a stenoendemic occurring on Milá hill (situated ca 9.5 km NNW of the town of Louny) where it grows on basaltic rocks, in ravines and on screes. The majority of the individuals grow in scree forests of the Tilio-Acerion alliance; other vegetation types include xeric scrub of the Prunion spinosae alliance and xerothermophilous grassland communities of the Festucion valesiacae alliance. A detailed distribution map for this species is provided as well as photographs of the type specimen.
Sorbus omissa is described as a new hybridogenous triploid (2n = 3x = 51) species belonging to the Sorbus latifolia group. This species is considered to be of hybrid origin, with S. danubialis and S. torminalis being its putative parental species. It is a stenoendemic whitebeam occurring in central Bohemia (Czech Republic) in the vicinity of the towns of Roztoky and Libčice nad Vltavou (Praha-západ district) in the valley of the lower Vltava river, where it grows primarily in oak forests (Viscario-Quercetum). The only two known populations contain approximately 150 individuals. This species differs from other similar Czech species of the S. latifolia group in having broadly elliptical to rhomboidal leaves with very shallowly lobed laminas, predominantly with 9–11 lateral leaf veins on each side, and is orange to orange-red fruit at maturity. Observation, morphological comparison and karyological (chromosome counts, DAPI flow cytometry) methods were used to identify this new species. A character-comparison table and a determination key including all taxa of the S. latifolia agg. endemic in the Czech Republic are provided. An illustration, a photograph and a distribution map of this new species are also presented.
Two new apomictic triploid (2n = 3x = 51) species from the Sorbus latifolia group, S. portae-bohemicae M. Lepší, P. Lepší, P. Vít et K. Boublík and S. albensis M. Lepší, K. Boublík, P. Lepší et P. Vít, putative hybridogenous species originated from a cross between S. danubialis and S. torminalis, are distinguished and described based on a taxonomic and chorological revision of Sorbus bohemica (a hybridogenous triploid species from the same parental combination). A number of contemporary biosystematic techniques, including molecular (nuclear microsatellite markers), karyological (chromosome counts, DAPI flow cytometry) and multivariate and geometric morphometrics were used to assess the variation of the species and justify their independent taxonomic status. All three species occur sympatrically in the České středohoří Mts (NW Bohemia). Sorbus bohemica is recorded from 31 localities, based on a revision of herbarium vouchers and field research. Recent field studies failed to verify five of these localities. Sorbus portae-bohemicae is a stenoendemic in the Porta bohemica gorge (situated ca 7 km WNW of Litoměřice) where it grows in open oak forests (Luzulo-Quercetum and transition vegetation type to Melampyro nemorosi-Carpinetum) on ENE-facing slopes and rocks. The only known population of S. portae-bohemicae consists of 14 adult individuals. Sorbus albensis occurs at 12 localities W to NW of Litoměřice. The total number of individuals is estimated at 600. Most are in acidophilous oak forests (Luzulo-Quercetum and its mesic derivatives), scree forests (Aceri-Carpinetum) or shrubby slopes (Pruno-Ligustretum, Antherico-Coryletum). Populations of the new taxa show little genetic variation and are phenotypically homogenous and well separated from other Bohemian hybridogenous Sorbus species. A distribution map of the three species is provided. Photographs of the type specimens and in situ fructiferous individuals of the new species are presented.
Sorbus eximia Kovanda, a hybridogenous species that originated from the parental combination S. torminalis and S. aria s.l., is thought to be an apomictic species, which includes diploid and tetraploid individuals. The present study confirmed the existence of only triploid individuals. A new tentatively apomictic triploid (2n = 3x = 51) species from the S. latifolia group: S. barrandienica P. Vít, M. Lepší et P. Lepší is described based on a revision of S. eximia. This species is assumed to have originated from a cross between S. danubialis or S. aria s.l. and S. torminalis. A wide palette of biosystematic techniques, including molecular (nuclear microsatellite markers) and karyological analyses (chromosome counts, DAPI flow cytometry) as well as multivariate morphometric and elliptic Fourier analyses, were used to assess the variation in this species and justify its independent taxonomic status. Allopatric occurrences of both species were recorded east of the town of Beroun in the Český kras, central Bohemia (Bohemian Karst). A distribution map of the two species is provided. Sorbus eximia occurs at four localities (the total number of adults and juveniles is 100 and 200, respectively) in basiphilous thermophilous oak forests (Quercion pubescenti-petraeae), mesic oak forests (Melampyro nemorosi-Carpinetum), woody margins of dry grasslands (Festucion valesiacae) and pine plantations. Sorbus barrandienica has so far been recorded at 10 localities (ca 50 adults). Recent field studies failed to verify two of these localities. It is mainly found growing on the summits of hills, usually in thermophilous open forests (Primulo veris-Carpinetum, Melampyro nemorosi-Carpinetum, Quercion pubescenti-petraeae) and woody margins of dry grassland. Its populations exhibit minimal genetic variation and are phenotypically homogeneous and well separated from other Bohemian hybridogenous Sorbus species. The epitype of S. eximia is designated here, and a photograph of the specimen is included. Photographs of the type specimens and in situ individuals, and line drawings of both species are presented.