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.
The longhorn crazy ant, Paratrechina longicornis (Latreille), is a ubiquitous agricultural and urban pest that has invaded most tropical and subtropical regions. Although P. longicornis has been found worldwide for more than a century, the genetic structure, origin, and invasion history of this species have not yet been extensively studied, partially because of the limited number of genetic markers currently available. In the present study, we developed 36 polymorphic microsatellite markers for P. longicornis and characterized these markers by genotyping P. longicornis workers from 74 colonies in East and Southeast Asia. All loci were polymorphic, with the number of alleles per locus ranging from 3 to 18 (8.5 on average). Extremely high levels of heterozygosity were found in all populations, suggesting that workers are invariably produced from the mating of divergent queen and male lineages. Queens and males possess non-overlapping allele size ranges at 18 loci, indicating the potential resolving power of the subset of markers in inferring the history of queen and male lineages. Genetic differentiation among three studied populations was low yet significant and may likely reflect their close association with human activities. Overall, the new microsatellite markers developed in the present study serve as a practical tool to reconstruct routes of invasion and assess the population genetics of this invasive ant.