A critical comparison of the type collection of the Peruvian Sisymbrium lactucoides with members of that genus worldwide reveals that the species should be assigned to Dictyophragmus. The new combination D. lactucoides is proposed. A key to the three species of Dictyophragmus is presented.
The new species Englerocharis dentata and Eudema peruviana are described, illustrated, and their relationships to nearest relatives are discussed. The former is readily distinguished from its other congeners by it broadly spatulate, 7–9-dentate leaves (vs. narrower, entire leaves). Eudema peruviana is the smallest plant in the genus and is hardly 1 cm tall and with linear, glabrous leaves, unbranched caudex without leaf remains, persistent sepals, and broadly globose, angustiseptate fruits. Keys to species of Englerocharis and to the Peruvian species of Eudema are given.
The present paper deals with the typification of 25 names (11 species, 13 varieties, and one form) in the Brassicaceae, of which the majority (19 names) is in Draba. In addition, Arabis tibetica var. bucharica, A. tibetica var. pinnatifida, Eutrema potaninii, Pseudobraya kizyl-arti, Sisymbrium mollissimum f. pamiricum, and Winklera patrinoides, which are currently treated as synonyms in the genera Crucihimalaya (3 names), Draba, Eutrema, and Lepidium (one name each), are also typified. Most of the original material was collected from the five Middle Asian republics of the Former Soviet Union (especially Kyrgyzstan and Tajikistan), and some other was from China, with a few syntypes of three Draba taxa originating from Asian Russia, Mongolia, Kashmir, and Sikkim.
Abstract Hybrid speciation is relatively common in plants compared to other well-studied groups. Polyploidy and apomixis are strongly associated with hybrid speciation, presumably due to the opportunities they provide for both reestablishing reproductive function in hybrids with incomplete chromosomal homology and creating rapid reproductive isolation in sympatry. Boechera, a species-rich genus closely related to Arabidopsis, is a particularly fertile ground for the study of hybrid speciation. Thirty-eight apomictic triploid hybrid species are currently recognized in Boechera. Recent research has shown that apomictic diploid hybrids, although very rare in angiosperms, are common in Boechera. Given this complexity, focused studies of individual species complexes are critical to understanding speciation and diagnosing biodiversity in Boechera. Here we analyze DNA sequences from seven nuclear loci and multilocus genotypes from 15 microsatellite markers in a group of closely related taxa formerly included in ...
Abstract— Pennellia yalaensis , a new species of Brassicaceae from Jujuy Province in Argentina, is described and illustrated, and its phylogenetic relationships with nearest relatives are discussed. This novelty is morphologically related to P. boliviensis and P. brachycarpa , which also grow in the Central Andes of Argentina. However, P. yalaensis clearly differs from both species by the plant height, inflorescence type, and petal length. In addition, trichomes of the basal leaves distinguish the new species from P. boliviensis , and fruit length and number of ovules/seed from P. brachycarpa . Phylogenetic analyses, based on DNA sequences of nuclear ITS and plastid trnL-F regions, confirmed these affinities.
Abstract Angiosperm genome evolution was marked by many clade-specific whole-genome duplication events. The Microlepidieae is one of the monophyletic clades in the mustard family (Brassicaceae) formed after an ancient allotetraploidization. Postpolyploid cladogenesis has resulted in the extant c. 17 genera and 60 species endemic to Australia and New Zealand (10 species). As postpolyploid genome diploidization is a trial-and-error process under natural selection, it may proceed with different intensity and be associated with speciation events. In Microlepidieae, different extents of homoeologous recombination between the two parental subgenomes generated clades marked by slow (“cold”) versus fast (“hot”) genome diploidization. To gain a deeper understanding of postpolyploid genome evolution in Microlepidieae, we analyzed phylogenetic relationships in this tribe using complete chloroplast sequences, entire 35S rDNA units, and abundant repetitive sequences. The four recovered intra-tribal clades mirror the varied diploidization of Microlepidieae genomes, suggesting that the intrinsic genomic features underlying the extent of diploidization are shared among genera and species within one clade. Nevertheless, even congeneric species may exert considerable morphological disparity (e.g. in fruit shape), whereas some species within different clades experience extensive morphological convergence despite the different pace of their genome diploidization. We showed that faster genome diploidization is positively associated with mean morphological disparity and evolution of chloroplast genes (plastid–nuclear genome coevolution). Higher speciation rates in perennials than in annual species were observed. Altogether, our results confirm the potential of Microlepidieae as a promising subject for the analysis of postpolyploid genome diploidization in Brassicaceae.
Sequence data from the nuclear ribosomal internal transcribed spacer (ITS) region and plastid gene ndhF of 95 species, represented by 147 accessions, were used to determine the tribal limits, monophyly status, and phylogenetic intra-tribal relationships of genera within the New World tribe Schizopetaleae (formerly Thelypodieae; Brassicaceae). Maximum parsimony, Bayesian, and maximum-likelihood analyses all support the separate recognition of three distinct and generally well-supported clades. The largest corresponds to the North–South American Thelypodieae (27 genera: Catadysia , Caulanthus , Chaunanthus , Chilocardamum , Chlorocrambe , Coelophragmus , Dictyophragmus , Dryopetalon , Englerocharis , Hesperidanthus , Mostacillastrum , Neuontobotrys , Polypsecadium , Pringlea , Pterygiosperma , Romanschulzia , Sibara , Sibaropsis , Stanleya , Streptanthella , Streptanthus , Thelypodiopsis , Thelypodium , Thysanocarpus , Warea , Weberbauera , and Werdermannia ). The remaining six South American Schizopetaleae genera were divided into two clades: SCHIZ I of four genera ( Aschersoniodoxa , Brayopsis , Eudema , and Onuris ) and SCHIZ II Schizopetaleae s. str.: Mathewsia , and Schizopetalon ). Resolution within the Thelypodieae clade was limited in both the ITS- and ndhF-based phylogenies. Based on ITS sequence data, elements of the Old World tribe Brassiceae were sister to the Thelypodieae, whereas the ndhF data strongly supported the Sisymbrieae as sister to the Thelypodieae, and the Brassiceae as sister to both tribes. Sister groups to the Schizopetaleae clades I and II were not clearly resolved. Morphological and cytological data support the separation of these three clades. In SCHIZ II, the sepals are always erect to form a closed tube, and the trichomes are mostly dendritic, although other types also occur. In both the Thelypodieae and SCHIZ I clades, the sepals are variously oriented but never form a closed tube, whereas the trichomes are either absent, or simple, forked, or rarely dendritic. The latter clade differs from both SCHIZ II and Thelypodieae by lacking trichomes or rarely having forked ones and by having exclusively basal, entire leaves. Thelypodieae circumscription should be restricted in future to the Thelypodieae clade, Schizopetaleae circumscription to the SCHIZ II clade, while a new tribe is needed for the SCHIZ I clade.
A general review of the taxonomic status of Thlaspi past and present is given, and a critical evaluations of its segregates based on both morphological and molecular data are presented. ITS molecular phylogenetic study of Thlaspi aghricum and related species, as well as seed-coat morphology and anatomy strongly support the placement of the species in Noccaea. The new combination N. aghrica is proposed, and detailed description and distribution of the species are given.
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