The genus Tribolium Desv. consists of nine species, i.e., T. utriculosum (Nees) Renv., T. ciliare (Stapf) Renv., T. echinatum (Thunb.) Desv., T. hispidum (Thunb.) Desv., T. acutiflorum (Nees) Renv., T. obliterum sensu Davidse, T. glomeratum sensu Davidse, T. uniolae (L.f.) Renv., and T. brachystachyum (Nees) Renv. The genus has a basic chromosome number of 6, and from diploid to hexaploid specimens have been examined. Precocious segregation of metaphase I bivalents were observed in four species. Multivalent formation results in unequal chromosome segregation during anaphase I, and several cells with an 11–13 chromosome distribution have been observed. The presence of univalents and anaphase I bridges in all T. brachystachyum specimens suggests a hybrid origin for the species. B‐chromosomes were present in specimens from four species. The B‐chromosomes are similar to the euchromosomes with the exception that they do not participate in meiosis. The B‐chromosomes have a possible isochromosome origin. The cytogenetic evidence presented supports the combination of Plagiochloa and Lasiochloa into Tribolium and indicates that the genus is closely related to Urochlaena, whereas it is not closely related to Prionanthium.
Summary
Du Plessis, H. & Spies, J. J.: Chromosome numbers in the genus Pentaschistis (Poaceae, Danthonieae). ‐ Taxon 41: 709‐720. 1992. ‐ ISSN 0040‐0262.
On the basis of a study of meiosis, new chromosome counts are reported for 7 of the 68 species of the genus Pentaschistis. Two different basic chromosome numbers are present in the genus, i.e. 7 and 13. Polyploidy is frequently observed and B‐chromosomes are present in some species, and existing data summarised. First chromosome numbers are reported for P. argentea (n = 21), P. aurea subsp. aurea (n = 7), P. capillaris (n = 7), P. curvifolia (n = 7), P. papillosa (n = 7), P. tortuosa (n = 7) and P. triseta (n = 7). Additionly two new ploidy levels, diploid and heptaploid, are described for P. eriostoma.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.