Study in Agaricus subgenus Minores and allied clades reveals a new American subgenus and contrasting phylogenetic patterns in Europe and Greater Mekong Subregion.

Within Agaricus subg. Minores, A. sect. Minores remains a little-studied section due generally to its delicate sporocarps often lacking taxonomically relevant morphological characters. To reconstruct the section, using the recent taxonomic system based on divergence times, and to evaluate the species diversity of A. sect. Minores in the Greater Mekong Subregion, 165 specimens were incorporated in phylogenetic analyses. A dated tree based on nuclear ITS, LSU and tef1-α sequence data allowed us to better circumscribe A. subg. Minores and to propose a new subgenus, A. subg. Minoriopsis, which is only known from tropical and subtropical regions of the Americas. A larger tree based on ITS sequences indicated that, with 81 phylogenetic species, the reconstructed section Minores is now one of the largest sections in the genus. Within A. subg. Minores, a new section, A. sect. Leucocarpi, and eleven new species are described from the Greater Mekong Subregion. Thirty-eight species of A. sect. Minores from this region of Asia were distributed in multiple clades that successively diverged over the past 24 million years. In contrast, species reported from Europe mostly grouped in a single non-tropical clade, suggesting a major species diversification following the middle Miocene climatic optimum.

Accuracy of biological trace-element determinations.

Mounting evidence suggests that the accuracy of much of the published information on trace-element concentrations in biological matrices leaves much to be desired. Potential sources of error are: (a) inadequate sample collection and preparation (sampling errors); and (b) inaccuracies at the moment of the measurement (measurement errors). Probably much of what has been maintained on trace elements in human health and disease in the past will have to be revised in the future.