Abstract A nomenclatural type is the element to which a name is permanently linked and must consist of a gathering, or part of a gathering, of a single species or infraspecific taxon. However, sometimes more than one species may be mounted on a single herbarium sheet (‘Frankenstein type’), causing a nomenclatural confusion (admixture) in the use of a name, which creates difficulties on the delimitation of the species and application of its name (‘taxonomic headache’). This is the case of the assigned holotype to Mimosa asperoides Izag. & Beyhaut that is composed also of other Mimosa species. To solve the ‘Frankenstein type’ of Mimosa asperoides, we analyzed the original material, the protologue, and performed a morphological comparative analysis to distinguish the species involved in the admixture. These analyses allowed us to identify which of the fragments of the ‘Frankenstein type’ correspond to M. asperoides, enabling its lectotypification and providing new diagnostic features to amend its description. Finally, we reported the first citation of M. asperoides for Brazil and discussed the link between nomenclature and taxonomy to solve a taxonomic headache due to admixture.

ABSTRACT Mimosa baptistae is a new species presenting stalked glandular trichomes that give it a glutinous appearance, mainly with respect to the leaflets. Furthermore, it is an aculeate species, with multijugate leaves, white stamens, and fruits also covered by glandular trichomes. A herbaria survey and fieldwork only recorded this species as occurring on sandstone outcrops of the city Caçapava do Sul, Brazil. The species may be confused with other species of Mimosa sect. Batocaulon ser. Stipellares such as M. bifurca, M. sobralii and M. lepidota. However, features such as absence/presence of aculei, stamens color, habitat, and flower features are useful for distinguishing them from the new species. Here, we provide notes on morphology, geographic distribution, as well as anatomical detail of its glandular trichomes and content. Finally, we discussed the taxonomic significance of the micromorphology of glandular trichomes and their content in Mimosa ser. Stipellares as well as the potential applicability of such features to better understand the morphology of this series.

A passagem do fogo pode quebrar a dormência de sementes de muitas espécies em ecossistemas suscetíveis ao fogo. Essa resposta ao fogo é especialmente bem conhecida para espécies da família Fabaceae, mas tem sido pouco estudado no Sul do Brasil. Coletamos sementes de quatro espécies de Fabaceae presentes em mosaicos de campo-florestas do Sul do Brasil: Mimosa bimucronata, Desmodium barbatum, Sesbania virgata e Collaea stenophylla. As sementes foram expostas a diferentes tratamentos de calor (60 °C e 80 °C, ambos por 5 minutos, e 100° C por 2 minutos, mais controle sem tratamento de calor). Nem todas as espécies foram submetidas a todos os tratamentos. Após o tratamento, as sementes foram mantidas em câmara de germinação com fotoperíodo 12/12 horas e temperatura de 25 °C. A porcentagem de sementes germinadas foi contada a cada 2 dias. Os resultados foram analisados por teste de aleatorização. A taxa de germinação de D. barbatum e S. virgata aumentou quando expostas a altas temperaturas (80 °C e 60 °C, respectivamente), enquanto M. bimucronata mostrou redução e C. stenophylla nenhuma resposta aos tratamentos. Esse estudo foi o primeiro para o Sul do Brasil a mostrar uma resposta positiva na germinação de espécies campestres expostas a altas temperaturas, simulando os efeitos do fogo. Como o estudo apresentou respostas distintas, é importante conduzir trabalhos com outras espécies da família a fim de detectar padrões gerais.

Passage of a fire can break dormancy of the seeds of many plant species in fire-prone ecosystems. This response to fire is especially well known for the Fabaceae family, but has been poorly studied in Southern Brazil. We collected seeds of four Fabaceae species present in grasslands-forest mosaics of Southern Brazil: Mimosa bimucronata, Desmodium barbatum, Sesbania virgata and Collaea stenophylla. Seeds were exposed to different heat treatments (exposure to 60° and 80 °C for 5 minutes, to 100 °C for 2 minutes, control without heat treatment); not all species were tested in all treatments. After the treatment, the seeds were kept in a germination chamber with a light period of 12/12 hours and temperature of 25 °C. Germinated seeds were counted every 2 days. The results were analyzed by randomization testing. Germination of D. barbatum and S. virgata was increased after exposure to high temperatures (80° and 60 °C, respectively), while M. bimucronata showed reduced germination after temperatures of 80 °C and C. stenophylla no response. This study is the first for Southern Brazil to show a positive response of germination for grassland species exposed to high temperatures, simulating fire effects. As the study presented distinct responses of species to the heat treatment, it seems important to conduct more works with other species from the family, in order to be able to detect more general patterns.