Herbarium

Most old herbarium specimens cannot be successfully sequenced due to their poor condition Some herbaria do not allow the extraction of DNA Therefore, even if the type material is in relatively good condition, one could argue that the taxon needs epitypifying, so that living material is available for molecular analysis Lack of molecular data or inability to extract DNA from type species is a good reason for epitypification Rules for epitypification (1) It is essential to obtain correctly identified fresh material –that has been compared with the type and has its characters and attributes, –so that DNA can be isolated and ex-type sequence data can be deposited in GenBank Dried herbarium material (the epitype) and cultures (ex-type living cultures) must be deposited in accessible international herbaria and culture collections When [...]

Type specimen   A type specimen is a herbarium specimen and it is the material representing the species name Therefore the type specimen (holotype, isotype, neotype, lectotype) is paramount and should be used in all taxonomic studies and resulting classifications The problem of this basic concept is that in modern-day molecular studies, it is usually not possible to obtain sequences from the types and therefore we must use fresh collections This creates the problem that sequence data may come from incorrectly named isolates which can make the whole taxonomic study questionable Holotype The one specimen or illustration used by the author or designated by the author as the nomenclatural type Isotype Any duplicate specimen of the holotype Neotype A specimen or illustration selected as the type when all of the material [...]