Progress or burden? Formal description of every apparently new species available in collections is neither necessary nor useful.

A new species of the Sub-Saharan spider genus Quamtana Huber, 2003 is described that has been collected in garden centers in Poland and the UK. Its closest known relative is probably Q.lotzi Huber, 2003, known from Free State Province in South Africa. Working on the premise that placing species in time and space is the fundamental task of taxonomy, and acknowledging that we cannot provide biologically meaningful spatial information for this species, we prefer open nomenclature to make this species known to science without formally describing it, using the unique provisional name Quamtana sp. ZFMK Ar 24490 aff.lotzi. We argue that the judicious use of open nomenclature can serve to improve the quality of species lists, reducing the noise in large-scale analyses of biodiversity data. We expand this argument to 'fragmentary' species descriptions in general, such as single-sex descriptions in large genera with many male-only and female-only descriptions. Not every taxonomic act allowed by the Code is necessarily beneficial. Under certain conditions, the informal description of a putatively new species may serve science better than a formal description based on inadequate material or data.