Identifying factors that boost species discoveries of global reptiles

Most species remain unknown to science and might go extinct before we recognize their existence. Although specimens belonging to many of these unknown taxa may already be housed in scientific collections, they can remain 'shelved' for years bearing the wrong name or without a formal name. We investigate factors underlying variation in time lag between collection and description dates for 2356 reptile species described worldwide between 1992 and 2017. We modelled the time to description using biological and sociological variables in a time-to-event analysis. Time lag between collection and description varied from zero to 155 years (median = 5). More than one-quarter of species involved specimens 'shelved' for 12 years or more. The time lag was shorter when the collector of the holotype-specimen serving as the name-bearer of the species-was an author of the description, while taxonomic revisions uncovered species with longer time lags. Unknown species collected by non-taxonomists and 'shelved' in scientific collections remained incorrectly identified for a much longer time. Taxonomic revisions are crucial to reverse this trend and improve benefits of the collecting performed by non-taxonomists. Our findings reveal the kinds of preserved reptile specimens that most likely represent unknown species in scientific collections.