We don't know how many different species there are in Leicestershire and Rutland, but after 16 years of recording, the number of new species being added to NatureSpot each year isn't levelling off as we might have expected. So where are all these new species coming from? 
Over the past 14 years we have added an average of over 300 new species to NatureSpot records each year (full species numbers, genus only records and aggregates not included). Some of the additions are a result of new species arriving in the County. For example, we are now seeing many species that were formerly only known from the south coast or the London area. Changing climate is at least part of the reason for this, but introductions are another source - several new species have been recorded in garden centres in recent years.
However, there's another underlying reason. Over time, some NatureSpot recorders become subject specialists and start to deep dive into difficult to identify species, such as those that need a microscope or dissection to confirm. Many of the new species added are in this category, such as microfungi like powdery mildews, or wasps - not the yellow and black social wasps but the tiny difficult ones such as Ichneumons and Chalcids. This means that the number of species we are adding each year could go on increasing for some time, which leaves us with another question - how many different species there are in Leicestershire and Rutland?