It is a question I generally find difficult to answer. It depends very much on how you define “discovery”. Is it the moment someone sees a spider that is later identified as new ? Is it the moment someone catches it ? Is it the moment perhaps someone recognises that it is in fact a new species ? Or the moment somebody names it ? And how about if a group of people is involved ? Is the discoverer the one who saw it first or is everyone in that group discoverer ? I could go on here with more examples. But you see already that the moment of discovery and the person who discovered something can be defined differently and hence the number of species someone discovered will change accordingly.