I was wondering, I assume all species classification is drawn from the British Natural History Museum which is presumeably linked to NBN atlas? I have noticed that when researching species classification there can be differences, and I presume this is regional? iNaturalist, for example, differs from the Natural History Museum in some instances. I believe iNaturalist uses several data bases to gather the most up-to-date and accurate taxonomic information. I have always used the Natural History Museum in preference, thinking that this is the most accurate and up-to-date data base, but is it? I know this is an ever changing subject, and there are differences of opinion amongst experts, but essentially, what is the best body to retrieve the most accurate, reliable and up-to-date information on classification of speces? There appears to be several, including the Encyclopedia of Life, not to mention Wikepedia, which does cite its sources. Some of these sites corroborate data, whilst other differ, and in some case quite differently.
UKSI it is
Thank you, James, for your detailed information and explaination. My original thoughts were in a very similar vein, and you have helped to reconfirm them. I have been fascinated by the intricacies of systematics and classification for many years, and have used iRecord for many years now, and will continue doing so. I just hope we can keep up with all these changes and advances, which are very interesting to say the least.
The "official" list of species recorded in the UK is the one you mention, the UK Species Inventory (UKSI) maintained by staff at the Natural History Museum. It is used for NBN Atlas, iRecord and I think is the main basis for iNaturalist UK, the UK version of iNaturalist. It will not necessarily be the most up-to-date source because any additions or changes in taxonomy have to be picked up or reported to the small team that manage it and then implemented.
"what is the best body to retrieve the most accurate, reliable and up-to-date information on classification of speces?"
In my opinion there is no one source of information that will always be the most up-to-date. As you allude to, new research, particular DNA related things, are being published all of the time. Then just because something has been published doesn't mean everyone agrees with it - some websites might change things straight away, others will wait to see if a consensus emerges. It also takes time to change names and sometimes further research is needed, e.g. if a species has been split then someone needs to go back over the previous records and decide if we have both 'new' species, just one etc.
My advice would be to tailor the source you use to the purpose you are using it for. If you wanted to encourage people to record UK species then you are best off using the UKSI because it will allow them to record things on iRecord. If you are only recording in the UK then it makes sense to use UK based sources rather than worldwide ones, and it makes sense to use complete lists published by authoriatitve bodies relevant to what you are looking at rather than something like Wikipedia that can be added to piecemeal. So for example for plants the BSBI plant atlas would probably be the best source as a complete and recently published list by an authoritative body (but even then note that some authors disagree as to what a species is, so are there 2 or 3 species of Elm, or 100+?)