Hello, I am unsure when to use the aggregates given in the species drop down list because in my mind it implies there are a number of species that I should understand before not choosing the agg. However I wanted to record Ligustrum vulgare: drop down list for Lig vul gives Ligustrum vulgare, Ligustrum vulgare agg. and the vulgare x ovalifolium hybrid. I cannot find any reference to an aggregate (Stace 3, NBN, BSBI Atlas). It has been suggested that iRecord uses the term when distinguishing species might be difficult rather than just recording to genus? Similarly Stellaria media has an agg. listed too. where can I look up the definitions of what is included in these aggregates? Where is the taxonomy list from?
Thanks very much
Cesca
iRecord uses the UK Species…
iRecord uses the UK Species Inventory taxonomy. The UKSI is managed by the Natural History Museum in conjunction with UK taxonomic experts. Ideally this will be kept inline with the BSBI DDb, although I am not certain how the current taxonomy was arrived at. For bryophytes it has recently been updated to align with A New Checklist of the bryophytes of Britain and Ireland 2020 (Blockeel et al, 2021).
There is no definitive answer, as what it means is that there are two or more species that many people are unable to discriminate. That is very subjective. To some extent Stace can help. Where he has subkeys for species, e.g. Sorbus intermedia, its an indication that things are getting tricky. For Stellaria media agg the 4th ed lists the aggregate as S. media, S. palustris and S. neglecta, and one of the key features is the seed size. If you are out in the field logging plants around a car park it is pretty certain to be S. media but recording it as the agg highlights that you haven't checked it fully so it could have been S. neglecta out of its normal habitat.