This index uses only the extant invertebrate fauna of acid mires in England. It should be noted that the acid mire fidelity grade assigned to each species refers to its fidelity to the whole range of acid mire habitats.
- Grade A – acid mire obligates: species that are exclusive inhabitants of acid mires, with almost all of their British records referring to these habitats.
- Grade B – acid mire specialists: species that are primarily found in seepages and their margins, but which occasionally occur in other situations. Generally in excess of 75% of British records refer to these habitats.
- Grade C – acid mire preferential: species found in other wetland habitats, but which nonetheless have a strong association with acid mires. Generally in excess of 50% of British records refer to these habitats.
For more information see: Boyce, D.C. (2004) A review of the invertebrate assemblage of acid mires. English Nature Research Report 592.