The Desmoulin's whorl snail, which was known to have a colony at Rack Marsh on the river Lambourn, has now also been found near the river Kennet on the route of the bypass.
Scientists say the Kennet supports one of the densest populations seen. According to Dr Martin Willing of the Conchological Society, who surveyed the route for Friends of the Earth, the colony is one "of extraordinary richness", with three times as many snails as Rack Marsh.
The snail is already protected under the European Habitats Directive, which requires the Government to protect its best sites as special areas of conservation (SACs). But last week the European Court went further in a preliminary ruling, decreeing that scientific criteria alone, and not economic criteria, should be applied in designating European nature and protection areas.
With the discovery of the new colonies, part of the bypass route abundantly meets the scientific criteria to become an SAC. Designation of an SAC would require the Highways Agency to make a detailed assessment of the road's impact on the snail, to consider all alternatives, and to put mitigation measures in place if it finally decided to go ahead. The process would cause delays of many months in building the road.
Until now the Government has taken economic as well as scientific criteria into account when designating nature reserves. But last week, in a case referring to Kent mud flats used by migratory birds, the European Court's Advocate General ruled that Britain was not allowed to do so.
The conflict arose after the Government tried to exclude Lappel Bank from the Medway Estuary Special Protection Area, in order to allow the Port of Sheerness to expand. "A member state is not allowed to take economic criteria into account," was the ruling. "They may not balance ornithological and, for example, economic and social considerations in choosing sites, however imperative they may consider the matter."
Friends of the Earth now says it will take legal action if the snail colonies along the bypass route are excluded from an SAC in the Kennet and Lambourn flood plains. FoE's Tony Juniper said: "This ruling means they cannot leave these sites out - it's as simple as that.
"They will have to go right back to square one and show that there is no alternative for this road - which of course there is, in the form of traffic management, upgrading the existing route and better rail-freight services. I believe this will finish this unnecessary and unpopular scheme off for good."Reuse content