Two species new to Dorset have been recorded and a rare plant not seen for more than 100 years has put down roots.

Turn over a boulder on the beach and you may encounter a false scorpion while a good-sized population of rove beetle has come to light at Kimmeridge.

And the very rare sea stock is now thriving on dunes at Studland – the nearest known sites are in North Devon and the Channel Islands.

Photographer and conservationist Steve Trewhella nearly walked straight past the succulent plant with its pale lilac flowers.

“I though it was from someone’s garden,” he said. “It didn’t look like anything I have ever seen before.”

But fortunately he did take a photo and it turned out to be Matthiola sinuata, a rare member of the brassica family, threatened by the disappearance of sand dunes and disturbance by visitors.

It is thought seed may have been blown in from the Channel Islands. “Studland is favourable for these and other plants because the seaweed strandline is left in place, this rotting down process gives these pioneering plants the nutrients needed to grow in sand,” he said.

Steve also discovered the false scorpion, Neobisium maritimum, at Portland and believes he found another one along the shore at Holes Bay, Poole.

This tiny member of the arachnid family lives in rock crevices and under boulders in a silken chamber, which allows it to spend most of its life underwater.

It has a poison tooth on the end of its claws which punctures its prey of tiny springtails and other invertebrates, stunning them.

The rove beetle, Aleochara obscurella, also lives on smaller invertebrates and has been found on beaches within Dorset Wildlife Trust’s Purbeck Marine Reserve including Broad Bench and Chapman’s Pool, especially where there are large piles of kelp seaweed.

“These finds are very exciting and show how important beach strandlines are for wildlife,” said Julie Hatcher, the trust’s marine awareness officer.

“Beaches where the strandline is not removed, such as Studland, Kimmeridge and Ringstead, are the ones with the richest and rarest plants and animals,” she said.

“So while you might screw your nose up at a smelly heap of rotting seaweed in a corner of the beach, rest assured that it is a wildlife haven, home to some of the rarest plants and animals in the county.”

A survey by the trust of eight beaches also found pygmy shrews at Kimmeridge and snow buntings at Studland.