The search for the Lemon Slug, Field Meeting in the Wyre Forest 30th October 2010

‘I’ve found one! Over here!’ This call was music to our ears as we scurried across to examine the find! Yes, we did locate the Lemon Slug Malacolimax tenellus on our field meeting to the Wyre Forest. In fact we found quite a few!

The Conchological Society joined forces with the Wyre Forest Study Group (WFSG) for the day. The WFSG has been seriously recording M. tenellus since the autumn of 2008 when, during an autumn fungus foray, a single individual feeding on Russula ochroleuca started the widening search! Since then many records have been made and notes taken about weather conditions, associated fungi, behaviour and habitat. This species has been photographed in a variety of situations feeding on a wide range of fungi, in copulation, with its distinctive yellow slime, and moving across open beech leaf litter. It has been shown that Lemon Slugs are more readily found after dark on warm damp evenings in autumn when there is a wealth of fungi fruiting bodies on which they feed, often in the same habitat as Limax cinereoniger. However, it is better to search before the leaves come off the trees, as these tend to hide both fungi and slugs!

The Wyre Forest is 2,500 hectares (6,000 acres) of ancient semi-natural oak woodland with some conifer plantation within it, and there has been a long history of woodland cover. The woodland straddles the county boundary between Worcestershire and Shropshire and the rocks are mainly acidic sandstones, shales and clays from the Upper Carboniferous period. Occasional thin bands of Spirorbis limestone and a few base-rich flushes provide intermittent contrasting soil conditions, but Wyre does not have a rich mollusc fauna.

The Wyre Forest field meeting had been arranged to coincide with the fungi season but local weather conditions play a big part in the success of the search. Thankfully, although the main fungi season was over due to a series of nightime frosts, the weather had been warm and damp during the previous couple of weeks and there were a few fungi fruiting bodies around. So the Lemon Slug hunt was on!

The key was to look for fungi that showed evidence of grazing and then to make a careful search on and around the fruiting body. When we found the slug by this method, it was either feeding directly on the fungus, tucked up under the cap or lying close by amongst the leaf litter. We also checked damp rotten branches and logs lying on the ground, and this was occasionally successful even though there were no large fungal fruiting bodies present nearby. It was in this manner that we located the Ash-grey Slug L. cinereoniger. Interestingly one of the individuals we found was the pale one seen in figure 1.

We were pleased to have Study Group mycologists along on the day enabling us to document the fungi that the Lemon Slugs were found in association with. The following were identified: Buttercap Collybia butyracea, Clouded Funnel Clitocybe nebularis, Brown Birch Bolete Leccinum scabrum, Purple Brittlegill Russula atropurpurea, Larch Bolete Suillus grevillei, Birch Polypore Piptoporus betulinus (on fallen trunk) and Woolly Milkcap Lactarius torminosus. To our surprise two rare fungi were discovered – Violet Webcap Cortinarius violaceus and Yellow False Truffle Rhizopogon luteolus and Lemon Slugs were found feeding on both of these species (see front cover and figure 2). There were cries of horror from the mycologists who had to watch their rarities being devoured before their eyes. On closer examination it was found that only the cap and peridium were being grazed, but they were only partly pacified! There was some discussion about whether the fungal spores would remain viable after being passed through the gut of a slug!

Other fungi species noted in association with M. tenellus in the Wyre Forest on previous occasions are Hairy Curtain Crust Stereum hirsutum, Candlesnuff Fungus Xylaria hypoxylon, Peziza sp., Sulphur Tuft Hypholoma fasciculare, Magpie Inkcap Coprinus picaceus, Deer Shield Pluteus cervinus, Tawny Grisette Amanita fulva, Common Rustgill Gymnopilus penetrans, Blusher Amanita rubescens, White Saddle Helvella crispa, Lilac Bonnet Mycena pura, Trametes sp., and Blackening Brittlegill R. nigricans. This demonstrates their catholic taste!

We visited three sites during the Wyre Forest meeting and these were reached by car with permission from the Forestry Commission. The first site was a planted beech wood at SO744749. This yielded Vitrea crystallina, L. cinereoniger, Zonitoides excavatus, Discus rotundatus, Euconulus fulvus seg., Oxychilus alliarius, Arion subfuscus and nine individuals of M. tenellus.

The second area started at SO750768 and we walked up a north facing slope and valley under oak, birch and later pine. Four individuals of M. tenellus were discovered and other species were Lehmannia marginata, D. rotundatus, Aegopinella pura, Nesovitrea hammonis, E. fulvus seg.,
A. ater agg., O. alliarius and L. cinereoniger.

The last stop was a contrasting habitat at SO740761 with secondary birch and oak woodland with much lying dead timber (See front cover and figure 3). 10 Lemon slugs were found plus Limax maximus, Arion sylvaticus, A. ater agg., N. hammanis, D. rotundatus, L. marginata, O. alliarius, Cepaea nemoralis, A. pura, and A. subfuscus.

A successful day was celebrated with tea and cakes in the Wyre Forest Visitor Centre during which lists were compared and memories exchanged. Lemon Slug records were added for two new 1 km squares in the forest, but there are still several more to search!

Present:
Rosemary Hill, David Long, Ron Boyce, Rosemary Winnall, Susan Limbrey (left to right in figure 3) together with Harry Green, John Bingham, Denise Bingham and Ellen Pisolkar

_{figure 1: A pale L. cinereoniger, Wyre Forest.}

_{figure 2: M. tenellus on Rhizopogon luteolus.}

_{figure 3: Some of the searchers for the Lemon Slug.
(photo: Harry Green)}