Moors, Dales and Molluscs The Yorkshire Conchological Society Recorder’s Report for 2008

Adrian Norris
The Yorkshire Conchological Society has an ongoing 1 km square distribution recording scheme for the land and freshwater mollusca. On the date of the AGM we had 39,251 records from 2,458 sites, an increase of 3,360 records and 272 extra sites. 114 species have been recorded from within the 5 vice-counties over the past year. However, a large number of mainly freshwater species have not been recorded; this may be as a result of the very high water levels at many sites due to the extremely wet weather experienced in 2008.
 The five main Yorkshire Naturalists’ Union field meetings proved, as usual, to be very successful with our members attending all 5 meetings. Two non- Yorkshire members of the Conchological Society of Great Britain and Ireland attended the VC63 meeting at Thorpe Salvin by the old Chesterfield Canal which produced a number of interesting records but perhaps the most interesting was the chocolate-coloured Limax cinereoniger which occurred in the upper reaches of Hawks Wood. At Ellington Banks in VC64 we recorded Zenobiella subrufescens in the damp woodland which backs onto the Army training grounds. We considered that June 14th was a very early date for this autumnal species. Thorp Perrow Arboretum in VC65 was notable for the occurrence of large numbers of Arion flagellus and Boettgerilla pallens. The North Cave Wetlands Bird Reserve in VC61 produced a large number of introduced species with several of the lakes and ponds containing numbers of Haitia acuta. Arion flagellus was again the most interesting find of our visit to Hornby in VC62 where it occurred in gardens within the village itself. These five locations produced a total of 279 records for the recording scheme.
 The Yorkshire Conchological Society had 3 official field meetings. The more interesting records found on these meetings included; Musculium transversum which was found in the main lake at The Hermitage near York VC62 (SE6557) on September 6th. From Drewtondale (SE9333) in VC61 on October 11th, we recorded Cecilioides acicula, a species rarely recorded off the chalk and Oxychilus helveticus navarricus, only the second record of this species from East Yorkshire.
 Individual members met in the field on a large number of occasions and, amongst other ongoing projects, surveys were undertaken of 10 limestone pavements in the Yorkshire Dales. Vitrea subrimata was recorded from 7 of these and Clausilia dubia from 8 out of the 10. In total, 41 species were recorded from the 10 limestone pavements.
 Monitoring of Truncatellina cylindrica in its only extant Yorkshire site in Brockadale (VC63 South-east Yorkshire) took place on the 3rd of September. Over the past 5 years the reserve volunteers have undertaken a large amount of work to remove trees which were threatening to shade the site and clear encroaching rank vegetation, as well as extending the number of suitable habitats in the area. This work has proved to be very successful with live specimens being easy to locate at the main site. We also made a visit to Ravens Ghyll near Pateley Bridge on October 20th to monitor the only reliable population of Malacolimax tenellus in Yorkshire and it was gratifying to note that this relatively rare slug was found in good numbers feeding on several different species of Russula.
 A visit was also made to the River Esk where we met up with Simon Hirst on September 8th. Simon is undertaking a survey of Margaritifera margaritifera in the river and its tributaries over the next few years. Although the river proved to be excessively high and cloudy, we were able to re-locate a group of pearl mussels we first identified many years ago using by a glass-bottomed viewing scope provided by Simon.