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NON-MARINE MOLLUSCA SURVEY,

1986

I. J. KILLEEN

Progress on t h e survey d u r i n g 1986 was n o t as good as originally h o p e d f o r . Less t h a n 100 n e w t e t r a d s w e r e r e c o r d e d , m a k i n g a total of 740 that have b e e n e x a m i n e d to d a t e . T w o large a r e a s r e m a i n sparsely r e c o r d e d : the B r e c k l a n d a n d t h e a r e a t o t h e n o r t h of L o w e s t o f t . A n e f f o r t must b e m a d e to fill in the m a i n gaps d u r i n g 1987 and ideally to t a k e t h e survey to c o m p l e t i o n . H o w e v e r , m a n y interesting n e w r e c o r d s w e r e o b t a i n e d in 1986, including t h r e e n e w vice-county records: Vertigo substriata ( J e f f r e y s ) . T h e r e w e r e five n e w sites for this locally r a r e species. It w a s f o u n d living in a small a r e a of relict acid f e n (TM4570) and an a d j o i n i n g w e t w o o d l a n d ( T M 4 6 7 0 ) to t h e west of D u n w i c h . T w o o t h e r scarce species, Vertigo antivertigo and Columella edentula w e r e f o u n d in association. T h e o t h e r sites w e r e all in t h e n o r t h - w e s t of t h e c o u n t y , t w o at E l v e d e n on w o o d e d h e d g e b a n k s (TL8389 and T L 8 3 8 0 ) and at S a n t o n D o w n h a m (see b e l o w ) . It s e e m s likely that f u r t h e r sites f o r V. substriata will be discovered in suitable h a b i t a t s in t h e B r e c k l a n d a r e a . Vertigo pusilla M Ăź l l e r . T h e only previous West S u f f o l k record in t h e last 50 years is at W e s t Stow on a dry ivy-covered wall, a quite typical h a b i t a t for this species. T h e discovery of a thriving colony at S a n t o n D o w n h a m (TL8086) associated with V. substriata and Columella aspera was quite surprising. S p e c i m e n s of all t h r e e species w e r e sieved f r o m leaf litter a r o u n d an old tree s t u m p in t h e marginal a r e a of oak a n d silver birch s u r r o u n d i n g a conifer forest. H o w e v e r , V. pusilla r e m a i n s a very r a r e species in t h e c o u n t y . Vertigo angustior J e f f r e y s . O n e very f r e s h shell f o u n d at M a r k e t W e s t o n F e n (TL9878). T h i s r e p r e s e n t s only t h e sixth site in Britain w h e r e this declining species is c u r r e n t l y r e c o r d e d living. T h e s p e c i m e n was sieved f r o m sedge debris in an a r e a of recently cut Cladium mariscus d u r i n g a field excursion by t h e C o n c h o l o g i c a l Society of G r e a t Britain. F u r t h e r searching on t h a t and a s u b s e q u e n t visit failed to yield f u r t h e r s p e c i m e n s . This would suggest that this snail is e i t h e r living at e x t r e m e l y low density a n d / o r t h e w r o n g a r e a was being s e a r c h e d . T h e typical habitat f o r Vertigo angustior is w e t , m a r s h y grassland o r d a m p , mossy hollows in s a n d d u n e s . H e n c e , the Cladium b e d s o n t h e f e n w o u l d a p p e a r to b e t o o wet f o r this species. It is possible that t h e s p e c i m e n f o u n d m a y h a v e b e e n t r a n s p o r t e d into t h e sedge b e d s f r o m t h e slightly d r i e r grassland margins. F u r t h e r work is r e q u i r e d to establish t h e exact status of V. angustior at M a r k e t W e s t o n F e n . It is w o r t h stressing t h e i m p o r t a n c e of M a r k e t W e s t o n F e n as an o u t s t a n d ing e x a m p l e of a h a b i t a t of its type. T h e mollusc f a u n a of t h e f e n is very rieh and includes several locally r a r e and e n v i r o n m e n t a l l y sensitive species, in fact t h e site could fully justify being a reserve o n t h e basis of its Mollusca a l o n e . It is very i m p o r t a n t that these f a c t o r s should b e t a k e n i n t o a c c o u n t w h e n p l a n n i n g f u t u r e p r o g r a m m e s of m a n a g e m e n t a n d c o n s e r v a t i o n .

Trans. Suffolk

Nat. Soc. 23


N O N - M A R I N E MOLLUSCA SURVEY, 1 9 8 6

25

Boettgerillapallens (Simroth). A second record from West Suffolk (v.c. 26) in a garden at Monks Eleigh (TL9647). Recorded in East Suffolk (v.c. 25) for the first time, from garden centres at Woodbridge (TM2648) and Trimley St. Mary (TM2736). This species is spreading rapidly in Britain and the trend is clearly following in Suffolk. This small slug is very slender, almost wormlike in appearance, with a greyish-yellow body and a darker bluish-lilac head and tentacles. Careful searching of garden and urban habitats is sure to yield further records. Limax valentianus Ferussac. Recorded from an Ipswich garden (TM1843) and a greenhouse at Levington (TM2339). A fĂźll account appearson page 26. Urtio pictorum (Linne) and Pisidium moitessierianum Paladilhe. Both species recorded for the first time in the Mildenhall Cut-off Channel north of Lakenheath (TL7284). There were also first records of P. moitessierianum from the R. Little Ouse north-west of Lakenheath (TL6885, TL6986 and TL7086). Many garden species are still under-recorded. Please assist me to remove the distortions in the maps by sending material from your garden. Ian J. Killeen, 163 High Road West, Felixstowe, IP119BD

Trans. Suffolk Nat. Soc. 23

Non-marine Mollusca survey, 1986  

Killeen, I. J.

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