THE ‘BOG SPIDER’ ARANEUS MARMOREUS CLERCK IN BRITAIN

THE ‘BOG SPIDER’ ARANEUS MARMOREUS CLERCK IN BRITAIN

C. A. Howes
Museum and Art Gallery, Doncaster

The type form of Araneus marmoreus Clerck is widespread on the continent but in Britain is exceedingly restricted in its distribution. It was first officially recognised here in 1947 when specimens were collected by Mr. C. S. Sweetman at Acomb near York. Currently it is known from eleven localities, their positions showing an eastern distribution tendency (see fig.  1), a feature possibly reflecting a preference for continental climatic conditions.

The magnificent chocolate and yellow variety A. marmoreus var. pyramidatus Clerck unlike the type, has been known in Britain at least since the late sixteenth century, being illustrated in Thomas. Muffett’s celebrated Theatrum lnsectorum completed in 1589.  Although by no means common var.  pyramidatus is relatively widespread, Bristowe (1939) recording it for twenty-eight counties (see fig.  2).

Both type and variety are typically bogland spiders favouring the acid conditions of Calluna and Eriophorum clad peat bogs colonised by Betula and Salix scrub. 

Where A. marmoreus occurs, it is usually accompanied and greatly outnumbered by var.  pyramidatus, the Ardingley colony showing a ratio in favour of var.  pyramidatus of 40 to 1 (Bristowe 1958 and 1966).  There appears to be no obvious separation of populations, my own limited observations during July, August and September of 1969 and 1970 on the Thorne Moor colonies confirms this, both type and variety occupying the same general areas.  Overlap of populations has been noted, particularly at Askham Bog where males of one and females of the other were seen occupying the same webs and intermediate forms were observed (McHugh 1966).  Intermediate forms are also known from Strensall Common (Locket and Millidge 1952).

Apart from a very generalised knowledge, the ecology of these spiders is not known and no doubt a close study of their respective habitat requirements and way of life would shed light on the reasons for their distributional, population and colour differences.  There is a possibility that on a European scale var. pyramidatus could represent a relatively montane form, the phenomenon in Britain of its consistent dominance and greater dispersion to the north and west than marmoreus would tend to support this, though a critical investigation of the status and distribution of both marmoreus and var.  pyramidatus on the Continent would be required for confirmation.

The following list represents a survey of available information on the distribution of A. marmoreus in Britain. The numbers allocated to the sites relate to fig.  1.

  1. Acomb (Yorkshire) Out of a batch of spiders collected by C. S. Sweetman at Acomb six proved to be this species (Dixon 1948). The specimens were presented to Frank Dixon, then Hon. Arachnologist at the Yorkshire Museum, who sent two females to A. F. Millidge for determination (Millidge and Locket 1952 Ford 1953).  One specimen, labelled the first British record, is in the Yorkshire Museum.
  2. Askham Bog (Yorkshire) Specimens were found by C. J.  Smith during his investigation of the site from 1959-1962 (Howes and Smith 1971). A visit by members of the British Spider Study group during their York spider course, 1-7 September 1965, revealed both A. marmoreus and the var. pyramidatus (Smith 1970:  Mackie 1970). Reporting on the course McHugh (1966) noted that webs were observed which contained the male of one form and the female of the other, presumably accounting for the intermediate forms such as those on Skipwith Common referred to in Locket and Millidge (1953).
  3. Allerthorpe Common (Yorkshire) Spiders collected on the 21st of August 1955, during an excursion of the Hull Scientific and Field Naturalists’ Club included one specimen of A. marmoreus (Geyer 1956).
  4. Skipwith Common (Yorkshire) The first record of it here is in Dixon (1949). Locket and Millidge (1953) noted that it was present “in some numbers on small birch trees”. C. J. Smith collected it here during his survey of the area from 1959-1962 (Howes and Smith 1971).
  5. Strensall Common (Yorkshire) In 1948 Messrs. A.  Smith and C.S. Sweetman collected a number of specimens of both sexes. Both A. marmoreus and var.  pyramidatus occurred together and several specimens intermediate in pattern were found (Millidge and Locket 1952: Ford 1953).
  6. Thorne Moors (Yorkshire) Specimens were collected or noted during surveys carried out by the Thorne Moors study group during July. August and September of 1969 and 1970 (Howes 1969.  1970:  Howes and Smith 1971).  Specimens were in abundance during August 1969; examples being collected for the arachnida collection at Doncaster Museum.  A.  C.  Braham, who ran an arachnological supply firm in Huddersfield, included several entries in his stock book (now in the Yorkshire Museum) of specimens collected in 1946 on Thorne Moors.  Of those specimens so far located all have turned out to be var.  pyramidatus.  Although Braham visited Thorne Moors he did not collect or see marmoreus (Braham, 1946).
  7. Scotton Common (Lincolnshire) Recorded for this locality though no data given (Merrett, 1971).
  8. Tumby Wood (Lincolnshire) Although its presence was not confirmed, an immature specimen possibly of A. marmoreus was collected in 1898 by C. A. W.  Peacock and noted in ‘Lincolnshire Spiders’ (Smith 1910).  The specimen was forwarded for determination to O.  P-Cambridge who commented “The identity of the spider, being immature, is uncertain …. Eperia (=Araneus) pyramidatus is generally considered to be a variety of E.  (= Araneus) marmoreus.  The true marmoreus however in the adult state has not yet been recorded in Britain” (Smith 1910).
  9. Thompson Common (Norfolk) Recorded during arachnological investigations carried out during 1969 and 1970 by the Nature Conservancy of Broadland and Breckland habitats (Duffey 1971).
  10. Tuddenham Fen (Suffolk) Recorded during arachnological investigations carried out during 1969 and 1970 by the Nature Conservancy on Broadland and Breckland habitats (Duffey 1971).
  11. Woodwalton Fen (Huntingdonshire) Recorded for this locality though no data is given (Merrett 1971 and Mackie 1971).
  12. Ardingley (Sussex) Recorded for this locality pre-1958. “When examining a colony of A.  marmoreus at Ardingley, Sussex, some years ago, I found only 4 whilst seeing 160 of the A. m. pyramidatus form” (Bristowe 1958 and 1966).

 Acknowledgements

For help in compiling the list of localities I would like to thank Dr. Eric Duffey of Monks Wood Experimental Station, Abbots Ripton, Huntingdonshire, Dr. Peter Merrett of Furzebrook Research Station, Wareham, Dorset, Mr. D. W. Mackie and Mr. C. S. Smith. Thanks, are also due to Mr. C. Simms for permission to inspect the A. C. Braham material in the Yorkshire Museum.

REFERENCES

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