Craspedosoma rawlinsii Leach, a new millipede for Worcestershire
During a visit to Worcestershire Wildlife Trust's reserve at Hunthouse Wood on 15th March 2015 I found a millipede which I did not recall seeing before. It was a rich brown colour with darker dorsal lines and was of the flat-back-type (01). It was found under debris near a wet flush in the woodland along with more familiar looking species.
On close inspection it appeared not to be a true flat-backed millipede of the family Polydesmidae but the presence of ocelli led me to the family Craspedosomatidae. Further characteristics checked in Millipedes (Blower 1985) proved it to be Craspedosoma rawlinsii. Although this appeared to be an easily recognised species I was still uncertain as the Millipedes of Britain and Ireland atlas (Lee 2006) suggests that C. rawlinsii is absent from Worcestershire. It was noted as being widely distributed across Britain but not common and is a species found in microclimates of high humidity within woodlands.
I forwarded a couple of photos to Paul Lee, the National millipede recorder, for his consideration and I received a very interesting response. “Had you sent me your photos a year ago I would have said without doubt that they show a specimen of Craspedosoma rawlinsii. However, you may have read on the BMIG website of the discovery of two species in South Wales last autumn (2014) that were previously unknown in Britain. One species,Ceratosphys amoena confusa has been mistaken for Craspedosoma in the past; it has turned up labelled as that species in museum collections dating back to 1983. The other could easily be mistaken for paler, immature Craspedosoma but that is not relevant to your specimen. The best way to distinguish between Craspedosoma and Ceratosphys is the male gonopods but obviously I cannot do this from your photos; I do not even know if it is a male. There is some difference in size between the two species with Craspedosoma being larger on average but again this is difficult to judge from your photos. A photo showing the animal against some short of scale, a ruler marked off in millimetres would be best”.
I sent a further photo showing the size of the millipede I had found (approx 16mm) and received a further comment. “Colour does vary and there is always a possibility of finding yet another new species - there are many more species of this group living just across the channel in France. However, based on size and without checking gonopods to see if it is an entirely different species it would seem that you have a specimen of Craspedosoma rawlinsii. Thanks for the record details”.
So another new invertebrate in the county and who knows what will be next.
Blower, J. G. 1985. Millipedes. Synopses of the British Fauna (New Series) No. 35. The Linnean Society of London. E. J. Brill/Dr. W. Backhuys, London.
Lee, P. 2006. Atlas of the Millipedes (Diplopoda) of Britain and Ireland. Biological Records Centre. Pensoft, Bulgaria.
01. Craspedosoma rawlinsii. Gary Farmer