Your pictures certainly look as though you must have the species, but you may well find that an actual specimen will be needed to be certain about your harvestman. In any case I suggest you contact Mike for opinion on your photo/s (details in SRS News articles).
Images on the Leiobunum tisciae page.
However Achaearanea really need adults under a microscope to identify with reliability and even then they are rather difficult to separate. Whilst it might seem reasonable to assume from the location and position in the habitat that this must be A. riparia, there are other species in Europe which could potentially be present in Britain and for which microscopical examination is needed. We have already had a number of spiders new to Britain recently which would not have been recognised without voucher specimen/s and microscopical examination.
Achaearanea riparia is a scarce spider, so it would be very good to gain definite confirmation of your spider. Can you provide information on the location with grid reference etc.
Could anyone suggest what this retreat might belong to? It was about 5 cm long, 1 cm wide at the entrance and positioned above a Lasius flavus nest. As well as soil from the nest, it had several dead ants incorporated into it. It seems to match the general description for Achaearanea riparia, but I don't know if anything else makes a similar structure? When I found it (18.9.12) it was occupied by a female spider and several young: I haven't been able to get a decent photo of them because of their size, but they did have the high abdomen which is apparently typical of the genus. Any thoughts much appreciated.
Ill try to revisit. It was not hard to find. My money is on you being reflex right as usual!
The problem with many spiders, and especially most linyphiid spiders, is that there is variation both in adults and even more so potentially in juveniles, and so whilst it may be possible to make educated guesses as to the species from appearance (pattern, colours, size, shape etc) it is ALL TOO EASY to make mistakes, even after a lifetime of experience making preliminary identifications in the field. Without confirmation of identification of genitalia under a microscope (and in quite a few cases where id is especially difficult and even experienced arachnologists can have problems, the opinion of other specialists) then an identification will not be reliable.
It is also necessary to appreciate the very real possibility that there may be other species waiting to be recognised in the British fauna, not necessarily even from the nearby European fauna. We have at least two new examples from recent events this year.
Archives: Nov 2017 Oct 2017 Sep 2017 Aug 2017 Jul 2017 Jun 2017 May 2017 Apr 2017 Mar 2017 Feb 2017 Dec 2016 Oct 2016 Sep 2016 Aug 2016 Jul 2016 Jun 2016 May 2016 Apr 2016 Mar 2016 Feb 2016 Jan 2016 Dec 2015 Nov 2015 Oct 2015 Sep 2015 Aug 2015 Jul 2015 Jun 2015 May 2015 Apr 2015 Mar 2015 Feb 2015 Dec 2014 Nov 2014 Oct 2014 Sep 2014 Aug 2014 Jul 2014 Jun 2014 May 2014 Apr 2014 Mar 2014 Feb 2014 Jan 2014 Dec 2013 Nov 2013 Oct 2013 Sep 2013 Aug 2013 Jul 2013 Jun 2013 May 2013 Apr 2013 Feb 2013 Jan 2013 Dec 2012 Nov 2012 Oct 2012 Sep 2012 Aug 2012 Jul 2012 Jun 2012 May 2012 Feb 2012 Jan 2012 Dec 2011 Nov 2011 Oct 2011 Aug 2011 May 2011 Mar 2011 Dec 2010 Nov 2010 Sep 2010 latest posts