According to various websites there are two variations of patterning for marbled spiders Araneus marmoreus
,the wavy foliate patterning (nominate marmoreus) which is most common in North America, and a “variation pyramidatus” pattern with a single large black diamond on the rear of the abdomen in an otherwise unmarked background, for example
The pyramidatus pattern is rare in North America and is found primarily in Europe (see for example http://animaldiversity.org/accounts/Araneus_marmoreus/
). I recently found what I think is the pyramidatus version in Quebec, which prompted me to check the Bugguide web site for other examples. It turns out that in 22 pages of images there are only 14 examples of the pyramidatus variant. All of them are either in Canada or Alaska. None of the web sources I tracked down discusses the distribution of the pyramidatus variant in North America, but I think the distribution is too clear cut to be in any way random. Is it a ‘known fact’ that the pyramidatus variant partitions to the North?
Pyramidatus variants in Bugguide are from:
Kenai Peninsula County, Alaska.
Whitecourt, Alberta, - five different entries.
Edmundston, New Brunswick.
Stewiacke, Nova Scotia.
St Bruno, Quebec.
White Fox, Torch River, Saskatchewan- two different entries.
The common nominate variant ((foliate patterning) is recorded in Bugguide for all Eastern US states except Florida, Mississippi, and Louisiana. It is also in California and Washington State.