Sunday, July 3, 2016

First Records of Zodarion rubidum (Zodariidae) in Washington, USA

Zodarion rubidum female from
Gold Bar, Washington
On a stop in Gold Bar on 6 June 2016 to tap an additional set of spiders from fallen Douglas-fir cones, I collected a mysterious female spider that I couldn't immediately identify.  When I showed the specimen to Rod Crawford yesterday, true to form he worked his way through numerous keys until he discovered the answer: my spider was a Zodarion rubidum (Zodariidae), a Washington first!

Zodarion rubidum is a European species first collected in North American in Wampum, Lawrence County, Pennsylvania in 1967.  It was subsequently collected in Colorado in 1999, Quebec in 2003, Indiana in 2013, Illinois in 2014, and British Columbia and Ohio on dates unreported in the links.

I decided I had better re-check the first set of spiders I collected from Gold Bar on 9 May 2016, because according to my notes I had collected a male spider that I hadn't gotten around to identifying yet.  The main reason I had been sampling in Gold Bar was to determine the local range of the introduced thomisid crab spider Ozyptila praticola, so identification of other spiders has been of secondary importance to me.  I checked that male specimen today, and it too turns out to be Z. rubidum!

Next I re-checked other unidentified specimens I'd made notes on like "odd eye arrangement".  Sure enough, I had previously collected juvenile Zodarion in DuPont on 28 November 2015 and in Tacoma on 1 April 2016.  Indications are that Z. rubidum is established in western Washington.

Map of Zodarion rubidum or Zodarion sp. collection sites in Washington.

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