30-Apr-2016 Snohomish, Washington

Site location map. Click to enlarge.

Having found the introduced European species Ozyptila praticola (Thomisidae) in Duvall earlier in the month, I was curious to continue my search for the northeastern limit of its local range.  That led me to my destination this day: Snohomish, where I tapped fallen cones at two sites.  Sunny, warm and with just a light breeze, it was a great day for spider collecting.

North of Snohomish High School

Doug-firs across street from
Snohomish H.S.

Fallen Douglas-fir cones

My first site was located across 7th St. from Snohomish High School.  Two Douglas-firs (Pseudotsuga menziesii) growing in the corner of a parking lot had dropped many dozens of cones onto needle litter, and most of those cones were well opened.

Male Phrurotimpus borealis

I tapped 50 cones and collected 19 spiders.  Eleven of those 19 were Phrurotimpus borealis (Phrurolithidae), the only identifiable species present.  Also present were a juvenile gnaphosid and juveniles from a few of the introduced species common in western Washington cones, like Enoplognatha probably-ovata (Theridiidae) and Cryptachaea blattea (Theridiidae).

Snohomish Pioneer Cemetery

Pinus monticola among other
species on cemetery margin

The Snohomish Pioneer Cemetery, located close to the Pilchuck River on the southeastern edge of town, is a curious place in that it is completely devoid of headstones or grave markers!  But it does have a row of mixed conifer trees growing along its northern edge, including two western white pines (Pinus monticola) that had dropped cones on the unmowed grass or conifer needle litter below.

Female Ozyptila praticola

I tapped 43 cones and collected 33 spiders, wow!  Three species were identifiable, all of them introduced.  Most notable among them, given my reason for sampling in Snohomish, was Ozyptila praticola.  I collected 10 in all, including 2 females and 6 males.  As I've noticed at other collection sites, O. praticola was absent from cones on grass, but common in cones on litter.  At present, Snohomish is the northeastern-most known limit of O. praticola's range in Washington state. 

The most numerous species in my sample was actually Tenuiphantes tenuis (Linyphiidae), with 12 individuals present.  The third identifiable species was Enoplognatha thoracica (Theridiidae). In addition to spiders, this set of cones was chock full of woodlice and juvenile harvestmen.  The harvestmen were exceptionally plentiful: I estimated 5-10 per cone.

View of the Pilchuck River from 2nd St. bridge, looking downstream