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| Site location map. Click to enlarge. |
Time to re-draw the
Ozyptila praticola (Thomisidae) range map again! I returned to the field this week to continue my search for the northern edge of this introduced crab spider's range in western Washington. I had previously sampled the urban corridor along Interstate 5 as far north as Arlington (as well as several non-urban sites well beyond there), but had not found any
O. praticola beyond Granite Falls.
Although I
sampled in Arlington in October 2015, I considered the city under-sampled since I had only tapped one full set (50 cones) and one partial set (13 cones) of cones there. Further, the partial set of cones had been lying in tall grass, a situation that I've found to be unattractive to
O. praticola in western Washington. So I returned to Arlington in search of at least one more set of more suitably situated cones to tap.
Arlington Denny's
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A welcome sight right off
the freeway |
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Fallen cones on pine needle litter: a
good place to look for O. praticola |
Exiting I-5 onto eastbound Route 530, the first thing I saw was a Denny's restaurant with black pines (
Pinus nigra) growing next to its parking lot. How fortuitous! Most of the 50 fallen cones I tapped had only partially opened scales and contained significant amounts of organic debris, but also 32 spiders from 6 families. Forty percent of them (13) were juvenile
Crustulina, presumably
sticta (Theridiidae), a spider I have found in fallen cones before, but rarely. Interestingly, all 13 were from a small number of neighboring cones. The next most common spider present were juvenile
Enoplognatha ?ovata (Theridiidae), a common spider in urban cones in western Washington. As for
O. praticola, it was a no-show until I tapped my 49th cone, which produced a mature female!
Mt. Vernon
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| An inviting spot south of Mt. Vernon |
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| Lots of cones but few spiders |
Next stop was Mt. Vernon, a lovely little city in the Skagit delta. I searched downtown and the industrial zone to its south for pines, and found many. But what I didn't find were cones. Groundskeepers had swept them all away. It wasn't until I hit the city's southern rural outskirts that I found an accumulation of accessible pine cones. Black pine once again, this time planted along the fence at a plant nursery. I tapped the usual 50 cones but only got 4 spiders: all juvenile
Philodromus (Philodromidae). Oh well.
Marysville Public Works
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| How could I resist?! |
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Excellent fallen cone microhabitat
at Marysville Public Works |
Heading home towards Seattle, I decided to take the scenic route from Mt. Vernon through Marysville before returning to the hurly-burly of the interstate. I'm sure glad I did! Just a few blocks before I had to get back on I-5, I spotted a delicious row of large black pines growing along the fence line of the Public Works. Only one tree was accessible to me, but it had dropped plenty of cones that a) had escaped groundskeepers and b) had accumulated on pine needle litter. I was in clover.
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Male Crustulina sticta. Note the
Steatoda patterning on his dorsum. |
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The characteristic granulations were
visible on the sternum as well as carapace |
So much so that I didn't pay attention to the time (6:30 p.m.) and almost got locked into that parking lot! I had just captured the spiders from cones 41 through 45 in my dry vial when I heard the gate being dragged closed. That sure snapped me out of my reverie! The employee kindly held the gate for me while I jumped in my car and zipped by, one thumb still stoppering my dry vial. As soon as I cleared the gate I had to pull over and transfer those spiders to my alcohol vial. Although I had only managed to tap 45 cones, I collected a whopping 45 spiders! Twenty-six of them were juvenile
Philodromus, 7 were
Tenuiphantes tenuis and 6 were
O. praticola. I also captured 3 more
Crustulina sticta, including a mature male.
At present, Arlington is the northern edge of
O. praticola's known range in western Washington. The search will continue...
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| Evening sun illuminates the Marysville water tower. |
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Rich farmlands of the Skagit delta were just across the
street from my Mt. Vernon site. |
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