Ozyptila praticola Catch-Up Post

Map 1. Sites sampled for Ozyptila praticola mid-August to 

mid-October, 2017.

The past two months have been a whirlwind. In addition to the usual collecting trips with Rod Crawford, I intensified my ongoing search for the introduced European crab spider Ozyptila praticola (Thomisidae). For the latter, I've tapped over 3,000 fallen conifer cones at 48 sampling sites (Map 1) since mid-August. I focused my search in areas that I suspected were on the periphery of or just beyond O. praticola's local range. I also re-sampled a few sites within its known range to confirm its presence with mature specimens where previously I'd collected only juveniles. Instead of blogging separately about each sampling day and site as I usually do, I'll summarize them together here.

Map 2. Ozyptila praticola confirmed during the mid-August
to mid-October, 2017, sampling period (blue pins)

I confirmed the presence of O. praticola at only three locations during this sampling period: Woodinville, Bainbridge Island and Mercer Island (Map 2). Only the Bainbridge Island sample represented an extension of the known range of the species.

Based on the data I've gathered to date (Map 3), the core range of O. praticola in Washington appears to be the urbanized western lowlands of King County and Snohomish County. In addition, there appears to be a small disjunct population in Bellingham (Whatcom County). The presence of O. praticola on Bainbridge Island signals the need for more sampling in Kitsap County, especially the Bremerton area. The search continues.

Map 3. Ozyptila praticola in Washington state.
Blue: O. praticola confirmed via adult specimen.
Yellow: Juvenile O. ?praticola found.
Red: No O. praticola adults or ?praticola juveniles found.
Purple: O. praticola confirmed in British Columbia, Canada by Bennett et al. (2017)

9-Oct-2017 South Fork Beaver Creek, Washington

Site location map. Click to enlarge.

Last year about this time, Rod Crawford and I sampled spiders in the gridspace covering the town of Plain and part of Little Chumstick Creek valley, both located in Chelan County. This day, since Stevens Pass was still free of snow, we decided to make what would likely be our last trip of the year over the pass, and sample an adjacent gridspace.

View down the "road".

As so often happens in field work, conditions on the ground were different than expected. Namely, the forest road paralleling South Fork Beaver Creek, which we had planned to take to our preferred sampling location, no longer existed! In fact, it hadn't existed for decades, judging from the volume of vegetation growing on its former bed. Luckily the main forest road was also in the gridspace, so Rod quickly returned to it to begin his sampling there.

One of several generations of markers
on the witness tree.

I didn't start sampling quite yet, since I was curious to follow a very narrow, almost hidden path along the former road that someone had pruned vegetation here and there to mark. And so I slogged on through the wet and slippery tangle, expecting to find a hunting blind. What I found was flagging hanging over the trail, which led me to notice a witness tree on the hillside directly above.

Male Spirembolus mundus

Female Pityohyphantes sp. #5

Curiosity satisfied, I beat conifer foliage as I worked my way slowly back to the main forest road. Interestingly, although the deciduous understory was quite wet, most of the conifer foliage was dry. Thanks to quite cool temperatures along the creek, many spiders were moving slowly enough to photograph, even in the dim light of the understory.

My main cone source

By the time I returned to the forest road, Rod had scouted the area and located a small grove of ponderosa pines (Pinus ponderosa) for me. Yay, cones to tap! Unfortunately the grove was fairly young and so I was only able to find 17 cones. However, after searching farther down the road, I found a pair of mature trees that had dropped hundreds of cones. It took a scramble up the steep roadside embankment to access them (going up is never the problem. It's getting down again...), but I was happy to get a good sample.

Lots of cones up the embankment!

From 100 cones I tapped 12 spiders from six families. Four species were identifiable, including typical denizens of eastside cones like Meioneta fillmorana (Linyphiidae) and Cryphoeca exlineae (Hahniidae). The surprise of the sample was an atypical female Pityohyphantes tacoma. Rod also found them in conifer foliage. They were atypical in the shape of their genitalia, but also in the sense that this was the first Pityohyphantes I'd tapped from a fallen cone.

You can read Rod's trip report here.

Fireweed (Chamaenerion angustifolium) and ocean-spray (Holodiscus discolor)

3-Oct-2017 La Center, Washington

Site location map. Click to enlarge.

Fall sampling has arrived! After barely making our species quotas in the dry heat of late summer, it's always exciting to collect in October. By then, days are cooler and autumn rains have begun, but there are enough consecutive dry days that collecting is still possible. And most importantly, we are usually able to collect many more species than our minimum daily target of twenty-one.

This day Rod Crawford and I headed south to La Center in Clark County, where a student's recent pitfall study in broccoli fields had provided Rod with interesting but incomplete samples from two adjacent gridspaces. Our goal was to raise the species total in each gridspace to at least twenty-one. Luckily, since we had a long drive to get there, accessible habitats in each gridspace were accessible within a few miles of the freeway.

Female Phidippus audax from shed

Our first stop was at a county reserve located at a convergence of agricultural land, forest and the East Fork Lewis River. I had little luck finding fallen open conifer cones to tap, but had some success sweeping riverside grass and collecting from the walls of a shed.

A formidable mantis...

The area was also good for some insect photo ops, including this European mantis (Mantis religiosa) that landed on me as I was walking down the road to the river. By its coloration, I'm guessing it had been spending most of its time on drying grass. Gardeners and farmers buy mantis egg cases and introduce these animals into their fields as pest predators. However, I am skeptical that they are effective since 1) they're generalist predators and so eat beneficial animals like bees and spiders as well as troublesome ones, and 2) like ladybirds, they have wings and don't stay put.

...and a decidedly unformidable woollybear

I also spotted my first woollybear (Pyrrharctia isabella) of the season, which was dashing headlong through the riparian grass.

Our second stop was at the Lake Rosannah Natural Area ("Mud Lake" on older maps) located at the lower end of the Allen Creek drainage. After collecting from gates and fences near the parking area, I walked the trail towards the lake and was happy to find open Douglas-fir (Pseudotsuga menziesii) cones next to the trail.

Female Gertschanapis shantzi

Cone tapping site by Lake Rosannah

Tapping 50 fallen cones produced only two spiders, a juvenile Phrurotimpus and a tiny, shiny dark-colored spider shaped like a theridiid. According to Rod, it turns out to be "Washington's first specimen of the extremely rare, minute palpless spider Gertschanapis shantzi (Anapidae), known from a few sites in California and Oregon"! If I had sampled more cones, perhaps I would have collected a male as well. But I was dissuaded by the poison oak (Toxicodendron diversilobum) growing through the forest litter, and didn't yet know I had found such a rarity.

Read Rod's account of the day here.

The lustrous leaves of poison oak.

Last blossoms of summer: Spiraea douglasii