Wednesday, November 13, 2013

A Cave Orbweaver and a forgotten Fishing Spider

Probably not an uncommon spider but seldom encountered, as its name suggests the Cave Orbweaver (Meta ovalis) prefers to "hang out" near the entrances of caves or in rock piles. Of course man-made habitats such as cellars will serve just as well, and that's how this male came to be on the side of a building downtown. And quite a hardy spider this is, because the photos were taken on a windy, rainy November 11th, 2013, with the temperature hovering only a few degrees above the freezing point.

Cave Orbweavers belong to the family Tetragnathidae – commonly called Long-jawed Orb Weavers – but they lack the huge, serrated jaws and elongated bodies and legs of their nearest relatives.

At a length of about 12 mm this spider is a heavyweight for a male; in many spider species the males are considerably smaller than the females. The enlarged palps, modified to carry sperm packets, are easily seen in the following three images.

The female spider depicted in the next two photos was encountered at a marsh east of Tweed on August 32rd, 2011. It was fairly large, a good 25 mm in length, and although I was unable to acquire an image of the eye arrangement its general aspect was that of a Nursery Web Spider, family Pisauridae. However, this individual was much darker, and the relatively dull, straight abdominal stripes contrasted sharply when compared with the undulating white lines of the ubiquitous Pisaurina mira. I thought it might be P. brevipes, and the photos ended up being filed in my Pisaurina folder and forgotten ...

Over two years later – November 13th, 2013 – I stumbled across the photos while reorganizing some files and decided to upload them to BugGuide.Net for a positive ID. My guess as to family was correct, but the species – P. brevipes – was wrong. This spider is actually Dolomedes striatus, and it's the fourth species of Fishing Spider I've found in this neck of the woods.