Six Spotted Fishing Spider (Dolomedes triton)

A Nursery web spider in the family Pisauridae

Houston, TX, 1 Sept 2009

Thanks to Jerrel G. for this excellent photograph.

Dolomedes triton 090109 Jerrel G Houston TX

Jerrel wrote: "I was curious about the spider in this photo. I thought it was a wolf spider at first, and then maybe a fishing spider, but I can't see to find any on your site or other sites with the colorations this one has. Although taken with a macro lens, I think it was no more than an inch and a half or so. It was taken in a wetland prairie setting outside Houston, on March 30. Thanks for any help you can provide--I've gotten involve din the local master naturalist group, but am not up on spiders yet."

I thanked Jerrel for the excellent photo, and informed him that I did have a photo of this species on the bugsinthenews website, but only in a photo posted on the snake encounter pages. A page devoted to some broad-banded water snakes photographed in 2007, at Cinco Ranch, Katy, Texas, happened to catch a six-spotted fishing spider in one of the photos (the last one on the page, in its upper right quadrant). His photo, however, was much better, and was a very welcome addition to the website.

In 1967, the Finnish arachnologist Pekka T. Lehtinen proposed that the fishing spiders be classified within a separate family, the Dolomedidae, rather than as a genus within the larger nursery web spider family, the Pisauridae--originally Pisaurinae, per the French zoologist Eugène Simon (April 30, 1848 - November 17, 1924)--but that proposal was rejected by the majority of Lehtinen's colleagues, presumably because of the numerous anatomical affinities they share with other genera within the Pisauridae. Lehtinen remains active as an arachnologist, though now officially retired. I cannot find much information about this investigator, but have noted two research tracts recently published under that name, in 2003 and 2004. In any case, the Pisauridae, in North America, is represented by three genera and 14 species, with the genus Dolomedes containing nine species.

Dolomedes triton 090109 Jerrel G Houston TX

The six spotted fishing spider is named for the fact that it sports six pairs of white spots that run down the abdomen's dorsal midline. This specimen has pedipalps (the hairy structures that stretch outward, beyond the the spider's face) whose distal ends are noticeably swollen, as would be expected in a male. The female's pedipalps appear more like diminutive legs, forward of the face.  As Jerrel noted in a later e-mail, this specimen is clearly smaller than the one shown in the link to the broad-banded water snake, and though we cannot observe the pedipalps of that specimen, more than likely it is a female, as the females are larger than the males.

Though several of the fishing spiders can be found some distance from water, this species is almost always found in an aquatic environment. With help from folks like Jerrel, we have an opportunity to learn more about them.

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Does it pique your interest in arachnology to see these photos, and read about the spiders they portray? Good. You may have gotten the impression that much is yet unknown about North American spiders, and if so, that was not a mistake. Ignorance about our arachnid friends--they are, in the main, rather beneficial, not the enemies most of us imagine them to be--is measured by the ton. Rather than discouraging you, that fact should make you want more than ever to get involved in helping us fill in the gaps and make strides forward in our understanding and knowledge. The field is still wide open, quite contrary to what you may have previously believed. So, consider doing as Kendra did and get directly involved in pushing our knowledge forward. If you happen across a spider in North America, please photograph your discovery and send me copies of your photos. Whenever possible, every inquiry is answered immediately--I try to answer every email inquiry within minutes of reading it, and every telephone inquiry is answered on the spot, as most (alas, some emails do fall through the cracks from time to time) who call will testify.

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