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Probable C. longipalpa - adult dorsal - Castianeira longipalpa - male

Probable C. longipalpa - adult dorsal - Castianeira longipalpa - Male
McKinney Roughs Nature Park, Bastrop County, Texas, USA
December 4, 2010
Size: 6mm
I captured this specimen on September 16, 2010. I found it under a wooden platform among similar-looking ants. The ants had been disturbed when I lifted the platform. When this critter ran to hide, something looked different about it, so I snagged it. I got really lucky, because it had ducked under the plank. I happend to have a stick in my hand, and I immediately swept beneath the plank, and the spider came out on the stick!

He was 3.2mm long and very ant-like when I captured him. The above is what he looked like two instars later, after feeding a diet of crickets. The additional pictures here show the previous two instars.

Det. by J.T. Lapp (myself). I looked at the palps under a scope and spent considerable time pouring through Reiskind 1969. C. longipalpa was the best fit according to the species descriptions, but I just could not key it out using the provided key. In particular, my scope isn't powerful enough to see the spiral at the tip of the embolus. The one thing that bugs me is that Reiskind describes the males as, "Carapace red-brown, covered with plumose white hairs; some black and white hairs predominant in head region." Not so this one.

Images of this individual: tag all
Probable C. longipalpa - adult dorsal - Castianeira longipalpa - male Probable C. longipalpa - penultimate dorsal - Castianeira longipalpa - male Probable C. longipalpa - pre-penultimate dorsal - Castianeira longipalpa - male

Have you made any sense of Reiskind's
description of the male longipalpa and his drawing in fig 50. I keep thinking he somehow got confused and fig 50 represents something totally different, but I don't know what?? -- john

I don't think I've yet seen anything match his figures for the abdomenal patterns. They must be highly variable.

Moved from Castianeira.

The ants?
Perhaps you could go back and try to capture a couple of the ants from the colony/location where you found this specimen? It would be interesting to know among which species it was found.


Will do. I should have thoug
Will do. I should have thought to do so at the time. Duh!

Looks good to me. Dondale & R
Looks good to me. Dondale & Redner (1982) write: dorsum with four or more white bands distributed over entire length and embolus of male slender but short; they also add that the abdomen can be orange-brown to purple or nearly black, which also agrees with my observations. Texas may be near the southern edge of their distribution, but D. Allen Dean has them on his Texas list.

Nice series of images!

What about cephalothorax?
Thanks Kevin! Do D&R have anything to say about the color of the cephalothorax?

"Carapace dark orange brown with purple iridescence, with few darker lines radiating from dorsal groove area, with eye area black." (p 108)

Perhaps this isn't C. longipalpa
It seems that there is complete agreement that the adult male C. longipalpa has an orange-brown carapace and not a black one. I guess I need to get a shot of the palp, but that's not going to help. It looks just like C. longipalpa illustrations to me.

Joe, you can't rely on color for species determination, particularly unless you are viewing the specimen under the same circumstances as the describer -- usually in alcohol or water with good illumination. An orange-brown carapace that is dark enough will look black under many lighting conditions; the specimen I collected in North Carolina has essentially the same coloring as yours.

Far more important are the proportions of the embolus that Dondale and Redner refer to: "embolus of male slender but short (length embolus / length tegelum + embolus = 13 or less)". (They don't mention it, but I think this comes directly from Reiskind.)


Thanks Kevin. I didn't actual
Thanks Kevin. I didn't actually measure the "male genital index" (as Reiskind calls it), but that's a good estimate just by looking at it. It is pretty short, but still slender.

I'm not relying on color determination to ID species; I'm using it to help confirm species ID'd by other means. If no one has ever collected a C. longipalpa with a black carapace, we absolutely should be concerned. We have either added to the information about longipalpa -- that it can have a black carapace -- or we have found something else.

My camera and photoprocessing exaggerate the hues actually there. I'm often muting the hues on the images to better match the actual specimen. No orange/brown here. However, it is possible that alcohol will change the black to orange/brown. In that case we'd still be looking at a contradiction, if this is indeed C. longipalpa, proving part of these papers on C. longipalpa incorrect.

Hi, Joe,

Have you got any palp photos?

No, haven't taken the time. T
No, haven't taken the time. That would take me 1.5 hours at least, as I have to go in to UT and I'm really inexpert and dissecting and propping palps. I'm waiting to hear back from Allen Dean first. He's going to check on some of his C. longipalpa specimens.

dark brown vs. black
There is a difference between truly opaque black pigmentation and a dark brown sclerotization (think of Bakelite), but to see this one usually needs to have the specimen in alcohol or water, with bright light, and under the microscope. Not to forget, we have to allow for intraspecies and/or regional variations (probably the real difference).

Take a look at this specimen...

I just pulled it out and put it back under the scope -- I would describe the carapace as "dark orange-brown, border somewhat darker, overlaid with white hairs".


[But I am going to take a closer look at this specimen this evening, just to be sure that I didn't make a mistake the first time!]

We're going with longipalpa
Allen Dean pulled out some of his C. longipalpa specimens and reports that his, too, have "dark" carapaces. So we have some confirmed longipalpa specimens that look like this. I'll go ahead and move to C. longipalpa. Thank you everyone for your help!

The Dondale-Redner book, The Sac Spiders of Canada and Alaska (1982) is available for free download here (11.1 Mb):

When this book was written Castianeira was placed in Clubionidae. Also, it covers mainly the species found in Canada, but it does include a complete description, with diagrams, of C. longipalpa.

Thank you for the link!
Thank you for the link!

Moved from ID Request.

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