What’s This Doing Here?

On 29 May, 2019, as I was walking into my house, I noticed a male spitting spider (that’s for real: the members of the family Scytodidae are called spitting spiders for good reason!) on my office’s door frame. I had seen 2-3 of them in the house we have inhabited for ca. 3½ years, but I honestly had not paid them much attention, as one species, Scytodes thoracica (Latreille, 1802) is fairly common, and–while they are consummately cool spiders–I had stopped collecting ca. forty years ago, and have not been actively involved in any spider activity other than the occasional and casual observation of them for the intervening decades.

My mystery Spider

So I really didn’t think much about this spider until I had gone inside the house, and mused about the fact that I had never seen S. thoracica outdoors before.

I went back out and looked at it some more, and realized that it simply didn’t look like S. thoracica, with which I had been familiar since….I don’t know: forever? So I went back inside and did some cursory research to see if we had other spitting spiders in North Carolina, and learned that another species, S. longipes Lucas, 1844, has appeared here and there in the area, and was extending its range northward.

bugguide.net/node/view/657373(opens in a new tab)

So I decided this must be S. longipes, apologized to it, and preserved it in alcohol so that I could examine its microscopic features (the structure of the male pedipalps, if you must know) to see if it was, indeed, not S. thoracica. It was decidedly not, so I naïvely figured I had found S. longipes, and put the now-pickled spider aside.

On 30 April 2020, I found a dead male Scytodes on my bathroom floor. Fortunately, it was freshly dead (i.e. still flexible but not rotten), so I pickled it, and set it aside.

Sometime that May, I went out one evening and found three scytodids concurrently on a different door frame. Foolishly, I did not collect any, or even note the date, still assuming all of these to have been S. longipes.

A few weeks later, my pet black widow died (awww…), so I got out my microscope for my son, Benjamin, to look at her cadaver. When he was finished, I figured I’d take a look at the bathroom Scytodes to see if it, too, was possibly S. longipes. Examination of its palp indicated it was indeed the same species. But this time, figuring something was going on, I dug into the literature to verify their really being S. longipes, and…they clearly weren’t!

Intrigued, I dug deeper, looking for palpal structures that looked like the spiders at hand. After many hours of reading papers (going back to 1837), I found a 2007 paper by Cristina Rheims, Antonio Brescovit, and César Durán-Barrón on Mexican species of the genus Scytodes, in which they described 13 new species. One of those new species, S. atlacoya, had palpi similar to those of my specimens, and unlike those of any other Scytodes I could find.

On 26 May, I sent an email to each of the authors (the first two in Brazil, the third in Mexico) with crude photographs of my spiders and their palpi, asking if they thought I might have a Mexican spider now in North Carolina. Naturally, the response was “could be, but we can’t tell without seeing the specimens” (Hey, I was happy simply to hear back from each of the three authors, and had been hoping for that very answer!).

I packed up the two male spiders and made arrangements to send them to Brazil (Señor Durán-Barrón proclaims himself not to be a Scytodes expert, but had “merely” sent the Mexican specimens to Dr. Rheims and Senhor Brescovit, each of whom is).

After sealing that carefully prepared shipment, I walked outside on the evening of 29 May 2020 (one year to the day after finding that first male) and saw a female Scytodes (again on a door frame!) who looked suspiciously like my male specimens. Naturally, I collected her and examined her genitalia (sorry, but that’s how one does it with spiders!).

Sure enough, she, too, looked to my eye likely to be S. atlacoya! So on 02 Jun 2020, I repacked everything, emailed a photo of her genitalia (an admittedly scientifically useless photo) to Brazil, repacked the now-three spiders, and sent them off to the lab in São Paulo, where they arrived safely 09 Jun.

A Female Scytodes atlaoya

On 28 July Senhor Antonio Brescovit, who had been quarantined away from work (thanks, COVID), was able to go back to his lab and confirmed that the specimens I had sent are, indeed, S. atlacoya Rheims, Brescovit, and Durán-Barrón 2007.

“So what?” I hear you ask? Well some research revealed that only few specimens have been reported in the USA: a few in TX, a couple in OK, and some in MS, FL, and GA: but none had ever been recognized in NC.

Meanwhile, I kept finding these spiders all over my house and even some in my tool shed. One night, I went out with a light and observed 27 of them on the side of my house, 11 of them on my front porch, and about 20 of some very young spiderlings by the door where I collected the first female (though not her offspring–their mother and five of her kids live on my desk at this writing)!

I have since been observing their behavior and rearing them from eggs; and have already learned a lot about them. They also prompted me to buy a macro lense for our DSLR, so I can actually get some closer shots now.

A female carrying her egg sac (from which hatched >50 spiderlings)

So I’m sure I shall be adding more information here as things develop. Suffice it to say, this old spider-nerd is really enjoying himself these days!


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2 Responses to What’s This Doing Here?

  1. Malorie

    I have actually recently found one in my bedroom (looking identical to your first photo). A while ago I had one in a roll of paper towels and even further back I had one eating another spider. The one eating another spider had a more bulbous body so maybe it was female or a different species? It had less speckling and more of a marbled look on the abdomen; bands at the “knee” joints. The legs were as thin as the other two.

    They are a little bizarre the way they “sit.”

    I’m just outside of Raleigh, NC.

    All spiders found inside were transported outside. 🙂

    • zeppmusi

      Very cool. I strongly suspect it is, then, S. atlacoya based on their striking difference from S. thoracica and the high numbers of them I’ve been finding. They not only eat other spiders, but I have observed them entering the webs of–and using aggressive mimicry to lure–the cobweb spider Parasteatoda tepidariorum as prey. (I’ve also found the latter consuming the former, so success is not a given!).

      Incidentally, I’ve found dozens of photos on BugGuide.net of atlacoya misidentified, and have submitted a list of suggested changes and corrections. Do you have any of the spiders pickled? Did you take any photos?

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