Latrodectus Black Widow Identification

[RMELovesLife]

I found a sling in my home and I'm just getting into tarantualas and other invertabrates. So I caught it and placed it in a small spider enclosure to identify and possibly keep as a pet. I believe it's a widow and I'm trying to identify which species. It's small and brownish. Thats why I'm sure its a sling. I took a magnifying glass and found a light colored hourglass shape on the bottom of its abdomen. Upon looking at previous photos on this forum I haven't seen any with hourglasses on spiders this small. Any ideas which mine may be? Thanks in advance !

 

[darkness975]

I found a sling in my home and I'm just getting into tarantualas and other invertabrates. So I caught it and placed it in a small spider enclosure to identify and possibly keep as a pet. I believe it's a widow and I'm trying to identify which species. It's small and brownish. Thats why I'm sure its a sling. I took a magnifying glass and found a light colored hourglass shape on the bottom of its abdomen. Upon looking at previous photos on this forum I haven't seen any with hourglasses on spiders this small. Any ideas which mine may be? Thanks in advance View attachment 433882 !

Immature Latrodectus hesperus or mactans would be my guess. But it's hard to tell from those images. Can you take some clearer ones in better lighting ?

 

[The Snark]

Latrodectus hesperus or mactans

Once mature, what would be the distinguishing characteristics to positively determine which is which?

 

[darkness975]

Once mature, what would be the distinguishing characteristics to positively determine which is which?

That's why I said immature. When mature the adult females are very similar. hesperus sometimes has more broken hourglasses but not always.

These first 3 pics are hesperus and the last 2 are mactans.

 

[The Snark]

Taking natural variations of the individual spiders into account it appears even the experts could misidentify now and then.

 

[AphonopelmaTX]

Taking natural variations of the individual spiders into account it appears even the experts could misidentify now and then.

The experts use characteristics of the male and female genitalia to identify species of Latrodectus because of the huge variation in patterns. Levi 1959c gives a good identification key to the American Latrodectus species along with a discussion of how even variations in genital characters can be problematic on delimiting species. So basically, if you really need to know which species of Latrodectus is in your possession, you have to kill it, remove the spermathecae or palpal bulbs, and examine it under a microscope while following along with the dichotomous key. Trying to list out what the differences are here, without pictures, is pointless so you can read the paper for more detail.

Levi, H. W. (1959c). The spider genus Latrodectus (Araneae, Theridiidae). Transactions of the American Microscopical Society 78(1): 7-43.

 

[The Snark]

@AphonopelmaTX Lacking microscopes and expertise it sounds like us on AB should take a page from the physicians diagnostics manual and liberally use words like probable, similar and reminiscent of.

 

[darkness975]

Taking natural variations of the individual spiders into account it appears even the experts could misidentify now and then.

Definitely. Most of the time you can guesstimate based on locale but in areas where their ranges overlap it muddies the waters.

Like posted above by @AphonopelmaTX even the experts have difficulty.

 

[The Snark]

@AphonopelmaTX I loathe dichotomous keys.
My favorite Doc at a hospital was an all around wonderful guy. And I was his victim. A neuropathologist who loved puns and jokes. All day long he stared into the microscopes and the only bright points between that and acting as a world wide reference source was hearing the squeaky wheels on my service cart. He would flag me into his office or sometimes even go to the door and wave me down. Then he would lay the most gawdawful anatomically explicit ribald bawdy lewd puns on me he dug up from heaven knows where and could share with only a tiny selection of colleagues on rare occasions and me. I spent many days cringing to myself on through my duties while wincing at his latest edition.
Then the pause, dearth. He had been formally requested by the Academy of Sciences to write up dichotomous keys for various analytic cerebropathology post mortems. Standardized procedural formats. Three months of dour, taciturn glowering Doc J, often muttering to himself as he in part dredged up 40 years of memories along with a trip or two a week of me driving over and retrieving a preserved brain or two from his storage for him to revisit.
I saw some of those keys. Page after page of precise step by step methodologies that took away your will to live if you actually had to follow them.

 

[RMELovesLife]

Guys! He/she molted! See photos. I couldn't get a good above photo bc it's upside down and there's a bit of dirt on the inside wall so the dirt blocks the camera. I don't want to disturb just for photos. But it's darker with a more prominent red hourglass and the top of it looks like one red stripe. I don't care as much about which species anymore. I'm more excited just to have it and watch and learn more about them! Thanks so much for the comments and replies! I'll keep updating you as I can. Let me know if I can identify gender yet or not.

 

[darkness975]

Guys! He/she molted! See photos. I couldn't get a good above photo bc it's upside down and there's a bit of dirt on the inside wall so the dirt blocks the camera. I don't want to disturb just for photos. But it's darker with a more prominent red hourglass and the top of it looks like one red stripe. I don't care as much about which species anymore. I'm more excited just to have it and watch and learn more about them! Thanks so much for the comments and replies! I'll keep updating you as I can. Let me know if I can identify gender yet or not. View attachment 433959

Can you take some more pictures when you can? I am curious why it looks like there are two huge prominent bulbs on the face. I have my suspicions but I'd like to confirm before I say anything.

Also make sure you spritz water tomorrow so it can drink post molt.

Thanks !

 

[RMELovesLife]

Can you take some more pictures when you can? I am curious why it looks like there are two huge prominent bulbs on the face. I have my suspicions but I'd like to confirm before I say anything.

Also make sure you spritz water tomorrow so it can drink post molt.

Thanks !

I just sprayed on the other side of the enclosure for it. I noticed those too but assumed they were the fangs like a tarantula? But again, I'm very new and still learning. Lol once home I'll take more photos.

 

[RMELovesLife]

 

[darkness975]

View attachment 433968 View attachment 433968 View attachment 433969 View attachment 433970 View attachment 433970

Even though the images are blurry it looks like you have a mature male there. It will not grow larger or live much longer now. It also will likely not feed as the mature males in the wild take up residence in a female's web and share her kills until he croaks.

Enjoy him while you can but don't be shocked when he passes on in 2 or 3 month's time.

 

[The Snark]

Even though the images are blurry it looks like you have a mature male there.

Pretty robust specimen. I'm more used to males being emaciated shadows of the females. And an hourglass leaning towards Mactans

 

[darkness975]

Pretty robust specimen. I'm more used to males being emaciated shadows of the females. And an hourglass leaning towards Mactans

The coloration does make me think mactans as well. Hesperus MMs are strikingly different in color.

Most of my captive raised males will molt out to maturity looking well fed. But it doesn't take long for them to start shrinking. Because I rarely breed them in captivity and because they usually tend to refuse food once they really get going their clocks start ticking.

 

[The Snark]

But it doesn't take long for them to start shrinking.

I can't get the dimorphism of Nephila out of my head. It's a good thing the males have no spontaneous thought processes -> "You can't be serious! That's my bride?? She's half the size of a modest planet and legs that go on forever!"

 

[darkness975]

I can't get the dimorphism of Nephila out of my head. It's a good thing the males have no spontaneous thought processes -> "You can't be serious! That's my bride?? She's half the size of a modest planet and legs that go on forever!"

Bridezilla

 

[RMELovesLife]

I rehomed him to a clean enclosure. Heres some better pics I hope! I have a video too. I'll see if I can upload it.

 

[RMELovesLife]

View attachment received_842331130379565.mp4