Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Clickable Guide
Moths Butterflies Flies Caterpillars Flies Dragonflies Flies Mantids Cockroaches Bees and Wasps Walkingsticks Earwigs Ants Termites Hoppers and Kin Hoppers and Kin Beetles True Bugs Fleas Grasshoppers and Kin Ticks Spiders Scorpions Centipedes Millipedes

Calendar

TaxonomyBrowseInfoImagesLinksBooksData
Photo#826410
Spider-Colorful-Flower Garden - Latrodectus mactans

Spider-Colorful-Flower Garden - Latrodectus mactans
Amarillo, Texas, USA
August 18, 2013
Size: 10mm, including legs
Found around 9:00 am on the side of plant fertilizer container. Had a small, un-patterned shaped web. He was scrunched up, looked dead, but moved when touched. Not very active. Stayed still for long periods of time, making it easy to photograph, but could move very quickly.

Images of this individual: tag all
Spider-Colorful-Flower Garden - Latrodectus mactans Spider-Colorful-Flower Garden - Latrodectus mactans Spider-Colorful-Flower Garden - Latrodectus mactans

Moved
Moved from Widow Spiders.

looks to be a mactans
looks to be a mactans

 
distinguishing features?
I have some L. hesperus collected in Colorado last fall and the immature male and female both have this exact abdominal pattern, though instead of jet black as the base color, it's more of a brown. But I had thought this pattern of stripes was typical of that western species? I haven't raised many, so don't know what the limits of variation are for them, though. In Kaston's black widow monograph, it also appears that this pattern is L. hesperus too. Are there any specific features on this (or others that look like this and have been placed in L. mactans) that help to peg them as L. mactans? I've been attempting to get comfortable with the patterns of each species, but ones like this throw me off and make me wonder if I'm even on the right track.
Here are some others that I would have guessed were L. hesperus:

(compare that last one with #704061 & #797690 filed in L. hesperus)

And with so many "cross-over" specimens in regard to range, I don't like to be dependent on location for them anymore (it used to be the first thing I looked at). For example, L. hesperus has been recorded in South Carolina, Arkansas, Ohio, just to name the few verified eastern records that I know of (it gets transported in produce a lot). And L. mactans recorded from Arizona and all over Colorado (even far west on the UT border and also central)... and that's just the few western records I know of, there's probably more.

 
Widow fun
Hi Mandy!! Good to chat with you again :)

You raise some very good questions, and hopefully I can help out and provide at least a couple explanations. Before we get started, let me issue the always-present disclaimer statement: It is very difficult to positively ID a spider 1) from picture alone 2) from just a snapshot of its life without looking at the other stages it passes through 3) before it's an adult (juvenile or spiderling ID) and 4) without all the other helpful angles (hourglass shots for example). It is SO much easier (not definitive) to ID widows when you can see all stages of the spider, in person, and observer the hourglass!

That being said, many of the IDs are given from personal experience and best guesses, and as such may be incorrect sometimes- nobody is perfect! the 3rd picture shown is a classic example of just the outline of the colors left (as are the 2 links below the pictures). They are classic before-mature hesperus. Hesperus markings are quite distinctive in this stage, just the outside edges of white are left, and these usually disappear with the final molt. Mactans are -typically- much more strikingly colored dorsally (this applies to the southern ranges, not so much the northern ranges). Mactans also usually have tan leg banding as well, whereas hesperus lack strong banding. I would love to see glass shots with most of these pictures, but I know this is not possible most of the time.

OK, a word on the ranges... Except in the rare case of widows being shipped in grapes, there are NO hesperus in the eastern US, just as there are NO mactans in the western part of the US (speaking natural populations here). Range is still one of the best indicators of species. The confusion here comes not only from old publications (I personally have a biology book from the 50's where it still states there is only 1 species of Latro in the US) and old records (many of the incorrect records are from many years ago and are still around), but also from incorrect IDs. For instance, one could easily mistake a dark variolus in Ohio with a hesperus. :)

Hope that helps some! Anything I missed?

 
widows
Thanks, widowman! I definitely agree about the difficulties in identifying spiders from images (that probably speaks for all of us here at BugGuide! =)

What I was curious about is the three thumbnails I linked, plus the very top image by sford122, are all ID'd as L. mactans right now, but after I've been looking and looking, I can't get over how much the patterns actually look like L. hesperus in all 4 of them, so I was wondering if they are variations or something or if there is something specific that says they are mactans? I thought I was getting these down and the pattern on those was throwing me off. I look at them and they make me think hesperus because of that solid line down the center of the abdomen (as opposed to being separate dots) and the strongly diagonal lateral stripes, but if they truly are mactans, then does that mean both species actually have that pattern?

But as you just said, the 3rd thumbnail above is classic L. hesperus? So that means it is misplaced? (You ID'd it as L. mactans originally -- which I have made my share of mistakes here in previous years, so not even a big deal, I'm just trying to get a better grip on these.) And then the other two thumbnails are currently ID'd as L. mactans, too. Would you say those still are? Or do they actually look like L. hesperus?

I've heard that there's currently work being done on Latrodectus and that there may actually be more species in the USA than we know of, can't wait to see where that leads. You could be right about there not being established populations of the cross-overs, but I was just trying to make a point that there are interceptions of specimens outside their known range — which I brought up because, for example, that 3rd thumbnail I posted looked exactly the same to me as the two in the links below it, and the two in the bottom links were from California and quickly pegged as L. hesperus... but then this 3rd thumbnail, which looked the exact same to me (just faded pattern), but was found in Missouri, was ID'd as L. mactans -- I guess I assumed that range had something to do with that decision, I guess. But! Since I just learned that now you think it is L. hesperus that is one conundrum for the solved pile! =)

And so this original image (at top, by sford122) is for sure L. mactans? That one also has the solid median band down the center of abdomen and strongly diagonal lateral stripes that I keep thinking is supposed to be L. hesperus?

I'm practically confusing myself here, so I apologize for going all over the place! haha

 
Haha, I think you're confusin
Haha, I think you're confusing me now :) The first 2 images you linked very well could be mis-ID'd. I'd love to see more detailed images. The third is, I still believe, mactans.

 
.
Sorry, ya, LOL, my questions get convoluted sometimes, I need to be more direct. I guess this is a big can of worms... considering possible variations and not being able to see their different instars, or hourglass, etc, like you mentioned (I totally agree). I have to wonder if some should stay at genus level or something unless we're really sure enough, though. Especially in the zone where the two species potentially overlap. Those 2 images, you seemed pretty confident they were mactans originally, but now since they could be misID'd, do you think that seems uncertain enough that they should go to genus level instead? I think I would probably rather have them there, just considering they confused me when trying to get familiar with mactans markings, so I assume it could happen to others too. I know this is all a big guessing game to begin with, since we're not looking at dissected genitalia (which is the only way to be sure).

 
Not a bad idea for the moment to leave them at genus level. Perhaps someone who knows them better than I will show up and will be able to help out!

 
.
Went ahead and did that. I was probably focusing on something pretty unimportant, but I feel better now that I moved them, LOL. I still think this specimen we're commenting under here has a hesperus-like pattern, too. Have you seen mactans that look like this->

Looks like an immature male. I've never kept any mactans so have no idea really the extent of their variation. Have only kept hesperus and geometricus.

Moved
Moved from ID Request.

Don't touch it again!
I'm not sure, but that reminds me of an immature black widow!

 
Don't Touch It Again - Spider Now Dead
Thanks Bill. I didn't touch it with my finger... used a stick.
Have found black widows at my residence last year (3) and this year (2) so I'm always looking for them. I love jumping spiders and orb weavers and never harm them, but black widows have to go.

Maybe a young widow spider

 
Very well may be... thanks fo
Very well may be... thanks for the ID.

Black widow
Juvenile Latrodectus have these bright colors. L. mactans, the southern black widow, is likely the most common in TX, but I can't distinguish it from a northern or western black widow, which are also present in the state.

 
Thanks Robert
I'm treating this one as a black widow, based on your ID. Thanks again.

 
Good call!
I didn't refresh my page before commenting, else I would've seen your comment. Sorry about that.

Comment viewing options
Select your preferred way to display the comments and click 'Save settings' to activate your changes.