US Widow or Redback?

[Tyler S]

Hey guys, I found this spider at my work and at first I thought it was just a normal black widow because I live in Montana, but it looks kind of like a redback spider.

 

[chanda]

It's highly unlikely that an Australian Redback spider would have found its way to Montana. What you have there is most likely the Western Black Widow, Latrodectus hesperus. Both males and immature females can have the red dorsal stripe like that.

Comparison pictures: https://bugguide.net/node/view/1574467/bgimage and https://bugguide.net/node/view/1295571/bgimage

 

[Tyler S]

You're probably right, Thank you.

 

[NYAN]

This is a photo of one of my latrodectus Hesperus when it was a subadult. They can have that pattern, but I think it’s less common.

 

[Tyler S]

View attachment 287961


This is a photo of one of my latrodectus Hesperus when it was a subadult. They can have that pattern, but I think it’s less common.

Alright, Thanks man.

 

[Quetzalcoatl Nyarlathotep]

More undeniable proof that North American widow's originated from the Australian redbacks. Due to the present distribution, and the current state of evolution among L. Hesperus, leads me to suspect that L. Hesperus lost it's dorsal stripe when migrating to rockier terrain where it could build safe shelters which protected the dorsal side of the spider from attack, needing only the deep red hour-glass for achromatic responses to be effective since attacks from above would be more likely. It would have to take a few million years for that to evolve into effect. It would not be unfeasible that a few redbacks by miraculous chance, ballooned onto a piece of driftwood or the like and started a separate colony, given how close the two continents would have likely been. The European widow is far too different in patterning to be the original progenitor of the North American widows, but it is possible that it is the progenitor of L. Variolous and L. Bishopi. due to the resemblance of patterning and size in the younger stages of life. It is far more likely that L. Mactans is a split off of L. Hesperus, but that is another conjecture for another time. It would just make sense, being that California is likely where L. Hesperus originated, and spread. Just my two cents. Don't take any of it with a glow of certainty, because I know I'm not certain about it.

 

[Smokehound714]

More undeniable proof that North American widow's originated from the Australian redbacks. Due to the present distribution, and the current state of evolution among L. Hesperus, leads me to suspect that L. Hesperus lost it's dorsal stripe when migrating to rockier terrain where it could build safe shelters which protected the dorsal side of the spider from attack, needing only the deep red hour-glass for achromatic responses to be effective since attacks from above would be more likely. It would have to take a few million years for that to evolve into effect. It would not be unfeasible that a few redbacks by miraculous chance, ballooned onto a piece of driftwood or the like and started a separate colony, given how close the two continents would have likely been. The European widow is far too different in patterning to be the original progenitor of the North American widows, but it is possible that it is the progenitor of L. Variolous and L. Bishopi. due to the resemblance of patterning and size in the younger stages of life. It is far more likely that L. Mactans is a split off of L. Hesperus, but that is another conjecture for another time. It would just make sense, being that California is likely where L. Hesperus originated, and spread. Just my two cents. Don't take any of it with a glow of certainty, because I know I'm not certain about it.

all our native widows sans bishopi can have fully intact 'redbacks' as adults.

 

[Quetzalcoatl Nyarlathotep]

all our native widows sans bishopi can have fully intact 'redbacks' as adults.

So does the Mediterranean/European widow, which I believe is older on the taxonomy chart if I'm not mistaken for reading incorrectly. I believe two separate progenitors produced our beautiful North American widows.

 

[The Snark]

Due to the present distribution, and the current state of evolution among L. Hesperus, leads me to suspect that L. Hesperus lost it's dorsal stripe when migrating to rockier terrain where it could build safe shelters which protected the dorsal side of the spider from attack, needing only the deep red hour-glass for achromatic responses to be effective since attacks from above would be more likely.

I had several discussions with the curators at the Darwin museum regarding the connection/migration of Hasselti to N. A. The general opinion is the red back is higher up the Phylogenetic tree and the ancestor species, but with a big problem. So Hasselti hitchhiked over to N.A. somehow, but plate tectonics indicates pre African landmass around India-Madagascar was connected. In turn there was a land bridge between Asia and Australia with the India wolf being the ancestor of the Dingo. So why are there no representatives of Hasselti in India, Madagascar and Africa?

As far as terrain goes, the land from Arnhemland on west and south towards the Great Sandy are extremely similar to the American southwest of today.``````

 

[Quetzalcoatl Nyarlathotep]

I had several discussions with the curators at the Darwin museum regarding the connection/migration of Hasselti to N. A. The general opinion is the red back is higher up the Phylogenetic tree and the ancestor species, but with a big problem. So Hasselti hitchhiked over to N.A. somehow, but plate tectonics indicates pre African landmass around India-Madagascar was connected. In turn there was a land bridge between Asia and Australia with the India wolf being the ancestor of the Dingo. So why are these no representatives of Hasselti in India, Madagascar and Africa?

A very thought provoking question indeed. Perhaps the Katipo is the the true progenitor? I know that the Mediterranean Widow looks similar to the red backs and the katipo's, then, that would make the Mediterranean widow the original ancestor to the red backs and katipo's?

 

[The Snark]

Oh fook thees sheet. Time to write a letter to Jaeger. See if Senckenberg has a genetic tree for us yet.

Anyone care to contribute to the wording? @Geb Arachnia Whitney ? @Smokehound714 ? Anyone? Bueller? Bueller?

 

[NYAN]

@The Snark Madagascar has latrodectus menavodi, which has a simmilar dorsal pattern to hasselti, but also white dots and red in the front and sides of the abdomen. Africa has plenty of latrodectus species also. I’m not too sure about India, but it’s pososble that pallidus can be found there.

 

[Quetzalcoatl Nyarlathotep]

@The Snark Madagascar has latrodectus menavodi, which has a simmilar dorsal pattern to hasselti, but also white dots and red in the front and sides of the abdomen. Africa has plenty of latrodectus species also. I’m not too sure about India, but it’s pososble that pallidus can be found there.

The African species are likely a separate offshoot of latrodectus sp. to those found in presentday austrailia, possibly a more ancient species of latros. These are my theories from reading a couple of well written articles from fellow arachnoboard members, as well as those on the internet.

 

[The Snark]

If genetics has taught us anything, it is that coloration and minor mutations are most often caused by habitat and environment and may not be reflected by phylogenetics. Ex: the Isan cobra. In appearance, and habits decidedly different from any other cobra. A quick check of the genes revealed it's a Kaouthai and the environs around eastern Thailand were the cause of the pretty radical divergent appearance.

So I suggest we throw the appearance of Latro out the window, keep an open mind, and hope that Senckenberg clears their genetic lab backlog before the turn of the 23rd century.

 

[NYAN]

A very thought provoking question indeed. Perhaps the Katipo is the the true progenitor? I know that the Mediterranean Widow looks similar to the red backs and the katipo's, then, that would make the Mediterranean widow the original ancestor to the red backs and katipo's?

You bring up a good point regarding Katipo. However, I think it’s Katipo which is a descendant of hasselti. Do we know any Australian species which are descended from New Zealand species? I do know that hasselti isn’t thought to have been an Australia wide species. It was thought to originate from a smaller area, and has since expanded into Asia. As for tredecimguttus, it can also be black like Hesperus or indistinctus. I also think that there are species which are unidentified or have incomplete ranges. I saw an Ecuadorian species which looked like a mix of hasselti and mirabilis, and another weird Mexican species.

 

[NYAN]

The African species are likely a separate offshoot of latrodectus sp. to those found in presentday austrailia, possibly a more ancient species of latros. These are my theories from reading a couple of well written articles from fellow arachnoboard members, as well as those on the internet.

I misunderstood the context of this conversation. I realize we are talking about ancestry now. You’re probably correct. I would even go as far to say that all Mediterranean species, African, middle eastern, and possibly Asian species are related. For all we know it could be a similar situation to Loxosceles species.

 

[Quetzalcoatl Nyarlathotep]

I misunderstood the context of this conversation. I realize we are talking about ancestry now. You’re probably correct. I would even go as far to say that all Mediterranean species, African, middle eastern, and possibly Asian species are related. For all we know it could be a similar situation to Loxosceles species.

You're good, no need to apologize. We are all brothers and sisters here. I think we're onto something here. Maybe one of the Mods can move this ancestry bit to a new thread in the true spiders forum?

In any case, the South American widows could have come from the African widows, as Africa and South America split only 120 million years ago.

 

[pannaking22]

I'll be curious to see how this shakes out once the taxonomy of the North/Central/South American species mess gets figured out. Does anyone know the taxonomic status on the African/Asian species? I admit I've gotten behind on my Latrodectus taxonomy lately.

 

[Patherophis]

This thread is getting a bit confusing.
Coloration has basically no importance for deciphering evolutionary relations.
On the scale we are talking here, we cannot say that one recent species is ancestor of another, they may have common ancestor and be sister taxa, but not ancestor/descendant of each other.
Can You guys please post links to the articles You are talking about ? As I only have Garb et al. 2004 and it is not very consistent with this discussion.

as Africa and South America split only 120 million years ago.

so it was waaay before genus Latrodectus evolved

 

[Quetzalcoatl Nyarlathotep]

This thread is getting a bit confusing.
Coloration has basically no importance for deciphering evolutionary relations.
On the scale we are talking here, we cannot say that one recent species is ancestor of another, they may have common ancestor and be sister taxa, but not ancestor/descendant of each other.
Can You guys please post links to the articles You are talking about ? As I only have Garb et al. 2004 and it is not very consistent with this discussion.

so it was waaay before genus Latrodectus evolved

Your heart is in the right place. Think of it like this, many spiderlings balloon themselves many miles from where they originated, even crossing the ocean, they have been found as high up as 40,000 feet. Even if that was before latrodectus evolved, by the time latros did evolve, the two continents wouldn't have been all too far apart yet for this to have occurred.