L mactans info page

RJ Adams states

"Both species (hesperus and geometricus) are discussed in Levi's (1959) review of North American widow spiders, although at that time the Western Black Widow, L. hesperus, was synonymized within the Southern Black Widow, L. mactans."

… john and jane balaban, 11 June, 2017 - 10:50am

OK -

thanks. I fixed the "range" section to reflect that mactans is not expected west of Texas based on the current taxonomy. I deleted the sentence above and one that suggested it occurred in all of the SW deserts. Please let me know if there are any problems or issues.

… Ken Schneider, 14 June, 2017 - 9:47am

More info -

I think one of the issues is that Levi, in at least two papers, describes L. mactans as occurring west to CA, but that was a "subspecies" of mactans that Kaston 1970 calls hesperus, who says of L. hesperus:

"This is the only species of black widow found west of about the middle of Texas, Oklahoma, and Kansas to the Canadian provinces. Levi has recorded both L. mactans and L. variolus (sub curacaviensis) from the west but, based especially upon the appearance of males and spiderlings, I am unable to ascribe to either of these two species any black widows I have seen from the areas indicated".

So there seems to have been disagreement between Kaston and Levi over the years about what to call the western widow? But, given that L. hesperus is currently accepted as a good species by the WSC, I think this means that mactans sensu stricto doesn't occur west of Texas or so?

… Ken Schneider, 11 June, 2017 - 10:41am

Latrodectus species limits

I remember having a conversation with Herb Levi about the widows. After describing many different species he had a change of heart and was in a mood to lump them back into one polytypic species. He did this with Gasteracantha too, and I believe those lumps have "stuck" but the Latrodectus lumps have not, they are still recognized by the WSC as separate species. There is quite a lot of variation in Latrodectus (as you all know), so it is tough to be definitive without a close look at those genitalia, and for them the internal epigynal structure is key. It is a lot of trouble and usually beyond the scope of a casual naturalist to do this, so we will stick with the somatic characters, such as the hourglass shape most of the time.

… Richard Bradley, 3 July, 2017 - 7:45pm