I've had some trouble identifying Latrodectus spp found within the Cross Timbers and Prairies ecoregion in north central Texas. This individual was an immature, but was about the size of adult female L. mactans that I have seen farther east near Paris, TX and Houston, TX. The hourglass does not appear to have the block-like lower section seen in L. mactans in eastern and southern Texas, and I suspect that this might be L. hesperus - based on size and hourglass shape. Other characters used to separate the two species seem highly variable. This individual does have a long red line on the top of the abdomen which reaches the spinnerets, but it is also a juvenile and I don't know if western L. hesperus immature also exhibit this trait. The boundaries of L. hesperus and L. mactans in this state do not appear very clear, and introductions are probably making this less clear. I've seen a 2004 paper that disputed the validity of the two species as distinct based on genetic analysis, but that paper compared specimens from the western U.S. to specimens collected near Wichita Falls, TX, which might not have been far enough east to be a good comparison between the two populations. I've looked at widowman's website and a few others and I'm still not sure that I can ID this individual for certain. I can say that I've seen my share of L. mactans that were very typical. Can anybody out there help out with this one?