Reptile & Amphibian Forums

I discovered what I thought to be two male latrodectus native to southern california, one immature and the other possibly mature. Well I caught them both and on closer inspection.....they look like hessalti. I thought they were only in australia? Maybe I'm crazy but the bigger one has thered stripe down the abdomen that thins as it gets towards the spinnerets and is outlined by silver. The stripe has a dot above it with similar colorations toward the middle of the spider. The dot is identical in color and outlining as the stripe and then there's two or three smaller stripes on the sides of the abdomen pointing outward and down. Maybe I've completely forgotten about another type of spider or I'm just crazy. I'll try to post a pic of it as soon as possible. Any help would be greatly appreciated!

Latrodectus bishopi!

Neither L.hasselti nor L.bishopi are known to be in California. What you may have is Theridion murarium, which does have a fluted band of red, lined with white running down the middle of the abdomen's upper side, and has the general body shape and habits of a widow spider, as it is a Therididae cobweb weaver, just like the genus Latrodectus. This species ( T. murarium ) is not dangerous, and is widespread across North America. I haven't found any images of it online, but the book "Spiders and Their Kin", by Golden Guide has a picture of it. The below photo bank has a picture of a definite L.hasselti :

http://207.68.162.250/cgi-bin/linkrd?_lang=EN&lah=bdba210368b2bed2ce373872d6fa553b&lat=1089838624&hm___action=http://images.google.com/images?hl=en&lr=&ie=ISO-8859-1&q=Latrodectus+geometricus

( just copy / paste into your address bar )

Actually I contacted an entomologist I know from UCR who connected me to their resident spider specialist, Rick Vetter. He said that it's most likely an immature western widow. Apparently they sometimes have such markings. I'll try and post a pic soon. Thanks for the reply, I'll check my copy of the book and compare the two. Who knows now?

It's also got the hourglass

Well if it has the hourglass, it can't be the other. Rick Vetter is right, western widows can exhibit a dorsal stripe when young, and if it has the hourglass ( which the T. murarium does NOT have ) it is most certainly a Latrodectus species. This website has pictures of immature western widows ( L. hesperus ):

http://www.kaweahoaks.com/html/latrodectus_hesoerus.html#Immature Black Widow

As they age, the dorsal markings disappear, until only a few red dots are left on the back, as shown in this image:

http://members.aol.com/TheWyvernsLair/WidowSpiders/

The Theridion murarium:

http://www.kaweahoaks.com/html/spi_cobweb_spider3.jpg

do you suppose that what the first website said about young widows being dangerous is true? im sure now that i wasnt bitten by the one that was crawling on me the other day, but i would still like to know if they are dangerous or not.

Although they are less likely to penetrate the skin, and would inject only a small amount of venom, they shouldn't be taken lightly. Granted, the chance of fatality in an adult human from a small immature would be almost insignificant, it would not be an enjoyable experience. Unless the victim were particularly sensitive to the toxin, the bite would be a scaled down version of the adult's envenomation, possibly entailing nausea, muscle twitching and spasms, sweating and tension. It depends on the size of the spider however. Larger immatures may be almost as dangerous as the adults, and should be treated as such. I would go by the size of the spider, not whether it has adult patterning or not, and be very careful with it anyway. Dangerous? Serious at least. How big was the spider that crawled on you, and may I ask how it happened?

the details of this incident are in the above post labeled "at what age or size are black widows dangerous?".

Yeah...I noticed AFTER I posted! Doh!