I found one last night that looks like an albino black widow. A white widow, perhaps? Anyway, she's creamy white with the red hourglass on her belly. She doesn't like it when I shine a flashlight on her at 9pm at night. Another smaller black widow nearby has exactly the same red hourglass, so I reckon they're pretty much the same.
It might be a brown widow spider. They range from dark brown to light tan and have the same hourglass marking on the abdomen. While their venom is twice as toxic as a black widow's, they don't inject as much and so are less dangerous.
I think there is, I just found one in my backyard today. I am no scientist though, so your going to have to ask a spider specialist