I caught a spider today. It’s shaped like a black widow, and is a very dark (almost black) brown. I caught it behind my couch in a dark corner. Its underside is a lighter shade of brown. There is no hourglass. Instead there are two small white spots where the legs emerge, and a thin white longitudinal line. I don’t think I can get a good photo of it. Can anyone identify it from its description? This is in Northwestern Washington.
Let’s see. It shaped like a black widow, but looks different, is a different color, has no hourglass, and has different markings.
This aught to be easy. 
Okay, seriously, it sounds like one of the many brown recluse spiders, but I don’t know what their markings are. But I’m sure you know the nasty ol’ recluse.
Someone here has a link to a spider ID site. Maybe he/she will chime in.
Sorry about the smarty pants reply, I just want to get on the “notify” list. 
No, not a brown recluse. It’s shaped like a black widow, and about the same size as a medium-sized one.
Here’s a limited site, but they’ll send you a real cool spider ID chart.
Johnny LA, If it’s shaped like a black widow, probably not a recluse, as they don’t have the more rounded abdomen of a Black Widow. My really offhand guess is some sort of Orb weaver, as they are making themselves more visible this time of year, and have a very rounded abdomen.
This site is from the Burke Museum of Natural History in Seattle. Scroll down and look at the photos on the far right. Is that in the right direction?
Not an orb weaver. Its web is a bit of a messy cobweb. I’ll try to get a photo.
No luck on the photos. My little CoolPix just isn’t up to the task of macrophotography.
Anyway, I’m kind of leaning toward some sort of Steatoda, or ‘false black widow’ or ‘cupboard spider’. In better light the abdomen is lighter than I thought it was, and appears to have a little mottling on it.
Here’s another Washington site. Hope it might help.
I would put money on it being a false widow of the genus steadota. Their range of coloration is vast.