Latrodectus mactans

Definition: the black widow spider, a venomous jet-black spider found in protected dark places; it is especially common in the southern U.S.; the full-grown female (slightly more than 1 cm long) has a brilliant red dumbbell- or hourglass-shaped mark on the ventral aspect of the abdomen; her bite may be extremely painful, producing a syndrome mimicking an acute abdominal crisis; some deaths, though rare, have been reported, particularly in small children; the male spider lacks the hourglass mark and is not venomous.

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