Wanshang is Mandarin for "evening" or "night." In Chinese mythology it is known as a "trickster dog," capable of shape-shifting and displaying human intelligence.
Dholes are a real species of wild dog native to Southeast Asia. However, the wanshang dhole (晚上豺) and the myth surrounding it are a largely fictional invention of the show. There are various Chinese myths about wolves and foxes that have shape shifting and trickery elements.
Dr. Ian Detweiler discovered a living wanshang dhole in early 1999, and was transformed into a wanshang dhole himself. He attempted to hide his condition, but in the process killed the crew of the T'ien Kou and Jake Conroy. He was killed by Karin Berquist. (TXF: "Alpha")