hahaha...yep, it's pretty striking and totally unlike the Paramesotriton I'd seen here on sale here in Japan before.
But I recall Mark saying chinensis, along with guanxiensis, shows up most frequently in U.S. stores. Here it seems to be guanxiensis and various others (incl. hongkongensis) that almost invariably have brown backs, and are not mottled.
Referring to again to remarks attributed to Henri Janssens, the underside of the tail of P. chinensis has an unbroken red/orange line (just like in the pic above!)
while the orange line in the case of P.fuzhongensis is sometimes broken up by the brown coloration.
And according to Frank Pasmans, P. chinensis has a more faint grey-brown coloration (when not stressed) than P. fuzhongensis, and "typical for this species are some scattered yellow dots on the lateral side and at the attachment points of the limbs. The warts are like little knobbles and not pointed."
Indeed, these yellow dots at the attachment points are really prominent on the individual in the first two pics (and I'm tempted to rush home and check the others!)
The summary of Pasman's remarks (for anybody who missed them the last time I reposted them from the Urodela newsletter) goes on to say P. fuzhongensis "have a darker brown coloration, and their warts are more sharply pointed. They lack the yellow dots."