And there is this even more recent Birdlife report showing even wider distribution.
http://www.wing-wbsj.or.jp/~vietnam/pdf/reportHG.pdf
[A Rapid Field Survey of Xin Man and Yen Minh Districts, Ha Giang Province, Vietnam]
Issued last August, it says:
"During the rapid field survey...the most interesting finding was a population of Vietnamese Salamander Paramesotriton deloustali in Xin Man district. Voucher specimens were collected, identified by herpetologists at the Institute of Ecology and Biological Resources (IEBR) and Fauna and Flora International (FFI), and stored at the zoological museum at IEBR."
"On 17 May 2002, four Vietnamese Salamanders were collected in two different streams near Ban Xe village, Na Chi commune, Xin Man district. One specimen was collected at an elevation of 1,000 m asl, while the other three were collected at an elevation of 900 m asl. The colouration of the underside of the first specimen was brighter than that of the other three, and was determined to be a female by the herpetologists at IEBR."
"Vietnamese Salamander is listed in the 2000 IUCN Red List of Threatened Species (IUCN 2000) as vulnerable, and in the Red Data Book of Vietnam...as endangered. In addition, exploitation and utilisation of this species are strictly prohibited in Vietnam, following Decree No. 18/HDBT, dated 17 January 1992.
"Vietnamese Salamander is endemic to northern Vietnam, and its distribution includes Vinh Phuc, Thai Nguyen, Tuyen Quang, Bac Can, Lao Cai and Yen Bai provinces. The species often inhabits pools in streams, 0.5 to 1 m in depth, where stream flow is slow and the stream bed has a substrate of sand or stones. The breeding season of this species is from December to April."
"These records of Vietnamese Salamander, extend the known distribution of this endemic species, and, also, highlight the significance of natural freshwater habitats in Xin Man district for biodiversity conservation."
Ha Giang also borders China and is #3 on the above-linked map (which seems to be missing a couple of provinces...)