The winged imago of Prorhinotermes japonicus (Holmgren 1912) is described herein for the first time. The soldier caste and two morphs of the neotenic caste also are redescribed. Based on the similar morphology of soldier, alate and neotenic, two Chinese species, Prorhinotermes xishaensis Li & Tsai 1976 and Prorhinotermes hainanensis Ping & Xu 1989, are reverted to junior synonyms of P. japonicus. The current distribution of P. japonicus includes tropical islands surrounding the northern part of the South China Sea. Another Chinese species, Prorhinotermes spectabilis Ping & Xu 1989 from Yunnan Province and two Philippines species, Prorhinotermes tibiaoensis (Oshima 1920) and Prorhinotermes gracilis Light 1921, were compared and included in discussion.