Typically female M. gopara have longer tail at v4 than other species but this varies.
http://v3.boldsystems.org/pics/BOPMB...1341158498.JPG
You can look at all three species, namely ,biggsii, gopara & gaesa at PL 8 & 9 here.
http://www004.upp.so-net.ne.jp/jamid.../borneo-e.html
TL Seow: Cheers.
PS. The only way to be sure if this is something new is to see the upperside.