Bornella japonica? from Japan

Dear Nishina,
I think this is probably Bornella japonica. I beginning to think that the best distinguishing feature is not three pairs of dorsolateral processes ('cerata'), but their colour. In all the photos I have seen which seem to fit B. japonica, the dorsolateral processes are white and don't have the distinctive subapical orange band found in Bornella stellifer. The rhinophore stalks are also white.

Baba also described secondary papillae on the most posterior papilla on the rhinophore stalk. In your upper right photo [see inset] and lower right, secondary papillae are clearly present. Baba (1949) and Atsushi Ono (1999) both publish pictures of animals that are clearly Bornella stellifer, so it seems there are two very similarly coloured species of Bornella to be found commonly in Japan.
Best wishes,
Bill Rudman