Koh's aeolid is Favorinus pacificus

Dear Atsushi,
Thanks very much for you suggestion. As with Rie Nakano's message [#13535], it is helpful in illustrating the problems I have in identifying  Favorinus japonicus, a species which was unfortunately based on a single specimen. I have discussed this more fully in a separate message [#13616]. I have included close-ups of the rhinophores from Koh's earlier photos and they show little sign of lamellae or even constrictions but this could be dependent on how extended the rhinophores are are any one time.

One example of the problems is that Baba described the cerata as being arranged in 'oblique rows' and yet if you look at Koh's photo, the first 3 rows of cerata are clearly in arches. You will see 3 pinkish arches on the left side of the animal. What has happened here is that the animal has dropped the cerata [autotomy] from these 3 rows - perhaps through being handled. Another point is that Rie Nakano's photo, and Koh's show a white tip to the oral tentacles and a white line continuing down towards the base. Baba does not mention any colour on the oral tentacles. However in your 1999 book (Photo 276, p.164) you have a Favorinus sp. which also fits Baba's description quite well, but that animal has translucent yellowish oral tentacles, with no trace of white, and has a yellow median line on the head between the rhinophores. Since these features were not described by Baba could this animal be the real Favorinus pacificus?

In a recent message from Singapore [#13607], Lim Han Peng has posted a photo of an animal very much like the one on your book, with a yellow line between the rhinophores. The cerata are pinkish rather than yellow, but that colour is due to the colour of the eggs they have been eating so is variable. The Singapore animal has much more pronounced lamellae on the rhinophores than your animal, but that suggests the degree of lamellae development is variable.

This brings up the question of Favorinus mirabilis, which I have discussed separately, is it one or two species?

Best wishes,
Bill Rudman