August 2, 2001
From: Irina Roginskaya
I wonder why our colleagues, absorbed in a hot discussion about colour peculiarities of different specimens of Dendronotus, forget the characteristic distinctions in the radular teeth of some species of this genus. For instance the form of the central tooth. I am sending here the pictures of central teeth of three of our common northern species:
TOP RIGHT: Dendronotus robustus (Verrill, 1870) from Dvinsky Bay of the White Sea.
LOWER LEFT: Dendronotus dalli Bergh 1879 - from Kandalaksha Bay, near the White Sea Biol.Station of Moscow State University
LOWER RIGHT: Dendronotus frondosus (Ascanius,1774) - from Spitzbergen.
The distinctions are rather obvious. And the laterals are also different in these three species. Perhaps it is worth to see at least radular structure of enigmatic specimens, which may be could help better, than colour, to separate species.
Roginskaya, I., 2001 (Aug 2) Radular teeth of Dendronotus.. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4705
Thanks for the radula photos. I think I can speak for all our colleagues who were discussing these North Atlantic species of Dendronotus, when I say that none of us had forgotten the radula or internal anatomy, just as we had not forgotten the radula when discussing how to identify the North Atlantic species of Flabellina.
It would be very useful if these animals hung their radula in a necklace around their necks so we could look but not touch. It is a major problem for ecologists, as well as amateurs and photographers, that many of these species can only be accurately identified by killing and dissecting them. Any help we can give them, and each other, on trying to identify these animals as living animals would be a help. Most of us pick up little clues over the years that help us to personally identify species. We usually don't publish these 'hunches' because we never have a chance to test them 'scientifically' but sharing them on the Forum may be a useful 'unofficial' way spreading the word.