Re: Tiny Dendronotus from southern Maine

January 31, 2002
From: Chad Sisson

Dear Dr. Rudman,
I realize this response is a bit delayed, but I've just gotten around to reviewing some of the past messages on the forum. I have been working with Dendronotus frondosus in the Gulf of Maine for the past five years during my graduate work at the University of New Hampshire, so I am familiar with the photos on this message string.

The smaller animals with small white spots are definitely D. frondosus judging from the pigmentation and branching patterns of the cerata. [message 1, message 2] The pale coloration is probably in part due to whatever they have been eating. These animals have planktotrophic veliger larvae and a radula typical for this species as described by Robilliard (1970).

The larger reddish-purple animals are definitely not D. robustus, as you mentioned [message 3]]. I have found D. robustus in a small tidal rapids on Mount Desert Island, and it has a remarkably large oral veil and flared anterior end of the foot. In my experience, they are also not D. dalli, judging by the morphology of the rachidian teeth (Robilliard 1970), although Dr. Bleakney's guide might suggest that. These animals probably should not be considered D. frondosus as we know it, so your placement on this page is justified.

These animals have lecithotrophic larvae and a radula very similar to D. frondosus. I am trying to sort out the systematics of these two types in this geographical area, so please stay tuned as I finish my thesis! For now, a description of the two larval types can be found in a paper I have in press with The Veliger (please pardon the personal plug).

There is certainly lots to be learned about the systematics and ecology of this genus in the northeast Atlantic and all northern waters.

Thanks to the underwater photographers for these great observations.

Chad Sisson

cgsisson@cisunix.unh.edu

Sisson, C., 2002 (Jan 31) Re: Tiny Dendronotus from southern Maine. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6111

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