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Possible Ctenodrilidae

Matthew R Lee mlee at genes.bio.puc.cl
Thu Mar 13 21:34:16 EST 2003

Dear Annelidans

I've just come across a very small worm which I think may belong to the 
ctenodrilidae.  There doesn't appear to be any record of this family in Chile 
so I've nothing to go on as far as identifiaction.  A wild guess is Ctenodrilus, 
but as I've never seen Ctenodrilus and the only info I have to go on is that in 
the black book (Rouse and Pleijel) it is just a guess. It could be a juvenile, but 
it is definitely complete.  The following observations were made of a single 
live specimen, which is still swimming around in a petri dish in my lab.  

Ctenodrilidae (Ctenodrilus sp??)

Total length 700um width 55-75um
10 segments

lobe shaped with two, dark, lateral "eyes" (can nuchal 
organs be pigmented?)

ventral circum oral

well defined with septum, no parapodia, junction between 
segment 2 and 3 ciliated laterally (excretory organs?)
chaetae highly mobile, orientation anterior or posterior can
be quickly reversed to allow the organism to move either
forwards or backwards.

segments 1-2
2 long flexible capillary chaetae
no hooked chaetae
group of five "toothed hooks"(length 8um/5 teeth) on either side
of the gut located internally with anterior-posterior
orientation, in both segment 1 and 2.

segments 3-9
3 long flexible capillary chaetae, the central chaeta is 
shorter (20um) and oriented in the opposite direction to the
two outer chaetae(40um)
single bifurcated hooked chaeta (21um -cord)hooks directed 
towards posterior end

segment 10
2 long flexible capillary chaetae
no hooked chaetae

small, rounded,undistinguished from segment 10

green colour
sinuous in segments 1-3, straight in segments 4-9,
tapering to anus (assumed not observed) in segment 10
bucal region and anterior part of the gut ciliated.

none observed.
there were free-floating cells in the ceolem of
several of the segments between segments 3-9

intertidal biogenic sediment (shell and barnacle fragments)
very coarse
exposed site
Punta del Lacho, Las Cruces, Region V, Chile.

Secondly, I have a Pisione species which is definitely new for Chile.  It 
comes out as P. ungulata in the key provided by San Martin.  I need to get 
hold of the reference to check this out can anybody help me out there:  

de Wilde & Govaere (1995) On the pisionids (Polychaeta: Pisionidae) from 
Papua New Guinea, with a description of six new species.  Bulletin de 
l'Institut Royal des Sciences Naturalles de Belgique, Biologie, 65:53-68.

Dr. Matthew R. Lee.
CASEB & ECIM, Dept. Ecologia, P.U. Catolica de Chile, Casilla 114-D, 
Santiago, C.P. 6513677. Chile.
mlee at genes.bio.puc.cl
www.meiochile.cl   (now up and running!!!)

from April 1st:
11 Briar Drive, Heswall, Wirral,
Merseyside. CH60 5RW.
United Kingdom.
leemr at btopenworld.com

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