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
Prostomium:
lobe shaped with two, dark, lateral "eyes" (can nuchal
organs be pigmented?)
Peristomium:
ventral circum oral
Segments:
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
pygidium
small, rounded,undistinguished from segment 10
gut:
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.
gonads:
none observed.
there were free-floating cells in the ceolem of
several of the segments between segments 3-9
habitat:
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.
Regards
Matt
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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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