andrewcowley's picture

Idotea sp. ?

Observed: 21st April 2011 By: andrewcowleyandrewcowley’s reputation in Invertebratesandrewcowley’s reputation in Invertebrates
Idotea-sp-201 1

Seems similar to Idotea granulosa, except for the two pairs of almost identical antennae, not shown in any illustrations I have found. Total length about 6mm. On Codium, in a lower shore pool, on a very exposed N. Cornish shore.

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dejayM's picture

Probably not..

I'm not so certain about I.granulosa.
See mine here
Your antennae are no quite right are they.
It is remarkably similar to granulosa.
Any more ideas after 18 months?

dejayM's picture


(171 reads)
And 18 months later, I am still puzzling. The even spacing of the segments is odd - idotea tends to have a narrowing of these towards rear - see Graham's granulosa
But this is no I.granulosa because the telson says so and it is very short for Idotea,. And then the antennae configuration - odd.
So I think it might be an amphipod - tapered, plated abdomen, an array of antennae and only 6mm long. Oh for two more pictures!
So over half-way down, the paragraph Recognition, right hand picture.

dejayM's picture

Likely but....

(243 reads)
I think it is worth keeping some of Andy's posts alive. It is difficult to know how to do this without him being alive to respond.
However, I have returned to add an ID, in the hope others might get a New flag and then someone might feel they can contribute.
It was not my intention to make my ID Likely but that is unfortunately inevitable. However, I do believe it IS more likely to be a Amphipod. Bear in mind Andy's clear statement "Antennae not like any illustrations I have found". He was an expert in his field - see
As one may read in Wiki, the group Gammaridean Amphipoda is "..however considered paraphyletic, and is under deconstruction by the amphipod taxonomists" (2014)
The difficulties of separation, of even Genera, are shown in this American paper
This powerful Australian paper is a long download and, for me, a difficult read but is excellent resource
Even so it is unlikely that anything beyond the broad genera will get agreements.

Andy died in 2012 and I certainly did not know that when I placed my first comment here.