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Asterocarpa humilis

(Heller, 1878)

Angela Gall Here is another image of the Compass seasquirts, Asterocarpa humilis with other ascidians growing on them. They are hard and closed up out of the water, very tough, like little golf balls.

Becky Hitchin gosh, interesting]

Anne Bay-Nouailhat well, haven't seen that species here yet!

Message posted on NE Atlantic Tunicata on 28 Jun 2012
Angela Gall Compass seasquirt, Asterocarpa humilis, found on pontoons at Falmouth during a course run by John Bishop

Message posted on NE Atlantic Tunicata on 28 Jun 2012
George Brown Can anyone help me out with the ID of this tunicate? I've many pictures of similar individuals but they display subtle differences which I'm trying to level out.

Keith Hiscock Could be a straightforward Polycarpa sp. (It will take a brave man or woman to put a specific name - Bernard?) But could be Asterocarpa humilis - a non-native species and new arrival - the stripes inside the siphon are characteristic but those on your image not very strong. John Bishop might be able to help.

George Brown Hi Keith, many thanks. I should have added that it's from the mouth of Loch Eriboll, on Scotlands north coast. Around 22 metres depth on a limestone cliff.

Claire Goodwin I'm with Keith - probably P. pomaria or P.scuba (the colour looks more like what we call P. scuba but depends how big it is). All these squirts need a lot more ground truthing with photos and dissections.

David Kipling Did you ever decide what this was, George? Is one possibility Pyura microcosmos, which has internally-striped siphons (I'll post a picture)?

Message posted on NE Atlantic Tunicata on 27 Apr 2012
Niels Schrieken Aplidium glabrum. Netherlands, Bruinisse, Oosterschelde.

David Kipling Looks like a thin transparent delicate test over zooids, as opposed to a solid mass. I would have said Diplosoma?

Niels Schrieken You are right David. This is Diplosoma listerianum.

Bernard Picton Is this Asterocarpa humilis in the background?

Niels Schrieken Ascidiella aspersa.

Bernard Picton Oh, not with those siphons I think! Have you got other photos?

Niels Schrieken Tomorrow I will go back to the same spot will make some pictures.

Niels Schrieken Why do you it's asterocarpa? As far as I know this sea squirt is never found in the Netherlands.

Bernard Picton Just a guess, Niels. I've not seen many ascidians with siphons like that, with such obvious papillae. I've not seen Asterocarpa either! It is well established in Northern France and SW England now. http://www.springerlink.com/content/e01215217m4q8864/

David Kipling http://www.springerlink.com/content/e01215217m4q8864/MediaObjects/10530_2012_286_Fig1_HTML.jpg

David Kipling (that should be a link to the key pic in the paper)

Bernard Picton Oh, it's not that then, I remembered the nice pattern, but Asterocarpa doesn't have any papillae.

Message posted on NE Atlantic Tunicata on 03 Oct 2012
David Kipling Does anyone have "in the field" pictures of the non-native sea squirt Asterocarpa humilis (as found on south coast and some other UK sites)? I'm struggling to find any on the web.

Message posted on Seasearch Identifications on 25 Jun 2012
João Pedro Silva From yesterday's night dive in Sesimbra, Portugal. Maybe Ascidia mentula?

David Kipling Ascidia mentula (in my mind) has a more gelatinous test, as opposed to leathery. This reminds me more of something like a Polycarpa, although perhaps not with that amount of crud on it. As a left-field suggestion, how about Asterocarpa humilis (the non-native Compass Squirt) based on the stripey siphons....was this dive near a harbour or marina by any chance?

David Kipling Probably not this actually, stripes are a bit wild! http://www.ceab.csic.es/web/wp-content/uploads/2013/01/Asterocarpa-humilis-4.jpg

João Pedro Silva This spot is about 2km away from Sesimbra's harbour and although the budy harbour of Setúbal is over 20km, ships pass relatively near.

David Kipling Hmmm, not exactly prime territory for a non-invasive. They tend to stick around the harbours/marinas (with the exception of Corella eumyota which seems to be very happy about spreading out onto local reefs!).

Message posted on NE Atlantic Tunicata on 11 May 2013
Animalia (Kingdom)
  Chordata (Phylum)
    Tunicata (Subphylum)
      Ascidiacea (Class)
        Stolidobranchia (Order)
          Styelidae (Family)
            Asterocarpa (Genus)
              Asterocarpa humilis (Species)
Associated Species