Trapania lineata

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Toni Palermo Trapania lineata

Ana Lama Trapania lineata y bebitos

Jørn Ari Snoghøj - Lillebælt OLYMPUS DIGITAL CAMERA Copyright: Jorn Ari

Jim Anderson I would say it is not - it looks more like Flabellina browni to me

Jørn Ari But what about the red oesophagus, situated just behind the rhinophores, is clearly visible?

Robert Eriksson Look at the length of the oral tentacles,, they are about the same as the rhinohores=flabellina if much longer then Facelina! Rings and colour are not very stable traits for species discrimination!

Robert Eriksson .. blooper.. Rings on the Rhinophores (lamellae) are a stable trait though. Not sure what you mean mean rings Jorn? Coloured rings of e.g. White pigmentstions are not stable for species deduction in any species of the Flabellina or Facelina (personlopinion).

Robert Eriksson ... Mind that the oral tentacle and rhinophores are retractible and you need to Watch the animal for some time to be able to deduce it's "normal" relaxed state. I agree that it is a Flabellina, but never saw brownii as a good species - any gene-studies done on brownii?

Jørn Ari I ment lamellae

Bernard Picton Sorry, but I completely disagree with you Robert Eriksson, details of coloration are very good characters, but you have to weight them by how big and mature each individual animal is. There is considerable evidence that CO1 barcode sequences are identical in closely related species of marine invertebrates, so the DNA evidence is partly dependent on which bit of DNA you sequence. There is a lot of observing and collecting to be done yet before we have all the answers...

Lucas CerCur I agree with you Bernard Picton

Bernard Picton Oh, and I should say I've seen hundreds of Coryphella browni in the field, kept them in containers with Coryphella lineata which they were sharing their Tubularia indivisa with, watched them considering whether to mate with a C. lineata and deciding not to....

Lucas CerCur I have seen photos of Trapania lineata mating with supposed T. fusca!!!!! from southern Spain.

Bernard Picton ;-) so then we have to determine whether the offspring were fertile. Horse + Donkey = Ass.

Bernard Picton So absence of mating is evidence of separate species, if mating is possible by the species normally sharing a habitat.

Bernard Picton But cross-species mating occurs, and sometimes hybrids are even fertile. It is thought from DNA evidence that the "species" Alcyonium hibernicum is a hybrid, yet it occurs in areas where neither parent is present.

Lucas CerCur Of course.

Lucas CerCur As I told to my students, Biology is no Maths

Lucas CerCur Fortunately....

Robert Eriksson Don't be sorry, for disagreeing, Bernard Picton, these discussions are advancing our knowledge! I would like to expain myself briefly about the colouration issue. In Flabellina, the colouration of the rhinophores and the cerata is very variable, at least when looking at Nordic specimens. Some specimens have rings, some have a partial ring, some have only spots of pigment. I am only claiming these traits in adult specimens. Colouration might be stable in other species. Of course variability of genes depends on what part of the DNA you are sequencing, as you stated. Thats why you tend to use noncoding or at least more variable genes (with a "faster evolution") for deducing closely related species. I am truly confident in that we never will have all the answers...