Richard:

You may have a glimpse of Physa acuta from topotypic material in the link provided hereunder:

http://www.bioline.org.br/pdf?oc03112

Best

Syed

Fauna Europaea may help - faunaeur.org 

Thanks Syed & Dmitry. That's immensely helpful.

Cheers,

Richard

Physa heterostropha (Say, 1817)  is synonymous with Physella acuta. Physella gyrina is a valid name. Physa skinneri is recorded recently from Ukraine. Physella (=Haitia) acuta is very widespread. These are from Physinae and nonnative.

Also from Physinae, Physa fontinalis is in Physa. Aplexa is in Aplexinae, a separate subfamily, and Bulinus is in Planorbidae. These are native.

A total of 5 Physidae species are known from Europe.

Thanks Umit - I think I have the measure of this now, with your help.

All best,

Richard

Using Taylor's (2003) Revision of the Physidae. The two introduced physid species in Europe would be Haitia acuta (Draparnaud, 1805) and Physella gyrina (Say, 1821). If you follow the work of Wethington and Dillon, then as far as they are concerned there are only two genera, Physa and Aplexa but they do not deal with anything that occurs outside of the US and Europe.

Thanks Stephanie. I think this is the substance of my confusion. My inclination was much more towards Wethington & Dillon, but there seems to be crossovers between taxonomists on the issue. Anderson (2005) has both species under Genus: Physella, but Gloer (2015) as G: Physa. What is at least clear from the answers is that P. gyrina is clearly a safe species. Gloer (2015) also had Physa adversa (Da Costa 1778), but, as far as I know, this hasn't yet reached Britain.

Cheers,

Richard

Physella is considered whether as a "full" genus or as a subgenus of Physa, nonetheless the name is a valid.

Thanks Ivan. A subgenus approach makes sense.

Richard Physa adversa (Da Costa 1778) may be synonymous with fontinalis

That's most interesting, Umit. Thanks for that.

Dear Dr. Chadd - As usual, not all authors are agreed and this is good for the development of knowledge. Worms considers only four genera (Physa, Physella, Aplexa, Archiphysa), but from the monumental work of Taylor (2003) would be a much more complex classification. I attach the file. Sincerely Gianluigi

Hi Richard,

I personally follow the line of thought of Amy Wethington and Rob Dillon, but my life is probably made easier by the fact that apparently -- and please let me underline "apparently" -- we have only Physa acuta around here (central Italy).  The native Physa fontinalis is long gone, well before I was born.  Cianfanelli et al. (2007) report that, based on museum records, P. fontinalis disappeared right at the time P. acuta (which they call Haitia acuta) appeared in central Italy, some ~150 years ago.  I have never seen Physa gyrina around here.

When I was based in the US I encountered Physa integra, which later was renamed P. acuta by Dillon and coworkers (P. integra = P. heterostropha = P. acuta), based on molecular and reproductive behavioral observations.  Dillon and coworkers also lumped several (pseudo)species of North American Physa together, coming up with maybe a dozen species (if memory doesn't fail me) from the original 40+.

I personally use the genus name Physa, as this is what Dillon suggested, Physa acuta being the oldest nomen for this species.  (Funny how this North American native was named for the first time in Europe!)

Please let me know if you need detailed bibliographic references on the subject -- or at least the references that I have.

I'm not a taxonomist (just a simple ecologist), but I hope this helps a bit.

For more details, maybe try to contact Robert T. Dillon Jr. (he's on ResearchGate).

-Paola

Many thanks Gianluigi and Paola - that's very helpful. My co-workers and I are starting to get to grips with this, at last.

I didn't know P. fontinalis was extinct in Italy - it's a hugely common species for us. Subdominant in some environments.

I may well follow your advice, Paola & contact Robert Dillon

All best regards,

Richard

I don't think P. fontinalis is totally become extinct, although it became rarer as  Cianfanelli et al. (2007) mentioned. P. acuta is also responsible for the demise of Bulinus truncatus in Portugal.

Hi Umit,

As far as I remember Cianfanelli et al. (2007) report that P. fontinalis got locally (central Italy) extinct based on museum specimens, so in situ surveys might have given different results.  However, I confirm that, personally, I have never, ever observed a single P. fontinalis individual in central Italy versus a gazillion P. acuta in almost every lake that I have visited.

Hi Umit

I'm agreed with Paola. Me too I have never found a single, living, individual of P. fontinalis in central Italy. The only two italian specimens in my collection come from Veneto (Sottomarina - Chioggia), found by a friend of my in the 1991.

In Turkey, also it is local. I dont know if it always had a patchy distrbution or become localised. Frankly I also know a single population. It is apparent that there is competition among several species of the same niche. However, as you would agree, extinction is difficult to term even when you seem to lose everything, let alone having trazillions to sort out. For sure, P. acuta is an undestructible invasive and Italy is one of the quickest 'occupied' lands regarding published reports. It probably killed out others taxa as in the case of Bulinus.

Hi All,

That's most interesting. I work predominantly in river environments in the UK and have never regarded P. acuta as especially invasive. For sure, we have streams in which this is the dominant physid, but these tend to be highly urbanised, small and polluted. The larger rivers and drainage systems rarely support them, but have plenty of P. fontinalis. I wonder if a differential tolerance to winter temperatures has held P. acuta back in the UK and maintains P. fontinalis as a common species in the UK.

Dear Richard, 

It is an established invasive in most places, say for instance just as house sparrow in your country and most of Europe. I would say rather summer heat, or rather eutrophication, is what boosts P. acuta. While P acuta can be found in extends into even tropical areas, it is notable to say P. fontinalis has boreal distribution and it is marginally distributed already in countries like Italy and Turkey (so its kind of natural to be scattered and rarer).

Makes sense. Thanks Umit.

Thank you Paola and Ümit for introducing me to the concept of gazillions and trazillons! Not sure if gazillions < trazillions, though?

@Irene:

:)  I'm not sure if gazillions < trazillions either -- I must confess that "gazillions" come from the Disney characters tradition (Uncle Scrooge and his gazillion $$ in his money bin), while I'm not sure about "trazillions"...  :)

@Paola:

Uncle Scrooge? I have to check this one!! Thank you!

The NBN Gateway lists Physa fontinalis but  one recent book refers to it as Physella (Physa) fontinalis.  Has its genus been changed or is Physa still correct?

Still correct. At least Physa has the precedence over Physella.

Many thanks.

In the Netherlands Physa fontinalis and Haitia acuta are very common in stagnant and slow flowing waterbodies. Physa fontinalis is only present when there is some aquatic weeds in less organically polluted sites. H. acuta is mostly abundant in either organically polluted or anthropogenic waterbodies with no aquatic weeds. If we find H. acuta abundantly the habitats are in most cases unstable environments. Both species are rarely found together at the same place.

Thanks Ton. This matches with what I find in the U.K. P. (H) acuta is pretty much exclusive to urban streams, whereas P. fontinalis is ubiquitous in rural rivers, streams and ditches