Pearling in Leptodictyum?

**lampeye** · 7th Dec 2010, 00:04

A moss that I've collected in a nearby spring appears to be one of the many forms of the variable Leptodictyum riparium. When growing "in the wild," the moss always has bubbles at the growing points, giving it a silvery appearance. Be assured that the plants are constantly submerged, and it grows side-by-side in the same spring with a Fissidens species (either F. fontanus, or F. halli, or something similar - that moss is by far the most abundant in the spring).

In the aquarium, it is much less compact, becoming somewhat stringy (it is not one of the vertical-growing forms), but often it will still have these bubbles at every "stem" tip. I've yet to grow it with CO2, but I'm curious - is this a common observation among those of you who grow Leptodictyum?

Also, keep in mind the word "appears;" perhaps it is some other genus - do any of you have any experience with mosses that regularly keep bubbles at their stem-tips?

I think I promised photos of the place where the moss was collected some time ago, but I've yet to get around to it. Soon!

**stephan** · 8th Dec 2010, 20:03

If I forget the lights on Leptodictyum is the moss which pearls the most. My aquarium has injected CO2. Being a fast grower it stands to reason that this moss will photosynthesise and pearl the most.

How did you get to the possible ID of Fissidens halli? Any photos?

regards
Stephan

**lampeye** · 9th Dec 2010, 04:35

I'll have to get some pics soon. First, I mis-typed -I meant F. hallianus. Whether the fissidens is that species or not is something of a guess. I have an OLD moss ID book by Conard, and I know that halli is similar to fontanus (possibly a synonym?) and that it has records for PA. I have not much confidence in the ID, but it's a possibility.

**bossteck** · 9th Dec 2010, 09:28

Any pics of the moss you're talking about?

**lampeye** · 6th Jan 2011, 22:01

I still haven't gotten around to getting decent photos, but it's some kind of Amblystegium-type (Eurhynchium? Hygroamblystegium? Leptodictyum? That whole family is a nightmare, ID-wise).

And does anyone have current info as to whether F. fontanus and F. hallianus are synonymous?

**stephan** · 8th Jan 2011, 20:53

Fissidens hallianus is an accepted species. It is not a synonym of F. fontanus. see http://www.tropicos.org

If found it might make a welcome addition to the hobby.

(I have a Fissidens fontanus variety from France, It is larger then the US variety and not as compact.)

regards
Stephan

**lampeye** · 10th Jan 2011, 23:37

Hm. Mosses of Eastern North America (1981) suggests synonomy is likely, based on the quality/condition of the type specimen. Hopefully this huge URL works, but if not, see pg 113 of Vol I of MoENA http://books.google.com/books?id=Rdf...lianus&f=false

I have found that the moss from the spring in Allentown is, so far, (macroscopically) indistinguishable from F. fontanus hobby material when grown with CO2 supplementation.

**stephan** · 13th Jan 2011, 01:29

Could not find the book. Sorry. But it is a 1981 print and the Tropicos database is updated. So much so, that as one of the authors of the Mediterranean Moss checklist I have been instructed to use it as a reference to synonyms.

So if F. hallianus looks like hobby Fissidens, and F. Fontanus (from France) does not look like hobby Fissidens, could it be that what we are growing in aquariums all over the world is Fissiden hallianus and not fontanus??!!

**lampeye** · 14th Jan 2011, 04:44

? No, I don't think that's the case. F. fontanus is a widespread and well-known species, at least here in the U.S. F. hallianus looks very much like F. fontanus, unless a new type specimen was declared since the publising of that book. There are one or two minor differences, but the authors of MoENA suspected that most of those differences were a result of the type specimen of F. hallianus being deprived of light and adequate nutrients. Stephan, did you try the link I supplied? It should bring up Google's archived copy of that book. The discussion of F. hallianus/fontanus is on page 113, I believe. There is a drawing of F. "hallianus" as well.

There was really NO thinking on my part when I first mentioned F. hallianus. I simply mentioned it as a possibility. The moss in Allentown looked different from the F. fontanus I've seen, but it is subject to natural outdoor conditions, high flow rate, and plenty of biocover. I totally jumped the gun and was making a hopeful suggestion - most likely it is the much more common F. fontanus.

**stephan** · 15th Jan 2011, 06:11

Sorry can't open the link, but I have found a more recent publication at Flora of North America which says;

Fissidens hallianus, named for Elihu Hall, has been confused with F. fontanus; they can be found growing together and both have similar vaginant laminae, although in F. hallianus there can be a weak limbidiuim on the proximal margin. ... http://www.efloras.org/florataxon.as...n_id=250075573

Given that there are differences between Fissidens fontanus from different areas i would be greatly surprised if there is no visible difference in the growth habit of the two species. The fact that the description mentions that they are found growing together appears to support this visible difference.

**lampeye** · 16th Jan 2011, 01:09

Originally Posted by stephan

Given that there are differences between Fissidens fontanus from different areas i would be greatly surprised if there is no visible difference in the growth habit of the two species. The fact that the description mentions that they are found growing together appears to support this visible difference.

I'm not sure what your point is, here. The link you supplied GIVES THE DIFFERENCES. In WRITING (which seems, btw, to be taken from the description in Mosses of Eastern North America). If you've kept mosses in an aquarium, you know that even individual clones can be so variable as to appear as different species when grown under even slightly different conditions. For that reason, a visible difference in the field wouldn't be terribly useful if the species are similar, and the description you copied even SAYS that the two are difficult to distinguish!

I'll try linking the archived page 113 of Mosses of Eastern North America, Vol. I again- http://books.google.com/books?id=Rdf...lianus&f=false

The book is not public domain so I can't copy an paste the relevant paragraphs, but in a nutshell, it says that the "gametophytes are indistinguishable" and while it acknowledges the differences in the fruiting bodies, closes out the discussion with "until other fruiting material is available, we do not feel that F. hallianus can be justified as a taxon genetically distinct from F. fontanus."

Bottom line, they are very similar, and one could speculate until one is blue in the face, but until one has fruiting material, ID is uncertain. If you find any citations mentions newer fruiting material of F. hallianus, that would be of some use.

**lampeye** · 18th Jan 2011, 02:51

FINALLY generated some useful pics

Pic one shows what the moss looks like shortly after collection, kept in a jar with no supplemental CO2. It is slightly etiolated, but only slightly. The second and third pics are the moss after a few weeks of CO2 injection. As of the past few days, it has produced an abundance of side-shoots and therefore will be much bushier, but I'll wait to supply a photo until the "transformation" is complete. Like many mosses (but not a feature I've seen with most Leptodictyum/Amblystegium/Hygroamblystegium) it went crazy with the rhizoid production (the brown "fur") after going into the aquarium.

Unlike "stringy moss," this moss doesn't grow straight up when left to its own devices. The upright habit visible is unusual for this particular moss, and seems to be related to the high light/high CO2/heavy current conditions. When grown in a jar, it doesn't reach for the surface like S.M. does. The pearling visible in the third photo is only a fraction of what you'd see had the photo had been taken in the afternoon. In habitat, the moss is a deep blackish-green due to biocover and the pearling is very noteworthy. It is ALWAYS covered with a silvery film of bubbles.

I didn't bother with the Fissidens, because, well, it looks like typical "us fissidens" when grown with CO2.

**stephan** · 18th Jan 2011, 21:08

Here is the difference between "US Fissidens" on left and "Paris Fissidens" on the right, grown in identical conditions.
Fissidens spp.jpg
The French F. fontanus (5 stems on the right) is larger and a deeper green;
Fissidens spp2.jpg

It would be interesting if you can locate F. hallianus.

best regards
Stephan