mini pellia reappearance (after years)

[66north]

I've been particularly nice to my planted tank for the past few months, keeping on top of ferts and water changes. But all of a sudden I've seen the remergence of mini pellia which for some reason died out back in 2016 and hasn't been seen since. I've had fissidens come back after moving to the UK, appearing at first on driftwood that had it, but had been bone dry for over two years.

I just thought this was something that looked like malformed moss or something that looked like mini pellia but doing a trim tonight I got a closer look and there is no doubt. I can't see how it could have snuck in with anything else plant wise lately. Anyone see this type of re-emergence of a plant/moss after years of being gone?

 

[Hufsa]

I believe liverworts like your Riccardia chamedryfolia can produce spores, this might be one possible way it has reemerged in your tank.
I once had a wild species of liverwort hitchhike along with a wild collected moss, it was not present when I put the other non liverwort moss in a cup, but a while later it appeared and started growing.
I wonder if the spore was triggered by conditions being more suitable, the cup got nutrient rich aquarium water.

Riccardia in aquariums are also really good at breaking off a small piece and hiding away for quite some time. Maybe the small piece was dislodged from its hiding place and ended up where you found it, or perhaps it was there for a while, just small enough not to see?

 

[PARAGUAY]

Java Moss will often come from nowhere, l remember adding old wood and it just appeared and thrived

 

[bazz]

I could well imagine BBA making a reappearance on reused Bog Wood if not cleaned off effectively before use.

 

[_Maq_]

Numerous uninvited guests can be brought in with plants we purchase.

 

[66north]

Yes, or bonus plants. When I first got the mini pellia there was a flake of 'regular' pellia which took off, and established, I also got a strand of xmass moss which established.

The the mini pellia I'm just surprised at the gap in time, must have been around six years.

 

[louis_last]

I've had this happen often with various mosses and liverworts - and exactly the same experience with fissidens fontanus regrowing from wood that was dried and in the dark for at least a year. I think in the case of the riccardia and some others tiny fragments can settle in some dark corner of the tank and remain dormant for long periods of time, surviving but not growing, until something disturbs them and flushes them out into higher light. I don't think riccardia can produce spores underwater.
I also find that elatine hydropiper will spontaneously reappear after long absences from a tank. I was very confused when it started growing in a tank after being absent for years and it was actually one of the mods here who explained to me that this species can flower and produce seed even when completely submerged. Whenever I significantly disturb the substrate elatine hydropiper starts growing from seeds that are churned up and exposed to the light.