I asked dr Finke about this fish. I’m uploading the e-mail, as asked by him:
“Sverting, yes, this is quite an extraordinary fish. I can well imagine one could think it’s a P. deissneri, but equally one could think it is not. I shall explain my opinion: It is no deissneri and should be deleted from a homepage trying to explain that species.
The fish shown exhibits some features typical for a deissneri-male:
The dorsal fin is rather long
The pattern of blue markings especially in the caudal resembles to some extent deissneri
The same holds to a lesser extent for the dorsal
And to a still lesser extent for the anal fin.
But there are some important characteristics of a male deissneri missing:
There is no black filament at the end of the caudal
The caudal is rounded, whereas that of deissneri has a rhombic from
The length of the dorsal is not enough for deissneri
The markings I spoke of in caudal, dorsal and anal are not of the typical deissneri-character (short parallel streaks with clear black intervals between each). Even in the most similar fin, the caudal, they do not show that streaky form and they are not directed strictly parallel and horizontally.
So, what is this fish?
It is clearly no deissneri. All deissneri we know (I have seen many from diverse origins: wild caught one by K. Bieler, G. Kopic, A. Brown, offspring bred by these and by K. Keibel, B. Wilden, B. Bussler, and my own) do not show any marked variation. The pattern of specific fin structure and markings is remarkable stabile. P. deissneri has one of the longest dorsals of the genus (XII-XIII, 6); in fact the male deissneri appear to be rather longly drawn in general. And there was always that typical pattern of well-isolated and parallel blue streaks in all unpaired fins, and the rhombic from of the caudal with a black filament of several millimeters.
P. deissneri is one of the easiest species to determine. There are very good photos of it, especially those of Keibel or Linke. Take the cover-picture of the Parosphromenus-AMAZON-issue, showing one quindecim and two times deissneri.
Nevertheless the picture is disturbing. Which licorice gourami does it show to us? I do not know. It’s a bintan-type with its rounded caudal, but I cannot say it to be typical for the one or the other. What disturbs me most is the statement you cite that this fish is an offspring of a clearly determined deissneri. So I infer from that: This fish shown here in not wild-caught. Its an aquarium breed.
Would it be wildcaught, I should say: Well, it’s new to us, or: It’s a natural hybrid, or: It’s deformed by immissions into his natural habitat. We have very bad reports of immission of old dirty tin mines into the blackwaters of Bangka (Yashuyuki Kishi from the “Team Borneo”). But apart from my conclusion on the basis of your citation that the fish must be aquarium bred it is very unlikely that so many clear markers of deissneri would be affected simultaneously as it is the case with this fish. That it should be new to us would be possible (if it is wildcaught), and that it is a natural hybrid, too. But both is not very likely.
One interpretation I have is that it is an aquarium bred hybrid including a deissneri as ancestor. This is possible, of course, although we have little proof of it. The female deissneris could more easily be interchanged than the males. The other interpretation is that it is an unknown bintan-type (P. cf. bintan) that shows a bit more variation than we see normally. We know that P. bintan occurs on Bangka, too.
At any rate this picture does not show a deissneri. So, it should be removed from the page that tries to explain that species. There are enough perfect pictures of that species. And I appreciate the written text very much: it is well-founded with one exception: Several times only one location is named again and again. There are quite a many locations where deissneri was found and still is found. Three members of our project will travel to that island in autumn this year to look for the real deissneri.”