P. bintan is nearly a mysterious species as is P. deissneri, but for other reasons.
In 1998, there was a scientific redescription of the first Paro that was found in the 19th century already and named “deissneri” at that time by Peter Bleeker. But it was a female! And in the nineties of the 20th century, the holotype in the natural history museum of Amsterdam was damaged to such an extent that it was impossible to decide which of the two species known from the island Bangka it has been. So, Kottelat and Ng decided that the one with a clearly pointed tail with black filament should be deissneri, and named the other with a round tail newly: P. bintan, since they knew it from another island, too: Bintan.
But what they didn’t know at that times was that there were quite a many new forms to be discovered on other islands , too, e.g. spec. Belitung on the island of Belitung, or spec. Pemantunglumut on Borneo, or even at least seven new forms on Sumatra: spec. Pelantaran, spec. “blue line”, spec. Sentang, spec. Dua, spec. Sungai Bertam, spec. Langgam (now named P. phoenicurus) and spec. Danau Rasau (now named P. gunawani).
Since 2005, their last publication, the description-machine of Kotellat and Ng has stopped, since they see that their limited methods of looking at outer (= phenotype-)features (structure of the fins, colouring of the males) in order to describe species has come to an end. Seeing that we find more forms when we search more intensely in hitherto unsearched regions, and seeing that this is rather young a genus obviously heavily in current evolutionary development, they saw the borders of their decription method and became quiet. The only two decriptions since then were that of gunawani and phoenicurus by Schindler and Linke 2012; but both new species may have been decribed prematurely: phoenicurus as a evolutionary variant of tweediei and gunawani as an evolutionary variant of bintan. But speceis of their own already? Question mark.
And this is the real question: What do we make of the many variants of bintan that we know today (as there are Dua, Sentang,”blue line”, Pematunglumut, perhaps gunawani and others)? Is bintan really one species distributed on all those islands (that not have been islands 10.000 years ago) developing presently in slightly different variants, or are those variants already new species? We (and Kottelat and Ng) do not know this at the present time, and therefore have become more cautious than formerly in saying: this is P. bintan. Certainly, the fish from the island Bintan will be bintan, but are the fish from Bangka really the same as Kottelat and Ng thought in 1998? These two decribers have become much more reserved nowadays than they were fifteen years ago, seeing all those new forms.
Therefore Helene’s cautiousness to speak of a bintan-like form or a scheme fitting in the pattern of the bintan-forms is fully right and Bill’s taking her to have said: “it’s bintan” was premature and not justified. The fish may be “blue line” or Sentang or Sungai Bertam which all were traded already; it’s even possible they are gunawani or even phoenicurus: the latter traded indeed last year for the first time (and easy to be recognized by the many red colouring of the males), the former not surely traded the year before, but definitely named “gunawani” by traders who like to use new names in order to sell their fish.
The conclusion is: Our genus is very interesting indeed since one is for sure: it’s developing. Every river-system that survived the big destructions until now and not linked with the next may hold Parosphromenus that just presently develop new features and will be a new species at some time in the future (maybe today already, but we do not know that presently for sure) under one condition: if the big destruction gives it enough time. And this is the real problem: Man – we – do not any longer give evolution the time she had for thousands of years. Our genus shows: she can be very fast, faster than we thought formerly, but nevertheless too slow for cutters of the rainforest and street-builders and land-drainers and … fish-describers with more differentiated methods.