[Peter Finke]

For me, P. bintan is one of the riddles of the genus. It was described at a time where we were far of the knowledge of the many local forms that are more or less similar, quite a few of them native to Sumatra that was hardly well-known at that time. This holds for Maurice Kottelat, too. in the two decades since we came across many bintan-like forms. Take Belitung, an island near Bangka on which Horst Linke found P. spec. Belitung. The problem is at least as much a problem of theoretical biology than as much a problem of empirical knowledge of localities. It is mirrored by the fact that Kottelat is silent on Parosphromenus since his last description of five new species in 2005. They were rather clearly separable by structural criteria, not by mere colour. Since then description has become difficult: You hit the border of the traditional methods that ignore genetic means. But all we have learned since then by genetic analysis is that the many different but similar forms are extremely near to each other. Since then bintan has become a catch-all-species, and as aquarist-specialists we react by speaking of bintan-like fish.
Clearly, these fish to be seen here are bintan-like. If you take only the well-described species they are bintan, no doubt. The association “P. deissneri” is clearly wrong, for that species can be distinguished by clear structural criteria. Without any reliable information on their location there is no other determination possible. But a question remains: Are all those bintan-like forms bintan or not? Is blue-line bintan? Is Sentang bintan? Is Belitung bintan? And that reduces to the question: Is the description of bintan sufficient and final even in 2016?
My position is the following: Parosphromenus is so interesting a genus since we come across fish that are highly diversified locally. Why? Because the species are still developing, on the basis of local segregation. Presently, we encounter a still-photo of a highly dynamic evolution, the evolution of different species from a common mother-species, but in many cases the process has not come to an end so far. This is the reason why Kottelat is silent. What with his traditional taxonomic methods and in the light of the genetic similarity should he do otherwise?
Conclusion: The Glaser fish is not deissneri, but a bintan-like form. Whether it is bintan, is not a question of exactly looking at these fish but a question of the species-concept we use in the case of the dynamics of presently ongoing evolution. My tendency is to use it in rather restrictive a way, say: all are bintan, because for developing species I prefer to be a lumper. And that means we have to reformulate – at least to supplement – that decription of bintan in the light of the many new forms. But my impression is that many people, even taxonomists, and especially aquarists (even notorious discoverers as Horst Linke) prefer to be splitters; they tend to take developing species to be (hitherto undescribed) species already.
I don’t think we could say more at present. For a more detailed analysis we need better photos (lighter!); then we could possibly make some suggestions on the locality the fish might come from. But that’s all. We could not say whether they are bintan or only bintan-like. Since that’s a question of how to deal with ongoing evolution in the taxonomic business.