Oh my, I am about as confused as ever!
Good point, but also in your fish the dark saddles extend below the lateral line (which they don't in P. alternans sensu stricto, although the top fish in fig. 3b in the Kottelat and Lim paper appears to contradict this ) and the fins contain markings (all fins hyaline in P. alternans sensu stricto).
Yeah. The coloration's just not quite right, almost like it falls somewhere between the common patterns in the
kuhlii and
shelfordii groups. Some of my fish almost have
P. pulla (from S. Borneo) coloration, just not as many bars nor skeletal similarities. My fish have the dark caudal base & barring on the rays, like a
shelfordii. On the other hand,
P. myersi (Thailand), currently in the
kuhlii group, also has a stripe on the tail, but not the thin black bar at the caudal base, so I guess there's still quite some color overlap between the current groupings. DNA! DNA!
Kottelat & Lim do briefly question the group they've placed
P. alternans into on p. 206, stating:
"... For the same reasons,
P. alternans is placed into the
kuhlii group with which it also shares the general body shape, although the type of coloration is reminiscent of some populations of
P. shelfordii."
I'm still having trouble telling for sure, but I think at least some of my batch has either a lobed lower lip or perhaps even complete, smallish lower lip barbels -- which of course is more indicative of the
shelfordii group. Unfortunately, a few of mine had worn-down barbels coming from the shop so it's a little hard to be sure. Kottelat and Lim show the wide variability of the
shelfordii group in Fig. 22, but remark that some locations only had juveniles and further revision of the group would need to wait for collection of specimens in intermediate areas.
At any rate, whatever these are, I think they're unidentifiable given the available info.
Perhaps Thomas's fish and mine are the same regional variety/species, and Emma's fish are their counterpart from a slightly different region of Borneo. Which again, may or may not be regional color variations of
P. alternans! Yikes.
Emma, do you know which area/river in Borneo your batch came from? I'm going to give my LFS a call later to see if they know anything about the origin of my fish.
Looking forward to more input from all you Pangio experts on here
Jen