Publication2 med aquascape Publication1cs complete | Page 195

Vieja melanura, red headed morph,
a beautiful population from
Rio Sarstun, Belize.
Distribution Range
Map © Google
Taxonomy
It was only later that McMahan et al 2011 re-
leased a paper detailing the systematic morpho-
logical study of the two fish entitled
“Paraneetroplus synspilus is a junior synonym of
Paraneetroplus melanurus”. This study was based
on some 25 meristic, morphometric, and geomet-
ric morphometric characters. This was quite a
comprehensive study using the holotypes of both
V. synspila and V. melanura as well a 253 speci-
mens collected and identified as both fish respec-
tively. The study concludes that using all available
characters, they failed to recover diagnostic differ-
ences between these two forms, therefore a re-
description of V. melanura is provided and V.
synspila now becomes a junior synonym. Accord-
ing to rules set out by The International Code of
Zoological Nomenclature; the older fish (V.
melanura) prevails.
Many still put forward the argument based on two
morphological points…body shape and colour.
Some say the difference is quite clear because the
Lago Petén fish by all accounts are slimmer and
orange and the Grijalva-Usumacinta fish have a
pinkish coloured head with blue/yellow un-paired
fins and have a thicker profile. This is true to a
point, but hardly conclusive as there is much vari-
ability throughout the fish’s distribution range.
Günther original description of V. melanura was
very brief, only describing that the fish displays a
deep black bar going along the length from the
caudal base. Length or angles aren’t mentioned in
the description of the caudal bar, so comparing
Hubbs description that V. melanura has a less
downward slope than V. synspila, would be a little
unfounded! A straight or sloped caudal bar is
hardly a solid enough trait to separate a fish into
two different species?
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