As part of the Goby family, the Dartfishes of the Nemateleotris genus are well-known to hobbyists with species such as N. magnifica and N. decora being a mainstay of the marine hobby for years. In more recent years, N. helfrichi (Helfrich’s/Lavender/Lilac Dartfish) became available commanding a high price compared to it’s more common sister species. It has long been known however that 2 distinct forms of N. hefrichi existed, with specimens collected from the deep waters of the Cook Islands and French Polynesia exhibiting a notable overall pink colouration on the head, as opposed to a distinct yellow-face with purple/pink crown in other locations. The type species for the genus was even based on the Cook Island form.
Just yesterday, a new paper was announced in the Journal Raffles Bulletin of Zoology. In this, authors Yi-Kai Tea & Helen K. Larson divide the two species with the yellow-headed form now being described a N. lavandula, or the Lavender-blushed Firefish. The development is interesting as the vast majority (if not all) of these fish imported are the yellow-head form, this making it very unlikely that any true N. helfrichi are being kept or offered for sale. If you’ve already got a helfrichi, chances are that the correct name for it is now N. lavandula. If other recent reclassifications are anything to go by, it will take many months for the new naming to filter through to retailers. While giving the yellow-head form a name that seems more befitting to it’s close relative initially seems somewhat confusing (and makes both species commonly-used names based around the lavender theme), there’s no denying that the new name is as pretty as the fish in question.
It’s also interesting to note that the authors suggest that the similar species N. decora and N. exquisita do not exhibit sufficient differences to be classified as separate species. For this reason, N. exquisita is now regarded as a synonym of N. decora.
Read the paper HERE