M. atrodorsalis, oualanensis, tongaensis, smithi, fraseri, mossambicus & nigrolineatus
The atrodorsalis species complex represents the only widespread Indo-Pacific species group in the genus and is comprised of numerous endemic taxa, both scientifically described and undescribed. What all these species share is a similarly unstriped appearance, a mimicry relationship with Plagiotremus blennies, and a biogeography in which the various phenotypes appear to fit together like a phylogenetic jigsaw puzzle.
Variation in M. nigrolineatus, all from Red Sea. Credit: John Rochester, Richard Field, Arne Kuilman
In the Red Sea we find the most aberrant member, M. nigrolineatus, which can be recognized by its blue and yellow coloration and from the unusual black line which emanates behind the eye and proceeds posteriorly to the upper margin of the caudal peduncle. The location of this stripe doesn’t seem to match well with any of its congeners, giving this blenny the sort of sui generis appeal rare fish enthusiasts get excited for. It has been exported on rare occasions, and captive-bred specimens are on the books, but, in general, this is not a common find in the aquarium industry. There is also surprisingly little photographic documentation for such an ostentatious fish given how well-studied and photographed the Red Sea is. Most specimens identified online as M. nigrolineatus are in fact Ecsenius gravieri, a remarkably accurate mimic.
M. fraseri (above) and mossambicus. Credit: Phil Heemstrai & unknown
The coastline of Eastern Africa is home to M. mossambicus, a rather drab grey and black species accented with a bright yellow caudal fin—the only Indian Ocean species lacking black margins to this fin. There is little known about the true extent of this fish, with Mozambique being the southernmost record. It has been documented as far east as Northern Madagascar, where it may or may not co-occur with M. fraseri, a species primarily known from Mauritius and Réunion Islands. This poorly known Mascarene species differs in having a clear anal fin (black in mossambicus) and a clear caudal fin with black margins. M. fraseri has not been exported yet for the aquarium trade, though collection takes place in both Mauritius and Northern Madagascar.
M. smithi, showing typical soft coral and algae-rich habitats. Specimens from Similan Islands and Sumatra. Credit: Takeshi Omura, Dive to Blue, Josh Hatton
M. smithi is an elegant fish which is woefully overlooked by aquarists—when it comes to predominantly white coral reef fishes, there are few which can rival smithi for its combination of beauty and affordability.… More:
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