Opisthobranch of the Week Data
Mexichromis mariei is considered to be very rare on Okinawa's main island as I have seen and collected only three individuals. The above featured animal was collected from an area of strewn coral rubble at the reef forefront during a mid-morning Scuba dive. It was found, as depicted above, crawling on a fragment of a dead (Schizellozoon?) bryozoan colony.
M. mariei is one of two described species of Mexichromis which I've found as of this date (late June, 2003) on Okinawa's main island. The other species found here is M. multituberculata, of which six animals have been collected. In addition, I've collected and photographed several unknown Mexichromis spp. which may turn out to be undescribed species or possibly variations of M. mariei and M. multituberculata.
The following information is taken from Rudman (1999) as described on the Sea Slug Forum
Originally described from New Caledonia, Mexichromis mariei seems to be characterised by the tendency to form reddish purple-tipped rounded papillae on its back. The background colour ranges from translucent white or purple to a deep cream yellow. The mantle border usually consists of a row of orange or yellow spots, but can sometimes be a continuous band. It is similar in colour to Mexichromis festiva but the radular teeth of Mexichromis festiva have many more denticles, and the purple spots are not noticeably raised. I initially (Rudman, 1973, 1983) identified animals from the western Indian Ocean with Mexichromis mariei, but perhaps that species should be considered a distinct species. I have posted it here as Mexichromis cf. mariei. It seems to be consistently different in having bluish purple rather than reddish purple spots. Another species with dorsal papillae, Mexichromis macropus, differs in radular morphology and in having a border of radially arranged orange or yellow lines. See also Mexichromis cf. multituberculata which varies in the colour border and has pointed wine-red tipped tubercles.