Opisthobranch of the Week Data
Mexichromis multituberculata is considered to be uncommon at most dive sites on Okinawa, with the exception of Tengan Pier, where these animals are commonly observed. I've collected only six individuals, but I've certainly seen, and in some cases, photographed others, especially at the Tengan site. The above featured animal was found at the Seragaki dive site crawling upon the surface of a patch of fine sand, amid strewn coral rubble within spur and groove formations of a live stony coral reef.
M. multituberculata was originally described by Baba (1953) as Glossodoris multituberculata. The description was based upon a single 20mm specimen collected in 1951 from Sagami Bay, Japan. Prior to Rudman's (1990) description based on a photograph of a single specimen from Hong Kong, the animal was known only from Seto, Kii, Japan and Hainan, China.
M. multituberculata is one of two described species of Mexichromis found to date on Okinawa. The other species found here is M. mariei, of which only 3 animals have been collected as of late June, 2003. I've collected and photographed several unknown Mexichromis spp. which may turn out to be undescribed species or possibly variations of M. multituberculata.
M. multituberculata is readily distinguished from other Okinawan chromodorids by the numerous large purple-tipped tubercles covering the dorsum, purple rhinophores and gills, and the irregular gold-colored marginal line which all the Okinawan animals collected, and/or photographed, possess. The above featured animal is typical of the pattern in respect to the marginal line seen in the Okinawan material. It's interesting to note that Baba's original description didn't mention the marginal line, although as noted above, the original description was based on a single specimen. Baba (1989) later described the marginal line as being "a broad band of opaque white which is regularly interrupted by red-purple tubercles." Still unlike that seen in the Okinawan material.