Eubranchus echizenicus Baba, 1975

Description

A small aeolid, 5-7 mm in length alive. A diagnostic external feature is the angular, anteriorly projecting foot-corners (rounded in most congeners), combined with strikingly elongate, narrow fusiform cerata (cerata in most congeners are shorter and somewhat swollen). The cerata bear a few small, inconspicuous tubercles on the surface. Oral tentacles equal in length to the rhinophores, the latter simple. Cerata arranged in 6 oblique rows on each side, the largest row containing 3-4 cerata.

Ground colour of the skin yellowish white; the head, dorsum, sides and lower half of the cerata surfaces are conspicuously sprinkled with numerous orange-red spots. Oral tentacles fully orange-yellow; rhinophores orange-yellow above and yellowish-white below. Cerata opaque-white on the upper portion with a yellow cap at the tip and yellowish-white below; the central liver canal is greyish yellow and opaque. Sole entirely colourless.

Distribution

Type locality: shallow rocky shore at Ayukawa, Echizen Coast (Fukui City, Japan Sea side of central Honshu, Japan).

Etymology

The specific epithet echizenicus ("of Echizen") is a toponymic adjective derived from the Echizen Coast, the type locality.

Remarks

Distinguished from congeners by the elongate, narrow fusiform cerata combined with the angular, anteriorly projecting foot-corners. Closely compared with the Tanzanian Eubranchus rubropunctatus, which similarly bears scattered spots on the back, sides and cerata, but in which the spots are yellowish brown rather than orange-red.

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References

• Eubranchus echizenicus n. sp., Baba, K. (1975). On Two New Species of Eubranchus from Ayukawa, Echizen Coast, Japan Sea Side of Middle Japan (Nudibranchia: Eolidoidea: Eubranchidae). Venus (Jap. Jour. Malac.). 34(3-4): 65-72.
• 高岡生物研究会. (2002). 日本海のウミウシ. 第2版.