Costasiella formicaria
(Baba, 1959)

Order: SACOGLOSSA
Superfamily: LIMAPONTIOIDEA
Family: Costasiellidae

DISTRIBUTION

Known only from Japan

PHOTO

Location: Futo beach, Izu Peninsula. Intertidal, May 2004. Photo: Nishina Masayoshi

Originally described as Stiliger formicarius (Baba, 1959) Baba later (Baba, 1961) moved the species to Costasiella.

This species grows to about 10 mm in length. It has a translucent bacground colour with a pattern of black markings. The cerata range in colour from black to green and usually have opaque white specks on the skin. The dorsal surface of the tentacular rhinophores and anterior foot corners are black and there is a black line around the eadge of the head. There is a black band runing back from the rhinophores down under the cerata and this black band can be seen along the edge of the posterior tip of the foot. Baba named the species formicarius because the black specimens he had available to him reminded him of small black ants. It is reported to feed on filamentous green algae.

• Baba, K. (1959) The family Stiligeridae from Japan (Opisthobranchia- Sacoglossa). Publications of the Seto Marine Biological Laboratory, 7: 327-334.
• Baba, K (1961) Three new species of the genus Catriona from Japan (Nudibranchia - Eolidacea). Publications of the Seto Marine Biological Laboratory 9(2): 367-372, Pls.14-15.
  

Best Regards,
Nishina Masayoshi

Authorship details
Rudman, W.B., 2008 (July 18) Costasiella formicaria (Baba, 1959). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/costform

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