Berthella agassizi
(MacFarland, 1909)

Family: Pleurobranchidae


West Atlantic - Caribbean to Brazil. Pacific coast of Mexico.


Lark Cay, Belize, Caribbean, in shallow water. Photo: Jeff Hamann.

Body translucent reddish brown to pink with scattered opaque white spots. It is sympatric with Berthella stellata in both the Caribbean and the East Pacific. Grows to approx 25mm long.

  • Gosliner, T.M. & Bertsch, H. (1988) A Review of the genus Berthella (Opisthobranchia: Notaspidea) from the Pacific Coast of North America. The Veliger, 31(1-2): 46-67.
  • MacFarland, F.M. (1909) The opisthobranch Mollusca of the Branner-Agassiz Expedition to Brazil. Leland Stanford Jr University Publication, 2, 1-104.
  • Marcus, Er. (1955) Opisthobranchia from Brazil. Boletim da Faculdade de Filosofia, Ciencias e Letras. Universidade de Sao Paulo, Zoologia 20: 89-261. (Pls. 1-30)
  • Marcus, Er. (1957) On Opisthobranchia from Brazil (2). Journal of the Linnean Society of London, Zoology, 43(292): 390-486
  • Marcus, Ev. & Marcus, Er. (1957): Sea-hares and side-gilled slugs from Brazil. Boletim do Instituto Oceanografico, 6(1-2): 3-48.[for 1955]
  • Marcus, Ev. (1984) The western Atlantic warm water Notaspidea (Gastropoda, Opisthobranchia), Parte 2. Boletim de Zoologia, Universidade de Sao Paulo 8: 43-76.
Authorship details
Rudman, W.B., 2002 (October 10) Berthella agassizi (MacFarland, 1909). [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

Berthella agassizi from Brazil

March 24, 2006
From: Vinicius Padula

Dear Bill,

This is the Berthella agassizi  from Rio de Janeiro, Brazil.

Locality: Rockshore, 1 metre, Rio de Janeiro, Brazil, Atlantic, 10 October 2005. Length: 14mm. Photographer: Vinicius Padula.

Vinicius Padula

Padula, V., 2006 (Mar 24) Berthella agassizi from Brazil. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Padula,
Thanks for this record. I note that Ernst Marcus (1955) records the shell as being quite small for a Berthella - 6 mm long in a 25 mm long animal. Have you had a look at the shell in this species? Is the whitish outline in your photo cuased by the shell?
Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Mar 24). Comment on Berthella agassizi from Brazil by Vinicius Padula. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Berthella agassizi from Caribbean

October 16, 2002
From: David Behrens

Dear Bill:
Another addition for the Caribbean portion of your virtual opisthobranchs of the world monograph. I believe this is Berthella agassizi.

It was collected and photographed in shallow water at Lark Cay, Belize, Central America by Jeff Hamann.
David W. Behrens

Behrens, D., 2002 (Oct 16) Berthella agassizi from Caribbean. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Dave,
Bill Rudman