Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

Discovery of a Radical Metamorphosis in the Commensal Amphipod Family Anamixidae.

Event Name/Location

Annual Meeting of the American Society of Zoologists, American Microscopical Society, Animal Behavior Society, Crustacean Society, International Association of Astacology, and the Society of Systematic Zoology / Louisville, Kentucky

Presentation Date


Document Type

Conference Proceeding

Proceeding Title

American Zoologist - Vol 22, No. 4




Small, pene-bearing males of the Leucothoides stage transform in to the larger and radically distinct pene-bearing males of the Anamixis stage in a single ecdysis. This is the first known transformation of its kind in the Amphipoda and requires the synonymy of Leucothoides Shoemaker with Anamixis Stebbing and redescription of the family Anamixidae. Transformations were observed in living material of Anamixis hanseniStebbing, 1897 and Anamixis n. sp. from the barrier reefs of Belize. The amphipods were collected with their ascidian hosts and removed for observation. Major morphological changes include reduction of size and complexity in mouthparts and the change of size and configuration of gnathopod 2. The Anamixis stage has enlarged maxilliped palps that are used in feeding. All species formerly assigned to Leucothoides must now be connected to Anamixis and Paranamixis based on pairs of intertransforming taxa. Amplexus has not been observed in either stage and reproductive strategies remain unknown.



Oxford University Press

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