Note 6 - What Is a Cichlid? The Technical Details What Is a Cichlid? The Technical Details
A nontechnical introduction to cichlids is given elsewhere at this site. Cichlids are often characterized as freshwater perchlike fishes that have only a single nostril on each side, have a divided lateral line, and lack a subocular shelf, among other features. Unfortunately, these characteristics do not a cichlid make, because they are plesiomorphies - character states that are primitive with respect to cichlids. To be sure you've got a cichlid, and to substantiate cichlids as a monophyletic group, you need to know the synapomorphies, or shared derived characters, of cichlids.

The following five apparently independent internal characters, from the cranial muscles and gill arches, are hypothesized to be synapomorphies of the Cichlidae, and provide rather strong evidence that the family is monophyletic (Stiassny, 1981a: 309):

  1. "The loss of a major structural association between parts A2 and A of the adductor mandibulae muscle and the musculous insertion of a large ventral section of A2 onto the posterior border of the ascending process of the anguloarticular.
  2. "The presence of an extensive cartilaginous cap on the anterior margin of each second epibranchial bone.
  3. "The presence of an expanded head of each fourth epibranchial bone.
  4. "The presence of characteristically shaped and distributed microbranchiospines on the gill arches.
  5. "The transversus dorsalis anterior muscle . . . is subdivided into three distinct parts."

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The Cichlid Fishes of Lake Malawi, Africa:

Last Update: 14 June 1998
Web Author: M. K. Oliver, Ph.D.
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