Thick-lipped and thin-lipped Midas cichlids in Apoyeque differ in the shape of their pharyngeal jaws. (a) Ten homologous landmarks describe jaw shape using one side. (b) Discriminant function analysis of mean shape of thick-lipped (black; n = 36) and thin-lipped (grey; n = 135) pharyngeal jaws (scale factor = 4). (c) The morphological variation associated with the first two principal component axes (scale factor = 4), responsible for most of the shape variation. (d) Exemplars of a molariform and papilliform pharyngeal jaws from Apoyeque Midas cichlids. Note the squatter, broader teeth and thicker horns in the more molariform jaw.
Elmer et al. BMC Biology 2010 8:60 doi:10.1186/1741-7007-8-60