Fig. 8

Summary of pigment pattern developmental differences in C. azureus and D. compressiceps. a, b Xanthophores cover the body in both C. azureus and D. compressiceps at the onset of metamorphosis. c, d Melanophores appear in the skin of C. azureus and D. compressiceps during metamorphosis, with a similar strip of metamorphic melanophores at the base of the dorsal fin in both C. azureus and D. compressiceps. c Patches of metamorphic melanophores appear on the flank skin in C. azureus and grow in size by new melanophore addition in and around each patch. d Metamorphic melanophores appear along the dorsolateral-, lateral midline- and ventrolateral myotome boundaries in D. compressiceps. e, f Chromatophore distribution at the end of the larval period in C. azureus and D. compressiceps. e Melanophore patches elongate dorso-ventrally and become resolved into bars flanked by iridophores in C. azureus. New bars appear by appearance of new melanophores. Xanthophore density increases under bar melanophores. f New melanophores appear largely along already formed horizontal stripes in D. compressiceps. Xanthophores increase in density under stripe melanophores and disappear from interstripe regions. Iridophores appear in interstripe regions. g, h Pigment cell patterns in C. azureus and D. compressiceps adults. g In C. azureus bars are composed of dense melanophores lying on dense xanthophores and under loose iridophores. Melanophore densities are lower in interbars than in bars, while iridophore density is greater. Xanthophore distribution is similar in bars and interbars. h In D. compressiceps stripes are composed of melanophores and xanthophores in varying densities (greatest in SML, intermediate in SDL, lowest in SVL). Ventral interstripes are composed of iridophores exclusively, while dorsal interstripes also contain loose melanophores. i Model of differential migration of metamorphic melanoblasts in the skin of C. azureus (left) versus D. compressiceps (right). We propose that migratory potential is a major developmental difference in metamorphic melanoblast behavior between C. azureus and D. compressiceps. Under this model, C. azureus metamorphic melanophores do migrate dorsally and ventrally once they reach the skin, while skin migration is minimal in D. compressiceps, which results in melanophore positioning over horizontal myotome boundaries and formation of horizontal stripes