Visual pigment diversity in two genera of mantis shrimps implies rapid evolution (Crustacea; Stomatopoda)

1. Interspecific diversity in the visual pigments of stomatopod crustaceans was characterized using microspectrophotometry. We examined the 10 visual pigments in main rhabdoms in retinas of 3 species of each of two genera of stomatopod crustaceans of the superfamily Gonodactyloidea, Gonodactylus (G. oerstedii, G. aloha, and G. euracaoensis) and Odontodactylus (O. scyllarus, O. brevirostris, and O. 'havanensis'). Species were selected to provide a matched diversity of habitats. 2. In each genus, visual pigments varied in λ(max) in several regions of the retina, as revealed by analysis of variance. The variation within closely related species of the same genus implies that visual pigments can evolve rapidly in stomatopods. 3. In photoreceptors of the peripheral retina, which are devoted to spatial vision, visual pigment λ(max) decreased as the depth range of the various species increased, a typical pattern for marine animals. In contrast, visual pigment λ(max) in photoreceptors of retinal regions devoted to polarization vision (midband Rows 5 and 6) is not obviously correlated with the spectral environment, implying that polarization information may be confined to particular spectral ranges. Visual pigments of the tiered rows of the midband, which are committed to spectral analysis, span a larger spectral range in shallow-water than deepwater species