The Biogeography of Brachylophus (Iguanidae) including the Description of a New Species, B. vitiensis, from Fiji

TLDR: The new iguanine can change color rapidly from light green to jet black in less than five minutes, though reversal to green takes far longer, and is apparently more primitive than B. fasciatus, and shows more obvious affinities with other iguanin genera including Conolophus, Iguana and Cyclura.

Abstract: Brachylophus fasciatus (Brongniart 1800) is widely distributed throughout Fiji and Tonga Groups, though little is known about its abundance on different islands. Brachylophus vitiensis sp. nov. is described from Yaduataba Island (16? 50' S; 178? 20' E), Fiji. Since B. brevicephalus Avery and Tanner 1970 is here regarded as synonymous with B. fasciatus, the genus has until now been monotypic. B. vitiensis differs from B. fasciatus in several morphological features including larger size; longer spines on the nape; little sexual dimorphism; a differently shaped dewlap; narrower vertical bands on the body; pinkish-gold eye coloration; greater numbers of upper and lower labial scales; structure of the nostril scale; the greater color lability; whitish ventral coloration; and larger eggs and hatchlings. There are also ecological and behavioral differences. The new iguanine can change color rapidly from light green to jet black in less than five minutes, though reversal to green takes far longer. B. vitiensis is apparently more primitive than B. fasciatus, and shows more obvious affinities with other iguanine genera including Conolophus, Iguana and Cyclura. The ancestral form of Brachylophus probably arrived in the South Pacific from the Americas on rafts of floating vegetation on a course determined by the South Equatorial Curent. The presence in Fiji and Tonga of the Atlantic mangrove, Rhizophora mangle, is in line with this view.