Weather-Related Color Polymorphism of Rothschildia lebeau (Saturniidae)

Abstract

In 1868, Guérin-Méneville described an orange-colored male saturniid moth from the vicinity of Caracas, Venezuela, as Rothschildia lebeau. In 1905, Schaus described a rusty brown male Honduran Rothschildia as R. aroma and in 1921 he described a pinkish male from Guatemala as R. morana. In 1934, Benjamin described the south Texas portion of the R. lebeau population as R. forbesi. As is commonplace with large saturniid moths, wing color, shape, and size played a major role in the authors' decisions to view these animals as different species. On the bases of genitalic comparisons and familiarity with wing variation in the genus Rothschildia, Lemaire (1978) and Draudt (1929) synonymized these (and other) Rothschildia under R. lebeau; Lemaire (1978) retained several subspecific names, the bases for which were geographic range, wing shape and size, and wing color. In 1980, I did not yet know of this astute act of taxonomic lumping and was confronted with the identification of dark chocolate-colored Rothschildia (Fig. 1) in the lowlands of northwestern Costa Rica as R. aroma and sympatric rustto orange-colored Rothschildia (Fig. 1) as R. lebeau. Hoffmann (1942)was confronted with the same problem in lowland Chiapas, Mexico, and concluded that R. lebeau and R. aroma were sympatric and different. As these two different-colored moths did not appear to differ in ecology in my study site, I set out to determine if they were the same species. The inquiry quickly evolved into an exploration of what appears to be an environmentally-controlled color polymorphism, which is of adaptive significance in that the colors track the seasonal shifts in the background against which the moth is cryptic. Here I describe this seasonal and interhabitat color variation and discuss its probable adaptive environmental significance.