Note 33 — Chapter VI

It is a feature of mimetic resemblances among butterflies that a given species in a given locality may serve as a model for several other species belonging to unrelated groups. Generally such mimics belong to presumably palatable species, but other presumably unpalatable species may also exhibit a similar coloration and pattern. In this way is formed a combine to which the term "mimicry ring" has sometimes been applied. An excellent example of such a mimicry ring is afforded by certain species of butterflies in Ceylon, and is illustrated on Plate IV. It is made up in the first place of two species belonging to the presumably distasteful Danaine group, viz. Danais chrysippus and D. plexippus. The latter is a rather darker insect but presents an unmistakable general likeness to D. chrysippus. Those who believe in Müllerian mimicry would regard it as an excellent example of that phenomenon. For those who believe only in Batesian mimicry D. plexippus, being the scarcer insect, must be regarded as the mimic and D. chrysippus as the model. In both of these species the sexes are similar, whereas in the other three members of the "ring" the female alone exhibits the resemblance. One of these three species is the common Nymphaline, Hypolimnas misippus, of which the female bears an extraordinary likeness to D. chrysippus when set and pinned out on cork in the ordinary way. The male, however (Pl. IV, fig. 8), is an insect of totally different appearance. The upper surfaces of the wings are velvety black with a large white patch bordered with purple in the middle of each[33]. The "ring" is completed by the females of Elymnias undularis and Argynnis hyperbius. The former of these belongs to the group of Satyrine butterflies and the female is usually regarded as a mimic of D. plexippus, which it is not unlike in so far as the upper surface of the wings is concerned. Here again the male is an insect of totally dissimilar appearance. Except for a border of lighter brown along the outer edges of the hind wings the upper surface is of a uniform deep purple-brown all over (Pl. IV, fig. 6). In Argynnis hyperbius the appearance is in general that of the Fritillary group to which it belongs. But in the female the outer portion of the fore wings exhibits much black pigment and is crossed by a broad white band similar to that found in the same position on the wing of D. plexippus (Pl. IV, fig. 2).