This is Graphium policenes. Known as the common swordtail, it may be found throughout large parts of Africa south of the Sahara. With its arresting pattern and the long tails on its hind wings, it is a typical kite swallowtail. But how typical is it? Dick Vane-Wright and Campbell R. Smith of the Department of Entomology at The Natural History Museum have been studying Afrotropical Graphium to try to answer this question. We also wanted to discover how many species there are, where they live, how they are related to each other and how they are related to kite swallowtails from elsewhere.
In fact, of the 39 species of the kite swallowtail genus Graphium found in the Afrotropical region (Africa, Madagascar and the neighbouring islands), only about one-third have prominent tails, and not all of these are brightly patterned.
If Graphium policenes is not typical, what of the tailless majority? Fourteen species conform to a pattern with a dull background and pale marks, like the creamy Graphium, Graphium ucalegon, shown here (left). It is believed that these species have come to resemble other butterflies, such as milkweed butterflies of the genus Amauris, which are distasteful to birds, significant predators of butterflies. Amauris does this by storing noxious chemicals. A young bird that tries to eat an Amauris is put off from trying another. The mimetic Graphium species do not appear to have such chemical protection, but their deceptive resemblance means that the birds also tend to avoid them.
|Another group that may have mimetic protection includes the veined swallowtail, Graphium leonidas (right), which resembles another milkweed butterfly, Tirumala petiverana. In this case, however, it seems possible that G. leonidas may have some chemical protection of its own.|
A further group of species usually have a pattern of white marks on a black background, like the widespread white lady swallowtail, Graphium angolanus.
In the closely related red swallowtail, G. ridleyanus, this pattern has been transformed into a bright brick red, considered to be mimetic of certain bright red Acraea species, another group of chemically protected butterflies.
In yet other species, the pattern has been transformed into various yellows or greens on black,
as in the coppery swallowtail, G. latreillianus, and the green-spotted swallowtail, G. tynderaeus.
As we have seen Afrotropical kite swallowtails are variable in pattern and shape. Why do taxonomists classify them with 50 or so other butterflies of the Old World tropics in the genus Graphium?
What characters unite them?
As so often in the Lepidoptera, the key is in structural features of the genitalia. In particular, the female genitalia of all Graphium open into a cup-like indentation known as the vestibulum. In the Afrotropical species, and some others, there are lip-like folds of the body wall over the hind edge this cup (see methods).
Another characteristic feature of the genus Graphium is that the inner margin of the hindwing of the male forms a rolled tube that surrounds bundles of fine scales called androconia. These can be released to carry pheromones to the female during courtship. Not all Graphium have this feature, but among the Afrotropical species only G. ridleyanus lacks them, and this loss seems to be a recent evolutionary event.
Other characters that link the Afrotropical and other species together are features of the male genitalia, wing venation, and structures of the larvae and pupae.
The Afrotropical members Graphium are generally placed in their own subgenus, Graphium (Arisbe).
We discuss the relationships of the kite swallowtails with other swallowtails and the rest of the butterflies in our section on higher classification.
To summarise our main objectives in studying the Afrotropical kite swallowtails, we sought to answer the following questions:
We have organised this account in several sections. We hope that each page is sufficiently self-contained for them to be read in any order.
Over the next few months we intend to put more of our results, including detailed accounts of each species, on this website. In the meantime, we present an outline of our study and results on these pages as a 'work in progress'.
2-Dec-2002 Dr B R Pitkin