Butterfly of the Week: Yellow Kite

Is it critically endangered, or is it already extinct? Nobody's seen Brazil's rare Yellow Kite Swallowtail, Eurytides iphitas, in the last few years. 

Photo from lepidoptera.eu. Only males seem ever to have been collected or photographed, suggesting that the one distinguishing feature of this species, or subspecies, may be visible only in males.

One possibility about this rarity is that it may not be a true species. It looks just like Eurytides dolicaon but the long "tails" on its hind wings are only yellow-tipped, rather than mostly yellow. Neither species has been well enough studied to rule out the possibility that iphitas was just a mutation that has naturally bred itself out of the population, as mutations with no special function seem to do.

This possibility would, however, be embarrassing and discouraging to academic biologists, who have set up iphitas as "the type species for the genus" and have some emotional investment in believing it to be a distinct species. 

When collected specimens look this much alike, the basis for classifying them as distinct species is usually that dissected specimens showed internal structural differences. In butterflies the structural differences are often in the elaborate three-dimensional jigsaw puzzle that is the butterfly's reproductive system. Insects' reproductive systems are built differently from birds' and mammals; it's possible to identify some structures that can be identified with counterparts in birds and mammals, but not possible to guess what other parts of the system are there for. Internal differences between butterflies of similar size and color can be enough to make crossbreeding impossible. Internal differences between male iphitas and dolicaon were found under a microscope, but whether they are enough to make crossbreeding impossible is not known. 

Iphitas. If-it-is. If-it-was. As a low-altitude Kite Swallowtail, attracted to brackish water, it lived on the Brazilian coast and was threatened by the development of properties near the beach. It may still live on parts of the coast that remain unoccupied by humans. The normal lifestyle of Kite Swallowtails is symbiotic with small trees in the custard-apple and laurel families. Nobody bothered to find out what iphitas ate. If the color mutation had something to do with its having adapted to eat a different kind of leaves, and its host plant was crowded out of existence, then iphitas may never be seen again.

"No time should be lost in locating and protecting its present haunts," advised the IUCN Red Book, but only one "haunt" for this species or subspecies was located. And for several years it's not been seen there.