Graphium glycerion, the Spectacled Swordtail, is easy to recognize if it shows a marking that looks like a pair of eyeglasses on its hind wings.
Detail of a photo of museum specimens at Wikipedia.
Photo from Lepidigi.net, taken in West Sikkim.
However, it's not altogether certain that all individuals of this species show this marking, or that it's enough to make them a separate species from Graphium mandarinus or even from Graphium eurous. Scientists have been debating this for years. Not much has been published about the Spectacled Swordtail and much of what has been published consists of arguments for or against recognizing this species, dividing it into subspecies, or lumping it together as a subspecies of something else. In addition to its similarities to mandarinus, eurous, and also paphus, some scientists also count a relatively new species, Graphium garhwalica, which can also show "spectacle"markings. Others want to discard the whole traditional system of classification of this group of Graphiums and start all over with new species names.
Because of all this confusion there is also some debate about where glycerion flies, how many broods it has in a year, what it eats, or even what it looks like. Most sources agree that it's a pale "zebra"-type butterfly with long pointed tails on its hind wings, but at the time of writing one respectable source shows a dark butterfly with no tails as glycerion! Are we confused yet? This confusion may be due to the fact that the species name glycerion was first given to a different butterfly, in a different genus. The current Wikipedia page for this species contains a flat statement that the name Graphium glycerion is "permanently invalid," though many species lists use it.
And, of course, while hiking in India or Thailand people sometimes see and photograph the butterfly when it's showing very little of its hind wings.
Photo from Thaibugs.com. The photographer thought it was "spectacled."
According to Hu, Cotton, et al., Graphium glycerion is small for a Graphium, with a wingspan of three inches or less. One brood a year flies in April and May, in a wide range including India, China, Nepal, Bhutan, and Myanmar, but not Thailand. The host plant is not known. This group of scientists think glycerion is the same thing as paphus.
You know a species is poorly documented when you see a recent post of yours, about a confusible species, in a search for material about it:
Well...the Six-Barred Swordtail has six clear black "bars" on its fore wings, while the Spectacled Swordtail's black bars are harder to count, as shown.
Glycerion comes from a Greek word for sweet things, and appears in Greek literature as a man's name. As a word it is the origin of chemical names like "glycerin" and "glycerol." Some proud Indian scientists would be delighted to replace this name with the Indian name garhwalica. It's not yet altogether clear that garhwalica is the same species as glycerion--butterflies and moths can look just alike while being unable to crossbreed--and older lists don't show garhwalica at all, but the butterflies shown on searches for these names do look similar. With a warning that garhwalica may or may not be exactly the same species as glycerion, this web site will look at garhwalica next week.
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