Monday, April 1, 2024

Butterfly of the Week: Eurytides Asius

Must quarrels rage? "Cease fire," I cry,
"And contemplate the butterfly."

(Explanation at the end.)

For a Swallowtail Eurytides asius gets remarkably little attention. It's not especially rare or threatened. It's big and showy, but some other Swallowtails are bigger and showier. Nobody claims it's less beautiful than other just doesn't seem to be a species of great interest to anybody. Very little has been published online about Eurytides asius. Most of what has been written about this butterfly seems to be bickering about what to call it, and much of that's not been written in English.

Photo by Guidurante, who says it was taken in October in Imbituba.

The species name has generally remained constant. It was named after Asius, a character in ancient Greek literature. It was also named after Manlius, a character in ancient Roman literature, but this name was soon dropped from use. 

Scientists bicker about what to call the long-tailed tropical and subtropical Swallowtails because their genus names reflect beliefs about macroevolution-as-a-religion. Worldwide there are several species of Swallowtails whose colors are predominantly black and white, or blackish gray and pale green, who have long thin "tails" on their hind wings and other similarities of shape. The African and Asian genus is Graphium; the American genus is Eurytides, but some scientists prefer to classify some of these species in separate genera they call names like Protographium or Neographium, depending on which way they believe macroevolution travelled, or Protesilaus, a try-to-be-neutral genus name proposed in honor of a species. 

In the mid-twentieth century when many of the science books I read as a child were being written, some children who were interested in biology were turned off by the way writers who had not learned any new facts about a plant or animal used to waffle on about how it might have evolved from some other kind of plant or animal. That species evolve, within the limits of what is possible for their kind of plant or animal, as favored by natural selection, is an indisputable fact. That one species has ever really evolved out of a different species is believed by some people as a matter of faith but has never been documented as a matter of fact. That science writers who try to conceal a lack of facts behind blather about theories used to turn me off, even when I was five years old, and that they still do, is a solid fact. Enough of us felt that way that "scientist" and "biology major" were words my generation said with a certain supercilious air. It is much more fun to read what's known about plant or animal species now than it used to be, as more facts have become known, but pockets of that old ignorance remain and it's always disappointing when so-called scientists try to fill in the space for missing facts with idle speculation.

We don't know, in a scientific way, whether macroevolution ever happened. We don't know, in a scientific way, whether "intelligent design" ever happened. It's easier for me to believe that an infinite and awe-inspiring Creator designed all the different butterflies, in one day if He chose to do it in one day, sitting in the Garden of Eden, than it is to believe that all the different butterflies macroevolved out of wormlike or silverfish-like proto-insects, but in fact the Bible doesn't say that. The Bible writers were not concerned with the precise definition of "kinds" of animals, nor with how or whether different "kinds" have developed. And valid schools of biblical interpretation teach that the mortal creatures, including lost races of "man, male and female," were created before and outside the Garden of Eden. I have no idea. I wasn't there. I believe that "kinds" of living things were created, intelligently designed, and that they've evolved and developed since, but trying to work out exactly how or when it happened is at best unscientific (we can't replicate experiments in macroevolution). 

We know that there are fossil records of insects that looked like dragonflies, only much bigger, that have gone extinct. In the mid-twentieth century people thought those insects must have evolved into the dragonflies we know, with damselflies presumably coming later. Now people think that the extinct insect genus Meganeura was "related to" dragonflies, perhaps descended from a common ancestor, but that they couldn't possibly have evolved into dragonflies. 

In the same manner, although the tradition of butterfly books beginning with the Swallowtails could logically have come from the fact that Swallowtails are the butterflies North Americans are likely to notice first, it used to be based on a claim that Swallowtails evolved earlier than other butterfly species did. This theory used to be based on the fact that a butterfly fossil had been found and thought to look like a Swallowtail. Photographs of the fossil do show some traces of its wing venation. It could have been a Swallowtail. But its wing structure is not clear enough that we can know, in the scientific sense, whether it was a Swallowtail or not.

And what about species? The lists of animal and plant species have certainly changed during my lifetime, not because living creatures have changed that much in fifty years, but because what we know about them has. When I first looked up the North American butterfly species in the Kite family, they were called Papilio marcellus. Now there's a debate about whether to call them Eurytides or Protographium or maybe Protesilaus marcellus. One scientist whose e-book on the Swallowtails is available, free of charge, in Spanish has said that for any given number (N) of biologists in a room, the number of working definitions of "species" will be N+1. This is only a slight exaggeration. Meanwhile these biologists aren't telling us much about the actual butterflies while they argue about how to classify them. Eurytides or Protographium asius is similar to marcellus in shape and habits but we don't really know, even with DNA studies, how closely the species are "related" as distinct from merely fitting into similar ecological niches.

Eurytides asius is found in southwestern Brazil and Paraguay.  Its shape is similar to our Zebra Swallowtails. It lacks "zebra" stripes, and has just one band of paler color across its wings. Linnaeus called it Papilio asius, and described it thusly:

17. P. E. T. alis caudatis nigris, fafcia cogmuni alba, pofticis fubtus bafi apiceque rubro maculatis.

Habitat in America meridionali. Dorm. 77ats.

Corpus paruum nigrum. Thorax linea laterali cinerea. Punctum cinereum vtrinque in pectore et linea lateralis fubtus in abdomine. — Alae anticae concolores, nigrae fafcia alba. Pofticae nigrae fupra faĆ­cia alba lunulis tribus coccineis ad angulum ani, et quinque albis ad marginem, fubtus fufcae fafcia alba, punctis bafeos rubris, linea ad marginem tenuiorem lunulisque tribus anguli ani rubris. Lunulae quatuor albae marginales.

Later, in English, it was described: 

Upper Side. Antenne, thorax, and abdomen black. Wings raven-black, having a pale yellow bar rising at the anterior edges near the tips of the superior wings, and crossing these and the inferior ones, meeting even with the abdomen, becoming wider gradually. Posterior wings furnished with two tails, and along the external edges having four small yellow crescents, and another at the abdominal corners ; above which are two long square red spots, and another yellow crescent on the abdominal edges.

Under Side. Palpi, legs, and breast black. Abdomen black, with a white longitudinal stripe on each side. Wings marked nearly as on the upper side; the posterior having several red spots and streaks more than on the upper side, and placed next the body from the shoulders to the abdominal corners.

Rothschild added a note on the scent folds on its inner wings:

better developed than in any other member of the present group ; the abdominal edge bent upwards, forming a narrow pocket ; vein SM- and a narrow stripe in front of SM- and another behind it covered with small scent-scales, the scaling having partly a somewhat woolly appearance.

Like our Zebra Swallowtail, asius exists in a symbiotic relationship with a tree in the genus Annona, which has some resemblance to Asimina triloba

Photo by Bariza. 

Photos by Diogoluiz (and others) show these butterflies engaging in "lekking" or "puddling" behavior. (A lek is a gathering place where lonely males display themselves, mostly to one another, but as females occasionally flit past to check them out, males eventually pair up. A puddle can be a lek; not all lekking takes place at puddles.) Male Swallowtail butterflies who congregate at puddles often form flocks of mixed species. This photo was taken in December at Xerem.

Photo by Rick Costa, November, Sitio Barrocada. Is softer coloring typical of the female of the species? The butterfly looks egg-loaded.

Photo by Nunesopedro, January, Sana. In some of the bigger Swallowtail species, the hindwings function independently of the forewings, and the tails help the butterfly steer itself through the air. In the smaller Kite Swallowtails, we see where Rothschild and other early naturalists got the idea that the function of the tails is to confuse predators about which end of the butterfly to bite into. The butterfly seems more interested in traces of saltwater on the human's shorts than in sweat on his leg. 

Nobody seems to have studied this butterfly's behavior and life cycle. The Kites generally are pollinators more than composters, and the caterpillars have smooth rather than warty skins, but nobody seems to have documented what young asius look like. If we have any readers in Paraguay or Brazil, here is your opportunity to become famous...

...and here's another one, if you happen to be poets. April is National Poetry Writing Month for some US-based web sites, and Rajani Radhakrishnan has supplied a list of prompts that promise challenging, different, possibly grim, serious poems, not just the usual pretty spring scene warbles. There is no rule that says poets have to use the prompts. If the lovely April weather inspires pretty spring scene warbles, they will continue to happen. Anyway, here's the list...

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