Beginnings of a Taxonomic Adventure -- Words, Rules, and Butterflies

I have hunted butterflies in various climes and disguises:  as a pretty boy in knickerbockers and sailor cap; as a lanky cosmopolitan expatriate in flannel bags and beret; as a fat hatless old man in shorts.

                                                        ~ Vladimir Nabokov, Speak, Memory

I, in contrast, have spent a couple of weeks trying to untangle the complex taxonomic history of a small fish fossil (won in a silent auction).  Its label gives provenance and genus, and it’s that name that has led to immersion in a growing generic swamp of papers, articles, and books.  I’m not sure even yet that I’ve successfully wrenched the taxonomic history from the textual muck.

That history will be the subject of a later posting; this one is context setting, offering some random and inchoate thoughts on the science, art, and idiosyncrasies of taxonomy.  This posting is also prompted by news of the validation of an hypothesis published in 1945 by Vladimir Nabokov about the colonization of the North and South America by Polyommatus butterflies.  Taxonomy and Nabokov are conjoined.

For most of us, the first encounter with taxonomy, “the science of classifying,” is a stumble over the scientific binomial (or binominal? see below) name given to a living or once living species – the first name, capitalized, identifying the organism's genus; the second, lower case, its species (this naming protocol was Carl Linnaeus’ brainchild).  There are three detailed international codes for naming and classifying – one each for zoology, botany, and bacteria – anchoring taxonomic decisions and communication about organisms.  To that end, they preclude duplication – under their aegis, no species or genus may have the same name as another, and no name may refer to more than one species or genus.  And, critical to the enterprise, the principle of priority provides that a valid name that is the first published has priority, while subsequently published names are invalid.  The introduction and enforcement of priority addressed the chaos that reigned in the early years of the use of the Linnaean system when names were changed arbitrarily.

To me, taxonomy can be a beautifully logical process, at times even somewhat quaint and charming.  Still, I know I am but an inexperienced tourist in that “country,” coming to understand (appropriating the opening line from L.P. Hartley’s novel The Go-Between) “they do things differently there.”

Though some of the language used in this country appears deceptively close to mine, I often fail at first to grasp its meaning.  Consider a few examples.  Synonyms, a boon to this writer, are taxonomic poison, violating the rule against duplication – there cannot be different names for the same organism.  Being preoccupied, which I often am, violates taxonomic rules – a name that has already been applied to another organism is preoccupied.  Despite my understanding of the adjective, the trivial name isn’t unimportant in taxonomy, it’s the second, lower case name in a binomial name, the one that identifies the species.  And so on, including generic in the opening paragraph of this posting.

Oh, wait, there’s a small but different kind of linguistic trap for the tourist, one I cited earlier.  Does the Linnaean system rest on binomial or binominal names?  The International Code of Zoological Nomenclature says binominal (Article 5.  Principle of Binominal Nomenclature),  Donald Prothero and others say binomial.  Michael Allaby in the Dictionary of Zoology (2009) accepts either but appears to give greater weight to binomial, because it merits the definition and binominal gets only the cross-reference.

This tourist has enjoyed exploring another part of the taxonomy landscape, perhaps because the guidebooks can be particularly caustic in their reviews of this locale.  The priority principle, that lynchpin of the nomenclature code, has come in for some pointed and witty criticism from within scientific ranks.  Paleontologist Stephen Jay Gould fashioned a wonderful story of what happened when a new species was named under less than ideal conditions:

[W]hen Ignatz Doofus publishes a new name with a crummy drawing and a few lines of telegraphic and muddled description in the Proceedings of the Philomathematical Society of Pfennighalbpfennig (circulation 533), it passes into well-deserved oblivion.  Unfortunately, under the [code] of strict priority, Herr Doofus’s name, if published first, becomes the official moniker of the species – long as Doofus didn’t break any rule in writing his report.  The competence and usefulness of his work have no bearing on the decision.  The resulting situation is perversely curious.  What other field defines its major activity by the work of the least skilled?  (Bully for Brontosaurus:  Reflections in Natural History, 1991, p. 82)

Gould concluded that the priority principle, on its own, encourages “petty legalists” who scour the arcane literature to garner some little bit of fame as they upset long accepted names.  He summed it up by quoting Charles Michener (“our greatest taxonomist of bees”):

In other sciences the work of incompetents is merely ignored; in taxonomy, because of priority, it is preserved. 

But, with the adoption of the plenary powers rule (initially approved in 1913), the International Commission on Zoological Nomenclature has attempted to compensate for this.  In Gould’s words, these plenary powers provide that 

. . . the first designation shall prevail, unless a later name has been so widely accepted that its suppression in favor of a forgotten predecessor would sow confusion and instability.

(See Article 81 of the International Code of Zoological Nomenclature.)

As I struggled in the taxonomic weeds with my fish fossil, I took a break and read about Nabokov’s posthumous success in the world of Lepidoptera.  Fascinating story and one that reinvigorated me, but, in fact, never took me away from taxonomy.

Nabokov himself defies classification.  Novelist, poet, essayist, translator, or lepidopterist?  As for that last label, in the 1940s, Nabokov worked as a research fellow at Harvard’s Museum of Comparative Zoology, where he was the Museum’s “de facto curator of Lepidoptera and one of the authorities on South and especially North American polyommatine butterflies, the ‘Blues.’” (Brian Boyd, Nabokov, Literature, Lepidoptera, in Nabokov’s Butterflies:  Unpublished and Uncollected Writings, edited by Brian Boyd and Robert Michael Pyle, 2000, p. 9)

Among the research papers Nabokov published in this period on butterflies was Notes on Neotropical Plebejinæ (Lycænidæ, Lepidoptera) (Psyche, March-June 1945) in which he speculated on the manner in which these butterflies came to the New World.

One can assume, I think, that there was a certain point in time when both Americas were entirely devoid of Plebejinæ but were on the very eve of receiving an invasion of them from Asia where they had been already evolved.

They came in waves, he suggested, the first reaching South America before the waves that gave North America some of its generations of “Blues.”  Coming across the Bering Strait made sense to him. 

. . . I find it easier to give a friendly little push to some of the forms and hang my distributional horseshoes on the nail of Nome rather than postulate transoceanic land-bridges in other parts of the world.

 In a paper just published in the Proceedings of the Royal Society B (Phylogeny and palaeoecology of Polyommatus blue butterflies show Beringia was a climate-regulated gateway to the New World, January 26, 2011), Naomi E. Pierce of the Museum of Comparative Zoology and her co-authors have built a case supporting Nabokov’s hypothesis in detail, using DNA sequencing, among other tools.  They concluded,

Phylogenetic results support Vladimir Nabokov’s hypothesis that the New World Polyommatus are the product of at least five colonization events through Beringia that occurred successively from ca 11 Ma [million years ago] until 1 Ma.

Pretty neat.

Yet that wasn’t really what distracted me from my own taxonomic quest.  What really hooked me was the stanza from a Nabokov poem that Carl Zimmer quoted in his article on this new research.  (Nabokov Theory on Butterfly Evolution Vindicated, The New York Times, January 25, 2011.)

Here are the last three stanzas of the poem, originally published May 15, 1943, in the New Yorker as On Discovering a Butterfly:

I found it and I named it, being versed

in taxonomic Latin; thus became

godfather to an insect and its first

describer – and I want no other fame.

Wide open on its pin (though fast asleep),

safe from creeping relatives and rust,

in the secluded stronghold where we keep

type specimens it will transcend its dust.

Dark pictures, thrones, the stones that pilgrims kiss,

poems that take a thousand years to die

but ape the immortality of this

red label on a little butterfly.

“I found it and I named it . . . .” – a paean to taxonomy as well as the virtues of museum collections – “safe from creeping relatives and rust, in the secluded stronghold . . . .”  A bit more taxonomy resides in the poem.  In the second stanza quoted above, “type specimen” is that specimen upon which a species’ original description is based.  A red label (see last stanza) is how many museum denote the type specimen.  Fascinating that, in the poem at least, Nabokov would see this naming, not the creative arts, as the avenue to immortality.

Nabokov collected his first butterfly in 1906 at the age of 7.  From the beginning, he was fixated on finding and naming a new species.  As a young boy, he thought he had, submitting a description to The Entomologist, only to be informed, gently, that the particular creature had a long standing description.  Nabokov noted, in Speak, Memory, that he later exacted revenge on the man who’d named his moth “by giving his own name to a blind man in a novel.”

In 1938, a couple of years before immigrating to the U.S., Nabokov caught two male specimens of a butterfly in the Alps of southern France.  Shrugging off initial suspicions that the butterfly was a hybrid, he subsequently named a new species Lysandra cormion in a paper published in the Journal of the New York Entomological Society (Lysandra Cormion:  A New European Butterfly, September, 1941).  It is the discovery of  this butterfly that is described in the poem.  (See Between Climb and Cloud:  Nabokov Among the Lepidopterists, in Nabokov’s Butterflies.)  Unfortunately, Nabokov’s first impression was right, Lysandra cormion was a hybrid, not a valid species at all.

Pictured below are the species that produced the Nabokov’s hybrid – on the left are male Chalkhill Blues (Polyommatus coridon), on the right is a female Meleager’s Blue (Polyommatus daphnis).

 

In the words of Dieter Zimmer who wrote the fascinating A Guide to Nabokov’s Butterflies and Moths 2001 (2003, excerpt), “Hence, there is no cormion.”

But, not to worry, Nabokov successfully named several butterflies and moths, such as the subspecies Cyllopsis pertepida dorothea Nabokov 1942, and was honored in the names of others, such as Hesperia nabokovi, Madeleinea vokoban (trivial name is Nabokov spelled backwards), and Madeleinea lolita.

[Later edit:  In these last several paragraphs, I have used the scientific names for these butterflies as provided in Zimmer's guide.]

Note on Sources

I’ve drawn here on several sources regarding taxonomy, including Prothero, Bringing Fossils to Life:  An Introduction to Paleobiology (1998); Moore, Lalicker, Fischer, Invertebrate Fossils (1952); Donald J. Borror, Dictionary of Word Roots and Combining Forms (1960); The International Code of Zoological Nomenclature (1999).)

The pictures of the butterflies are from the Wikimedia Commons.  The Polyommatus daphnis photograph is credited to Ettore Ballocchi; that of the Polyommatus coridon is credited to Entomart.  [Later edit:  The identification of these butterflies given with these pictures appears to be correct but appearances may be deceiving.]