How frequent is form melanescens amongst Papilio antimachus?

[mothylator]

Hi guys,

Has anyone seen examples of the partially melanized Papilio antimachus?
Or have any idea how frequently it occurs amongst normal forms?

I was reviewing the variants and historical literature on P antimachus, and came across FD leCerf's fascinating annotated catalogue of African butterfly forms and variations amassed amongst JJ Joicey's huge and financially ruinous 380,000 piece "Hill Museum" collection.

James John Joicey deserves a whole thread of his own. He was a double-bankrupt owing to his obsessive interest in collecting first orchids (bankrupted owing a huge sum of £30,000), then butterflies. He died in 1932 shortly after being declared bankrupt owing a colossal £300,000. Just shows how collecting can get out of hand....
(erm. yes. well I could give it up, any time, honestly........!).

Adam Cotton probably knows le Cerf's article by heart, but it's here [edited to correct the date]: Catalogue Annoté des "Types" et formes nouvelles des Papilios de l'Afrique contenu du "Hill Museum". Bulletin of the Hill Museum, 1, 1924, 369-399

Papilio antimachus f. melanescens (forme nouvelle) is described (p372) from a specimen ex. coll. Suffert, in the Hill Museum. Holotype location "Congo" [sic].

The description reads:
"Forme mélanisante avec la coloration brun fauve des ailes supérieures obscurcie au bord interne as sur le disque; extrémité de la cellule et régions avoisinantes noirâtres. Sous la cellule il n'y a qu'une tache brune, très foncée, la seconde failt défaut ainsi que les croissants subterminaux fauves des intervalles 3 et 4, et les traits clairs subapicaux placés entre les nervures 5 et 8, de sorte qu'il n'existe que deux croissants bruns, réduits et abscurs entre 1b-3."

"Melanised form with tawny brown coloration of the forewings darkened at the inner edge and within the disc; the end of the cell and surrounding areas blackish. Beneath the cell there is only one brown spot, very dark, the second is deficient [lit. lacking?], as well as the short submarginal cross-markings of intervals 3 and 4, and the subapical pale markings placed between ribs 5 and 8, so that there are only two brown cross-markings, reduced and obscure between 1b-3."

I recently saw one matching the description (top example in pic attached) - first one I've seen.



Anyone have more pics or information to share?

[mcheki]

Sorry, can't help as this is the first time I have heard of this form. Thank you for drawing attention to it.

[africaone]

Mar 1, 2019 15:46:07 GMT mcheki said:

Sorry, can't help as this is the first time I have heard of this form. Thank you for drawing attention to it.

first time for me too

[deliasfanatic]

First for me too. If it's recurrent, it must be quite rare.

[mothylator]

Thanks, that’s what I imagined.
Clearly must be a recurrent, the photo fits exactly the le Cerf desription, and is not the original specimen, but very rare 🧐🧐🙀

[mcheki]

I have just checked "Afrotropical Butterflies and Skippers. A Digital Encyclopaedia" by M. C. Williams. 2015 Lepsoc. South Africa. which does include the form melanescens Le Cerf 1924 as well as about 14 other forms and aberrations of P antimachus, not to mention a couple of obsolete subspecies names. So it is listed, but obviously very rare.

[nomad]

This is a rare aberration and not a form? Those that rarely occur are in my own definition an aberration. A form is frequent occurrence within a species.

[deliasfanatic]

Yes, I'd regard it as an aberration and not a form; my definitions of those are the same as yours.

[mothylator]

Mar 3, 2019 10:21:41 GMT nomad said:

This is a rare aberration and not a form? Those that rarely occur are in my own definition an aberration. A form is frequent occurrence within a species.

The 5-minute argument:
Yes, nice point, I fully agree in principle, though not necessarily agreeing exactly with your own definition of how you deduce whether a specimen is a form (see Howarth’s terms below)… 😊


The full half-hour:
This specimen is named as such in le Cerf's original description from 1924, preceeding the historical progression of terminology in variation to date.


I'm not sure I would accept a premise that either “form” or “aberration” are scientifically defined or absolutely definable, but rather a semantic convenience. I would argue that use and abuse of these terms is rife, as is the term var.
Personally, I find no dissonance in noting a recognisable repeating pattern of phenotypic variation either as a form or an aberration, because otherwise the persistence of old terminology among infraspecific terms, which are not rigorously regulated or ruthlessly policed, would soon make me howl.


Choice of language:
Actually, "form" is inherently non-judgemental, though ill-defined here.
Perhaps it should etymologically refer to morphisms which we take to refer to population morphism - sexual, seasonal, geographical, geologically-associated, (although arbitrarily not to pathological or environmentally extreme phenotypes for example, no matter how reproducible (eg V. atalanta ab. klemensiviczii or V. cardui ab. elymni)?.
By this semantic arbitrary argument, the yellow variant of the blue morph of P. phorcas should not be termed a form, because it is an environmentally induced variant, though quite often seen and easily reared.

In defining "form", Frequency has nothing to do with it, surely?
I've lived in Stoke for 25yr and have never seen a melanic form of Biston betularia.
But I wouldn't class it as an aberration, its clearly a single allele polymorphism which obeys the pattern of natural selection factors determining prevalence (see Howarth's terms and melanism below).


Whereas "aberration" has an unfortunate pejorative judgemental overtone with inferences that it is an unwanted deviation.
Natural selection determines whether a variation has selective advantage.
Human choice of language implying that a variation is unwanted deviation is unfortunate.


There is also the term "var.", which previously meant “variety” and now is taken to mean “variation”.
When should this term be used??
(Semantics - pah!
Humpty Dumpty all over again. A word means what you want it to mean...etc.)

All the above terms preceeded our understanding of DNA, and of environmental effects on an individual’s epigenetic state (which can affect subsequent generations' phenotypes), though Mendelian inheritance was already known. 


History of emerging terms and useage:
F.W.Frohawk by 1939 had evolved his view that aberration is "when a specimen varies in markings and coloration from “variety” ie geographical races , sexual dimorphism, and seasonal forms; differing from the normal type", and included gynandromorphism and homoeosis. So he used aberration as a widely embracing term irrespective of genetic (eg allele variation) vs. environmental (eg cold shock etc) causes.


Bright and Leeds (1938), agreeing with Frohawk’s emerging view, took the task of aberration description to extreme lengths, with a 17-page index of systematic description terms for only British variants of the single species L. corridon (Poda). Thereafter, a great many butterfly individual forms or recurring variations and scale defects were no longer called var. or form, and became ab.


T.Graham Howarth (1973), however, used the term “variation” as an all-encompassing term for all aspects of difference, and made distinction between collective and individual classes of variation.

Individual Variations: variant abnormalities of individual nature, involving sexual, structural, and pathological phenomena, eg intersex, gynandromorphs, mosaics, homoeosis, peroneural and scale defects, hybridisation. These would not require a named ab.or var. but a descriptor term of the nature of variation.

Collective Variations: geographical races or ssp., geologically-associated forms, seasonal and sexual morphs, polymorphism, albinism and melanism, and lastly, aberrations. His divisions were based on adapting the older semantics to new logical reasoning and breeding experimentation post-1953 in the new era of DNA genetics. A.S. Harmer (1999) adds that for the most part, Howarthian distinction of aberrations generally divide into marked alterations of ground colour, and wing pattern / wing spotting. Within his excellent book, Harmer uses the terms variations and aberrations in sensu Howarth.


FWIW, Personally I think that albinisms and melanisms, if not part of polymorphism within a species (eg some moths), could be argued to be genetic (eg mutations) aberrations, or environmental (eg high altitude M. arion ab. obscura) aberrations, but Howarth does not classify them as aberrations. So there it is.


So….
Is P. antimachus f. melanescens a melanism?

Not in my opinion, no, it is an infrequently-recurring wing-marking variation characterised by increased black markings on the forewings upperside. I think le Cerfe cleverly named the variant melanescens ie tending to melanic.

Therefore an aberration in sensu Howarth, cause unknown.

[nomad]

I honestly believe that this is an aberration, and certainly not a form. I believe the word form is misused widely. Certain authors regard everything as a form, an aberration, seasonal variation and so called form locals in Ornithoptera. Examples of true forms would be Colias croceus f. helice and Argynnis paphia f. valesina. This may be a subject that many authors, and others are going to disagree on.

[Adam Cotton]

It is worth noting that under the ICZN Code names described as forms or varieties before 1961 (when the first ICZN Code was published) are deemed to be available names if they were not clearly introduced as equivalent to aberrations or sexual/seasonal etc forms/varieties. They are available if for example the meaning of form or var. was either clearly geographical (ie equivalent to subspecies) or if the meaning was not stated or inferred in the paper in which they were described. Anything described as an aberration ("ab. xxx") is regarded as unavailable under the Code from its description, regardless of date.

In the case of melanescens Le Cerf, it was described as "f. indiv. melanescens n. f.", which is clearly meant as a new name for an individual specimen and is thus equivalent to an aberration under the Code.

By the way, the paper was published on 16 July 1924, not in 1932.

Adam.

[mothylator]

Thanks yes I got the date of joiceys death conflated with publication mistyped oops.

So we all agree it should be classed as an aberration, and Adam explains why it is interpreted as one under Code Rules.

And do we all agree that the criteria for use of “form” doesn’t include a minimum population prevalence?

[bobw]

Mar 3, 2019 16:58:32 GMT Adam Cotton said:

It is worth noting that under the ICZN Code names described as forms or varieties before 1961 (when the first ICZN Code was published) are deemed to be available names if they were not clearly introduced as equivalent to aberrations or sexual/seasonal etc forms/varieties. They are available if for example the meaning of form or var. was either clearly geographical (ie equivalent to subspecies) or if the meaning was not stated or inferred in the paper in which they were described. Anything described as an aberration ("ab. xxx") is regarded as unavailable under the Code from its description, regardless of date.

I believe you mean implied rather than inferred Adam.  Anyway these rules cause all sorts of problems with Verity names, he used all of these terms and trinomials and quadrinomials pretty randomly.  We had to write a 7 page appendix just on his Colias names for the book!

[wollastoni]

I agree with the ICZN code to not integrate the millions of form and ab names... it is already hard to monitor all the sp and ssp names.

This said, it doesn't mean that abs and forms are not scientifically interesting ! On the contrary !
The study of Carabus forms can explain you the genetic dispersion and evolution of a species. It tells you a lot about the forest implantations of a country before massive agriculture and so on.

Some abs are also triggered by deseases (peroneurose abs for example), by some genes and so on. In genetics, they are tons of stuff to learn thanks to the study of abs.

And to study them, having some "names" can help collect and classify them.
So in the case of recurring abs, I highly encourage people to "name" them, even if the ICZN code won't recognize it.
For individual ab or freak, a name is of course useless.

[Adam Cotton]

Mar 4, 2019 8:08:22 GMT bobw said:

I believe you mean implied rather than inferred Adam.  Anyway these rules cause all sorts of problems with Verity names, he used all of these terms and trinomials and quadrinomials pretty randomly.  We had to write a 7 page appendix just on his Colias names for the book!

Sorry if I chose the wrong word, I tried to explain the ideas behind the Code regulations in plain English, anyway, "not [stated or] inferred"/implied is still negative.

As for Verity, his classification was not really binomial and it is very difficult to decide whether his names were Code compliant or not. Kudrna (1983 - J. Res. Lepid. 21(1): 1-106) tried to sort them out. I can imagine his Colias names must have been a real problem. Most of his Papilionidae names are unavailable because he described them as quadrimonials, but some are Code compliant. Kudrna didn't always make correct conclusions about the availability of Verity's names, so I guess you had to check all of the Colias names individually.

Adam.