Taxonomy question

[Pete Eeles]

I feel I should know the answer - but don't

By convention, the Linnaean binomial system is extended to a trinomial system when describing subspecies. E.g. Lycaena dispar batavus.

My question is with regard to forms. For example, f.rhoumensis of Small Heath. Is this Coenonympha pamphilus f. rhoumensis, or Coenonympha pamphilus pamphilus f. rhoumensis? (i.e. it's a form of the nominate subspecies)?

Cheers,

- Pete

[Padfield]

Often, the same named form occurs across many subspecies of a species. For instance, if you look at the ilia pages in Bozano, you will see illustrations of ssp. ilia f. clytie, ssp. laura f. clytie, ssp. albatheia f. clytie, ssp. praeclara f. clytie and ssp. phaedra f. clytie! Other named forms are only expressed in one particular subspecies.

If describing a given specimen, it is entirely appropriate to give it its full name - species, subspecies and form. If describing a form, I think it would be inappropriate to mention a subspecies unless you are describing particularities of that form peculiar to one or other subspecies, or if it only occurs in one subspecies.

Guy

[Pete Eeles]

Ah! Thanks Guy! Makes perfect sense. So are you saying that there are some subspecies of ilia where f.clytie does NOT apply? I assume so, otherwise this would be Apatura ilia f. clytie?

Based on that thinking, I assume we'd have the following groups:

Subspecies Not Shown
Colias croceus f. helice (ssp. not mentioned since the form applies to all subspecies, not just the nominate subspecies)
Polygonia c-album f. hutchinsoni (ssp. not mentioned since the form applies to all subspecies, not just the nominate subspecies)
Argynnis paphia f. valesina (ssp. not mentioned since the form applies to all subspecies, not just the nominate subspecies)

Subspecies Shown
Erebia epiphron ssp. mnemon f. scotica (assuming that the form only applies to ssp. mnemon)

Not sure - since the form is only found in the British Isles, and wouldn't be found elsewhere (I think!)
Argynnis aglaja ssp. aglaja f. scotica
Euphydryas aurinia ssp. aurinia f. hibernica
Coenonympha pamphilus ssp. pamphilus f. rhoumensis

No idea whatsoever!
Araschnia levana f. levana (the nominate subspecies seems to have turned into a form!)
Araschnia levana f. prorsa (not sure!)

Cheers,

- Pete

[Padfield]

I think the important thing here is that forms are not clades and cannot stand properly as fourth terms in the Linnaean system, which is strictly cladal. Some forms predate the diversification into subspecies - some even predate the diversification into species, though I believe we always use different names for forms across species (not sure about that). Forms and subspecies divide up the genetic pie differently.

Interesting that in Bozano, forms prorsa and levana are illustrated for ssp. levana but they are simply called spring form and summer form for ssp. obscura. Araschnia species in general have spring and summer forms, characterised by the same essential colour differences. Some forms get names in Bozano, others are just left as 'spring' and 'summer'. Perhaps this is something that has not been rationalised and codified as rigourously as the Linnaean system.

Guy

[Pete Eeles]

I think the important thing here is that forms are not clades and cannot stand properly as fourth terms in the Linnaean system, which is strictly cladal. Forms and subspecies divide up the genetic pie differently.

Thanks Guy - this hits the nail on the head for me; subspecies and forms are different "dimensions" when it comes to classification. I think I've been tying myself in knots trying to combine the two.

Cheers,

- Pete

[Pete Eeles]

I see that Adrian Riley's book has promoted all forms as defined in Bradley and Fletcher to subspecies (apart from f.helice, f.valesina and possibly f.hutchinsoni [forgot to check!]).

Makes you wonder what these authorities consider a form to be. More research required

Cheers,

- Pete

[Padfield]

Where can I find Bradley and Fletcher's list for comparison? You have probably sent it to me in the past but I am not sure when, or where I put it.

Guy

[Pete Eeles]

I'm working in the frozen north this week (snow outside!), but "a" representation of B&F is here:

http://www.ukbutterflies.co.uk/taxonomy.php

As I recall, the forms are listed alongside the subspecies for a given species.

Cheers,

- Pete

[Padfield]

B & F list 9 'forms' - viz.: helice, hutchinsoni, levana, prorsa, scotica (aglaja), valesina, hibernica (aurinia), scotica (epiphron), rhoumensis (pamphilus). Of those, helice, hutchinsoni, levana, prorsa and valesina are obviously not cladal. The others, being characteristic of local races, might well be and if so would qualify for being considered subspecies.

The word 'form' clearly implies morphological distinction. The words 'subspecies' and 'race' refer to phylogenetic ancestry and usually imply geographical distinction (at least, reproductive isolation). Where morphology and ancestry/geography go hand in hand I guess there's room for this kind of confusion!

Guy

[Pete Eeles]

Now that I'm back home, I'm checking a few things. And, blow me down, Emmet and Heath (MOGBI) use the following, which Riley seems to have drawn upon also:

f. helice
f. hutchinsoni
f. levana
f. prorsa
f. valesina

ssp. scotica (aglaja)
ssp. scotica (epiphron)
ssp. rhoumensis (pamphilus)

Marsh Fritillary is something else - and not something that Riley majors on. It is considered to contain ssp. hibernica (aurinia), but also f. anglicana and f. scotica! Riley refers to all 3 as forms.

I really like your rationale, Guy, for when to use "form" versus "subspecies" and Emmet and Heath would seem to (largely) concur with you. You should have been a taxonomist, Guy, and saved us from this mess!

So - where does this leave UKB? I've been sticking with Bradley and Fletcher because it's the most up-to-date taxonomic listing available (2000, versus 1990 for MOGBI). But making a decision on what to use changes the text in the subtaxa descriptions. For example, if Argynnis aglaia scotica is considered a form, then the nominate subspecies (Argynnis aglaia ssp. aglaia) is found throughout the British Isles, with Argynnis aglaia f. scotica found in Scotland. If it's considered a subspecies, then Argynnis aglaia ssp. aglaia does NOT occur in Scotland, but Argynnis aglaia ssp. scotica does. I'm sure you get the point Opinions welcome. And my head hurts But I do want to do what's right so that we don't confuse anyone consulting the website!

Should

[Gibster]

Anybody got Felix's number. This is where he'd shine...

[Mark Colvin]

Hi Pete,

Hopefully this will help:

The International Commission on Zoological Nomenclature (ICZN) acts as adviser and arbiter for the zoological community by generating and disseminating information on the correct use of the scientific names of animals. The ICZN is responsible for producing the International Code of Zoological Nomenclature - a set of rules for the naming of animals and the resolution of nomenclatural problems.

One key point is that 'Infrasubspecific names such as forms are not covered by the code. Only those names which state ‘subspecies’ are treated – all forms and varieties are not, unless elevated to subspecific status'.

http://iczn.org/

Thanks to OUMNH for this information.

Kind regards. Mark

[Pete Eeles]

Thanks Mark - indeed. I guess you need to stop somewhere. From B&F:

Form: population subset below the level of subspecies (infrasubspecific) ...

Cheers,

- Pete

[Pete Eeles]

'Infrasubspecific names such as forms are not covered by the code. Only those names which state ‘subspecies’ are treated – all forms and varieties are not, unless elevated to subspecific status'.

I'm having a very hard time navigating their website. Ideally, I'd like to see what subspecies they consider valid, but I can't find any subspecies at all as far as I can tell (e.g. "mariscolore", "vulgoadippe" etc.)

Cheers,

- Pete

[Mark Colvin]

Hi Pete,

I'm having a very hard time navigating their website. Ideally, I'd like to see what subspecies they consider valid, but I can't find any subspecies at all as far as I can tell (e.g. "mariscolore", "vulgoadippe" etc.)

You won't find what you are looking for on the International Commission on Zoological Nomenclature (ICZN) website. The ICZN is there to guide you on the rules of nomenclature i.e. the principles and recommendations to follow.

The following links will help expand my original post.

http://www.nhm.ac.uk/hosted-sites/iczn/ ... cle=5&nfv=
http://www.nhm.ac.uk/hosted-sites/iczn/ ... le=45&nfv=
http://www.nhm.ac.uk/hosted-sites/iczn/ ... le=47&nfv=

Kind regards. Mark

[Pete Eeles]

Thanks Mark; I was looking in the wrong place and got the wrong end of the stick - mainly because the ICZN does seem to maintain lists of approved taxa: http://iczn.org/content/official-lists-indexes-1

I'm still uncertain of what we should be doing - and am very tempted to "promote" certain forms to subspecies. For example, Argynnis aglaja scotica, when first described by Watkins, was described as a subspecies, which is how it's described in Emmet & Heath, and Riley. How and why it's referred to as a form in Bradley is beyond me

Cheers,

- Pete

[Padfield]

Where it is not clear which authority to follow (and it is really a matter of nomenclature, rather than phylogenetics, here - there's no debate about the facts in most cases), why not let the site admit this? So for example, the pamphilus page could read:

"Subspecies pamphilus:

Blah blah blah pretty picture blah blah description blah

Subspecies or form rhoumensis:

Endemic to the Isle of Rhum, this distinctive population is often considered to merit subspecific status.

Blah blah blah pretty picture blah blah description blah"

The 'or form' bit is intended to appear on the page - I don't mean it as an alternative wording.

Guy

EDIT : I've edited this comment - in case anyone should be composing a reply that no longer matches!

[Pete Eeles]

"Blah blah blah pretty picture blah blah description blah"

I'm sure that's how some members actually view the website

Thanks for the input, as ever. So ... since a form is "infrasubspecific" (i.e. "below subspecies") then (having thought about this further) it's actually "safer" to keep this as a form, since this immediately tells anyone reading the text that any critter they see in the field may, or may not, be of this form. They should therefore take a closer interest (if they're really interested!) to ensure that what they're seeing conforms to the definition of the form and not just assume that it is a particular subtaxon because they're at a particular locality. This is especially important for those subtaxa where the distribution isn't clear cut (e.g. Argynnis aglaja scotica). And, as you say, mention the fact that some authorities elevate the form to subspecies.

Phew! Yes - definitely happy with that approach

Cheers,

- Pete

[Pete Eeles]

Given the recent conclusions on this topic, especially that a form is "below" subspecies (and not formally recognised in some quarters), I still had something niggling at me and have just come across this in E.B.Ford's classic work, Butterflies, which addresses this concern:

We sometimes find that a single independent sub-species may have a discontinuous distribution, having become broken up into separate populations since it was evolved. One or more of these may sometimes be distinguished from the others by constant features which are but slight and involve a single character only. These are conveniently termed forms: clearly they are potential sub-species in the same sense that such sub-species are potential species. They may be distinguished by a name with the abbreviation f. (= form), added after that of the sub-species. Thus, a distinct sub-species of the Mountain Ringlet, Erebia epiphron, is restricted to Britain. This is called mnemon Haw., and it is divided into two dissimilar populations, inhabiting the Lake District and part of the Scottish Highlands and Lowlands. Specimens from these two regions are similar except that those from Scotland are consistently a little the larger and brighter, and they have been called the form scotica Cooke. We can therefore sub-divide our British Mountain Ringlet as Erebia epiphron mnemon f. scotica from Scotland and E. epiphron mnemon f. mnemon from the Lake District. The name of the sub-species is to be repeated for the typical form in the same way that the specific name is repeated for the typical sub-species.

This makes an awful lot of sense and this convention for naming forms is entirely consistent with the conventions used for naming subspecies. I therefore intend to refine some of the wording in the species descriptions accordingly. I believe (in the British Isles) we have the following. And feel free to tell me you already thought that :

Colias croceus croceus f. croceus (Clouded Yellow)
Colias croceus croceus f. helice (Clouded Yellow)
Polygonia c-album c-album f. c-album (Comma)
Polygonia c-album c-album f. hutchinsoni (Comma)
Araschnia levana levana f. levana (Map)
Araschnia levana levana f. prorsa (Map)
Argynnis aglaja aglaja f. aglaja (Dark Green Fritillary)
Argynnis aglaja aglaja f. scotica (Dark Green Fritillary)
Argynnis paphia paphia f. paphia (Silver-washed Fritillary)
Argynnis paphia paphia f. valesina (Silver-washed Fritillary)
Euphydryas aurinia aurinia f. aurinia (Marsh Fritillary)
Euphydryas aurinia aurinia f. hibernica (Marsh Fritillary)
Erebia epiphron mnemon f. mnemon (Mountain Ringlet)
Erebia epiphron mnemon f. scotica (Mountain Ringlet)
Coenonympha pamphilus pamphilus f. pamphilus (Small Heath)
Coenonympha pamphilus pamphilus f. rhoumensis (Small Heath)

And I hope you like the quote format from E.B. himself, as if he'd posted on UKB

Cheers,

- Pete

[Mark Colvin]

Hi Pete,

This appears to make a lot of sense. I'm just reading through Chapter 13 now ...

I particularly like the line from page 285 in the paragraph you quoted:

'These are conveniently termed forms: clearly they are potential sub-species in the same sense that such sub-species are potential species"

Great work as ever.

Kind regards. Mark