millerd wrote: ↑Fri Nov 18, 2022 11:04 pm
bugboy wrote: ↑Fri Nov 18, 2022 10:36 pm
Just read up on this ab/variation/form and to quote
"The red band of the forewings showing a white spot. Verity counts this spot in with the white submarginal ones, to make seven in all. He says that it only applies to males since the females usually have it and males do not. This is not so in England."
I'm not entirely sure how this statement works in the real world with a migratory species unless the males somehow usually shed the extra white spot on immigration across the channel. Also does the statement mean that it
does apply in other parts of the UK?
All this just adds weight to my thoughts about the artificial concept of "aberration" as opposed to variation or form - or at least how they are applied. Do we know what kind of research the authority quoted above conducted or examined before making such a statement? What were their definitions?
(Just as an aside, the second of the two photos posted above by StevieB look as if it shows a female (by its pose on nettles), and it lacks the spot altogether.)
Dave
Hi, Gang
I am pleased to see these comments finally come up for discussion. I have for some time considered presenting the following and now seems the right time to do so. The following definitions are lifted from my book co-written with Gaston Prior (deceased) in 2003
British and Irish Pug Moths: A Guide to their identification and Biology. Harley Books, Essex. They were agreed upon after many months of discussion amongst several eminent lepidopterists of the time. I hope the readers find this useful.
Infraspecific terminology
Subspecies
A subspecies is a taxon which is predominant, distinct in appearance and allochronic (separated by different adult flight periods) or allopatric geographically isolated) from the nominotypical or other subspecies. Genetic isolation is an essential prerequisite for the use of this term. It has often been used erroneously to describe clinal geographic forms (see below) which are sympatric (occupying the same locality) over part of their respective distributional ranges. Island subspecies, which appear to be part of a discontinuous cline, must be distinct in appearance from the subspecies, or the predominant form, occurring on the nearest adjacent island or the mainland.
The name given to the subspecies can either be used trinomially, e.g.
Eupithecia denotata jasioneata Crewe, or be preceded by the abbreviation 'subsp.', e.g.
Eupithecia denotata (Hubner) subsp.
jasioneata Crewe.
Form
A form is a taxon distinct in appearance and of infrasubspecific rank, but sympatric or synchronic with the nominal taxon, which can recur or predominate at a given geographical location. Although a form may predominate in some populations, it can occur elsewhere at very low frequency (e.g.
E. vulgata form
scotica Cockayne, which is to be found occasionally in southern England). Provided these individuals conform to the original description of the form, they should be referred to as such and not as aberrations. A form conforming to the original description of a subspecies, but found outside its isolated geographical range (e.g. some of the dark [subspecies]
fumosae-like individuals of
E. venosata which occur in Orkney), should be referred to as a form approaching that subspecies. Under such circumstances it would be unwise and unnecessary to describe a further formal taxon for these individuals. Forms occur in response to [changes in] various environmental factors such as climate, pollution and larval foodplant as well as to selective pressures such as predation. They may be controlled genetically (e.g. the melanic form
atropicta of
E. vulgata) or by external influences e.g. the
Calluna-feeding form
goossensiata of
E. absinthiata).
The name given to a form is preceded by the abbreviation 'f'.' e.g.
E. vulgata f.
scotica.
The continuous spatial gradation of superficial characters from one form to another is termed a 'cline'. Such geographical forms are sometimes [though now seldomly] referred to as 'races' e.g. the Scottish 'race' of
E. vulgata f.
scotica.
Aberration
An aberration is an individual variant, resulting from genetic mutation or extreme environmental anomalies, which can occur erratically in any given population. The degree of mutation may be extreme or slight; superficial or structural. Theoretically, it would be possible for the frequency of an aberration to increase over a period of time if it were subjected to neutral or positive selection. In such circumstances, the taxon would then be regarded as a form. In the past, many authors applied the term 'aberration' to any varietal taxon, regardless of how it had been formed or its frequency.
The name given to an aberration is preceded by the abbreviation 'ab.', e.g.
Gymnoscellis rufifasciata ab.
nigrofasciata.
Variety
A largely outdated blanket term denoting any individual showing morphological or superficial deviation from the nominotypical form.
Race
A synonymic term used to describe geographic forms or hostplant-related populations of a given species, e.g. the buckthorn-feeding 'race' of
E. fraxinata or the Scottish 'race' of
E. vulgata. (See 'form' above).
Comments welcome!!!
Ade