Alpine Heath (Coenonympha gardetta) and Darwin's Heath (Coenonympha darwiniana)
2009 photos highlighted in yellow. Click on any photo to go to an enlarged picture, or simply scroll down the page.
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| 12178_sex?_Hautes Alpes_8Jul08 - gardetta | 12194_sex?_Hautes Alpes_8Jul08 - gardetta | 13427_sex?_Valais, Switzerland_20Jul08 - gardetta |
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| 17735_sex?_Hautes Alpes_10Jul09 - gardetta | 7613_sex?_Alpes Maritimes_26Jun07 - arcania? | 17390_sex?_Alpes Maritimes_07Jul09 - darwiniana |
Gardetta is an altitude specialist occurring mostly at altitudes over 1500m, and although I have usually encountered it only in small numbers, occasionally it is common, but always over 2000m. It is relatively easy to identify, in France at least, because the bold black rings are all inside the white band. It has the characteristic silver unh submarginal band most apparent in fresh specimens. There is, however, huge scope for confusion, not only between arcania and darwiniana but also, and more probably, between darwiniana and the Pearly Heath (C. arcania).
From what I can glean, these are the key identification points:
1) colouring: darwiniana is more noticeably orange, whereas gardetta is more grey, rather cooler in colouring. Lafranchis' ID book says that darwiniana unh is grey; this does not match with the description given on Matt Rowlings' site or with several of his photos of this species.
2) unf white band: the darwiniana unf white band is a similar dentate shape to arcania, but narrower especially in the centre of the band, while the gardetta white band is of broadly constant width.
3) unf margin colouring: the submarginal unf areas is generally the same orange as the ground colour in darwiniana, in gardetta it is grey.
4) unh s6 ocellus: in darwiniana it is inside the band at the internal edge, whereas for gardetta it is toward the outer edge of the band, and in arcania it is generally just outside the band.
5) ocelli colouring: the arcania ocelli outer rings are generally orange, whereas for gardetta they are yellow, often quite faint.
6) ocelli size: the ocelli in s2, s3 and s6 are larger in darwiniana and often absent in s1 and s5; there is a step gap between the ocelli in s6 and s5 (if present).
7) unf ocellus: this seems to be variable but usually present in arcania, absent or very small in gardetta and darwiniana. It is not clear to me whether this holds true in all cases.
With acknowledgements to Matt Rowlings' and Guy Padfield's darwiniana pages. They seem to be the only people who know anything about darwiniana (and are prepared to publish on the web).
However... it is known that hybrid populations of darwiniana and gardetta (and sometimes arcania) occur in the region around the Col de Larche on the French/Italian border, extending northwards and into southern Switzerland. These are known as the form philedarwiniana and exhibit characteristics of the hybridising species. It is acknowledged that the relative distributions are not well known and need further study. So no-one really knows. The 2008 photos were all from this region, and the observations on each are given below. I feel that several exhibit darwiniana characteristics to a greater of lesser extent, but probably that none are pure 100% darwiniana. I actively invite comment.
To extract from the taxonomic study "Bad Species" by Henri Descimon & James Mallet (
http://www.ucl.ac.uk/taxome/jim/pap/descimon&mallet07.pdf), "Coenonympha darwiniana may actually be a stabilized hybrid between arcania and gardetta, since it is found at intermediate elevations between the areas where arcania and gardetta occur (Holloway, 1980, Porter et al., 1995; Wiemers, 1998)."
12178: the unh is quite orange except in the basal area, the unf is quite a warm orange not quite extending to the apex. The white band is clearly dentate (ruling out gardetta?) and the outer rings are pale (ruling out arcania?), and at the edge of the band (ruling out gardetta?). This looks quite a good candidate for darwiniana or at least 50%+ darwiniana. Altitude 1990m.
12194: mildly orange but not warm, the white band is narrow and dentate and the ocelli are ringed yellow. The unf orange does not quite reach the margin or apex, but the gap between the ocelli in s5 and s6 appears greater than the gap between the others, and indicator of darwiniana? Altitude 1990m.
13427: very similar to 12178, maybe not quite as orange. Altitude 2200m.
17735: this, in my opinion, is classic gardetta. The ocelli are large and strongly black, the ocelli are all nicely within the white band, and the unh ground colour is dark greyish. Altitude 2100m.
7613: from the arcania page, reproduced here for comparison purposes. Orange to the unf apex and margins, indicative of darwiniana. Altitude 1875m.
17390: I believe this to be 100% darwiniana. It was seen at a location that was outside the region of known hybridization. The unh white band is narrow but of broadly consistent width and the ocelli are clearly circled yellow. The ocelli in s2, 3 and 6 are appreciably larger than the others and there is a clear step gap between the ocelli in s5 and s6. The unf ocellus is vestigial. I feel that all of these pointers strongly indicate darwiniana and probably preclude arcania and gardetta. However, as always, opinion invited. Altitude 2100m.
12178_sex?_Hautes Alpes_8Jul08
12194_sex?_Hautes Alpes_8Jul08
13427_sex?_Valais, Switzerland_20Jul08
17735_sex?_Hautes Alpes_10Jul09 - gardetta
7613_sex?_Alpes Maritimes_26Jun07 - arcania?
17390_sex?_Alpes Maritimes_07Jul09 - darwiniana
