False Dewy Ringlet (Erebia sthennyo)

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2019 photographs highlighted in yellow. Click on any photograph to go to an enlarged picture, or simply scroll down the page.

46259_male_Hautes-Pyrénées_5Jul19

46275_male_Hautes-Pyrénées_6Jul19

46279_male_Hautes-Pyrénées_6Jul19

43916_female_Hautes-Pyrénées_08Jul17

46255_male_Hautes-Pyrénées_5Jul19

46269_male_Hautes-Pyrénées_5Jul19

 

46262_female_Hautes-Pyrénées_5Jul19

46265_female_Hautes-Pyrénées_5Jul19

 

A very local and uncommon Erebia limited in its distribution to the central Pyrénées. 43916 was the only sthennyo I had seen until 2017, despite several trips to the region. And I was - and am still not - entirely convinced that 43196 is sthennyo.

 

Other high altitude Erebia fly in company with sthennyo, including the Mountain Ringlet (E. epiphron), Gavarnie Ringlet (E. gorgone) and the Pyrénées Brassy Ringlet (E. rondoui). The Dewy Ringlet (E. pandrose), which it superficially resembles, also flies in a small area in the Ariège département of the eastern Pyrénées, and their ranges overlap slightly.

 

It can be differentiated from pandrose in that pandrose has a wide upf post-discal band with four ocelli and a clear discal line on the inside edge of that band. Also the red areas around the sthennyo ocelli tend to just "surround" the ocelli. The undersides of the two species are different, at least to the extent that differentiation should be possible, so an underside view should be definitive even if an upperside view should leave room for doubt.

 

The unh discal lines are different between pandrose and sthennyo for both sexes. The lines are much more pronounced for pandrose and in the case of the males, the discal line is more jagged in pandrose. The lines are not that different in shape for the females of the two species, but the pandrose line is much stronger.

The identification clue relating to the upf red post-discal band "hugging" the ocelli seems to be  principally applicable to the male as the illustrations of the female in T&L show a rather wider and more diffuse band. I have not had a clear view of a definitive female upperside so I am unable to say whether this is the case based on personal experience.

 

The unh of the sexes are different in that the male has a more pronounced discal line and the shape of the discal line is different between the sexes, the female discal line being rather more jagged.

 

On 2019 I returned to the same location as i had visited in earlier years. I found that they tend to stay close to damp areas and that may be the key to finding them, even within their known localities.

 

It seems to be to be a very nervous species, difficult to approach, the more so that it frequents damp areas. It has a weak flight but rarely stops and when it does, it settles deep in the grass with closed wings. So the underside shots on this page from 2019 are distance shots and rather obscured by blades of grass.

 

The flight period is said to be late June to early August. However, even in the very late year of 2019, every specimen I saw was quite worn even at the end of the first week of July.

ref

sex

observations

alt. m

46259

M

a male, that the red upf band seems to be rather diffuse may be a function of ageing.

2070

46275

M

a male, also quite worn.

2070

46279

M

a male, nearer to the expected norm of the red band hugging the ocelli.

2070

43916

F

with numerous Erebia flying in the region, often difficult to photograph, my objective was to take photographs first and later assess what I had seen. This was not the moment to try to remove the intervening blade of grass!

 

It has been suggested that 43916 is actually epiphron, and not sthennyo, principally on the grounds that the upf series of post-discal spots should be nearer to the margin in sthennyo. This may well be true, although 43916 was flying in company with numerous epiphron but noticeably different in terms of its colour (43916 was much darker), the width of the red post-discal band (the epiphron bands were much wider), and to some extent the upf black post-discal spots (the epiphron spots were generally larger and many had white centres). I planned to revisit the location in 2019, when hopefully I would be able to get an underside shot, which would be definitive as sthennyo and epiphron are very different. 2019 footnote: I did indeed get some underside shots which confirmed sthennyo, but it did not resolve the conundrum of 43916. However, having seen numerous sthennyo at this site, I am more inclined to believe that 43916 is in fact sthennyo on the grounds that the red band hugging the ocelli is not as pronounced in the female as the male, so the fact that it is not hugging the ocelli is not as relevant.

2070

46255

M

a distance shot with several blades of grass in the way, but this is clearly a male sthennyo and it matches the T&L Illustration almost perfectly.

2070

46269

M

another distance shot, at least this time with a clear view. The discal line is not quite a pronounced as 46269.indicating that it is a male.

2070

46262

F

a female as indicated by the weak and almost indiscernible discal line.

2070

46265

F

a female with a jagged discal line, clearly indicating female, and strong contrast across the line.

2070

 

46259_male_Hautes-Pyrénées_5Jul19

 

46275_male_Hautes-Pyrénées_6Jul19

 

46279_male_Hautes-Pyrénées_6Jul19

 

43916_female_Hautes-Pyrénées_08Jul17

 

46255_male_Hautes-Pyrénées_5Jul19

 

46269_male_Hautes-Pyrénées_5Jul19

 

46262_female_Hautes-Pyrénées_5Jul19

 

46265_female_Hautes-Pyrénées_5Jul19