Mountain Alcon Blue (Phengaris alcon (rebeli))

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2016 photographs highlighted in green. Click on any photograph to go to an enlarged picture, or simply scroll down the page.

12120_male_Alpes-de-Haute-Provence_7Jul08 22078_male_Hautes-Alpes_13Jul10 12086_female_Alpes-de-Haute-Provence_7Jul08
26241_female_Alpes-Maritimes_03Jul11 22077_male_Hautes-Alpes_13Jul10 33121_female_Alpes-de-Haute-Provence_30Jun13
17759_female_Hautes-Alpes_10Jul09 26278_female_Alpes-Maritimes_03Jul11 26458_pair_Alpes-Maritimes_07Jul11
   
34008_hostplant_Côte-d'Or_18Jul13    

Rebeli is very closely related to the Alcon Blue (P. alcon), and the major differences are described on the alcon page (but see the note at the end).

 

Apart from possible confusion between rebeli and alcon, it is a large butterfly and could only otherwise be mistaken for the Large Blue (P. arion), which also flies at high altitudes and often in company with rebeli, although the male rebeli upperside is blue with clear black borders, lacking the black upf "splashes" of arion.

 

The female is largely brown-black with a varying amount of blue in the basal regions and a series of post-discal black "splashes" (common to Phengaris species) often merging into the dark borders.

The underside ground colour does seem to be different between the sexes, although not indicated in T&L; the males seem to me to have a bluish colouring and slight basal blue flush, whereas the females have a distinctive brown colouring.

 

The female seems to spend all of its time seeking out the larval hostplant Cross Gentian (Gentiana cruciata) and egg-laying on it. If you see a female in flight it is very likely to lead you to G. cruciata which often have a number of white rebeli ova visible in the newer shoots.

 

In the new European taxonomy, this species is now considered to the higher altitude subspecies of alcon and no longer a separate species. This species was previously known as Maculinea rebeli.

ref sex

observations

alt. m
12120 M

a male, with the clear mid-blue colouring and distinct black borders, albeit slightly faded.

2200
22078 M

a male, slightly fresher than 12120 and a brighter blue.

1800
12086 F

a female upperside which matches the illustration in T&L quite well. It is very similar to the high altitude form of arion, and arion was present at this site, but I had seen the underside clearly so can be fairly sure it was rebeli.

2200
26241 F a typical female. 26278 is the underside. 1400
33121 F a fresh female, the sex being confirmed by having seen the upperside. 1080
22077 M

a male, rather darker and with a basal blue flush.

1800
17759 F

a female egg-laying on G. cruciata. One egg is visible in this shot.

2100
26278 F this is actually a female despite the apparent territory-guarding pose. 26241 is the upperside. 1400
26458 PAIR a mating pair, the inevitably-bedraggled male on the left. This shows the slight difference in the ground colour of the sexes. 1400
34008 HOSTPLANT the larval hostplant, G. cruciata. The eggs are usually laid on the higher, newer, leaves. 430

 

12120_male_Alpes-de-Haute-Provence_7Jul08

 

22078_male_Hautes-Alpes_13Jul10

 

12086_female_Alpes-de-Haute-Provence_7Jul08

 

26241_female_Alpes-Maritimes_03Jul11

 

22077_male_Hautes-Alpes_13Jul10

 

33121_female_Alpes-de-Haute-Provence_30Jun13

 

17759_female_Hautes-Alpes_10Jul09

 

26278_female_Alpes-Maritimes_03Jul11

 

26458_pair_Alpes-Maritimes_07Jul11

 

34008_hostplant_Côte-d'Or_18Jul13