Phengaris alcon (rebeli)

Mountain Alcon Blue (Phengaris alcon (rebeli))

2024 photographs highlighted in yellow. 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	47252_male_Savoie_11Jul20	12086_female_Alpes-de-Haute-Provence_7Jul08

26241_female_Alpes-Maritimes_03Jul11	52797_female_Savoie_7Jul24	52825_female_Savoie_7Jul24	22077_male_Hautes-Alpes_13Jul10

33121_female_Alpes-de-Haute-Provence_30Jun13	17759_female_Hautes-Alpes_10Jul09	26458_pair_Alpes-Maritimes_07Jul11	34008_hostplant_Côte-d'Or_18Jul13

Rebeli is very closely related to, and now considered a subspecies of, the Alcon Blue (P. alcon), and the differences (such as they are) are described on the alcon page.

Apart from possible confusion between rebeli and alcon (which I believe do not fly together), 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 females seem to spend all of their 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
47252	M	a male, rather darker than usual, which appears to a result of fewer blue scales.	2060
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
52797	F	a very appealing female, the upperside of 52825.	1400
52825	F	a female taking a rest between spells of egg-laying. It is the underside of 52797. The hindwing shape and post-discal series of spots are rather elongated in an exaggerated way, although other females have shown this to some extent e.g. 33121. It is not an effect of the camera angle. It was seen at a location that had extensive Cross Gentian growing there, and was fenced off, so clearly the location was known and protected (the photographs were taken from the right side of the fence, I hasten to add). It was apparent that other females were present and the occasional male, so clearly a strong colony (for rebeli).	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
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