Bathroom visitor

[The Woodman]

This small Ladybird arrived on the bathroom windowsill this morning.

I don't recall seeing one with the spots arranged like this....





Is it unusual?

[Rossco]

Looks like one of the melanic morphs of the 2-spot ladybird.

[Paul mabbott]

I can only see it as a sexpustulata form of Adalia bipunctata, the 2-spot ladybird. It's a bit unusual since individuals with such small median and frontal spots usually have no rear ones at all!
Can't see an alternative really.
About 5mms long?

[The Woodman]

Thanks both - yes, about 5mm max in length. I don't recall seeing spots on the trailing edges of the elytra before.

Are the forms of A.b. quite variable or even random and what causes the departure from the norm?

[Dogghound]

This is definately Adalia bipunctata f.sexpustulata. Are you thing of f.quadrimaculata Paul? that form lacks any hind spots and only has the two median ones and the front (shoulder) ones.

[Paul mabbott]

Originally Posted by Dogghound

This is definately Adalia bipunctata f.sexpustulata. Are you thing of f.quadrimaculata Paul? that form lacks any hind spots and only has the two median ones and the front (shoulder) ones.

No. The point I was making is that a sexpustulata f. with anterior/medial spots that small does not usually have any posterior spots. It's a sequence based on the genetics: pale spots/patches fade in sequence, as it were. There is a tendency in some books to state that there are these well defined forms such as sexpustulata & quadrimaculata but life isn't so simple: in fact there's a continuum with some parts gradually fading away ....
Must stress that this is a gene-based series; it isn't what happens to any individual.

[Paul mabbott]

Originally Posted by The Woodman

Thanks both - yes, about 5mm max in length. I don't recall seeing spots on the trailing edges of the elytra before.

Are the forms of A.b. quite variable or even random and what causes the departure from the norm?

As mentioned in my other reply, the sexpustulata
form is about as common as the quadrimaculata form but often the hind spots are very small or, because we tend to view them from above, we sometimes don't notice the rear ones when they're very small.

This isn't an abnormality and we should be careful about using the word 'norm'! I'll try to be brief and hope that I'm up-to-date with the genetics. Adalia bipunctata colouration in one series (the annulate, annulata series) is determined by three gene pairs (acting as a 'super-gene'). Let's call them r (red) and B (black). If an individual has all six r genes then its elytra will be all red; if all are B then the elytra will be all black). Other combinations, with increasing numbers of B genes, will cover a span from red with one black spot [the typica of NW Eurpe]; red with one black spot and smaller satellite spots; red with a black bar; red with two black bars; mainly black with twelve, ten, six, four or two black spots ..... It's a little more complex than that .......
The 'norm' is an ecological thing: most of the specimens we see are red with two black spots although even that varies during the year - over the next month or two there will probably be more 4-/6-spotted melanics than red ones, especially amongst males. If however we analysed patterns across their natural range to Japan we would find almost the reverse. (... and in America they get quite weird)

[The Woodman]

Thanks for the explanation Paul and the confirmation Dogghound - I've learnt something there and will look at Ladybirds in a different light from now on.