jccurd's picture

Mismatched Pair of Darters?

Observed: 22nd September 2009 By: jccurdjccurd’s reputation in Invertebratesjccurd’s reputation in Invertebratesjccurd’s reputation in Invertebratesjccurd’s reputation in Invertebrates
IMG_3414_full_size
Description:

I was spinning through some older shots looking for presentation material when I came across this pair which originally I can't have looked at very closely. I don't know how best to put this in but ...
The male (front) of this tandem pair looks like a classic Common Darter but his chosen partner (rear) looks more like a Red-veined Darter female to me - yellow wing roots, yellowish wing veins, black-edged yellow pterostigma and tick marks the full length of her abdominal segments.

Identifications
  •  
    Likely ID
    Common Darter (male) and Red-veined Darter (female) (Sympetrum striolatum (male) and Sympetrum fonscolombii (female))
    Confidence: It's likely to be this, but I can't be certain.
Species interactions

No interactions present.

Comments

chrisbrooks's picture

ID Comment

Hi John what a great image. I'm trying to work out what they are.

jccurd's picture

2nd Mismatch

Chris, I had a mismatched pair in this country a few years back - that was Ruddy Darter male with a Common Darter female. That was in my first year watching dragonflies and, naturally, I didn't notice. It took an iSpot expert to clarify the issue.

Apparently, it does happen occasionally but confirmation of my suspicions would be good. Tempting not to believe ones eyes. ;-)

John

chrisbrooks's picture

ID Comment

Hi John, I've been puzzling over this for ages. It's the male I cannot decide upon. There is little sign of antehumeral stripes which are present on the Common Darter. I think I can see red veins in the wings as well but there are things that do not fit with a male Red-veined. Your comments would be appreciated. Regards Chris

jccurd's picture

Agree

Yes Chris, me too - I keep looking at it again, myself. This is a site which is usually lousy with Red-veined Darter pairs.

To me, the abdomen colour and pattern looks very Common Darter but I hear what you're saying about the antehumerals. It would be nice if I'd got a view showing the side of the thorax, underside of eyes and the legs more clearly - ain't it always the way? And in those days, I was just happy to get a reasonable shot. :))

I think I've been trying to convince myself that it must be a Red-veined male - I fancied a hint of red in the wing veins, too - but, at the same time, I know there are occasional mismatched pairings - I've got a UK Ruddy male/Common female pair.

Normally, I'd expect a mature Red-veined male to have clearly yellow pterostigma with thick black leading and trailing edges, as in this female. I'd also have expected noticeably yellow patches at the base of the hind wing. The frons would be reddish, too, though there may well be too little on view (just the very top). The abdomen usually looks plainer red rather than this patterned - orangey red with the goldish dots.

Now I'm wondering if this could be a male Red-veined that is still developing its full colouration - they start yellow, rather like the females.That might make the abdomen look like this. Still concerned about the red pterostigma, though.

Bit of a conundrum. ;-)

John

Limnoporus's picture

The female is newly emerged

Whatever the male is (really need a side view) the female is a newly emerged individual. The abdomen has not fully expanded which explains why it is so short, and perhaps may not expand any further. If you look at the stick it is absolutely thick with exuvia so lots of individuals have used it for emergence. Look also at the hind legs of the female which are extended in front of it. She doesnt have a grip on the stick and she is an involuntary partner in this in my opinion.

jccurd's picture

Good Point

A very crowded stick vis-a-vis exuviae. :))

I'm not sure she's very teneral, though, given the developed colour of the pterostigma (brand new ones tend to be rather grey) and the lack of shine of her wings. That could be due to the light being at an inappropriate angel, though, I suppose.

jccurd's picture

Larger Photo

I've swapped the photo for a full sized version, just in case that shows any further revealing details.

RoyW's picture

Female Red-veined Darter and an unidentifiable male!

The female darter here is definitely a Red-veined Darter (a very mature individual that has started to develop the red colouration more typically found on males - young females are a much brighter yellow). Red-veined Darters tend to be small in comparison to other species, so the shorter abdomen length is expected.

The male is unfortunately not identifiable from this photo (though it is definitely not a Red-veined Darter).
It is quite likely that it is a Common Darter (so I'll give agreement to the posted ID at the confidence level given), but Southern Darter, S. meridionale, and Vagrant/Moustached Darter, S. vulgatum, can't be conclusively ruled out as possibilities.

In situations like this, while are rarely seen but not excessively infrequent, the female usually is an unwilling participant, as mentioned by Limnoporus. Males grab hold of any female that they consider to be a potential mate, and the female is then forced to go along "for the ride" until the male releases her. The male cannot force the female to mate though, a male that has a female in tandem will often be seen to bend his abdomen underneath himself to try and coax the female to bend the end of her abdomen forward towards his secondary genitalia. Without the females cooperation the mating "wheel" cannot be completed - so while tandem pairs of mis-matched species are not infrequently seen, it is rare to see mating pairs comprising of two different species.

jccurd's picture

Welcome back

Just back from Madeira myself so slightly belated thanks for your typically comprehensive and cogently phrased observations, Roy. ;-)

John