Small Dark Springtails 2 - Hypogastrura

Moved

Moved from Poduromorpha.

… Ashley Bradford, 28 April, 2014 - 11:14am

Hypogastrura sp.

… Frans Janssens, 28 April, 2014 - 11:12am

Thank you!

I actually collected a couple of them - is there some detail I can photograph that will tell you which species?

… Ashley Bradford, 28 April, 2014 - 11:13am

That would be a great experiment!

Hypogastrura taxonomy is quite challenging. There are about 43 lookalike USA species, divided into 5 groups.
We will follow the key of Christiansen & Bellinger of 1998.
To find out the group we need to check following characters: number of tenacular teeth, number of tenent setae of footcomplex, type of tenent setae, shape of dental granulations, type of first unguiculus, number of setae of area verticalis.
We will check the details one by one.
The first thing to check is the number of tenent setae of the footcomplex. On the outer side of the leg, distally just above the claw, are the tenent setae (sticky setae). These are quite distinct and can be different in number for each leg. There are 2 types of tenent setae: acuminate ones (pointed) and clavate ones (knobbed). You need to take a lateral aspect shot with the feet in focus to check the number of tenent setae. Good luck, Ash!

… Frans Janssens, 28 April, 2014 - 12:52pm

I don't know if it's good enough,

but I just attached a photo showing a close-up of the foot. It's not very clear, though, and may not be clear enough, in which case I may need to send it to you because I think this is the best my gear an do...

… Ashley Bradford, 1 May, 2014 - 12:29pm

Perfect!

1 tenent seta distinctly visible. This excludes the viatica-group, which has 2-4 tenent setae. Next to check is the shape of the unguiculus (small claw) of the first leg. Collembola have 2 types of claws: a large claw, outer claw (unguis) and an opposite small claw, inner claw (unguiculus). In Hypogastrura, the unguiculus may be acuminate (without basal lamella) or lamellate (with basal lamella). To check the shape you need to make a shot in which both the unguis and unguiculus can be seen from 'aside'.

… Frans Janssens, 1 May, 2014 - 1:05pm

That sounds even more challenging

But I will try. Does it need to be on its back for me to see this?

Thanks for the above analysis!

… Ashley Bradford, 1 May, 2014 - 1:08pm

Not necessarily...

but it might help. Black-field illumination also might help to make tiny structures (such as the lamella) visible: black background, specimen illuminated from aside (e.g. using a glassfiber illumination technique to produce a narrow beam of light).

… Frans Janssens, 1 May, 2014 - 1:20pm

Good suggestions -

I was wondering last night as I took photos if a black background might be better, but hadn't thought of the side lighting. I'll give that a try.

… Ashley Bradford, 1 May, 2014 - 1:34pm

Haha - I will need the luck!

But I'll give it a try if they'll cooperate. Thank you!

… Ashley Bradford, 28 April, 2014 - 1:08pm