Wednesday 17 April 2013

Pseudagrion hageni, Karsch, 1893

I'm going to shake things up a bit, and start with the picture, this time.


While I've yet to fork out for the most comprehensive (but already outdated) text on central African dragonflies, this colourful character seems to be

Pseudagrion hageni 
Karsch, 1983

Or Hagen's sprite. Which, as is expected of the species it seems to be, was hanging out in the thickets around a shady stream just off Leopard's Hill Road, in Lusaka, Zambia. 

Starting with that seems to ruin the suspense a little. Ah well. 

It is a member of, in ascending order;
                                      Pseudagrioninae, a subfamily commonly referred to as "Sprites" (but no known magical powers, and also not trademarked by the a soft-drinks company.
                                    Coenagrionidae, the narrow-winged damselflies.
                                  Coenagrionoidea, the friends and relatives of narrow-winged damselflies.
                                Zygoptera, or the damselflies. 
                              Odonata, the Dragonflies and pals (i.e. dragonflies and damselflies) 
                            Holodonata, which includes a few more distant (and extinct) relatives of the dragonflies. 
                          Odonatoptera ('Dragonfly-winged' insects), includes yet more extinct relatives (precise contents vary, as genetic comparison with long-extinct species is very difficult (a.k.a impossible) when said species exist only as inorganic impressions in rocks, and the alternative - morphologically derived phylogenies - can be very unreliable)
                        Metapterygota includes most modern insects, with the exception of the mayflies, silverfish, and various bristletails. 
                      Pterygota includes the mayflies, but continues to exclude the ancestrally wingless (i.e. they don't have wings, and neither did any of their grandparents, or great-grandparents, or great-great-great-great...(etc)...grandparents, back to the very dawn of life on Earth). 
                    Dicondylia still leaves the jumping bristletails (Archaeognatha) out in the cold, but every other extant insect is included. 
                  Insecta... I'm going to let you work out what group of insects joins the reunion party here. 
                Hexapoda - six legs (although animals exist which have six walking legs and are not hexapodes, but we'll come back to them another time), which brings in a couple of groups, such as the Collembola, which didn't quite make the grade to be called insects, but have been off a-partying elsewhere. 
              Arthropoda. In uncertain order, the crustaceans and chelicerates (spiders, scorpions, horseshoe crabs and friends) join the party. 
            Ecdysozoa also brings the nematodes and a handful of other worm-like creatures into the picture. These deserve more of a mention, really, but they don't photograph all that well, so we'll probably never get around to most of them. 
          Protostomia includes on another important invertebrate group, the Lophotrochozoa, which is comprised of Molluscs (Slugs, snails, nudibranches, nautilus, clams etc.), Annelids (segmented worms, including earthworms and their relatives), and a handful of free-living and parasitic worm-like creatures. 
        Nephrozoa... still not sure whether this level has a function. It includes the vertebrates and assorted relatives in the Deuterostomes, and may exclude several very primitive (and quite small) groups of animals, although most if not all of these groups have been suggested to have quite close relationships within the Nephrozoa, so... 
      Bilateralia is the taxon uniting all animals which, at some point in their life, have only one line of symmetry - that is, animals that have a left side, a right side, dorsal side, a ventral side, a front and a back. It is important to bear in mind that our front, in this definition, actually comprises our head, not the ventral side of our body which, due to our bipedal (walking on two feet) lifestyle is general in front of us. 
    Eumetazoa includes all modern animals except for a few ancestrally deviant (think very, very, very distant cousins) groups, such as the sponges, which themselves are included in:
  Animalia, which hopefully needs no introduction,

and 

Eukaryota, which includes almost all multicellular life, and a good deal of unicellular life, but excludes the Archaea, a group of phylogenetically troubling extremophiles (Adrenaline junkies on a microscopic level, which thrive in corners of the planet where no-one else could live even if they wanted to), and the Prokaryota (the bacteria, best identified by their lack of a nuclear membrane (i.e. their genetic material is floating freely around their cells, rather than tidied away in a bag)).

Well, that's that. Enjoy Pseudagrion hageni, or (as is possible) a startlingly similar relative. 


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