Showing posts with label 1867. Show all posts
Showing posts with label 1867. Show all posts

Thursday, 20 October 2016

The Return of the Giant Earwig (No, not that extinct one).

Earwigs.

They are probably the largest order of insects that I am inclined to forget exists; a quick google search puts the number of described species close to 2,000; with their generally inconspicuous lifestyles, it's easy to imagine that twice that many species actually exist.

An easier number to reach are how many are recorded from Zambia; a rather unimpressive 17 (given that our 8 neighbours average 45 species each; and excluding the two arid/desert nations brings that up to 59) are listed by Fabian Haas on his excellent map which you should definitely look at. Even this isn't concrete - as with everything else, the community at large seems to forget that Zambia used to be called Northern Rhodesia, and any pre-1965 records from 'Rhodesia - North' are generally attributed to the tropical quarters of Zimbabwe (even when they mention specifically Zambian sites, such as the Broken Hill mine; now Kabwe).

So far as I know, this is one of those 17:


Dacnodes cf. acutangula; photographed in Chongwe Distr., Lusaka Prov., Zambia in February 2016, using Olympus E420 with 40-150mm lens and 2 58mm KOOD magnifiers). 
This particular earwig is a member of the tropical genus Dacnodes, which I believe is largely Afrotropical, but with Dr. Haas' website playing up, I can't actually check up on). It is most probably Dacnodes acutangula Hincks, 1955, which is recorded from Zambia, but I'm not convinced of the distinction between D. acutangula and the more widespread Dacnodes caffra (Dohrn, 1867), which occurs in the wider region but doesn't appear to be recorded from Zambia.

And why should I care?

Well, because they're interesting. Partially phylogenetically - the position of Earwigs within the insects has changed quite a bit over the years; they spent a good while being squashed in next to beetles before they settled into their current - more comfortable - space next to the grasshoppers and stick-insects.



This one's most striking feature is its size; it is - 
at least for an earwig, massive. 
For a sense of scale, here it is sitting on a 58mm (diameter) magnifier lens: 





But aside from being big and difficult to classify, they have suffered the long indignity of superstition; the very name 'Earwig' is a contraction of their Old-English name Ear-Wigca (ear-crawler), a nod to the still-prevalent belief that they are inclined to crawl into people's ears - a lot of insects do this accidentally, but none - and certainly not earwigs - do it as a regular habit.

Instead, most earwigs are either innocuous decomposers, predators of small insects (which some species, possibly including Dacnodes, rather impressively grab in their forceps) or nibblers of pollen and flowers; most go for a combination of all three. They often get into trouble because of the last habit, but one of the most widely-maligned flower-nibblers (a much smaller earwig in the genus Forficula) recently received something of a reprieve when it was found that, on wind-pollinated crops, the effect of occasional pollen-nibbling is hugely offset by its tendency to eat something else, far more destructive: pollen mites. Despite conspicuous damage to flowers, earwigs can actually improve their effectiveness by eating away smaller, often overlooked pests which do much more damage.

A bit of a ramble, but the upshot is: most earwigs are really quite unfussy about what they eat. This is not unheard of for insects - most true crickets are similarly catholic in their tastes - but it is unusual. And it does mean that - despite that (fairly) high-profile extinction of the (really) Giant St. Helena Earwig, which is double the length and much, much chubbier than this one.



But to be perfectly honest, my favourite thing about this Earwig has very little to do with the Earwig itself: Some [insert long, long list of expletives here] stole my Laptop in January this year, and with it, my pictures of a lot (a very lot) of invertebrates that I hadn't yet backed up.

Three days later, this was the first species that I had lost the pictures of to return to my computer - and - half-drowned in a swimming pool - it was very tolerant of a few dozen camera-flashes.



But, moving on swiftly and without delay, to see how it (currently) fits into our slow-growing tree-of-life:

  
-Pygidicraninae
-Pygidicranidae  
-Pygidicranoidea  
-Protodermaptera  
-Neodermaptera       
-Dermaptera                
-Dermapterida               
-Polyorthoptera                
-Anartioptera                        
Also includes web-spinners and stoneflies. 
-Polyneoptera                          
Also includes the Dictyoptera, such as Idolomantis dentifrons and Sibylla pretiosa 
- Neoptera                                   
As well as the Polyneopterans, includes most major insect orders such as Dichtha inflata, Oedemera nobilis, Otiorhynchus atroapterus,Malachius bipustulatus , Phyllobius pomaceus, Cheilomenes lunata, Melolontha melolontha, Neojulodis vittipennis, Demetrias atricapillus, Anthia fornasinii, Lophyra cf. differens, Synagris proserpina, Vespula germanica, Astata tropicalis, Anthophora furcata, Andrena nigroaenea, Enicospilus, Zebronia phenice, Crambus pascuella, Nemophora degeerella, Sphinx ligustri, Laelia robusta, Acada biseriata, Metisella willemi, Anthocharis cardamines, Catopsilia florella, Papilio demodocus, Panorpa germanica, Chloromyia formosa, Senaspis haemorrhoa, Helophilus pendulus, Episyrphus balteatus, Metadon inermis, Diasemopsis meigenii, Dolichotachina caudata, Megistocera filipes, Pephricus, Grypocoris stysi, Ranatra and Anoplocnemis curvipes.
- Metapterygota                             
As well as the Neoptera, includes dragon and damselflies such as Pseudagrion hageni, Lestinogomphus angustus, Rhyothemis semihyalina, Orthetrum brachiale and  Enallagma cyathigerum.
- Pterygota                                         
In addition to the Metapterygota, includes the primitive Mayflies. 
- Dicondylia                                        
In addition to the familiar winged insects, includes several primitive, wingless orders such as the silverfish.  
- Insecta                                                
- Hexapoda                                              
- Arthropoda                                             
- Ecdysozoa                                                   
Other than the Arthropoda, includes mostly small, worm-like animals. 
- Protostomia                                                   
As well as the Ecdysozoa, includes the Lophotrochozoa; such as Burtoa nilotica.
- Nephrozoa                                                         
 - Bilateralia                                                                 
- Eumetazoa                                                                  
- Animalia                                                                        
- Eukaryota                                                                        
                                           



Sunday, 25 August 2013

Trachylepis varia (Peters, 1867)

So I know that it can seem that I have a thing about invertebrates, so much that people (well, tourists) have asked me "Do you work in entomology?" or something to that effect.

But my primary fields of study were actually ecology and genetics, and my primary areas of interest are conservation and... herpetology.

This is to placate that unfed interest.

 - Eukaryota
   - Animalia
     - Eumetazoa
       - Bilateralia
         - Nephrozoa -see also Ligia oceanica, Dicranopalpus ramosus, Hyllus argyrotoxus, Pseudagrion hageni, Sybilla, Stictogryllacris punctata, Cyathosternum prehensile, Pephricus, Anoplocnemis curvipes, Ennalagma cyathigerum, Hagenomyia tristis, Synagris proserpina, Melolontha melolontha, Otiorhynchus atroapterus, Demetrias atricapillus, Anthia fornasinii, Zebronia phenice, Laelia robusta, Anthocharis cardamines, Acada biseriata, Panorpa germanica, Megistocera filipes, Diasemopsis meigenii, Episyrphus balteatus, Helophus pendulus and Senaspis haemorrhoa
           - Deuterostomia
             - Chordata
               - Craniata
                 - Vertebrata
                   - Gnathostomata
                     - Teleostomi
                       - Osteichthyes
                         - Sarcopterygii
                           - Tetrapoda
                             - Reptiliomorpha
                               - Amniota - see also Hipposideros vittatus.
                                 - Reptilia
                                   - Romeriida
                                     - Diapsida
                                       - Sauria - see also Chalcophaps indica , Ardea goliath and  Sterna hirundo.
                                         - Lepidosauromorpha
                                           - Lepidosauria 
                                             - Squamata
                                               - Scleroglossa - see also Thelotornis capensis and Lygodactylus capensis.
                                                 - Scincomorpha
                                                   - Scincidae
                                                     - Lygosominae


Trachylepis varia
(Peters, 1867)

As you may be able to guess from the specific epithet (varia), this is a rather variable species, which - in addition to the uncharted diversity of tropical african reptiles - makes it a bit difficult to say with certainty that it IS this species. However, based on the facial scales of species of Trachlyepis known in Southern Africa (which Lusaka city is only just outside of), it should be this species. Should being the operative word. 

And here it is: 
Trachylepis varia, Chongwe, Lusaka, Zambia.
Its rather pointed face readily separates this species from the common urban species in the genus, Trachylepis striatus, although in most populations, the overall pattern is sufficient for that. The males were more frequently seen, and seemed to develop earthy-red hindquarters as the breeding season approached:

Both photographed in Chongwe, Lusaka, Zambia - male in August 2011, female in October 2011.