Showing posts with label Spider. Show all posts
Showing posts with label Spider. Show all posts

Monday, 14 November 2016

The Net Casting Spiders (Deinopidae)

Meet Deinopis Macleay, 1839. 

Male. Photographed in Chongwe District, Lusaka Prov., Zambia, November 2016, using Olympus E-420 and 3 KOOD lenses. 

Deinopis is the more iconic of the two genera of Net-Casting Spiders, distributed throughout the warmer regions of the world; it lends its name to their family (Deinopidae), and is the source of another common name for the family - Ogre-faced Spiders - and, locally at least, species of this genus are physically much larger, and difficult to overlook. This impressive male, found wandering on a driveway on a hot, humid night, had legs that spanned over 5cm.





To put this in context, his legs are very long; unusually long, you might think (if you are used to thinking about these things) for a spider that neither lives in caves (where anything and everything has a license to have very long legs) or live in a web





But this little Kangaude (Chewa - spider) does build a web. To those who know a little about spiders, this doesn't really resolve much: while his legs make slightly more sense, now, his eyes become something of a puzzle: of the other spiders blessed with such large and conspicuous peepers, most belong to either the Jumping Spiders (family Salticidae) or the Wolf Spiders (family Lycosidae); the vast majority of which are active, free-living predators, which use their eyes to see, hunt and capture prey - or, in the case of most jumping spiders - to communicate via semaphore.

To explain all of this, we have to turn to Deinopis' smaller and more abundant relative - and the only other genus in the family - Menneus Simon, 1876 - for a practical demonstration: 


Photographed in Chongwe, Lusaka, Zambia in April 2015. 

As already mentioned, one of the common names for this family of spider is Net-Casting Spider (and I will eventually find the direct Chewa translation for that, in theory); and they do precisely that; they wander around in search of a crossing point of nocturnal insects to wander through, and then, suspended above it by a simple thread, they spin an entire web between their (very long) front legs, and they wait.

And they wait.

Eventually something wanders past, and, seeing the movement, they whip down the net and voila, pre-wrapped meal - and a unique method of hunting that needs both a web and excellent vision.
Menneus - note the smaller eyes and the abdominal 'hump'. 




It is worth noting that Menneus' vision isn't quite like Deinopis'; they are probably most easily identified, in fact, by lacking the massive enlargement of the posterior median eyes seen in Deinopis; their eyes are still larger, on the whole, than those of most web-spinning spiders, but if it wasn't for their extraordinary webs, and the curious protuberances from their abdomen (earning them the alternative names of Camel-backed Spiders and Hump-Backed Spiders), they might be mistaken for free-living nursery-web spiders (family Pisauridae). 













Although identification to genus for this family is extremely easy - especially now that Avella and Avellopsis have been shoehorned into Menneus - you'll notice that I haven't listed a species name for either of our two guest-stars; although none appear to be recorded specifically from Zambia, a number of species are recorded from neighbouring countries and the wider region (see the World Spider Catalog page on the family); and - as the spiders are inconspicuous, nocturnal and easily overlooked - there is every chance that these do not belong to described species at all.

So I'll get back to you on that. 

Friday, 2 May 2014

Nephila fenestrata, Thorell, 1859, or possibly N. senegalensis (Walckenaer, 1842), and a warning for the phobics.

I have mentioned before that I'm quite fond of spiders, and it's probably been apparent in those posts that I am a touch unsympathetic towards people who have worked themselves up so much about something essentially harmless that they'll even hide from an image...

I wasn't always that way. When I was about 8 years old, my dear uncle informed me that the brownish spiders building their webs in the shower were close relatives of the black widow, known as brown button spiders and possessing extremely potent venom. This wasn't entirely dissimilar to something bearing a resemblance to the truth, and this little seed of information threatened to grow into a full blown phobia, before I gained a house-mate who overreacted to wasps in much the same way.

Nevertheless, as this is a member of one group of spiders that I still would be quite uncomfortable handling, I will give spider-fearing men - and women - fair warning: You might not want to look at the pictures.

I will leave it up to you whether you let an irrational fear own you, or take that fear and punch it repeatedly in the face, saying 'Hey, you, fear! Listen up - spiders are extraordinary and valuable members of society, and even if I don't want to touch them, I'm not going to freak out over a bunch of pixels on the interweb. Yeah, I said web, fear, because I'm not afraid of pixellated silk!'

Or something to that effect.

I think that's enough pre-amble that real fraidy-cats should be able to click away without seeing the Kanguade (Chewa for spider) of the day:




You may notice that the pictures on this post are without caption; they are all taken in Chongwe, Lusaka, Zambia, scattered through February and March 2013, although the spider itself is present from the middle-to-late rains (in the late season of the 2013-14 rains, they only showed up in Chongwe in December), and usually persist until July or August.

Unfortunately, this means that all these photographs feature incompletely mature individuals, which can make I.D. a little tricky. For example:

The distinct yellow 'window' on the underside of this little lady would comfortably identify her as

Nephila fenestrata
Thorell, 1859

Also known as the black-legged Nephila (The genus' actual common name, 'Golden Orb-Weaver' is longer than the genus name itself, so we'll stick with Nephila), or Windowed Nephila which has a number of subspecies - and some pictures online certainly resemble this series, but whether those actually belong to this species, or are just hopeful I.D.s by people who've taken the stance that this is more windowed and black legged than it is red-legged or banded legged (the two most promising alternative species; also, in a not entirely unrelated note, the other two species present in numbers in South Africa, arguably the most comprehensively-studied microfauna in Sub-Saharan Africa)

But both these pictures were taken in shady areas, which necessitated the use of partial flash - which masks the translucency of parts of these oversized spiderlings' (okay, a little beyond spiderling) bodies. Which brings us to the third picture: 


This one, as you can probably tell, was caught in early-morning sunlight, which didn't simply allow us to see the transparency of the legs, but it's exaggerated it somewhat, while, to an extent, masking the brushes of dark red hair on three pairs of legs; without that, it seems as though it could grow into an adult Nephila inaurata, or Red-legged Nephila (it can't - there are other more convincing differences in colour and range). 

Even with the brushes, it's not an excessive stretch of the imagination to translate this to the colouring of Nephila senegalensis, which other people of uncertain credentials have done online. 

And, if we take a look at this larger subadult - losing a battle to a Sphecid wasp (probably Sceliphron sp.), we see more of that non-black colouring on the legs: 


The windowing of the abdomen is also reduced to two yellow lines, and the ratio of black to orange on the palp - the little mouth-leg held in the wasps mandibles - is different from each of those seen in the younger individuals already shown, but - as with all the individuals photographed, the femorae (first long bit) of all legs are black - whereas in all images of N. senegalensis I can find on the web or in my (rather limited) books, from Kenya to South Africa, the last (and usually second last) femur is orange-red. 


Two things prevent me from ruling out either of these species. 

1) They are known to be variable, and patterns in adults aren't always readily extrapolated from subadult patterns.

2) It's possible that, despite the saturation of the environment to the point that the dense populations of these spiders weren't separated by more than two or three metres within the entire area these were photographed, there were multiple species, and possibly even hybrids, in the mix.

Until I go out for longer, and get a more continuous series of photographs of the a specific web-group over time and into adulthood (Wasps' and Bulbuls' appetites permitting), I will favour N. fenestrata for these images, but be unable to rule out N. senegalensis. 

I'll add the taxonomy tomorrow - now, with a quick illustration of why these are known as Golden Orb Weavers, I'm off to bed. Behold their silk: 



Yup. It's a rich yellow colour, poetically known as gold. Not really noticeable on fine strands most of the time, but on the thicker threads that anchor the webs, it's a handy clue that you're looking at Nephila.










And, for now, that's all, folks: Goodnight.

Additional: here's the taxonomy.



- Nephilidae                     
- Araneoidea                      

- Entelegynae                       
- Araneoclada                        
See also Dysdera crocata
- Neocribellatae                       
- Araneomorphae                       
- Opisthothelae                             
- Araneae                                        
- Megoperculata                                
- Micrura                                              
- Arachnida                                            
See also Dicranopalpus ramosus
- Chelicerata                                            
- Arthropoda                                             
See also Ligia oceanica, Dichtha inflata, Oedemera nobilis, Otiorhynchus atroapterus,Malachius bipustulatus , Phyllobius pomaceus, Cheilomenes lunata, Melolontha melolontha, Neojulodis vittipennis, Demetrias atricapillusAnthia fornasinii, Lophyra cf. differens, Synagris proserpina, Vespula germanica, Astata tropicalis, Anthophora furcata, Andrena nigroaenea, Zebronia phenice, Crambus pascuella, Nemophora degeerella, Sphinx ligustri, Laelia robusta, Acada biseriata, Metisella willemi, Anthocharis cardamines, Papilio demodocus, Panorpa germanica, Chloromyia formosa, Senaspis haemorrhoa, Helophilus pendulus, Episyrphus balteatus, Metadon inermis, Diasemopsis meigeniiDolichotachina caudata, Megistocera filipes, Pephricus, Grypocoris stysiRanatra, Anoplocnemis curvipes, Idolomantis dentifrons, Sibylla pretiosa, Tettigonia viridissima, Stictogryllacris punctata, Enyaliopsis, Humbe tenuicornis, Lobosceliana loboscelis, Cyathosternum prehensile, Heteropternis thoracica, Pseudothericles jallae, Enallagma cyathigerum, Pseudagrion hageni, Lestinogomphus angustus, Rhyothemis semihyalina and Orthetrum brachiale
- Ecdysozoa                                                
- Protostomia                                                
See also Burtoa nilotica
- Nephrozoa                                                     
- Bilateralia                                                            
- Eumetazoa                                                            
- Animalia                                                                 
- Eukaryota                                                                



And now that really is all, folks!




Note: 

Other African Nephila not discussed within the text: 

N. comorana - not found on the mainland.
N. constricta - seems to have hairless legs, a la N. inaurata.
N. komaci - described as having a long, broad abdomen, a very distinctive colour pattern and a disjunct range.
N. pilipes  - in Africa, found only in Madagascar and associated islands.
N. sumptuosa - has a long, broad abdomen, unlike those seen in adults in and around Lusaka.
N. turneri - although range unclear, very distinctively coloured.


Although not particularly user-friendly, and there are definitely a few images that have been incorrectly assigned, the South African National Survey of Arachnids Virtual Museum is probably the most ambitious resource currently freely available for the full diversity of African Arachnids. It's worth noting that, given the shortage of information on this group, that's not as prestigious as it sounds.

 

Saturday, 5 April 2014

Dysdera crocata; Koch, 1838

This is probably a record - photograph and upload on the same day.

Today, at work, I was pleasantly surprised by an unexpected guest.

Several of my co-workers were not-so-pleasantly surprised, and wanted to squish the guest. I not-so-delicately reminded them that arachnophobia is in no way the fault - or the problem - of the spider, and took her outside, where she rewarded me with this:

Female. Photographed in Bosham, West Sussex, UK, in April 2014 (today) using Olympus E-420 DSLR, Zuiko 40-150mm lens and 3 KOOD magnifiers.
That isn't an aggressive pose, by the way, but a defensive pose adopted when I loomed in closer than she liked with the camera. And while it's perhaps not the best way to endear her to an audience which is on the fence, those rather extraordinary chelicerae are relevant, because this is the (recently cosmopolitan) European Woodlouse Spider,

Dysdera crocata
Koch, 1838
  
As you might have guessed, she feeds upon woodlice and other comparably crusty creatures. Those formidable fangs are what allow her to bite through the calcium carbonate coating of the average woodlouse, or the chitin of a millipede or even - if you were so incautious as to poke her in the face - the somewhat softer keratin of human skin.

If you do - as quite a few people have - find yourself inciting a woodlouse spider to bite, don't panic  - the recorded effects on humans are in the region of nettle and honeybee stings (see the Natural History Museum's bite records here). 


With that, then, let's explore her taxonomy: 
- Dysderinae         
-  Dysderidae          
- Dysderoidea           
- Haplogynae             
- Neocribellatae           
- Araneomorphae           
- Opisthothelae                
- Araneae                         
- Megoperculata                  
- Micrura                              
- Arachnida                             
- Chelicerata                            
- Arthropoda                            
See also Ligia oceanica, Eremoides bicristatus, Hagenomyia tristis, Dichtha inflata, Oedemera nobilis, Otiorhynchus atroapterus,Malachius bipustulatus , Phyllobius pomaceus, Cheilomenes lunata, Melolontha melolontha, Neojulodis vittipennis, Demetrias atricapillusAnthia fornasinii, Lophyra cf. differens, Synagris proserpina, Vespula germanica, Astata tropicalis, Anthophora furcata, Andrena nigroaenea, Zebronia phenice, Crambus pascuella, Nemophora degeerella, Sphinx ligustri, Laelia robusta, Acada biseriata, Metisella willemi, Anthocharis cardamines, Papilio demodocus, Panorpa germanica, Chloromyia formosa, Senaspis haemorrhoa, Helophilus pendulus, Episyrphus balteatus, Metadon inermis, Diasemopsis meigeniiDolichotachina caudata, Megistocera filipes, Pephricus, Grypocoris stysiRanatra, Anoplocnemis curvipes, Idolomantis dentifrons, Sibylla pretiosa, Tettigonia viridissima, Stictogryllacris punctata, Enyaliopsis, Humbe tenuicornis, Lobosceliana loboscelis, Cyathosternum prehensile, Heteropternis thoracica, Pseudothericles jallae, Enallagma cyathigerum, Pseudagrion hageni, Lestinogomphus angustus and Rhyothemis semihyalina
- Ecdysozoa                               
- Protostomia                              
See also Burtoa nilotica.
- Nephrozoa                                  
- Bilateralia                                     
- Eumetazoa                                     
- Animalia                                          
- Eukaryota                                         

There are two species of Dysdera present in the UK, both of which can occasionally be found indoors - much more frequently in the case of today's distinctly synanthropic (does well near humans) guest. They're not too readily distinguished, as colour characters are often unreliable, but the presence of one external character can readily rule out Dysdera erythrina [although its absence cannot, unfortunately for the spiders, rule out D. crocata, and so dissection is sometimes necessary if perfect identification is vital to the survival of the human race]. Behold;

Although not at their most visible in this shot, our lovely lady has a couple (three, actually, on the circled thigh - two is usual) of small, black bristles on the dorsal surface (top side) of her fourth femur (thigh bit). So - despite having colouring suggestive of D. erythrina, and being in a region where both are known, we've got a known specimen.

Which is nice, don't you think?


And with that, that really is all, folks.


An excellent starting point for UK spiders is the Spider (and harvestman) Recording Scheme - link in name. With pictures of probably a majority of species, maps of known records, and absolutely stunning graphs and pie-charts (I love statistics. I didn't always. But now I do. Thank you, Dr. Tom Reader, for showing me the light. If I'd only realised my love before I handed in my dissertation three years ago...). 

Wednesday, 26 March 2014

Phrynarachne rugosa (Latreille, 1804)

There are a great many things that can distract me when I am pulling Lantana camara seedlings, saplings and assorted other -ings out of the ground (read more about the horror of Lantana camara everywhere outside of its native range here (wiki link), and if, living outside of South and Central America, you even think of adding it to your garden, I quite unreservedly loathe you).

This very nearly failed to distract me:

Photographed in December 2013 in Chongwe, Lusaka, Zambia, using Olympus E-420 DSLR, Zuiko 40-150mm lens and 3 KOOD magnifiers.
I'm hoping that you, as I did, initially dismissed it as the source of my prickly troubles - just another berry-filled bird-dropping. Having recognised it as a spider, however, I find the resemblance to a bird dropping much harder to see, and have to wonder whether it was ever as convincing as I thought.

But there we go. This, unless I am tragically mistaken, is a member of the widespread Paleotropical <is that a word?> genus Phrynarachne, or the Bird-Dropping Crab Spider. Perhaps unsurprisingly, I can't seem to find a specific Chewa, or derived Nyanja word for Crab Spider, but a literal translation would be along the lines of Mbalame-Matuvi Nkhanu-Kanguade.

There are a fair number of species in the genus, however, only two described species are known from areas closer to Zambia than Equatorial Guinea. One - Phrynarachne melloleitaoi, is only known from neighbouring Angola, while the second is found from Madagascar, through central Africa and into parts of West Africa.

Which makes our likely candidate today:

Phrynarachne rugosa
(Latreille, 1804)

I will add that the nominate subspecies is only known from West Africa, and therefore this is likely to be Phrynarachne rugosa infernalis, but I shall keep it in minute font, because I don't want to push my luck.

This lovely mbalame-matuvi nkhanu-kanguade (and what do you mean, that's a mouthful?) belongs, with more confidence, to: 

- Phrynarachnini
- Stephanopinae    
- Thomisidae           
- Thomisoidea           
- Dionycha                  
- Entelegynae                
 - Araneoclada                  
- Neocribellatae                 
- Araneomorphae                 
- Opisthothelae                       
- Araneae                                  
- Megoperculata                          
- Micrura                                         
- Arachnida                                        
- Chelicerata                                          
- Arthropoda                                             
See also Dichtha inflata, Oedemera nobilis, Otiorhynchus atroapterus,Malachius bipustulatus , Phyllobius pomaceus, Cheilomenes lunata, Melolontha melolontha, Neojulodis vittipennis, Demetrias atricapillusAnthia fornasiini, Lophyra cf. differens, Synagris proserpina, Vespula germanica, Astata tropicalis, Anthophora furcata, Andrena nigroaenea, Zebronia phenice, Crambus pascuella, Nemophora degeerella, Sphinx ligustri, Laelia robusta, Acada biseriata, Metisella willemi, Anthocharis cardamines, Papilio demodocus, Panorpa germanica, Chloromyia formosa, Senaspis haemorrhoa, Helophilus pendulus, Episyrphus balteatus, Metadon inermis, Diasemopsis meigeniiDolichotachina caudata, Megistocera filipes, Hagenomyia tristis, Pephricus, Grypocoris stysiRanatra, Anoplocnemis curvipes, Humbe tenuicornis, Lobosceliana loboscelis, Cyathosternum prehensile, Heteropternis thoracica, Stictogryllacris punctata, Enyaliopsis, Tettigonia viridissima, Sibylla, Enallagma cyathigerum, Pseudagrion hageni, Lestinogomphus angustus, Rhyothemis semihyalina and Ligia oceanica.
- Ecdysozoa                                                 
- Protostomia                                                  
See also Burtoa nilotica.
- Nephrozoa                                                       
- Bilateralia                                                           
- Eumetazoa                                                             
- Animalia                                                                    
- Eukaryota                                                                     
 
As with most crab spiders, this is an ambush predator; having chosen a spot where it is well concealed or camouflaged, it will wait for hours on end until suitable prey happens past, and then reach out with its surprisingly long forelimbs, grab its prey and, with a fast-acting venom, disable it before it has really grasped the severity of the situation.

A similar approach is popular with several of Africa's chubbier vipers, and the marine cone-snails. Although their venom is geared towards rather smaller prey (probably flying insects) the potency of their venom does make them potentially more dangerous than many snare-building and active-foraging spiders.

Potentially. But then, they are also generally disinclined to interact with anything too large for them to eat, so despite being generally common in farmland, bites are rare, at best.

So avoid trying to kill 'em, basically, because I'm not sure how it would end if you provoked them.


And that's all, folks!

Monday, 14 October 2013

Pardosa amentata (Clerck, 1757)... Probably.

There are a number of Pardosa in the UK, and, without manhandling it under a magnifying glass, I cannot be absolutely certain that this is not, in fact, Pardosa hortensis. However, the general appearance is more in line with known P. amentata and I'll allow myself a little uncertainty in order to let the spider carry on spidering around. The distinct dorsal strip on the cephalothorax, in addition to the white spots along the abdomen, seem to favour P. amentata. Location and more distinctive features would seem to rule out the rest.




Time for a spider:

Pardosa amentata (Clerck, 1757), Bosham, West Sussex, UK
Photographed in March 2012, in Bosham, West Sussex, UK. Olympus E-420 DSLR with Zuiko 40-150mm lens and 3 KOOD magnifiers.
This lovely little Spotted Wolf Spider belongs to:

- Eukaryota
  - Animalia
    - Eumetazoa
      - Bilateralia
        - Nephrozoa
            - Protostomia
              - Ecdysozoa
                - Arthropoda
See also Heteropternis thoracica, Humbe tenuicornis, Cyathosternum prehensile, Lobosceliana loboscelis, Stictogryllacris punctata, Sibylla, Chloromyia formosa, Senaspis haemorrhoa, Helophilus pendulus, Episyrphus balteatus, Diasemopsis meigenii, Metadon inermis, Dolichotachina caudata, Megistocera filipes, Panorpa germanica, Metisella willemi, Acada biseriata, Anthocharis cardamines, Laelia robusta, Zebronia phenice, Crambus pascuella, Phyllobius pomaceus, Otiorhynchus atroapterus, Malachius bipustulatus, Oedemera noobilis,Cheilomenes lunata, Melolontha melolontha, Neojulodis vittipennis, Demetrias atricapillus, Anthia fornasiini, Synagris proserpina, Vespula germanica, Astata tropicalis, Andrena nigroaenea, Hagenomyia tristis, Pephricus, Anoplocnemis curvipes, Ranatra,Grypocoris stysi, Rhyothemis semihyalina, Pseudagrion hageni, Enallagma cyathigerum, Lestinogomphus angustus and Ligia oceanica.
                  - Chelicerata
                    - Arachnida
                      - Micrura
                        - Megoperculata
                          - Araneae
                            - Opisthothelae
                              - Araneomorphae
                                - Neocribellatae
                                  - Araneoclada
                                    - Entelegynae
                                      - Lycosoidea
                                        - Lycosidae
                                          - Pardosinae 

and, I'm reasonably certain,
Pardosa amentata
(Clerck, 1757)

As a wolf spider, this lovely little creature is an active hunter of small invertebrates in the undergrowth. Less active than you might think - anything from days to almost a month can pass between it needing a meal.

It is - as with almost all spiders - venomous, but this venom is intended for their prey and of less concern than a bee-sting. Additionally, these spiders are considerably more difficult to incite to bite than a bee is to sting.