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:
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.
- Araneae
- Micrura
- Nephilidae
- Entelegynae
See also Alopecosa barbipes, Phrynarachne rugosa, Hyllus argyrotoxus, Enoplognatha ovata, Argiope bruennichi and Pardosa amentata.
- Araneoclada
See also Dysdera crocata.
- Neocribellatae
- Araneomorphae
- Opisthothelae
- Megoperculata
- Arthropoda
See also Ligia oceanica, 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, 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 meigenii, Dolichotachina caudata, Megistocera filipes, Pephricus, Grypocoris stysi, Ranatra, 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
- Ecdysozoa
- Protostomia
See also Burtoa nilotica.
- Nephrozoa
See also Trachylepis varia , Trachylepis striata wahlbergi, Zootoca vivipara, Lygodactylus capensis, Thelotornis capensis, Agama armata, Caprimulgus pectoralis, Tockus alboterminatus, Larus argentatus, Sterna hirundo, Burhinus vermiculatus, Troglodytes troglodytes, Megaceryle maxima, Ardea goliath, Chalcophaps indica, Stigmatopelia senegalensis, Hipposideros vittatus, Syncerus caffer, Rana temporaria, Chiromantis xerampelina, Breviceps poweri, Kassina senegalensis and Synchiropus splendidus.
- Bilateralia
- Eumetazoa
- Animalia
- Eukaryota
And now that really is all, folks!
Note:
Other African Nephila not discussed within the text:
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.
No comments:
Post a Comment