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4 Dec, 12 tweets, 5 min read

Today's #ScienteaficABC spider family is ANAMIDAE! A brand spanking new family, having only been elevated to full family status in this hell year 2020. Formerly, these spiders were a tribe, then a subfamily, of the family Nemesiidae. (Images: iNat Creative Commons)

This family comprises 10 genera/104 species. These are mygalomorph spiders, an infraorder containing tarantulas, trapdoors, funnel webs, curtain webs & others characterised by their downward pointing chelicerae & fangs (& other things). (Chenistonia maculata by matthew_connors)

Native to Australia, 3 genera of this family (Aname, Chenistonia & Namea) are commonly called 'wishbone spiders' owing to the shape of the burrows they create. The silk-lined burrow is Y-shaped with one branch of the Y being longer than the other.

The longer branch terminates with the burrow entrance with the other branch remaining completely concealed underground which is believed to create an air pocket in the event of flooding so that the spider has a safe place to wait it out. (Namea sp. by aussiecreature on iNat)

Typically mygalomorph in appearance, these spiders have large chelicerae, a mostly flattened carapace with a cluster of 8, small eyes front & centre, & spinnerets that mostly remain tucked up, flush with the abdomen, like those of a tarantula. (Proshermacha sp. by npk on iNat)

They have short hairs all over their bodies, some species being metallic/gold, but most are black, dark grey, or varying shades of brown. Whilst not enormous like many tarantula species, they are decent sized spiders. Here's a lovely gold Aname sp. (Pic: ethanbeaver on iNat)

This image by iNat user npk shows a mature male Aname with a ruler for scale. Often, mygalomorph males are markedly smaller than females.

This family undoubtedly still has many undescribed species yet to be studied & classified, due to the fact that they live in deep burrows in areas of open dry scrubland Western and Southern Australia. Here are some little Chenistonia trevallynia spiderlings (Pic: mhedin on iNat)

Bites from Aname species are rare & their venom does not seem medically significant with most instances resulting in localised pain, redness & swelling and little more. Female A. inimica are known to be quick to bite, even earning an Aboriginal name that means 'unfriendly'.

As always, great care is taken to ensure that all images sourced are under Creative Commons license. If I have used an image here which you believe not to be CC, please let me know so that I can rectify!

iNat links:
inaturalist.org/observations/6…
inaturalist.org/observations/6…
inaturalist.org/observations/5…
inaturalist.org/observations/3…
inaturalist.org/observations/3…
inaturalist.org/observations/3…

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More from @tea_francis

🕷scienTEAfic🕷

@tea_francis

3 Dec

Bonus round! #ScienteaficABC. A small thread for this family AMMOXENIDAE! Why small? A few reasons. Firstly, it's a small family- 4 genera/18 species total, & secondly, they’re a specialised familiy so a broad summary should be pretty quick! (Images: Creative Commons, see end)

Ammoxenidae are commonly known as termite hunters. They are found in Africa & Australia, living on sand dunes, savannahs & bushland in both arid & tropical areas. They actively hunt for termites & when they're not hunting, they dig themselves into the sand. (Img: iNat cecileroux)

Once dug into the sand, they spin a silken retreat which is sticky on the outside so that sand grains stick to it & conceal it. They have adaptations to their chelicerae that enable them to dive face first into the sand and disappear from sight in seconds. (img: iNat peterwebb)

Read 9 tweets

🕷scienTEAfic🕷

@tea_francis

3 Dec

Another #ScienteaficABC. AMAUROBIIDAE! This family comprises 49 genera & ~275 species & can be found mostly around the world save for large swathes of the African, Asian & Australian continents, the Arctic & Antarctica. (images Wikimedia Commons & my own).

Amaurobiid spiders are generally quite rounded & velvety looking, not too vibrant or brightly coloured in most cases (though as you can see here, A. similis does try!), vary in size from 5-30+mm body length, & tend to inhabit cracks, crevices & other sheltered spots. (Pic: mine)

As with other spider families, eye arrangement is helpful (though by no means foolproof) in identifying Amaurobiidae. Here, enjoy another of my terrible diagrams! I shall accompany it with a photo to show you how they look on an actual A. fenestralis. (Image: Wikimedia Commons)

Read 12 tweets

🕷scienTEAfic🕷

@tea_francis

2 Dec

Next up in #ScienteaficABC, AGELENIDAE! This family comprises 87 genera, totalling 1307 species & has an almost cosmopolitan distribution making it a commonly encountered family. The pic shows a few examples of members & some common features. (Images: Wikimedia Commons & my own)

Agelenid spiders vary quite a lot in appearance from genus to genus, but generally can be identified by eye arrangement (see my awful pic), web type/habitat & shape of cephalothorax... though, as always, there are some that do not fall in line with this which makes things fun 😂

Some members of this family are commonly confused with other types of spider. Take this as an example... Agelenopsis sp. (grass spider) vs. Rabidosa rabida (wolf spider), both from Virginia. The most reliable way to tell them apart is their eyes & spinnerets. (Pics: Wikimedia)

Read 11 tweets

🕷scienTEAfic🕷

@tea_francis

1 Dec

Kicking off #ScienteaficABC, taking it from the top with Actinopodidae! This is a family of mygalomorph spiders (an infraorder of heavy bodied spiders with downward facing chelicerae), comprising just 3 genera- Actinopus, Missulena & Plesiolena. (All images: Wikimedia Commons).

Actinopodidae can be found in Australia and Central & South America. They are considered medically significant, which means their venom is potentially dangerous. Overall, they are heavy set, impressive looking spiders, usually with a stocky legs, large chelicerae & fangs.

Perhaps most recognisable of this family are Missulena spp. The mouse spiders! Found mostly in Australia, 1 of the 18 species is found in Chile. This is a male M. occatoria native to S. Australia. Females do not exhibit the bright red that the males do & tend to be heavier set.

Read 9 tweets

🕷scienTEAfic🕷

@tea_francis

29 Nov

This is the entrance to my Theraphosa apophysis’ burrow. It’s gone to ground to moult. This species possesses the most irritating urticating setae (specialised itchy hairs used for defense against predators etc) of all known tarantulas.

The spider has burrowed down in such a way that I have a window into its moult chamber. The whole thing is lined with silk, but most amazing of all is the protective measure it has taken to deter any would be attackers from disturbing it while it’s in its most vulnerable state.

See all that fluffy debris all over the spider (who is upside down here)? Those are its urticating setae. Prior to beginning its moult, it kicked them all over its silken moult mat & when it flipped on to its back, the result was it being covered in these hairs.

Read 4 tweets

🕷scienTEAfic🕷

@tea_francis

29 Nov

Throwback to last May. I found these two Clubiona terrestris wandering about on a planter. I only had one vial to hand so I risked putting them both in it together just to get them inside. As soon as they met, one piled on the other & I thought that was it, game over...

Then I saw that what I actually had was a male & female & he had pounced on her to mate with her. What was most remarkable about this was the total lack of any kind of courtship behaviour or caution in approaching her. He just got straight down to it as soon as he got a chance.

She didn’t stop wandering around for a while... almost like she hadn’t even realised what was happening either. Eventually, they settled & remained coupled like this for over an hour.

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