Theridion sp. [False House Button Spider]

in Arachnids5 months ago


Hello, hello, Hive!

This week we return to the one of the largest spider families, Theridiidae, the comb-footed spiders. I know I said Pisaurids were a weird family, but really, Theridiids are weirder. There are some species in this family that defy everything you may think you know about Theridiids, or comb-footed spiders.

But this time is still mild. I have yet to come across any of the wacky Theridiids. Hopefully one day, though. For now, we'll be looking at a very small species. They're adorable and gentle and oh, so good at controlling mosquito and miggie populations.

• THERIDION SP.•


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Female Theridion sp.

Meet the False House Button spider, Theridion. The common name came about due to the similarity of the body to that of the button spiders, Latrodectus. The difference between them is otherwise quite noticeable. Theridion is much, much smaller. They're tiny spiders.

Like this species that has decided to make my house their home. I'm not complaining, though. They're as effective as Dictynids (mesh-web weaver spiders) in capturing small flying insects. I'm not sure what species this Theridion is, however. It could be an undescribed or perhaps a variant of a described species. It's too small to see the eye arrangement, too.

Considering the amount of T. purcelli I find in the area, I'd wager this is a variant of that species. My reasoning being the distinct pattern on the abdomen and the banded legs. I have no way to make certain of this, however.

• GENUS •


img_20220114_160613.jpg

Male Theridion sp.

As their common name suggests, Theridion are often found in people's houses. And unlike button spiders, Theridion's webs are small and barely noticeable. Also unlike their cousin, their webs tend to be messy. Not only because of the carcasses, but also because it traps and collects dust so easily.

While a few Theridiid genera look similar, Theridion spiders are iconic for tending to have that chevron-like pattern down a round bulbous abdomen. It makes them easy to identify to genus, at least. But not all Theridion sp. have this patterning. Like I said, some weird spiders in this family. Theridiid genera are quite unique to their own in general.

• DESCRIPTION •


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Female Theridion sp.

Taxon:

  • Class: Arachnida
  • Order: Araneae
  • Infra-Order: Araneamorph (true spiders)
  • Family: Theridiidae
  • Genus: Theridion
  • Species: Unknown

Female

About 5mm in body length. Leg span of approximately 10mm diagonally.

Cephalothorax:
Reddish carapace with a dark line down centre and dark outline near edges.

Abdomen:
Round dark grey and mottled abdomen with a light grey mottled chevron-like pattern down centre from anterior to posterior.

Legs:
Reddish legs with dark bands at the joints. First pair longest, 4th pair second longest. 3rd pair shortest.


Male

As in female but the colours are more dull with a brownish tint. Leg pairs ordered in length as 1, 2, 4, 3. Large near-black, bulbous pedipalp tarsi. Abdomen not as bulbous as female.

• ABOUT THE GENUS •


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Male Theridion sp.

Theridion like to use surrounding debris, including the carcasses of their prey, to build their retreats with. As grotesque as that sounds, it's effective in helping to keep predators away and hiding from them during the day when they sleep 1.

As is typical of Theridiids, Theridion creates a tange-web, albeit very small and the silk very thin, making it difficult to see. Theridion are also harmless to humans. Their venom is medically insignificant and they are too small to pierce our skin with their fangs. So they're safe to keep around the house.

• NOTES •


This species of Theridion is particularly shy and sedentary. They hardly move at all except to capture any prey that lands near or on the web. The males of this species, too, don't wander much. From what I've observed, the males will move towards a female if they're nearby then settle and build their web and just chill there until it's time to mate.

After copulation, the male returns to his web and doesn't move around again. It's very peculiar behaviour. But I'm not certain whether it's indicative of this species or if it's due to the over-abundance of food available here that has made them lazy.

They seem to be reproducing well enough, judging by the frequency at which I find them and also the amount of egg sacs with each female (on average 2-3 at a time). Their egg sacs are small grey balls, however, and there doesn't seem to be many eggs in them on average. From the few I've dissected, I've counted between 30 and 50 eggs per sac.



Thanks for stopping by and reading and supporting!

And remember, spiders are friends.



 

• All images are Copyright © 2022 Anike Kirsten •


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