Tibellus Sunetae [Grass Running Spider]
Another week, another spider. Like I said in the first post, there will be many spiders to go through. I meant to post this yesterday but life go in the way. Better late than never. So let's get into today's spider.
The lady in the photograph below is what we call a Running spider, of the family Philodromidae. They're also sometimes called false crab spiders due to the first two leg pairs being significantly longer than the others, as seen in crab spiders. Unlike crab spiders, running spiders have 8 eyes arranged in two rows that curve sharply. They also don't run like a crab (the side-ways shuffle).
• TIBELLUS SUNETAE •
This one is a female grass running spider, of the genus Tibellus. Her species is T. sunetae. She decided my ceiling was a great place to hang out and catch mosquitoes.
I've been seeing running spiders of other genera on the ceiling and cornices for a while now, usually nestled in the fold of the cornice with their legs split flat to either side.
Catching them to relocate outside has been unsuccessful. Running spiders aren't given that name for nothing. They're fast little buggers that are quite skittish.
• GENUS •
This genus of running spider is rather unique among the South African known genera. With their long, thin bodies, and their legs not being too long, Tibellus spiders are masters of camouflage. They live on and make their egg sacs in grass where they're most protected.
For this lady, it was a matter of the long body and the leg formation typical of running spiders that pointed me to the genus Tibellus. Then it was off to the literature to find her species.
And, thanks to a revision in the Afrotropical species of Tibellus, I was able to narrow it down using the drawings, then reading through the descriptions of each species to find the one that fit. And that is Tibellus sunetae mainly for the dorsal markings, the spots, and the leg formation along with colouration.
• DESCRIPTION •
- Class: Arachnida
- Order: Araneae
- Infra-Order: Araneamorph (true spiders)
- Family: Philodromidae
- Genus: Tibellus
- Species: T. sunetae
Around 5mm in body length. Leg span of approximately 10mm diagonally.
Long and pale yellow carapace with thick darker yellowish brown band down centre, faint bands near edges, and dark spots all over. Dark setae on cylpeus and around eyes. Darker yellow tarsus on pedipalps.
Long, thin, creamy abdomen that tapers to spinnerets, with thick brownish-grey line down centre, faint lines on sides, and brown spots all over dorsal side.
Yellow with scattered dark spots and dark setae. Metatarsus and tarsus darker yellow. Leg formation of 2, 1, 4, 3.
• ABOUT THE GENUS •
Tibellus spiders fold their legs in front and behind them so they look like a blade of grass. They will also run at the slightest suggestion of a threat. Tibellus, like most spiders, prefer to be active and abundant during the summer months and are often found here between November and April, though I spot them more readily just after the January summer rains.
They are free-living hunting spiders, essentially, meaning they don't make webs to live or breed on. They're generally yellowish to brown, and a bit of red, with what's called a "heart marking" on their abdomen. Heart, in the case of spiders, refers to a tubular artery-like organ that pumps haemolymph (sort of like blood) through their bodies. The heart runs down the centre of the dorsal abdomen, and that's what a heart marking indicates.
• NOTES •
How I said running spiders are skittish and will bolt at signs of a threat? Apparently, this female didn't get the message. However, the day I found her did have a cold front blowing through and the air was rather cold. This could have slowed her movements and response time.
This commonly happens with spiders, due to the cold freezing their haemolymph which makes it difficult for them to "pump" through their limbs. And because spiders don't have muscles, they rely on hydrostatic motion to move around. Anything that interferes with this can impair a spider. The pressures in the abdomen and cephalothorax are also fragile, which is why a wound can be deadly, even though it's small.
Fortunately, this slowed side-effect allowed me to take a couple of photos of this T. sunetae with ease, snapping some lovely detail. Further than the sluggish movement, there was nothing else to observe. She stayed in the same position all day and was gone by the next morning.