Tuesday, 28 November 2006

Eight-legged enigmas

AÖrstan at Snail's Tales has a great photo of a pseudoscorpion that arrived in to his lab in a soil sample. His post inspired me to write about some of Australia's less familiar arachnids. Sure, everyone knows what a spider looks like. And a scorpion ... well, even if you've never seen a real one face to face, you'll have seen them in newspapers and magazines. (Not convinced? Look under the horoscopes.)

You can tick off ticks from the list and chop out the harvestmen. Mites might be mighty .... Oh, I can't keep this going. Ditch the funnies (I use the term loosely). Here are the groups I want to talk about: amblypygids and schizomids.

Australia has a handful of amblypygids (also known as tailless whip scorpions). These remarkable creatures look like spiders that have been flattened with a shoe. The first pair of legs are long and impossibly thin. They sweep the surface in front of the animal to detect and herd prey towards the business end. And the business end sports a couple of scaled-down bear traps. Anything caught in those spiked pedipalps doesn't get a second chance.

Only three species are known from the mainland, two in NE Queensland and one in the Northern Territory. The first species recorded from this country was Charinus pescotti, which was described in 1949 from specimens collected in the Barron Falls area near Cairns. This is still the best place to see them. The other two species—Charon trebax from vine thicket around Cromarty, near Alligator Creek, and C. oenpelli from the sandstone outcrops of Kakadu—were only described in 1998. There are almost certainly more species out there. How many have been mistaken for funny-looking spiders and ignored?

Schizomids are even stranger. When you see them crawling through the leaf litter of rainforests, they look more like tiny crickets than arachnids. But get up close and count the legs. Some species have eschewed the wet debris of the forest floor and live in caves. Cape Range in Western Australia is the centre of the universe for troglobitic schizomids.

Almost fifty species have been described from Australia, which isn't a bad haul on a global scale. Every one of them has been named by arachnologist Mark Harvey over the past fifteen or so years, including Barrow Island's cave-dwelling Draculoides bramstokeri. Who says systematists don't have a sense of humour?

1 comment:

AYDIN ÖRSTAN said...

Does D. bramstokeri feed on bat guano? Next time I am describing a new snail species I must come up with a funky name like that.