Cyriocosmus sp. catalina

Cyriocosmus sp. catalina is a species from the genus of South American dwarf tarantulas, among the smallest members of the whole family. The name "catalina" is the working name used by keepers: the exact origin is not yet documented in the literature, and the species itself still awaits formal description. A grown specimen (pictured) has a velvety black abdomen with a single rusty-beige patch, a greyish-brown hairy carapace and dark legs with a blue sheen and pale lengthwise stripes. The pattern sharpens with each moult, so raising one from a 1st instar spiderling lets you follow the transformation.

In the enclosure, Cyriocosmus behave like scaled-down versions of larger terrestrial tarantulas. Spiderlings live a terrestrial life, make good use of a hide and dig their own tunnels, often along the container wall, so you can sometimes watch them in cross-section. Feeding time is the highlight: the tiny spider waits motionless, then seizes its prey in a single burst and retreats with it into cover. The genus is calm by nature, shy rather than defensive, and the venom is considered mild.

Keep 1st instar (L1) spiderlings in a small, well-ventilated container with a few centimetres of coconut fibre. Mist part of the substrate regularly and let the rest dry slightly, but never allow the whole substrate to dry out. Spiderlings drink from droplets on the container walls after misting; a water dish only becomes useful for larger specimens. Offer small prey matched to the spider's size, such as young crickets or cut mealworms. Room temperature is fine. Adults need only a modest terrestrial enclosure with 5-7 cm of substrate and a cork bark hide.

This is a spider for keepers who already have a few tarantulas behind them, or who are building a collection of dwarf species. Cyriocosmus sp. catalina takes up very little shelf space and gives back what Cyriocosmus do best: movement, clever hunting and subtle changes in appearance with every moult. Species still carrying "sp." in their name are also a chance to follow a genus in which more discoveries await description.