Unless you wanted to look at chromosomes, you can only determine the sex of a spider after it is mature. It is easiest to recognize mature males. A male that is sexually mature will have swollen pedipalps (also called palps) that have a complex, sclerotized structure on the ventral side of the palp. This structure holds the sperm and is the spider's means to transfer sperm to the female.
* Adult males and females will vary from light tan to dark brown.
* Identify the length of the legs in proportion to the body. Even though males have a smaller body, they have considerably longer legs than females. A male has a leg span around the size of a quarter. A female has legs much shorter in proportion to the larger size of her body. If the spider has a smaller body and longer legs, it is male. If it has a larger body and shorter legs, it is female.
* Males are slightly smaller in body length than females, but males have proportionally longer legs. Both sexes are venomous. Adult females average slightly larger, about 9 mm compared to about 8 mm for adult males.
- I'll try to find some pictures later on tonight but as for now, I could only find information to help! Good luck! =)
Yeah, actually it is really tough to distinguish between the two of them. I don't know why, but I've seen mature females that are long and spindley and mature males as expected like that too. The mature males don't give you the typical pedipalp clues other spiders do. Tricky with recluses. I've usually figured it out by throwing any random combination of 2 different spiders in enclosures together and see if they eat each other or mate, and if they mate then I can watch and figure out which is the male and which is the female...