Read this -
www.tarantulas.co.za/forum/know-your-tar...3-sexing-a-tarantula

Now go look at the picture you posted and using paint or photoshop etc outline any structures you see and label them.

Thanks duke that is a good thread. Okay so here is what the newb (me) did.

L.P are actually quite hard to sex at 7cm... not impossible but harder that most spiders I find just wait until its about +10cm and you should know... seems to me there spermathecae develops quite slow as opposed to a B.smithi which you can sex easily at 5cm... this is just my theory not FACT.. reason being is that L.P reach around 28cm in size as where say a B.smith will get up to 15cm, so therefore at 10cm an L.P is still a juvie as were at 10cm B.smith is a sub-adult. make sense? i might be very wrong thou.

YOU DON'T HAVE TO SEE THE SPERMATHECAE TO DETERMINE THE SEX OF A TARANTULA! ... any more than you need to see tibial hooks to tell if you have a mature male.

What you need to see is the little flap of tissue, the bursa copulatrix (BC), that extends up into the female's body cavity to tell that it's a female. (Click the thumbnail for a larger image.)

(Female: adult Brachypelma emilia. Male: adult B. smithi)

In this illustration, note the photo on the left of the inside of the female's exuvia. The circled part is the BC, the structure that you need to look for. Note as well that the spermathecae are all but invisible. The spermathecae of Brachypelma smithi and B. emilia are just thickened margins on the BC and often very hard to see, especially on very young individuals. Here, it appears as merely a lighter colored margin on the right edge of the BC. If you were looking for spermathecae alone and didn't know any better, you'd make a completely erroneous determination with this species! LOOK FOR THE BURSA COPULATRIX AND BE CORRECT 100% OF THE TIME!!

The only time that the spermathecae are terribly important is when you're trying to identify a mystery tarantula and all you have is a dead female or the shed exuvia. Spermathecae are used for species identification, not for sex determination! That was the original intent of that montage of drawings that were posted earlier.

And, about those tibial hooks, there are a fair number of species wherein the male doesn't develop tibial hooks. So, if you're looking for tibial hooks you're going to miss some mature males. LOOK FOR THE CLUBBED PEDIPALPS AND BE CORRECT 100% OF THE TIME!!

Yet another instance where our little 8-legged buddies are trying to trick us!

Stanley A. Schultz wrote: What you need to see is the little flap of tissue, the bursa copulatrix (BC), that extends up into the female's body cavity to tell that it's a female. (Click the thumbnail for a larger image.)

In this illustration, note the photo on the left of the inside of the female's exuvia. The circled part is the BC, the structure that you need to look for. Note as well that the spermathecae are all but invisible. The spermathecae of Brachypelma smithi and B. emilia are just thickened margins on the BC and often very hard to see, especially on very young individuals. Here, it appears as merely a lighter colored margin on the right edge of the BC. If you were looking for spermathecae alone and didn't know any better, you'd make a completely erroneous determination with this species! LOOK FOR THE BURSA COPULATRIX AND BE CORRECT 100% OF THE TIME!!

Hi Stan

From what I read in your post it sounds like you have your terms mixed up. The bursa copulatrix is not a flap of skin but the oval to semi circular shaped alcove below the spermathecae and uterus externus. The uterus externus on the other hand is a transparent flap of skin that sits over the spermathecae.

I have outlined the bursa copulatrix in yellow and the uterus externus in blue in your pic

Snakekid this is what I see on your pic

Uterus externus in blue, spermathecae in red.


Encyocratella olivacea is a species of tarantula not a body part of any sort.