This might be a good reference in helping us identify the gender of our pet Ts via examining their exuviums or observing/taking a photo of their underside from beneath a clear container.
NOTE: to be able to see & read the details on each image below, you can enlarge each image by right clicking on a particular image, and select "VIEW IMAGE".
LEFT: FEMALE | RIGHT: MALE
Among different species a form of spermathecae has rather diverse shape.
Below are the Female Spermathecae as seen in an exuvium of different T species:
for more info, read the rest of the articles here: *** determination. | Theraphosids of the World. Kepping and breeding in captivity