I’ve been awaiting the molt of my larger Honduran curly hair tarantula (Brachypelma albopilosum) in hope of being able to verify its gender. Since I’m feeling pretty good about determining gender using fresh exuviae, I thought I would try doing so using a older, very dry exuvium.
I soaked the exoskeleton from the tarantula’s previous molt (10 weeks ago) in warm soapy water for several minutes and then photographed the exoskeleton. Note to self – just use one drop of dish detergent next time. The best image is shown above. I initially (optimistically?) thought this individual to be a female with small spermathecae, but correspondence with Jen Newman (Heartland Invertebrates) made clear to me that it is much more likely that this individual is a male. The structures I initially thought to be spermathecae are more likely male accessory organs.
Exact function of the accessory organs is unknown, though it is thought that they produce an adhesive liquid that helps the sperm droplet stick to the sperm web, used to transfer sperm from the gonopore to the pedipalps. Accessory organs can be very prominent in some species, including members of the genus Brachypelma.
I’m pretty disappointed in the result. Lifespans of males are so much shorter than those of females. Males curly hairs often live six months to a year after their final molt, which may be the one I’ve been awaiting. This individual, purchased as juvenile less than a year ago, has been the easiest and calmest handling tarantula of the bunch. I’ll miss him.