Determination of sexual maturity in amblypygids

[Phrynus]

Please bear with me this might get a little long-winded. But here it goes.

It's long been known that sexual dimorphism exist in amblypygi. While some genera are more dimorphic than others. In general, species of most Genera can be sexed visually... my observation is not in reference to determining male or female rather determining when a female is sexually mature and is a viable reproductive unit.

I have spent countless hours pestering my whipscorpions with LED lights, candling abdomens trying to make a determination whether or not it was time to introduce a mature male and a mature female. While most specimens in my collection are large enough that there is no question as to the maturity, the smaller specimens concerned me.
When and how long do mature whip scorpions stay fertile with OVA? Humans for instance have a very short window of fertility. Whip scorpions of the same species may not come in contact with each other due to drought or other environmental circumstances so it is important for them to have a very large window of opportunity for reproduction.

Here's what I found.



The first picture is of a female that molted four months ago and has not been paired with a male. This shows the eggs essentially remain on deck until she can locate a male of the same species. I decided to try the same method with a Florida tailless whip scorpion primarily because I have specimens that are captive-bred and the same holds true even with the dark pigmentation of the abdomen. My guess is you can determine sexual maturity in almost all whip scorpion species by candling/inspecting the underside for ova.

Thoughts?

Pb

 

[Phrynus]

This is a virgin female Florida whip scorpion. She has never been paired and is showing eggs. I made a statement in E&A's book that I was surprised at how small some of the gravid females where that I collected out of the Wild. I'm not sure what the exact "maturity" molt is but I do believe this method can be used to determine a viable female that is ready to be paired with a mature male.

Pb

 

[Phrynus]

....And a Paraphrynus Carolina female with OVA.

 

[chanda]

Very interesting! I'll have to try that with some of mine. I have Damon diadema which I have successfully bred several times (currently on my third generation) and what I believe are Paraphrynus mexicanus which - so far - have not reproduced. The Paraphrynus are kept communally, but the D. diadema are housed separately and I just pair them occasionally so I don't end up overrun with baby whip spiders.

I was going by a combination of size and when the males start showing the visibly longer pedipalps to determine when the D. diadema were mature, but it is not terribly accurate. I had a tank of what I believed to be juveniles (I couldn't tell the boys from the girls yet) that had been kept communally, but I decided to separate them into individual cages to prevent the cannibalism that seems to occur right around that "sub-adult" stage. A few months later, one of my allegedly virgin/sub-adult females surprised me with babies! She is still quite a bit smaller than my breeding females, but I guess even arachnids can be "teen moms."

 

[Phrynus]

Here's an example of what I would consider a sub-adult specimen. This is noted by the red pedipalps and she is approximately half the size of the larger adults. Again when candled ova are visible.

 

[Phrynus]

Hi Chanda, yes! Absolutely check ut out! urge anyone that keeps amblypygi, that also feel safe and handling them attempt this method. This is just my observation but I think it, (pardon the pun) shines a little light on the reproductive biology of these little creatures.
My next goal is to observe how long after a molt it takes before eggs are formed/visible. Feeding and temperature certainly play into it but I'd imagine egg production begins almost immediately post molt.

I say take a peek, you might be surprised that you have a mature female. And please post your observations, this is how we all learn

Pb