Visually sexing immature asian arboreals

[l4nsky]

Hola,

Long time since I've posted, but I've noticed something interesting in my collection and I want to have a discussion on the topic and see what comes to light. Asian arboreals have quickly become my niche in this hobby and one of the first I acquired was a 0.0.3 group of Phormingochilus sp Akcaya from the same sack. They're out on display every night, but rarely can I get a good look at them in the daylight (I use red LED torches for nighttime viewing). Currently, they are about 3.5" and I recently rehoused all three. I noticed something interesting when I got a ventral point of view with daylight. Of the three, two look like this:
Note the dark, sleek sternum and hair coloration on the underside of the legs. The last one looked quite a bit different:
I thought maybe it was an angle playing tricks on me at first, but the closer I looked, the more sure I was. I got to thinking about it and P. sp Akcaya ultimate males do change colors and patterns like a lot of Asian species. What if the color change actually starts gradually and subtlety and can be used as a sex characteristic before the ultimate molt? The three are virtually indistinguishable from a dorsal view, but this one just sticks out when viewed from a ventral angle. Of course the hard evidence would be to sex them and dont you know it, I havent been able to get a good molt from the oddball (I will update this thread when I do though). That being said, the other two have both sexed out as females.

So my question is this: Is visually sexing immature Asian arboreals possible and I just don't know that fact or could we have potentially stumbled on something here? The second question would be what other species could this method possibly be used for? A lot of Asian sp males change to a golden/green color upon maturity. Could they all show visual signs of sex prior to the ultimate molt?

Thanks,
--Matt

 

[Matt Man]

Personally, visually sexing Ts is an educated guess at best. Some folks are better than others, and there are all kinds of clues, and you may have stumbled upon one.
That being said I have seen enough experts be wrong to stick to the educated guess as a starting point

 

[l4nsky]

Personally, visually sexing Ts is an educated guess at best. Some folks are better than others, and there are all kinds of clues, and you may have stumbled upon one.
That being said I have seen enough experts be wrong to stick to the educated guess as a starting point

Agreed. Judging sex based on subtle pattern variations, book lung angles, size and shape of the epigastric furrow, and even the "white dot" for pokies has always been hit or miss for me. It leaves a lot open to interpretation and I will just always go the tried and true method of molt sexing. I'm only bringing this possibility up because the differences between the two at this size are highly noticeable and leave little room for interpretation (if this actually pans out). The oddball should molt again within the next two or three months and I'll make every effort to get an intact molt for verification. I also have a smaller, imported Akcaya that I will see if I can further verify this theory with. My sabah blue's will also need a rehouse soon and I'm curious if this phenomenon might apply to them as well. This is all speculation for now, but it has definitely got my interest.

 

[Matt Man]

Agreed. Judging sex based on subtle pattern variations, book lung angles, size and shape of the epigastric furrow, and even the "white dot" for pokies has always been hit or miss for me. It leaves a lot open to interpretation and I will just always go the tried and true method of molt sexing. I'm only bringing this possibility up because the differences between the two at this size are highly noticeable and leave little room for interpretation (if this actually pans out). The oddball should molt again within the next two or three months and I'll make every effort to get an intact molt for verification. I also have a smaller, imported Akcaya that I will see if I can further verify this theory with. My sabah blue's will also need a rehouse soon and I'm curious if this phenomenon might apply to them as well. This is all speculation for now, but it has definitely got my interest.

I hope your discovery leads to something. Hopefully other folks will join in and you can get a web based data set

 

[l4nsky]

@grayzone

Have you ever noticed something like this with any of the Asians you've worked with? These akcaya's are some you produced by the way.

 

[The Grym Reaper]

Lampropelma nigerrimum are dimorphic as juveniles, males turn light brown at around 2" or so whereas females retain their darker colouration. The change is quite dramatic (both pics below of the same specimen).

View media item 51009View media item 53314
Omothymus schioedtei turn green as juvies

Omothymus schioedtei - Immature Male

• Exoskeleton Invertebrates
• Jun 4, 2018
• juvenile juvenile male malaysian earthtiger tarantula male omothymus omothymus schioedtei schioedtei

Omothymus schioedtei - Immature Male

0.1 Omothymus schioedtei

• The Grym Reaper
• May 22, 2020
• female juvenile juvenile female malaysian earth tiger malaysian tree tiger omothymus omothymus schioedtei schioedtei

Dusk is now a confirmed female, here she is doing her best Pokie impersonation in her new suit.

 

[l4nsky]

As an update, the oddball akcaya that showed lighter ventral hairs is male. He went through his full color change this last molt. Still havent gotten a chance to get pictures or see if he's penult or ult though....

 

[CrazyOrnithoctonineGuy]

Necro, but this makes me more confident that the girl in my avatar is really a girl.

 

[curtisgiganteus]

As an update, the oddball akcaya that showed lighter ventral hairs is male. He went through his full color change this last molt. Still havent gotten a chance to get pictures or see if he's penult or ult though....

Once my two akcaya come out of their burrows I’ll get some ventral shots, I think I have one and it has the lighter setae like your male.

Here is the first one that molted. I think its a male

 

[l4nsky]

Necro, but this makes me more confident that the girl in my avatar is really a girl.

Don't let it be a false confidence . So far, I've only noticed this ventral hair subtlety with penult Phormingochilus sp Akcaya. For the Philippine Ornithoctoninae, I did notice one species displays visual sexual dimorphism early on via color (O. sp Surigao del Sur LL), but that isn't necessarily true for all of the undescribed Philippine species.

 

[CrazyOrnithoctonineGuy]

Don't let it be a false confidence . So far, I've only noticed this ventral hair subtlety with penult Phormingochilus sp Akcaya. For the Philippine Ornithoctoninae, I did notice one species displays visual sexual dimorphism early on via color (O. sp Surigao del Sur LL), but that isn't necessarily true for all of the undescribed Philippine species.

Just recovered a molt, and it turns out she indeed is female.....granted, I don't have a male to compare her coloration to.

 

[curtisgiganteus]

Don't let it be a false confidence . So far, I've only noticed this ventral hair subtlety with penult Phormingochilus sp Akcaya. For the Philippine Ornithoctoninae, I did notice one species displays visual sexual dimorphism early on via color (O. sp Surigao del Sur LL), but that isn't necessarily true for all of the undescribed Philippine species.

You’re right about the Surigao. The females have an underlying blue?violet? To their legs but the males are a tawny brown

3” Female O sp Surigao del Sur


3” Male O sp Surigao del Sur