Minor Sexual Dimorphism in Monocentropus balfouri

TexasTreeViper

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While looking through pictures of sub(adult) M. balfouri I began to notice a trend between the sexes. It seems that in male specimens the blue coloration on the legs extends almost all the way up towards the carapace whereas female coloration tends to stop just above the femur. Here are two really good pictures by Tom Patterson that reprensent what I'm talking about:

Male
http://www.net-bug.net/apps/photos/photo?photoid=95426039

Female
http://www.net-bug.net/apps/photos/photo?photoid=95426036

Has anyone else noticed this before and if so, does it hold true for all individuals and can it be somewhat (though not 100%) of a method for sexing?
 

Singapore_Blue1

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While looking through pictures of sub(adult) M. balfouri I began to notice a trend between the sexes. It seems that in male specimens the blue coloration on the legs extends almost all the way up towards the carapace whereas female coloration tends to stop just above the femur. Here are two really good pictures by Tom Patterson that reprensent what I'm talking about:

Male
http://www.net-bug.net/apps/photos/photo?photoid=95426039

Female
http://www.net-bug.net/apps/photos/photo?photoid=95426036

Has anyone else noticed this before and if so, does it hold true for all individuals and can it be somewhat (though not 100%) of a method for sexing?

That is a mature male bud.....:rolleyes:
 

Hobo

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I think he's pointing out the obvious dimorphism between mature females and mature males... Assuming that first picture is of a mature male. I thought you were talking about dimorphism between females and sub adult males.
 

TexasTreeViper

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I've noticed even in subadult males that the coloration extends past the femur. I don't see why this is so confusing.
 

Singapore_Blue1

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I've noticed even in subadult males that the coloration extends past the femur. I don't see why this is so confusing.
Well the picture you gave of the male is clearly a mature male...So if your talking about seeing a clear difference between a mature female and a immature male I would like to see a picture to back up that claim...
 

TexasTreeViper

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Well the picture you gave of the male is clearly a mature male...So if your talking about seeing a clear difference between a mature female and a immature male I would like to see a picture to back up that claim...
I have an immature male that just molted last week. He is only ~2.5" but all ready showing extended leg coloration. I can take a picture of him with a size reference but I cannot prove to you it's a male by the molt because I pretty much destroyed it in the process of sexing it. I will take a picture of him later tonight after I get off work and post it so you can see. In the meantime, I will see if I can't find some examples online.
 

AbraxasComplex

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To come to the aid of the OP, here are some pictures of an immature male I just took that exhibits the slight sexual dimorphism. He is quite ready for a molt, but notice the extension of blue on the femurs.








<edited>
 
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TexasTreeViper

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@ Abraxas: I appreciate you coming to aid in my absence. Unlike some people on this site I have a life outside the AB and I got too preoccupied yesterday to post the pic so thanks again.

@ Goomba: It's people like you that really degrade this site. I asked an honest, intelligent question and individuals such as yourself try and belittle me yet the countless noob questions such as "What T should I get next?" get pages of responses from people offering help. That makes absolutely no sense. The lack of serious, intelligent conversation on this site is rediculous! So unless you have something of true worth to add to this thread I suggest you keep your little remarks to yourself. <edited>

Here's the pic:
 
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synyster

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Usually people use a quarter for size reference on pictures.... That being said, sir, I like your style :worship:

On topic: Of course, any MM can be picked out by looking at it, but I too have noticed that M.balfouri IM's tend to have the blue extension on the femur. I even thought this was a common trait of differenciation up until now... Of course the spermathacae will be a 100% confirmation but so far I think this is a really good way to get the idea until getting that "still in good shape" exuvium.
 

TexasTreeViper

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Thank you synyster for your compliment and comment. This site needs more responses such as your own.
 
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xhexdx

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Good news: I learned something new.

Bad news: If it's 100% accurate, Becca's balfouri is male. :( :}

Thanks for posting, TTV.
 

fartkowski

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That's interesting.
I will have to be on the lookout for this when mine grow a bit.
Thanks for posting this TTV.
 

Hobo

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Neat.

How early can you notice it?
 

xhexdx

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I just looked at a couple of my 2" balfouri and they're still to brownish for me to tell. I'm hoping they will have more vivid coloration after their next molt.
 

TexasTreeViper

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I've had this guy for almost 2 months now and this was his first molt in my care. Looking back at pics taken when I first got him show the extended coloration. Going off of Joe's comment I would guess pretty early on once they start showing adult coloration. I wish I had a few more so I could do a better comparison.
 

xhexdx

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I have 6 that are around the 2" mark. I'll keep an eye on them and compare coloration to molts, to help to either prove or disprove this theory.

:)
 

jonk9194

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This is a very enlightening and intellectual thread. I wish there were more topics like this on AB.

Kudos to the OP for this thread and knowing what tarantula he is going to get next!
 

Jacobchinarian

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I read this 1 day to late, I have an m balfouri I bought at the ats conference and it is on it's way home in the mail now. I'll see tommarow and post my findings.
 
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