Interesting observation on Monocentropus balfouri female/male ratio

TarantulaHomes

Arachnosquire
Joined
Apr 30, 2010
Messages
78
Hey folks,

just wanted to share some interesting facts on this species.. For the past year I've received 3 batches from 3 different sources and in all three f/m ratio was skewed towards strong dominance of females. Here's a breakdown:

Batch 01: 60% / 40%
Batch 02: 70% / 30 %
Batch 03: 66% / 34%

There was another specimen that I received as a bonus with one of my European imports and it turned out to be a female.

Does anybody else keep statistics on this sp. sex ratio? If this is the case, we are going to face a strong deficit of males in the hobby and they will be in high demand..
 

Anastasia

Arachnoprince
Old Timer
Joined
Jan 8, 2007
Messages
1,848
hmm, that is what I remember you said about P smithi 80% females, not in my case..
Just have to ask, how you come up with this numbers?
did you purchase whole sac and raise them to sex? because that would be the most accurate
so if you got groups of 10 or 20 spiderlings to come up with this observation, I would say that is just a pure luck of picking
in the past I purchase 12 spiderlings that All end up to be males they wore 1/2" when I got them
also, I got group of 25 raised end up with 19 males 3 females and 3 diseased
To do more accurate project on the ratio males to females got to be working with whole sac
rest is just assumption and lucky pickings

Anastasia
 

Protectyaaaneck

Arachnoking
Old Timer
Joined
Jul 2, 2008
Messages
3,105
I have limited experience with this sp. but I have to agree with Ana here. You need to perform studies on entire eggsacs to draw any type of real conclusion.
 

TarantulaHomes

Arachnosquire
Joined
Apr 30, 2010
Messages
78
hmm, that is what I remember you said about P smithi 80% females, not in my case..
Just have to ask, how you come up with this numbers?
did you purchase whole sac and raise them to sex? because that would be the most accurate
so if you got groups of 10 or 20 spiderlings to come up with this observation, I would say that is just a pure luck of picking
in the past I purchase 12 spiderlings that All end up to be males they wore 1/2" when I got them
also, I got group of 25 raised end up with 19 males 3 females and 3 diseased
To do more accurate project on the ratio males to females got to be working with whole sac
rest is just assumption and lucky pickings

Anastasia
Could be that I just got lucky, but 3 times in a row with almost identical numbers.. hmm..
In your case, I'm pretty sure you got them sexed. M. balfouri spermathecae is huge compared to other species and can be easily spotted even in 1-1.25" spiderlings with 20x/40x microscope.

I have limited experience with this sp. but I have to agree with Ana here. You need to perform studies on entire eggsacs to draw any type of real conclusion.
No conclusions yet. I just presented my experience with them and was looking if anybody else could share this kind of statistics.
 

Anastasia

Arachnoprince
Old Timer
Joined
Jan 8, 2007
Messages
1,848
Could be that I just got lucky, but 3 times in a row with almost identical numbers.. hmm..
In your case, I'm pretty sure you got them sexed. M. balfouri spermathecae is huge compared to other species and can be easily spotted even in 1-1.25" spiderlings with 20x/40x microscope.
sexed at second instar?, well I cant even guess how can that be done
 
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