Male vs Female Chelicerae Size?

[WeightedAbyss75]

This is a random observation I have made in keeping/seeing quite a few MM T’s. Most of them, compared to their mature female counterparts, have much smaller chelicerae. Not even just in their smaller body size, but the ratio seems smaller compared to the body in each. Has anyone else noticed this? If so, is there any explanation as to why this is the case?

 

[Isaac Agao]

I guess it's just how nature made them to be. Just like how most MM are just smaller and live significantly shorter than most MF

 

[Mirandarachnid]

Have you documented this at all? Pics/measurements?

 

[WeightedAbyss75]

Have you documented this at all? Pics/measurements?

Unfortunately not, figured I’d see if this was a commonplace knowledge. If I can, I’ll try to find some pics that show what I am talking about

Just going to put a few examples. These are from completely unrelated spiders, but these L. parahybana from the FearnotTarantulas site seems to show this difference:

Also, in this video showing G. rosea:

it seems the male has extremely small chelicerae compared to its mate. Looking through many pictures though, it seems not all males have this. Could be species/genetic dependent...

 

[Patherophis]

Yes males do have smaller chelicers, it is just more/less prominent depending on sp.. My favorite example is Tapinauchenius, look at this pair of almost same carapax size: https://arachnoboards.com/gallery/tapinauchenius-violaceus.30094/ As for reason I dont know. But there are two things I am thinking about, mature males rarely eat so they dont need robust chelicers for hunt, and I think that maybe smaller chelicers allow better mobility of pedipalps.

 

[Vanessa]

As for reason I dont know. But there are two things I am thinking about, mature males rarely eat so they dont need robust chelicers for hunt, and I think that maybe smaller chelicers allow better mobility of pedipalps.

That would also tie into why it seems that my mature males have a much more difficult time of holding onto their prey. I have to tong feed a couple of my older boys, or they're just not going to manage it.
Although my first thought would be carapace size being the main contributor to their size. It would not be easy for me to find a mature male and female in my collection who would have equally sized carapaces.

 

[Patherophis]

So for those who wanted some numbers
Avicularia merianae
female:
carapax - 14,57; chelicerae - 6,14; ratio - 42,1 %
male:
carapax - 13,49; chelicerae - 3,46; ratio - 25,6 %
relative differece - 39,1 %

Avicularia purpurea
female:
carapax - 15,4; chelicerae - 5,38; ratio - 34,9 %
male:
carapax - 11,98; chelicerae - 3,79; ratio - 31,6 %
relative differece - 9,5 %

Avicularia juruensis
female:
carapax - 19,26; chelicerae - 8,77; ratio - 45,5 %
male:
carapax - 15,23; chelicerae - 5,60; ratio - 36,8 %
relative differece - 19,1 %

Homoeomma orellanai
female:
carapax - 7,22; chelicerae - 4,05; ratio - 56,1 %
male:
carapax - 6,84; chelicerae - 3,54; ratio - 51,8 %
relative differece - 7,7 %

Psalmopoeus pulcher
female:
carapax - 20,4; chelicerae lenght - 9,6; ratio - 47,1 %; chelicerae widht - 9,8; ratio - 48 %
male:
carapax - 16,5; chelicerae lenght - 8,3; ratio - 50,3 %; chelicerae widht - 4,3; ratio - 26,1 %
lenght relative difference - 6,4 %*
widht relative difference - 45,6 % !


Measurements taken from description/redescription works.
From these examples, only in case of P. pulcher male chelicerae are slightly longer than in female, but they are much thinner (only half as wide as female chelicerae). I personally think, based on visual differences, that widht difference may by more significant than lenght in many groups including Theraphosinae. Unfortunatelly only few works include chelicerae lenght and almost none chelicerae widht.
Feel free to add Your numbers or numbers You find.