Telling Phanaeus Vindex and Phanaeus Difformis apart? (Females, and minor males)

Hi there! let me know if this is the wrong forum to be asking this, but I was wondering if anyone was aware of or had any guides to tell these two species apart? I can tell the major males apart, but not anything else. are there any key differentiating features between the two? Common mistakes made when telling them apart? any guidance would be amazing.

I am very casually into the Entomology world, and I am young, unprofessional, and have no proper education or experience in these regards, despite this, im undoubtedly drawn to the Phanaeus genus as a whole, but if im being completely honest, it is very daunting with all the species. If anyone has any resources or recommended books I can read I would be over the moon.

Thank you for taking the time to read this any any help would be greatly appreciated.

Interesting question! I’m pretty sure P. vindex has a redder pronotum, even on tiny males, but the problem is color variation. It must be very hard without genitalia dissection.
Here is a Vindex minor male showing the red pronotum. I don’t have any difformis at the moment to compare.