This might be a worthy User Suggestion in the forums, as far as i'm aware there's no intention to separate or add gender flare to the book.

Growrr (#16845)- Both genders do count towards your total # rare beetle collected count, so there is a reason to save both if you're trying to get those Achievements easier & struggling to get some of the rarer ones.

W;hꧧågê; (#244378)- If you're collecting the beetles on the same account (Main or Side) that you're focused on building out your Beetle Book, you can still see the "Add to Collection" button on the beetle's page for the gender you don't have.
This requires the beetle to already be on your account, so you can't research or look up which gender might still count to your tally in advance. We can see others' Beetle Battle Books if they save a link to send, so it also won't work if you're advertising that you're willing to purchase a duplicate of a specific color/species provided you don't already have that gender, or using the your Main's Beetle Battle Book link to look up beetles you don't already have from your side (for example).
This won't help if you're trying to look up a beetle on Trading center before purchasing, or if you're trying to collect & raise on your side to add to your frozen Main's beetle book later, but it's a start!

If you feel that solution is not workable, feel free to make a Suggestion board post & i'm sure you'll get some traction. ^^

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It's not shown on the computers either. Moreover, both sexes are counted as one beetle in the book, so it just doesn't have sense to collect the other sex of the same beetle.

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⪘ SiRah (#159527): Just to be more precise -- I didn't mean the achievement count (and I didn't know that it includes both genders) , I just meant that the addition of a beetle of the other gender doesn't increase the count of collected beetles in the book. Same as the total number of 460 includes only one beetle of each species and color.

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Ah, I see! I'm referring to the Achievement page where it separates total beetles collected (both genders are counted as 1 tally, I believe?) from other achievements which count only unique species/color (where collecting both genders does not increase the tally, as only unique species/color are counted once).
Those totals do increase per gender, but are harder to track as OP mentioned since the count per gender isn't tracked in the beetle log.

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Thank you to both of you! 😊

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