OpenTaxa has an official Discord channel which is used, among other things, to handle asset requests and suggestions.
The official join link is here. Your account must be email-verified to join.
If you would like to send in a request without creating a Discord account, contact me on Twitter (@croomfolk) or via e-mail at yurinikolaizerozero(at)gmail(dot)com. Replace the written zeroes with 0s.