How to get observed species from iconic taxa with iNaturalist API v1

I want all the unique species observed in a project for a given iconic taxa using API v1, available at https://api.inaturalist.org/v1/docs/.

My problem is that the species count on iNaturalist website for the project and the one that I get as the API response, don’t match.

For example, on iNaturalist website, for taxa Amphibia, the species count for project id 226503 is 7. See this link - https://www.inaturalist.org/observations?hrank=species&iconic_taxa=Amphibia&project_id=226503&subview=table&ttl=900&verifiable=any&view=species

But I get different count, 11, when I try to retrieve data using the API - https://api.inaturalist.org/v1/observations?project_id=226503&unobserved_by_user_id=1&hrank=species&iconic_taxa=Amphibia

I am sure that I need to change the API parameters to get consistent results with the website.

I will appreciate any pointers. Thank you.

https://api.inaturalist.org/v1/observations/species_counts?project_id=226503&unobserved_by_user_id=1&iconic_taxa=Amphibia

Thank you so much. I totally missed the API endpoint.

The unobserved_by_user_id parameter is not required now, but you still have to provide the hrank=species parameter.