Hi, the advice by @ susanhewitt above to use an existing article of a closely related species as a template for a new article is a useful suggestion to create a new article on Wikipedia. You can usually use the taxonomy box on the top right of the article to click on the genus and from there see if there are any relevant species articles available to copy. Once you have found a similar stub, click “Edit source” as if you were going to edit the article, then copy all the text within the article to your clipboard. This will then include all the Wiki-markup and paragraph format that is present in the article that you are copying, including the taxobox (whether manual or automatic). Leave the page without saving, so as not to accidentally change anything, and look for the new page title.
When you click on the red link for the article name you wish to create (which you can find either on the genus page or from the results gained by typing it in the search bar), you will be invited to create a new article at that title as long as you are logged-in with a Wikipedia account. The article name should usually be at the scientific binomial, at least to start. Once you are at the new page, you can then paste the wiki-text from the other article to use as a template.
As you will be in edit mode, review the text in the new article and change the info to match the new species. You can just delete any sections that you don’t understand. Once you have completed your article, select “preview page” and then make any changes as necessary. Select “save changes” or “publish page” and include a short edit summary (like “Created page”).
Above all, do not be afraid to make mistakes or use the wrong format. Other more experienced users, such as @ plantdrew above, routinely patrol such new articles and help fix them. You cannot “break” Wikipedia, and any incorrect edits can always be reversed.
I would also suggest that any iNat users interested in editing Wikipedia should check out any relevant “project pages” on Wikipedia to benefit from any resources offered there (article layout formats, references, taxonomy sources, discussions, etc.). Some of the project areas are:
Other projects are listed at the WikiProject:Tree of Life.
You can edit most (but not all) Wikipedia articles without an account, but cannot create any new articles. If you wish to sign up for an account on English Wikipedia, you can follow this link.
If you have any further questions, you can contact me on my English Wikipedia account talk page.