Does anyone know how to create an additional pages library within a sub site?
You seem to have all the other document libraries (document, form, picture, wiki) but not Pages.
The reason there is no template for the Pages library is because a lot more is required to support publishing pages. What needs to happen is that the 'publishing' feature is activated on the site - this will create the Pages library and other supporting artifacts. Note also that a pre-requisite is that a similar 'publishing infrastructure' feature is enabled at the site collection level. The latter provisions artifacts at the root of the site collection such as the master page gallery, content types etc.