Pass parameters in triplets:

First parameter: Name of the higher-order taxon, e.g. "Suborder Chelodina"

Second parameter: Authority of the higher-order taxon, e.g. Smith 1889. (Leave blank if unknown)

Third parameter: A list of taxa within the higher-order taxon, probably generated using Template:Species list or {{Taxon list}}.

[Fourth parameter: first parameter of next triplet; ...]

To collapse the template at the first level, use Template:Collapsible taxon list as opposed to Template:Nested taxon list.