[littlemanpoet]

There are patriarchs in patriarchal societies,
and matriarchs in patriarchal societies;
likewise, there are patriarchs in matriarchal societies,
and matriarchs in matriarchal societies.

Of those named so far (Galadriel, Haleth, Lobelia, and 'Grandma Gollum'), the first three are matriarchs in patriarchal societies. Only Grandma Gollum is a matriarch in a potentially matriarchal society.

Numenor is another example of matriarchs in a patriarchal society, and is the most well-recorded instance of it: we have record that the law of the land was actually changed in order to make sure that the eldest daughter ascends the throne in the absence of a son. This law was ignored by certain treasonous usurpers, but it still was the law.

The conclusion is, as far as we can tell from Tolkien's writings, that Middle Earth appears to have been made up exclusively of demonstrably patriarchal societies. Within these societies, the standing of women varied from culture to culture according to historic developments within each.