Names of higher taxonomic groups (family and above) generally have an initial capital but no italics:
Mammalia Marsupialia Rodentia Muridae Myrtaceae
However, there are exceptions; see Bacterial names and Virus names.
The name of the rank (eg family, order) takes lower case in text:
The family Myrtaceae consists of ...
In one classification system, superorder Glires includes the orders Lagomorpha ...
but an initial capital in a taxonomic listing:
Superorder Glires
Order Lagomorpha
Order Rodentia
The names of families and higher-order taxa are treated as plural:
The Epacridaceae are endemic to Australia
