Revision of Australian Parathyginus with description of two new species, along with first detailed description of aedeagus in the family Heterogastridae (Hemiptera: Heteroptera: Lygaeoidea).

The Australian species of the small heterogastrid genus Parathyginus Scudder, 1957 have been reviewed, resulting in the establishment of the junior subjective synonymy of P. doddi (Distant, 1918) with P. signifer (Walker, 1872), and the description of two new species, P. australis sp. nov. and P. acuminatus sp. nov. A redescription of the genus is provided with emphasis on male and female genitalia characters, along with a key to all included Australian species. Male genitalia, particularly the details of the aedeagus, have been rarely studied in this genus or for that matter the family Heterogastridae particularly due to the difficulty in inflating the inflatable sections. In this study, therefore, an attempt was made to fully inflate and describe the aedeagus of all the species included in this contribution, as well as of Heterogaster urticae (Fabricius, 1775), the type species of the oldest genus Heterogaster Schilling, 1829, of the family Heterogastridae.