Descriptions and keys are provided for males of 12 philopotamid caddis fly species in the genus Hydrobiosella Tillyard, H. bispina group. Among these are ten new species from Australia: Hydrobiosella bilga, H. dugarang, H. gurara, H. moorda, H. mundagurra, H. nandawar, H. thurawal, H. unispina, H. woonoongoora and H. yokunna. Females of six of the species are also described. Group separation is based on male genitalic characteristics, the key features for the H. bispina group being inferior appendages with an elongate terminal segment, fringed ventrally by a row of dark setae, and nearly all species with paired, hooked lateral processes on segment ten. Of the 12 species treated here, all are endemic to the east coast region of the Australian mainland.