Medium-sized to large larvae, up to 8 mm long.
Dorsal surface of head with frontoclypeal apotome; no differentiated sclerites anterior to apotome.
Antenna half length of mandible, 5-segmented, segment 1 variable in relative length but can be squat and short, segments 2, 3, 4 reduced in size subequal in length, or segment 3 shorter than 4. Ring organ of 1st segment varies in location very basal. antennal seta near midpoint. Blade either slightly shorter or slightly longer than flagellum; accessory blade thin, extends to segments 3-4. Lauterborn organs slightly longer than 3. Style strong, extending beyond apex of segments 3.
Labrum with all S setae simple. Labral lamellae absent. Chaetae numerous (7-8), pectinate; at least 1 strong spina. Pecten epipharyngis consisting of 3 simple scales, apically rounded. Ungula consisting of 3-4 lobes on distolateral corners; basal sclerite elongate, straight-sided, tapering to blunt apex. Premandible heavily sclerotised with bifid apex, and stout triangular inner tooth; brush absent.
Mandible with apical tooth shorter than combined width of 3 inner teeth. Seta subdentalis pointed, extending to apex of innermost inner tooth. Seta interna sparse, weakly developed, perhaps absent in some spp. Inner margin smooth, without spines. Mandibular setae both strong and long.
Mentum with 1 broad median tooth bearing a nipple in unworn specimens, and 4 pairs of evenly sloping lateral teeth; heavily sclerotised. Ventromental plates essentially absent; beard absent. Setae submenti arising retracted from mentum, very long.
Anterior parapods separate, with apical crowns of claws. Posterior parapods well developed, separate and each bearing an apical crown of claws. Procercus squat, bearing 5-6 anal setae, with strong subapical setae. Supra-anal setae long. Anal tubules shorter than posterior parapods. Body setae strong and long.
This taxon was mentioned by Brundin (1966) as having an adult with a cordiform tarsomere 4, but without description. Halvorsen, who accessed Brundin's notebooks, found Brundin had associated the characteristic pupa. Halvorsen believed to be close to Cardiocladius (which tallies with the cordiform tarsomere 4) but unpublished molecular data suggests this is incorrect. Cranston associated larvae with several species of the morphologically distinct pupae [see Cranston (1996) for images, keys and short text]. The presence of only 4 lateral teeth on the mentum and the long body setae distinguishes all larvae of 'genus Australia' Brundin from the otherwise rather similar larvae of Cardiocladius.
This genus occurs sporadically in running waters, riffles and waterfalls of eastern Australia, from Davies Creek in Far North Queensland south to the Franklin River in Tasmania. Pupae have been found in New Zealand, in several moderate to large rivers in both the South Island and far northern North Island.