Two new species of Lambiella Hertel from Tasmania are described and illustrated: L. parvipsephota Kantvilas, which is similar to the widespread L. psephota (Tuck.) Hertel but differs by lacking norstictic acid in the thallus and sedifolia-grey pigment in the apothecia, and by having smaller apothecia and ascospores, 8−13 × 5−7.5 µm; and L. plumbea Kantvilas, characterised by a grey thallus lacking lichen substances, minute apothecia 0.075−0.13 mm wide, and small ascospores 4−8.5 × 3−5 µm. Both are currently known only from Tasmania. A further 11 species of Rimularia are transferred to Lambiella: Lambiella albotessellata (Kantvilas) Kantvilas, Lambiella applanata (Kantvilas & Coppins) Kantvilas, Lambiella aspicilioides (Kantvilas) Kantvilas, Lambiella asteriphila (Kantvilas) Kantvilas, Lambiella campestris (Kantvilas & Elix) Kantvilas, Lambiella circumgrisea (Kantvilas) Kantvilas, Lambiella coppinsiana (Kantvilas) Kantvilas, Lambiella exigua (Hertel & Rambold) Kantvilas, Lambiella globulispora (Sipman & Aptroot) Kantvilas, Lambiella ramboldiana (Kantvilas & Elix) Kantvilas and Lambiella umbratilis (Kantvilas & Coppins) Kantvilas. The complexities of assigning many, chiefly Southern Hemisphere taxa to new generic concepts derived essentially from molecular data are discussed briefly. Lambiella is considered to be the genus of best fit for a suite of lichens that share many salient features, particularly with respect to apothecial anatomy and their Trapelia-type asci. An identification key to the 14 species of Lambiella in Tasmania is provided.