All seven Hemicyrthus species are known from few specimens, sometimes only from the holotype (Dechambre 1982; Paulian 1991; Théry 2008). They all are known from either single locations or small areas (Fig. 5). The species with the widest known range is H. villiersi from Mont Mandjelia to Mont Panié, which are just over 30 km apart and are connected by a continuous mountain forest. The next largest range is that of H. blaffarti, with Refuge de la Rivière Bleue in the east and Grand Kaori in the west of its known range being just over 4 km apart. The other species are known from one locality only, with no available spatial data about the collecting area.
Short-range endemism is common in New Caledonia with numerous examples in, e.g., reptiles, plants and insects (Murienne et al. 2008), and is promoted by low dispersal capability and low ecological tolerance (Ponder & Colgan 2002). The ecological requirements of Hemicyrthus species are unknown, but the flightlessness and substantial size of the Hemicyrthus species greatly restrict their active and passive dispersal abilities.