This paper provides taxonomic, distributional and ecological data for 59 species in 17 genera of Trechinae and Psydrinae from Tasmania, and describes 18 new species in six existing genera (Pterocyrtus, Tasmanorites, Sloanella, Trechistus, Goedetrechus, Tasmanotrechus) collected from caves, forest and montane habitats: Pterocyrtus grayi sp. nov., P. meridionalis sp. nov., Tasmanorites beatricis sp. nov., T. daccordii sp. nov.,T. lynceorum sp. nov., T. microphthalmus sp. nov., Sloanella gordoni sp. nov., Trechistus gordoni sp. nov., Goedetrechus minutus sp. nov., G. rolanisp. nov., G. florentinus sp. nov., G. damperi sp. nov., Tasmanotrechus gordoni sp. nov., T. alticola sp. nov., T. montisfieldi sp. nov., T. osbornianussp. nov., T. moorei sp. nov., T. rolani sp. nov. Forty-one (41) previously described species have been re-examined and illustrated with supplementary descriptions. New collection records combined with the published literature revealed 196 records of 83 species in 21 genera, collected from 41 localities (including 11 karst areas). Regional-scale survey coverage has been patchy and three biogeographic regions stand out as poorly surveyed: Flinders, South East, and Northern Midlands. Local-scale survey efforts have been intensive at just a few localities, the richest being 18 species recorded at Cradle Mountain. Seventeen (17) described species of Zolini and Trechini are troglobites with distribution ranges restricted to individual karst areas. Some karst areas and caves harbour multiple congeneric species which differ in their degree of troglomorphic specialization suggesting heterochronic colonisations, possibly linked to multiple Quaternary glacial / inter-glacial cycles. Palaeo-climatic and palaeo-vegetation evidence is examined to test the ‘Climatic Relict Hypothesis’ as a mechanism driving evolution of the subterranean fauna. It is proposed that present-day troglobitic Trechinae in Tasmania are derived from troglophilic progenitors that colonised subterranean habitats from adjacent forest ground litter habitats during Pleistocene inter-glacial periods, while retreat of forests during glacial periods isolated subterranean populations from surface populations facilitating troglogenesis. It is predicted that future collecting efforts will reveal many additional new subteranean species, including in non-karstic Shallow Subterranean Habitats (SSH).

Terrestrial animals in subterranean habitats are often classified according to their degree of morphological or ecological specialization to the subterranean environment. The commonly held view is that, as distance into a cave increases, the frequency of morphologically specialized, i.e., troglomorphic, species or ecological specialization will increase. We tested this hypothesis for the fauna in 54 caves in Slovenia–the classical land for subterranean biology. We found that there exist two ecologically well separated terrestrial subsurface faunas: one shallow and one deep. 1) The shallow subterranean fauna, adapted to the terrestrial shallow subterranean habitats (SSHs) in the upper 10 m of subsurface strata, is most diverse. It consists of randomly distributed non-troglobionts and a major group of troglobionts adapted to the soil root zone. 2) The deep subterranean fauna is represented by a minor group of troglobionts, adapted to caves. Troglobionts are strictly divided between the two faunas. There is strong evidence that in karstic ecosystems with deep-rooted vegetation this might be a global pattern, or that in these locations only the shallow subterranean fauna exist.

Terrestrial animals in subterranean habitats are often classified according to their degree of morphological or ecological specialization to the subterranean environment. The commonly held view is that, as distance into a cave increases, the frequency of morphologically specialized, i.e., troglomorphic, species or ecological specialization will increase. We tested this hypothesis for the fauna in 54 caves in Slovenia–the classical land for subterranean biology. We found that there exist two ecologically well separated terrestrial subsurface faunas: one shallow and one deep. 1) The shallow subterranean fauna, adapted to the terrestrial shallow subterranean habitats (SSHs) in the upper 10 m of subsurface strata, is most diverse. It consists of randomly distributed non-troglobionts and a major group of troglobionts adapted to the soil root zone. 2) The deep subterranean fauna is represented by a minor group of troglobionts, adapted to caves. Troglobionts are strictly divided between the two faunas. There is strong evidence that in karstic ecosystems with deep-rooted vegetation this might be a global pattern, or that in these locations only the shallow subterranean fauna exist.

Karst environments can be grouped into three broad categories, based on their vertical position in the landscape. There are surface habitats, ones exposed to light; there are shallow subterranean (aphotic) habitats oft en with small to intermediate sized spaces; there are deep subterranean habitats (caves) with large sized spaces. Faunal records are most complete for caves, and on a global basis, more than 10,000 species are limited to this habitat. Hundreds of other species, especially bats, depend on caves for some part of their life cycle. A large, but most unknown number of species are limited to shallow subterranean habitats in karst, such as epikarst and the milieu souterrain superficiel. Species in both these categories of habitats typically show a number of morphological adaptations for life in darkness, including loss of eyes and pigment, and elaboration of extra-optic sensory structures. Surface habitats, such as sinkholes, karst springs, thin soils, and rock faces, are habitats, but not always recognized as karst habitats. Both aphotic karst habitats and twilight habitats (such as open air pits) may serve as important temporary refuges for organisms avoiding temperature extremes on the surface.