Abstract Orthoptera species are vulnerable to extinction on a global scale. Greece hosts 35% (380 species) of the European Orthoptera fauna with a high degree of endemic (37%) and threatened species (37%). We sampled 46 plots (100 m²) to investigate the distribution and ecological requirement of two Greek mountain endemic and red‐listed species: Parnassiana parnassica (Ramme, 1926; Orthoptera: Tettigoniidae; Critically Endangered [CR]) and Oropodisma parnassica (Scudder, 1897; Orthoptera: Caelifera; Endangered [EN]). Species had a restricted geographical range, with two isolated populations confined to high altitudes (1527–2320 m) of Mts. Parnassos and Elikonas. Species distribution models showed that slope affected their suitable habitat, together with the topographic position index the annual temperature range (P. parnassica), and the amount of green vegetation and evapotranspiration (O. parnassica). Connectivity analysis showed that P. parnassica‐suitable habitat consisted of few larger and well‐connected patches (26 patches: effective mesh size of 1.57 km2) and that O. parnassica‐suitable habitat consisted of more but smaller and less connected patches (56 patches: effective mesh size of 0.3 km2). Generalised linear models showed that the population density of P. parnassica was negatively influenced by the height of herbaceous vegetation and that of O. parnassica was positively influenced by altitude. The species face three main imminent threats: land take, wildfires, and global warming, whereas livestock grazing seems to have a positive impact and skiing a neutral impact on their populations. We assessed both species as EN after the International Union for Conservation of Nature (IUCN) criteria and a suite of conservation measures are suggested for their status improvement.

The dataset refers to the environmental parameters occurring in the localities of the presence of two Greek endemic species that are globally endangered (EN), according to the results of the paper related to the current dataset Parnassiana parnassica and Oropodisma parnassica.

The study area comprises the global distribution range of the two target species. It encompasses two mountains in central Greece: Mt Parnassos and Mt Elikonas.

We conducted field surveys for three consecutive years (2021, 2022, 2023) during August and surveyed a total of 103 sites. We employed the time-constrained visit method, actively searching for the species for 45 minutes. In almost all cases, upon encountering the species, we delineated a quadrat of a standard area of 100 m² and counted the number of individuals (40 quadrats). We recorded 12 microhabitat parameters at each quadrat with species occurrence: Altitude, slope, ground cover of soil, rocks, stones, and vegetation. Vegetation included herbaceous plants, (characterized by non-woody stems or roots), and robust herbaceous plants and shrubs (either a woody stem or a woody base or both).

The database consists of two matrices for the two target species respectively. For localities with presence only, the altitude is provided. For quadrats with a number of individuals, the values of the 12 environmental parameters are provided. P. parnassica: 30 quadrats X 12 parameters and 3 presences. O. parnassica:   30 quadrats X 12 parameters and 6 presences.

No coordinates are provided due to the red-list status of the species.