Urbanisation is widely recognised as one of the major drivers of biodiversity change, particularly in arthropod communities, where habitat structure, microclimate, and landscape connectivity play a crucial role (McKinney 2008). Spiders (Araneae), due to their high diversity, ecological specialisation, and sensitivity to habitat transformation, are commonly used as indicators of environmental change in urban and peri-urban landscapes (Marc et al. 1999; Shochat et al. 2004).

The spider fauna of Tbilisi was comprehensively documented in the early 2000s. Based on previously published data and targeted sampling across urban, suburban, and semi-natural habitats, Pkhakadze (2006) recorded 252 spider species in Tbilisi and its surroundings, providing a robust historical baseline for subsequent comparisons. Since then, Tbilisi has undergone rapid and spatially extensive urban development. Remote-sensing-based studies and urban sustainability assessments indicated a substantial increase in built-up areas, with the proportion of urbanised land rising by approximately 15% over the last two decades (Tsitsagi et al. 2022). This expansion has been driven not only by densification of the urban core, but also by lateral growth into formerly semi-natural and agricultural areas, accompanied by fragmentation and loss of open habitats. Such landscape transformations are known to have the potential to disproportionately affect ground-dwelling and habitat-specialist spider taxa, while favouring a limited set of synanthropic and ecologically generalist species (Shochat et al. 2004; Magura et al. 2010). At the same time, urban expansion and habitat transformation are expected to influence the composition and functional structure of spider assemblages, potentially masking local declines of habitat specialists through the accumulation of synanthropic or ecologically flexible species (McKinney 2008; Magura et al. 2010; Piano et al. 2017). Consequently, changes in species richness alone may be insufficient to capture the ecological consequences of ongoing urbanisation.

Surveys conducted in Tbilisi and its suburban areas do not indicate a straightforward decline in recorded species richness. On the contrary, despite the rapidly increasing rate of urbanisation, continued spider research in Georgia has resulted in the discovery of additional spider species within the urban and peri-urban landscape of the capital. Specifically, 119 species have been added to the fauna of Tbilisi and its surroundings, of which 63 represented first country records, 22 species were firstly recorded in the Caucasian region, and three species were described as new to science (Marusik et al. 2019; Seropian et al. 2023a, b; Seropian et al. 2024a, b; Seropian et al. 2025; Zamani et al. 2025). As a result, 371 species are currently recorded from Tbilisi. This increase most likely reflects a combination of intensified sampling effort, improved taxonomic resolution, and the inclusion of previously underexplored habitats, rather than a direct positive effect of urbanisation on spider diversity.

In the present study, we update the current knowledge of the spider fauna of Tbilisi by reporting the first Georgian records of Drassodes serratichelis (Roewer, 1928) (Gnaphosidae), Tolokonniella stigmatisata (Menge, 1869) (Lathyidae), and Scotargus pilosus Simon, 1913 (Linyphiidae), based on material collected in the capital of Georgia. Notably, D. serratichelis is recorded for the first time from the Caucasus, while the genus Scotargus and T. stigmatisata are newly recorded for Georgia.

All spiders were collected individually, preserved in 96% ethanol, and stored in the refrigerators of the scientific collections of Ilia State University, Institute of Zoology (Tbilisi, Georgia; hereafter – ISUIZ). The specimens were examined with a Zeiss Stemi 508 Stereo Microscope with 8:1 Zoom and a Zeiss Apo 1.5× FWD 53 mm front lens attached. A.S. prepared drawings based on microscope photographs taken with a Canon EOS 70D camera mounted on a Zeiss Stemi 508 stereomicroscope with an 8:1 zoom, using a custom-made adapter. The drawings were carried out using a Wacom CTH-690 Intuos Medium Pen and Touch Tablet with the programs Krita (version 2.9.7) and Adobe Photoshop CS6 (version 13.0). Drawings show the epigyne and endogyne; perspective and scale bars are given in the plates and their captions. Epigynes were cleared and cleaned prior to illustrations using a 30% potassium hydroxide (KOH) solution. All measurements are in millimetres. The elevations and GPS coordinates (given in WGS84) were obtained using a Garmin GPS MAP 64s.