Supplementary data for the following article: Kurita, T. et al. (2024). A new species of <i>Cnemaspis</i> (Squamata: Gekkonidae) from Temburong District, Brunei Darussalam

A new species of sandstone-dwelling rock gecko of the genus <i>Cnemaspis</i>, is described from Bukit Patoi, Temburong District, Brunei Darussalam. This is the first country record for the genus, expanding the known distribution of Bornean <i>Cnemaspis</i> and advancing our understanding of its species diversity. Molecular phylogenetic analyses using mitochondrial and nuclear DNA sequences confirm that the new species, <i>Cnemaspis</i> <i>gituen</i> sp. nov., represents a distinct evolutionary lineage, inferred to be the sister taxon of <i>C</i>. <i>lagang</i> from northeastern Sarawak. <i>Cnemaspis</i> <i>gituen</i> sp. nov. can be morphologically distinguished from all Bornean congeners by a unique combination of characters, most notably the presence of patches of aggregated tubercles on the lower flank associated with brilliant yellow spots in males. It further differs from <i>C</i>. <i>lagang</i> by having prominent trunk tuberculation (<i>versus</i> indistinct) and a suite of colouration differences in males (e.g., dark brown head <i>versus</i> grey). Unlike members of the <i>nigridia</i> species group, it is differentiated by its distinctive flank spots (<i>versus</i> faint vertical lines), fewer paravertebral tubercles (16–20 <i>versus</i> 23–38), and a continuous median row of slightly enlarged, keeled subcaudals (<i>versus</i> smooth median subcaudals). The new species is also distinguished by its small maximum SVL (50.8 mm) and 7–10 precloacal pores (in total) and unique caudal colouration in males.