Bisetifer tactus sp. nov. Figs 6 E, F, 7, 8, 9 Type material. Holotype • ♂ (ZMMU Ta-8255), Crimea, nr Sevastopol, Tshernaya River canyon, Tshernoretshenskaya Cave, 3. III. 2018, I. S. Turbanov leg. Paratypes • 3 ♀♀ (ZMMU Ta-8256), 5. V. 2017 • 1 ♀ (TNU 10235), 4. V. 2018, same cave and collector as for a holotype. Diagnosis. Bisetifer tactus sp. nov. has reduced eyes (Figs 7 A – F, 8 A – D) (vs other congeners, B. cephalotus and B. gruzin, have well developed eyes, see Tanasevitch et al. 2015: figs 1–6). Additionally, B. tactus sp. nov. differs from its congeners in having: 1) the embolus hidden between radix and distal suprategular apophysis (Figs 8 G, H, 9 A, C, D) (vs not hidden, well visible, see Tanasevitch et al. 2015: figs 7, 19); 2) the hook-shaped and pointed apical part of radix (Figs 8 G, 9 C) (vs conical in B. cephalotus and flat in B. gruzin, see Tanasevitch et al. 2015: figs 9, 14, 23, 28–29); 3) the distal suprategular apophysis without a complicated arrangement of apophyses, with barbs on its edge (Figs 8 G, 9 A, C, D) (vs with apophyses, without barbs, see Tanasevitch et al. 2015: figs 7, 19); 4) the oval posterior edge of epigyne (Figs 6 E, 9 E) (vs with nipple-shaped outgrowths in B. cephalotus, with bow-shaped outgrowths in B. gruzin, see Fig. 6 B, C and Tanasevitch et al. 2015: figs 17, 30). Description. Male. Total length 1.5. Carapace 0.63 long, 0.5 wide, pale brown; modified as in Figs 7 D, E, 8 C, D: head part conical, with setae. Eyes reduced, almost completely disappeared (head part with small pale spots, visible under light microscope; no lens visible under SEM). Chelicerae 0.31, brownish, transverse shallow cuticular grooves throughout the basal segment. Legs pale brown, chaetotaxy 2.2.1.1, metatarsi I – IV spineless, metatarsi IV without trichobothrium, TmI 0.35, leg I 2.47 long (0.69 + 0.18 + 0.63 + 0.52 + 0.45), leg IV 2.53 long (0.71 + 0.17 + 0.69 + 0.54 + 0.42). Palp as in Figs 8 F – I, 9 A – D: tibia with a ventro-retrolateral apophysis and two large setae on its tip, distally setae poorly serrate; paracymbium L-shaped; distal suprategular apophysis – flat, curved, and pointed, with barbs on its anterior edge; embolus small, situated in a cavity between distal suprategular apophysis and radix; apical part of radix hook-shaped and pointed distally, well-sclerotised process, retrolaterally with membrane. Abdomen pale grey. Female. Total length 1.58. Carapace 0.77 long, 0.59 wide; unmodified. Eyes reduced, almost completely disappeared (head part with small pale spots, clearly visible under light microscope; a few poorly developed lenses visible under SEM). Chelicerae 0.36, transverse shallow cuticular grooves throughout the basal segment. TmI 0.44. Leg I 2.64 long (0.73 + 0.21 + 0.7 + 0.54 + 0.46), leg IV 2.78 long (0.8 + 0.2 + 0.77 + 0.59 + 0.42). Body colouration and spination as in the male. Epigyne as in Figs 6 E, F, 9 E – G: epigynal plate oval, with lateral outgrowths in which copulatory ducts open; spermathecae consists of two parts: base with copulatory duct and head with receptacle and fertilisation duct; cavity of receptacle subdivided on ventral and dorsal parts. Variation. Females (n = 3): carapace width 0.53–0.59; femur I length 0.69–0.73. Distribution and records from the Crimean caves. Map (Fig. 17 B – purple circle). Only known from the type locality: Tshernoretshenskaya Cave, nr Sevastopol. Ecology. The species has troglomorphic characteristics related to the subterranean habitat, such as the pale body and reduced eyes. Based on the morphological features and the fact that this species is known only from caves, it can be considered a troglobiont. Etymology. From the Latin tactus, meaning touch, due to the fact that this species has the strongly reduced eyes and its life style as a true troglobiont relies on tactile sensations.

Published as part of Nadolny, Anton A. & Turbanov, Ilya S., 2025, A review of cave spiders (Arachnida, Araneae) of the Crimean Mountains, with descriptions of two new species, pp. 37-80 in ZooKeys 1230 on pages 37-80, DOI: 10.3897/zookeys.1230.137029