Mutatus Mu, Wang, Zhang & Zhang, 2025, gen. nov.

Mutatus gen. nov. Etymology. The genus name is derived from a Latin word “ mutatio ”, meaning “ variable ”, referring to the unique combination of characters in this new genus. Unlike the similar genera Lingulatus, which possesses only a tegular sheet, and Xilithus, which features only prolateral tegular apophysis, the new genus exhibits both characteristics in the male palp. Gender masculine. Diagnosis. The male of new genus resembles those of the genera Lingulatus and Xilithus in having both tegular sheet and prolateral tegular apophysis, but Mutatus can be differentiated by the absence of a ventral tibial apophysis (present both in Lingulatus and Xilithus), tegular sheet present in both Mutatus gen. nov. and Lingulatus (absent in Xilithus), and sperm duct V-shaped in both Mutatus gen. nov. and Lingulatus (U-shaped in Xilithus). The female of new genus resembles Xilithus in having a pair of large concavities (atria), a pair of small bursae, and clavate spermathecae, but it can be differentiated by the presence of a protuberance at the middle part of the lateral margin of the atrium (absent in Xilithus). Description. Small, total length 3.18–4.78 mm. Carapace oval, smooth, brownish to black, widest at coxae II and III, highest near fovea, with several markings resembling flowing water droplets beside fovea. Fovea dark-red. PER slightly wider than AER, PER recurved in dorsal view, AER recurved in dorsal view. Chelicerae brown, with 1 long and 1 short spine anteriorly. Endites longer than wide, labium wider than long. Sternum brown, shield-shaped, smooth and without pattern, longer than wide. Legs dark brown, all femora with 1 dorsal spine; femur I with 3–5 prolateral spines distally, femur II with 0–2 prolateral spines distally; tibiae I – II usually with 6–7 pairs of ventral spines, tibiae III – IV without ventral spines; metatarsus I with 4–5 pairs of ventral spines, metatarsus II usually with 4 proventral spines and 3 retroventral spines, metatarsi III – IV without ventral spines but with distal preening brush. Leg formula 4123. Abdomen oval, gray to black in dorsal view, with dorsal scutum covering almost entire abdomen in males, scutum in females absent. Male palp: femur with well-developed apophysis located at middle part; patella short, as long as tibia; tibia slightly bulged ventrally, with retroventral and retrolateral apophyses; cymbium longer than femur; bulb pyriform; prolateral tegular apophysis and tegular sheet (spade-shaped) originating near base of embolus; embolus acicular; conductor absent. Epigyne: epigynal plate weakly sclerotized, with pair of atria; septum dumbbell-shaped; copulatory openings small, separated; copulatory ducts thin; connecting tubes thick, shorter than copulatory ducts; bursae small; spermathecae clavate, located posteriorly; glandular appendages mastoid-shaped. Type species. Mutatus gelao sp. nov. Composition. Mutatus gelao sp. nov., M. tujia sp. nov., M. tianyan sp. nov., and M. yintiaoling sp. nov. Distribution. China (Hubei Province, Guizhou Province, Chongqing Municipality).