Xilithus Liu & Li, 2022

Mu, Yannan & Zhang, Feng, 2023, Further additions to the guardstone spider fauna from China (Araneae: Phrurolithidae), Zootaxa 5338 (1), pp. 1-104 : 92-93

Xilithus Liu & Li, 2022

Xilithus Lin, Li & Pham, 2023: 57

(type species: Acrolithus lingyun Liu & Li, 2022 , by original designation).

Acrolithus Liu et al., 2022: 5 (preoccupied).

Diagnosis. This genus can be distinguished from all other phrurolithid genera by the male palpal tegulum with a spiculate prolateral tegular apophysis and long, needle-like embolus; it can also be identified by the dark, slanted male palpal bulb with a nearly round distal tegular apophysis. Female epigynal plate with a pair of large shallow concavities.

Description. Medium-sized spiders. Carapace oval, dark brown, highest near fovea, with several distinct markings resembling flowing water droplets beside fovea. Chelicerae with two spines anteriorly (one long and another short). Femora I–IV with one dorsal spine, femur I with three to four prolateral spines, femur II with one or two prolateral spines; tibia I usually with seven pairs of ventral spines, tibia II usually with six pairs of ventral spines; metatarsus I usually with four pairs of ventral spines, metatarsus II usually with four proventral spines and three retroventral spines. Abdomen oval, with large dorsal scutum nearly covering entire abdomen in males. Male palp: femoral apophysis well developed; tibia with one retrolateral tibial apophysis and one small retroventral tibial apophysis (absent in some species); tegulum wider than cymbium, with spiculate prolateral tegular apophysis; embolus long, needle-like. Female epigyne: epigynal plate with median septum and pair of large shallow concavities; copulatory ducts longer than connecting tubes; glandular appendages digitiform or mastoid-shaped; spermathecae small and round.