Hypochilus xomote

Distinguished from other Hypochilus species by male palpal conductor morphology (loosely whorled with small distal projection) and female spermathecal duct structure (convoluted with relatively large receptacles). Geographic restriction to the Tule River and Cedar Creek drainages of the southern Sierra Nevada separates it from other California Hypochilus populations, which occur in different drainage basins. Extreme genetic divergence at nuclear and mitochondrial loci supports species status.

Males measure approximately 7.5 mm in body length; females reach 11.8 mm. Cephalothorax pale yellow to white with dusky markings. Chelicerae similarly colored. Males possess a distinctive palpal conductor that is loosely whorled with a small distal projection. Females have convoluted spermathecal ducts with relatively large receptacles.

Shaded granite boulder formations, abandoned mine shafts, and stream culverts in montane coniferous or mixed oak-conifer forests. Occurs near water sources in mesic, rocky microhabitats. Shows strong preference for shaded areas on large granite boulders, particularly those facing away from direct sunlight.

Endemic to the upper Tule River and upper Cedar Creek drainage basins in the southern Sierra Nevada of California. Predicted but unconfirmed to occur in the intervening White River drainage.

Constructs characteristic lampshade-shaped webs in rocky microhabitats. Exhibits extreme microhabitat specialization and extremely low vagility. Shows extreme genetic structuring at the population level.

Conservation concern due to short-range endemic status and restricted distribution. Habitat specialization on specific rock formations and dependence on mesic conditions may increase vulnerability to climate change and habitat alteration.

• Hypochilus petrunkevitchiOccurs in adjacent drainage basins of the southern Sierra Nevada; nuclear and mitochondrial lineages of H. petrunkevitchi correspond directly to drainage basins, with H. xomote representing the southernmost lineage. H. bernardino is nested within H. petrunkevitchi and sister to the southernmost basin populations that now constitute H. xomote.
• Hypochilus bernardinoSister taxon to the southernmost H. petrunkevitchi populations now recognized as H. xomote; occurs in the San Bernardino Mountains rather than the Sierra Nevada.

• short-range endemic
• microendemic
• montane
• rock specialist
• 2022 description

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• Phylogenomics of paleoendemic lampshade spiders (Araneae, Hypochilidae, Hypochilus), with the description of a new species from montane California