Hypochilus kastoni

Distinguished from congeneric species primarily by genitalic morphology, particularly male pedipalps and female epigynum, as described in the original species description. Geographic distribution helps separate it from eastern species such as H. thorelli and H. petrunkevitchi. Externally similar to H. pococki, from which it is distinguished by details of abdominal patterning and precise locality data. Identification to species level requires examination of reproductive structures or genetic analysis.

Medium-sized spider with elongated legs and a relatively flattened body. Coloration generally dark with patterning typical of the genus. The cephalothorax and abdomen show mottled or banded patterns that provide camouflage against rock substrates. Legs are long and slender, adapted for web construction on vertical rock faces. The species lacks the extreme elongation of some other Hypochilus species, with body proportions intermediate within the genus.

Rocky habitats, specifically cliff faces, rock outcrops, and boulder fields in mountainous regions. Webs are constructed on vertical or near-vertical rock surfaces, often in shaded or partially shaded locations. The substrate appears to be primarily sandstone or similar sedimentary rock formations. Habitat specificity reflects the ancestral ecology of the Hypochilidae family.

Known from the western United States, specifically from localities in Utah and possibly adjacent states. Distribution records are sparse, reflecting limited survey effort in appropriate rocky habitats rather than true rarity. The species occupies a geographic range intermediate between the more widespread H. pococki to the west and eastern congeners.

Constructs the characteristic 'lampshade' web typical of the genus: a flat, circular sheet web with a central conical retreat opening downward. The spider occupies the retreat, emerging onto the sheet to capture prey. Web architecture represents an evolutionary intermediate between ancestral cribellate webs and more derived araneomorph web types. Nocturnal activity pattern inferred from related species, with web maintenance occurring during darkness.

Predator on small flying and crawling insects in rocky habitats. Its specialized web architecture allows exploitation of vertical rock faces that are underutilized by other web-building spiders. The species contributes to invertebrate diversity in cliff and talus ecosystems, habitats often poorly sampled in biodiversity assessments.

No documented direct interactions with humans. The species is of interest to arachnologists studying spider phylogeny and the evolution of web-building behavior, due to its position as a phylogenetically significant lineage (Hypochilidae represents the sister group to all other Araneomorphae). Potential indicator species for intact rocky habitat ecosystems.

• Hypochilus pocockiOverlapping or adjacent geographic distribution in western North America; similar habitat preferences on rock faces; distinguished by genitalic morphology and subtle differences in abdominal patterning
• Hypochilus thorelliEastern congener with similar overall morphology and web architecture; allopatric distribution (Appalachian region) is the primary distinguishing feature
• Hypochilus petrunkevitchiEastern congener with elongated body form; geographic separation and proportional differences in leg length aid distinction

• spider
• lampshade spider
• cave-dwelling
• rocky habitat
• western North America
• web-builder

• BugGuide
• GBIF taxonomy match
• NCBI Taxonomy
• Catalogue of Life