Cybaeus

L. Koch, 1868

Soft Spiders

Cybaeus is a of araneomorph in the Cybaeidae, first described by Ludwig Carl Christian Koch in 1868. The genus contains approximately 198 distributed across America, Europe, Japan, Korea, and China. North species are classified into Holarctic and Californian clades, with many exhibiting restricted geographic ranges and concerns. Females of different species are difficult to distinguish, particularly in North America; species identification relies heavily on examination of male .

Cybaeus by (c) Toby, some rights reserved (CC BY), uploaded by Toby. Used under a CC-BY license.

Cybaeus morosus f2 by G. Blagoev, Centre for Biodiversity Genomics. Used under a CC BY-SA 3.0 license.

Pronunciation

How to pronounce Cybaeus: /saɪˈbiːəs/

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Identification

identification in Cybaeus relies primarily on male genital , particularly the structure of the . Females of different species are notably difficult to distinguish, especially among North . Some species groups exhibit distinctive genital characteristics, such as the elongated and tubular found in six Ryukyu Island species. Images of males that include pedipalps provide the most reliable means of species determination.

Images

Habitat

North are primarily moist-forest and woodland . The aspenicolens group species occupy very restricted distributions on the western slopes of the central and southern Sierra Nevada mountain range in east-central California. The consocius group occurs in the central Sierra Nevada Mountains of eastern California, the central coast of western California, and western Oregon. Four new species from South Korea were collected from leaf litter in mixed forests in hilly and mountainous terrain.

Distribution

The occurs in America, Europe, Japan, Korea, and China. In North America, are classified into Holarctic and Californian clades. The Californian clade shows highly restricted distributions, with many species to specific mountain ranges or coastal regions in California and Oregon. Japanese species have diversified extensively, with ~80 known species, including eight newly described species endemic to the Ryukyu Islands extending the range southward to the central Ryukyus. Four new species from South Korea appear to be endemic to that country.

Human Relevance

Some North in the devius and tardatus groups are likely endangered or already extinct; most have not been seen in many decades and none have been collected more recently than 1995. concerns are repeatedly highlighted in taxonomic revisions of Californian clade species groups due to restricted geographic ranges and specificity.

Similar Taxa

CicurinaBoth belong to the Cybaeidae and share moist-forest preferences in western North America; however, Cicurina are primarily cave-dwelling or associated with subterranean habitats, whereas Cybaeus species are epigean (surface-dwelling).
CalymmariaAnother cybaeid with similar body form and web-building , but Calymmaria construct distinctive sheet webs with retreat tubes, while Cybaeus retreat constructs differ in structure.

More Details

Phylogenetic Relationships

Cybaeus belongs to the marronoid group of within the clade. A 2023 study by Gorneau et al. clarified the evolutionary tree for this previously difficult-to-classify group using genetic data from museum specimens. The shows unusual biogeographical patterns in Japan, with some northern Ryukyu related to central Ryukyu rather than to geographically closer northern .

Species Diversity

As of September 2022, Cybaeus contains 198 . The has undergone extensive diversification in western North America and the Japanese Archipelago, with numerous new species described in recent years from restricted geographic areas.