The adenes species group

Diagnosis. Differentiating species of the Holarctic and Californian clades of Cybaeus is discussed in Copley et al. (2009). The species of the adenes group of the Californian clade are diagnosed by the undivided, concave to inverted U–shaped atrium (Figs 4, 15, 21, 30, 38, 47) and the reduced, sinuous vulval ducts with very short, laterally projecting copulatory ducts and short spermathecal stalks (Figs 6, 17, 23, 49, 55). Other Californian clade species groups have the vulval ducts more complex (Copley et al. 2009: Figs 12, 95, 101) or reduced but linearly oriented (Copley et al. 2009: Figs 6, 65) and/or longer and more complex copulatory ducts (Copley et al. 2009: Figs 6, 8 –12, 72, 75, 78, 84, 95, 101).

Description. Small- to medium-sized spiders, carapace lengths averaging 1.73–2.6 (males) and 1.94–2.8 mm (females). Abdomen usually patterned as in Copley et al. (2009: fig. 3) and Bennett et al. (2016: Figs 1–2), legs unbanded in most species (femora lightly to strongly banded in C. amicus, C. auburn, and C. torosus). Two complete pairs of ventral tibia I macrosetae: pattern 2-1p-2-1p-0.

Male: Patellar apophysis (Figs 13, 36, 45, 51) prominent, digitiform, length 2/3 ( C. auburn, Fig. 19) to nearly as long as (all other adenes group species) width of patella. Peg setae variable in number, diagnostic for some species. Retrolateral tibial apophysis carinate, nearly as long as tibia (Figs 14, 27, 37, 46). Inconspicuous retrolateral ridge dorsal to retrolateral tibial apophysis often present ( C. adenes, C. amicus, C. grizzlyi, C. reducens, C. sanbruno, C. schusteri: Figs 3, 14, 27, 36, 46). Embolus (Figs 1, 56, 58–59, 62–68) relatively short, thick. Distal arm of tegular apophysis (Figs 1, 58) short, not enlarged or lengthened. Proximal arm of tegular apophysis (Figs 1, 18, 56–68) prolaterally directed with species specific morphology.

Female: Atrium (Figs 4, 15, 21, 30, 41, 47, 54) simple, undivided, medially or anteromedially located on epigynum, of variable form; broad and slightly concave (Figs 21, 38, 41) to narrower and strongly vase- or inverted U-shaped (Figs 4, 9, 15, 30, 33, 47, 53). Vulva (Figs 6, 22, 39, 43, 48) simple, each half sinuous. Copulatory ducts usually separate at atrium (broadly contiguous across anterior of atrium in C. auburn, Fig. 24), relatively short, often very broad at atrium; proceeding laterally to outer margins of vulva then turning medially towards vulval midline. Spermathecal heads simple, small, dorsal lobes; occasionally becoming incorporated into surface of copulatory ducts and less distinctly lobe–like, particularly in older individuals (Figs 29, 31–32). Stalks very short, undifferentiated, with well-developed Bennett’s glands at junction with bases (Figs 6, 31–32). Bases simple, rounded with fertilization ducts exiting posteriorly close to junction with stalks.

Composition and distribution. Nine species: Cybaeus adenes Chamberlin & Ivie, C. amicus Chamberlin & Ivie, C. auburn Bennett spec. nov., C. grizzlyi Schenkel, C. pearcei Bennett spec. nov., C. reducens Chamberlin & Ivie, C. sanbruno Bennett, C. schusteri Bennett spec. nov., and C. torosus Bennett spec. nov. All species have restricted distributions in west central California from Sonoma and Napa Counties south to northern Monterey County and east central California (one species, C. auburn) from Placer and El Dorado Counties (Figs 69–71).