The septatus species group

Diagnosis. Unique among the members of the Californian clade of Cybaeus, the species group affiliation of the males of the septatus group is relatively easily to determine. The males of the septatus group are diagnosed by a combination of the prolaterally to slightly anteriorly directed patellar apophysis which is as long as or longer than the width of the palpal patella and bears four to 12 peg setae one of which is in a proximal medial position isolated from, or slightly to noticeably larger than, the remainder of the peg setae (Figs 1–2, 5–7, 22, 25, 34, 44, 47). To our knowledge, no males of other Californian clade Cybaeus species groups (adenes, aspenicolens, consocius, devius, and tardatus) or unplaced Californian species (C. cribelloides Chamberlin & Ivie, C. gidneyi Bennett, C. irreverens Bennett spec. nov.) show this combination of characters.

The females of the septatus group are diagnosed by a combination of features of the epigynum, atrium, and copulatory ducts. The epigynum is marked anteriorly by one or more “wrinkles” in the integument (Figs 10, 13, 27) and the atrium features paired longitudinal atrial openings medially (Figs 10, 13, 16, 27, 37, 40). The copulatory ducts (Figs 11–12, 14–15, 18–19, 28–29, 38, 41) are short and lead from the atrial openings medially to the midline of the vulva where they are contiguous prior to diverging and leading laterally to the spermathecal heads. As with the septatus group males, no females of other Californian clade Cybaeus species groups or unplaced Californian species are known which possess this combination of characters.

Description. As in diagnosis. Medium-sized spiders: carapace lengths averaging 2.15–2.5 mm (females). Males subequal. Abdomen usually patterned. Legs unbanded (femora rarely lightly banded). Two or occasionally three complete pairs of ventral tibia I macrosetae (distal pair present, absent, or incomplete).

Male: Retrolateral tibial apophysis (Figs 1, 33, 43) carinate, nearly as long as tibia. Embolus relatively short and thin, describing a compound (Figs 3, 23, 45) or simple (Fig. 35) curve. Tegular apophysis (Figs 3, 23, 35, 45) with distal arm short, unmodified, with rounded or angular terminus; proximal arm prolaterally directed, slightly swollen basally, and tip slightly twisted and swollen (Figs 3–4, 8–9), bluntly acuminate (Figs 23–24, 26), or sharply acuminate (Figs 35, 45, 48).

Female: Atrial openings (Figs 10, 13, 16, 27, 37, 40) conspicuous or not. Spermathecal heads (Figs 12, 15, 20–21, 29–30, 38–39, 41–42) small dorsolateral lobes; spermathecal stalks short (Figs 12, 14, 20, 38) or relatively long (Figs 29–30, 42); Bennett’s glands near junction with spermathecal bases (Figs 12, 14, 20–21, 39, 32, 39, 42); bases large, rounded; fertilization ducts exit bases posteriorly.

Composition and distribution. Cybaeus chauliodous Bennett, C. lockeae Bennett spec. nov., C. septatus Chamberlin & Ivie, C. somesbar Bennett, and C. viator Bennett spec. nov. Cybaeus septatus and C. chauliodous are relatively common within their known distributions; the other species are uncommon. All have restricted ranges within an area encompassing southwestern Oregon (Jackson and Josephine Counties) and northern California south to Alameda and Sierra Counties (Figs 49–50).