Cybaeus adenes Chamberlin & Ivie 1932

Figs 1–11, 59–60, 69

Cybaeus adenes Chamberlin & Ivie 1932: 24, fig. 59 (in part, holotype only). Roewer 1954: 89. Bonnet 1956: 1300. Roth 1956: 178. Roth & Brown 1986: 3. Bennett 2006: 479, Figs 17–20. Copley et al. 2009: 372, fig. 5. World Spider Catalog 2019.

Cybaeus grizzlyi: Roth 1956: 178 . Roth & Brown 1986: 3.

Cybaeus adenoides: Roth 1956: 178 . Roth & Brown 1986: 3.

Type material. Holotype ♀. U.S.A.: California: Marin County, R. V. Chamberlin (AMNH), examined but subsequently lost. Neotype ♂ designated by Bennett (2006) from U.S.A.: California: Marin County, San Geronimo (37°59'N 122°42'W), 19 September 1963, J. Ivie & W. Ivie (AMNH), examined. See discussion of type material and synonymy in Bennett (2006).

Other material examined. Specimens and locality data in Bennett (2006). (Note: Green Valley locality, considered by Bennett (2006) to be “probably Sonoma Co.”, could be in Solano Co.)

Diagnosis. The male of C. adenes is diagnosed by the morphology of the proximal arm of the tegular apophysis: tip bifid with the two tips slightly divergent (Figs 1, 59–60). Known males of the other species of the adenes group have either a single ( C. amicus: Fig. 56; C. auburn: Fig. 63; C. grizzlyi: Fig. 61) or trifid ( C. reducens: Fig. 57) tip on the proximal arm of the tegular apophysis. Males of some species also have a bifid tip of the proximal arm of the tegular apophysis but in those males there are fewer peg setae on the patellar apophysis and the bifid tips are more or less convergent ( C. sanbruno: Figs 45, 67; C. schusteri: Figs 51, 65).

The female of C. adenes is distinguished from all other females of the adenes group except C. grizzlyi by the form of the atrium. The atrium in females of C. adenes and C. grizzlyi is inverted U-shaped or lyriform, relatively narrow (length from epigastric groove to anterior margin> width between lateral margins), and widest anteriorly ( C. adenes: Figs 4, 7, 9; C. grizzlyi: Fig. 30). The atrium in females of all other species of the adenes group either has its lateral ends strongly curved anteriorly ( C. sanbruno: Figs 47–48), is inverted U- or vase-shaped (but not lyriform) and widest posteriorly ( C. schusteri: Fig. 53; C. amicus: Figs 15–16; C. torosus: Fig. 54; C. pearcei: Fig. 33), or is relatively broad with length <width ( C. reducens: Figs 38, 41, 43; C. auburn: Figs 21–22). (Most females of C. schusteri are distinguished by the inverted vase-shaped atrium (Fig. 53) but the atrial morphology of some specimens may resemble that of females of C. adenes and C. grizzlyi . Collection of males with females may be the only way to ensure reliable identification in such instances.) Females of C. grizzlyi and C. adenes apparently are morphologically indistinguishable but can be separated by their respective distributions: both are found in the San Francisco Bay area of California but C. grizzlyi appears to be restricted to Contra Costa and Alameda Counties to the east of San Francisco Bay (Fig. 70) while C. adenes is more widespread and found to the north and east of the Bay area in Marin, Napa, Sonoma, San Francisco, and possibly Solano Counties (Fig. 69).

Description. Femora unbanded.

Male: (n=9). Patellar apophysis (Fig. 2) with variable number of peg setae (most specimens have about two dozen) on concave or convex antero-dorsal surface. Very small retrolateral ridge anteriorly on tibia dorsal to carinate retrolateral tibial apophysis (Fig. 3). Dorsal keel (Figs 59–60) present on proximal arm of tegular apophysis, usually inconspicuous but occasionally prominent.

(n=8). CL 2.15–2.6 (2.5), CW 1.60–2.00 (1.83), SL 1.08–1.29 (1.22), SW 1.00–1.26 (1.17). Neotype CL 2.45, CW 1.80, SL 1.22, SW 1.17.

Female: (n=39). Atrium (Figs 4, 7, 9) usually conspicuous, occasionally indistinct such that atrium may appear divided, anterior margin often sinuous, length of atrium (from epigastric groove to anterior margin) 1.5–2 times width (between lateral margins). Copulatory ducts (Figs 5–6, 8, 10–11) well separated, attached to lateral margins of atrium.

(n=22). CL 1.58–2.8 (2.2±0.3), CW 1.12–1.90 (1.49±0.23), SL 0.86–1.35 (1.10±0.14), SW 0.79–1.28 (1.02±0.13). Holotype (lost) CL 2.20, CW 1.55, SL 1.12, SW 1.05.

Distribution and natural history. West central California: Marin, Napa, San Francisco, Sonoma, and possibly Solano Counties in the San Francisco Bay area (Fig. 69). Males have been collected from mid-September to mid- November. Cybaeus adenes and C. grizzlyi are the most commonly encountered species of the adenes group.