Figs 18–24, 63–64, 70
Type material. Holotype ♂. U.S.A.: California: Placer County, Elders Corner, five miles north of Auburn, 27 December 1986, D. Ubick (CAS).
Paratypes. U.S.A.: California: El Dorado. 2♀, near Nashville, 5.iii.1958, L.M. Smith & R. O. Schuster (CAS); Placer. 1♀, Auburn, 12.iii.1958, R. O. Schuster & V. D. Roth (CAS).
Etymology. The specific name is a noun in apposition taken from the type locality.
Diagnosis. The lightly banded femora of male and female C. auburn may often be sufficient to separate them from specimens of other adenes group species except for C. amicus and C. torosus.
In addition, the male of C. auburn is diagnosed by the relatively short patellar apophysis (Fig. 19) and, more reliably, the morphology of the proximal arm of the tegular apophysis (Figs 18, 63–64). The length of the patellar apophysis is about 2/3 the width of the patella; in the known males of all other adenes group species the length of the patellar apophysis is nearly equal to the width of the patella. However, this difference is slight and difficult to determine. The tip of the proximal arm of the tegular apophysis is single, slender, and slightly corkscrewed while dorsal to the tip there is a relatively large, blunt, proximo-ventrally directed process (Figs 63–64) which gives the proximal arm the appearance of being bifid. In the other males of the adenes group with a single pointed tip of the proximal arm, the tip is untwisted and the prominent blunt dorsal process is lacking (C. amicus: Fig. 56) or sharply pointed (C. grizzlyi: Figs 61–62). The remaining adenes group males have a distinctly bifid (C. adenes: Figs 59–60; C. sanbruno: Fig. 67; C. schusteri: Fig. 65), or trifid tip (C. reducens: Fig. 57).
The female of C. auburn is distinguished by the form of the atrium and, when present, the small epigynal pit. The atrium is broad, weakly concave, and located antero-medially on the epigynum (Figs 21–22). No other female in the adenes group has this combination of characters; in particular, the atrium in all other species is anteriorly located on the epigynum. As well, most females of C. auburn have a small pit located postero-medially on the epigynum (discernible in cleared specimens: Figs 22–23), lacking in females of all other adenes group species.
Description. Femora very lightly banded.
Male: (n=1). Patellar apophysis (Fig. 240) with about 25 peg setae on dorsal surface. No retrolateral ridge anteriorly on tibia dorsal to carinate retrolateral tibial apophysis.
Holotype CL 2.45, CW 1.83, SL 1.20, SW 1.16.
Female: (n=3). Length of atrium (from epigastric groove to anterior margin) about 3/4 width (between lateral margins). Posterior epigynal pit lacking in Auburn specimen.
CL 1.83, 1.93, 2.6; CW 1.35, 1.35, 2.00; SL 0.98, 0.99, 1.26; SW 0.92, 0.92, 1.18 (Auburn specimen listed second).
Distribution. Western lower slopes of the Sierra Nevada of Placer and El Dorado Counties in east central California (Fig. 70).