Cybaeus auburn Bennett, 2019

Bennett, Robb, Copley, Claudia & Copley, Darren, 2019, Cybaeus (Araneae: Cybaeidae): the adenes species group of the Californian clade, Zootaxa 4711 (2), pp. 245-274 : 254-256

Cybaeus auburn Bennett spec. nov.

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 ).

Figures

FIGURE 70. Distributions of Cybaeus auburn spec. nov. (▪), C. reducens (□), C. sanbruno (), C. schusteri spec. nov. (●). CA—California, OR—Oregon, NV— Nevada.

FIGURES 18–20. Cybaeus auburn spec. nov., male holotype, left palpus (18 genital bulb, ventral; 19 patella and tibia, dorsal; 20 patella and tibia, retrolateral). PA—proximal arm of tegular apophysis. Scale bars: 0.1 mm.

FIGURES 21–24. Cybaeus auburn spec. nov., females from vicinity of Nashville, California, copulatory organ (21 epigynum, ventral; 22 vulva, ventral; 23–24 same, dorsal). CD—copulatory duct, EP—epigynal pit. Scale bars: 0.1 mm.

FIGURES 61–64. Cybaeus spp., male left palpi, detail of tegular apophysis. 61–62 C. grizzlyi from Berkeley, California. 63–64 C. auburn spec. nov. holotype (61 proximal arm, ventral; 62 tegular apophysis, retrolateral; 63 proximal arm, ventral; 64 tegular apophysis, retrolateral). Red arrows indicate single tips of proximal arm. DK—dorsal keel (Figs 61–62) or blunt process (Figs 63–64) of proximal arm of tegular apophysis, E—embolus. Scale bars: 0.05 mm (Figs 61, 63), 0.1 mm (Figs 62, 64).

FIGURES 56–60. Cybaeus spp., male left palpi, detail of tegular apophysis. 56 C. amicus from San Mateo County, California. 57–58 C. reducens from Santa Clara County, California. 59 C. adenes from San Francisco, California. 60 C. adenes from San Geronimo, California (56–57 proximal arm, ventral; 58 tegular apophysis, retrolateral; 59–60 proximal arm, ventral). Red arrows indicate single (Fig. 56) and trifid (Fig. 57) tips of proximal arm. Red lines indicate divergence of tips of proximal arm. DA—distal arm of tegular apophysis, DK—dorsal keel of proximal arm of tegular apophysis, E—embolus, PA—proximal arm of tegular apophysis. Scale bars: 0.05 mm (Figs 56–57, 59–60), 0.1 mm (Fig. 58).

FIGURES 65–68. Cybaeus spp., male left palpi, detail of tegular apophysis. 65–66 C. schusteri spec. nov. holotype. 67–68 C. sanbruno from San Bruno Mountain, California (65 proximal arm, ventral; 66 tegular apophysis, retrolateral; 67 proximal arm, ventral; 68 tegular apophysis, retrolateral). Red lines indicate convergence of tips of proximal arm. DK—dorsal keel of proximal arm of tegular apophysis, E—embolus. Scale bars: 0.05 mm (Figs 65, 67), 0.1 mm (Figs 66, 68).