Cybaeus adenes, Chamberlin & Ivie, 1932

Bennett, Robb, Copley, Claudia & Copley, Darren, 2019, Cybaeus (Araneae: Cybaeidae): the adenes species group of the Californian clade, Zootaxa 4711 (2), pp. 245-274 : 246-247

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 ).

Figures

FIGURE 69. Distributions of Cybaeus adenes (●), C. amicus. (), C. grizzlyi (○). CA—California, OR—Oregon, NV—Nevada.

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

FIGURE 71. Distributions of Cybaeus pearcei spec. nov. (●), C. torosus spec. nov. (). CA—California, OR—Oregon, NV—Nevada.

FIGURES 4–8. Cybaeus adenes, females (4–6 holotype; 7–8 from San Geronimo, California), copulatory organ (4 epigynum, ventral; 5 vulva, ventral; 6 same, dorsal; 7 atrium, ventral; 8 vulva, dorsal). AT—atrium, BG—Bennett’s gland, BS—base of spermatheca, CD—copulatory duct, HS—head of spermatheca, SS—stalk of spermatheca. Scale bars: 0.1 mm.

FIGURES 15–17. Cybaeus amicus, females (15 from Stanford University, California; 16–17 from Holy City, California), copulatory organ (15 epigynum, ventral; 16 vulva, ventral; 17 same, dorsal). CD—copulatory duct. 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 28–30. Cybaeus grizzlyi, females (28 from hills above Berkeley, California; 29 lectotype of C. adenoides; 30 from Orinda, California), copulatory organ (28 teneral vulva, dorsal; 29 vulva, dorsal; 30 atria, ventral). CD—copulatory duct, HS—head of spermatheca. Scale bar: 0.1 mm.

FIGURES 38–43. Cybaeus reducens, females (38–40 from Carmel, California; 41–43 from south of Big Sur, California), copulatory organ (38 epigynum, ventral; 39 vulva, ventral; 40 same, dorsal; 41 epigynum ventral; 42 vulva, ventral; 43 same, dorsal). Scale bars: 0.1 mm.

FIGURES 47–49. Cybaeus sanbruno, females from San Bruno Mountain, California, copulatory organ (47 epigynum, ventral; 48 vulva, ventral; 49 same, dorsal). Scale bars: 0.1 mm.

FIGURES 54–55. Cybaeus torosus spec. nov., female holotype, copulatory organ (54 epigynum, ventral; 55 vulva, dorsal). Scale bars: 0.1 mm.

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).

FIGURES 1–3. Cybaeus adenes, male from San Francisco, California, left palpus (1 genital bulb, ventral; 2 patella and tibia, dorsal; 3 patella and tibia, retrolateral). DA—distal arm of tegular apophysis, E—embolus, PA—proximal arm of tegular apophysis, PTA—patellar apophysis, RR—retrolateral ridge dorsal to retrolateral tibial apophysis, RTA—retrolateral tibial apophysis. Scale bars: 0.1 mm.

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 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 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 9–11. Cybaeus adenes, females from vicinity of St. Helena, California, copulatory organ (9 epigynum, ventral; 10 vulva, ventral; 10 same, dorsal). Scale bars: 0.1 mm.

FIGURES 33–34. Cybaeus pearcei spec. nov., female holotype, copulatory organ (33 epigynum, ventral; 34 vulva, dorsal). CD—copulatory duct, HS—head of spermatheca. Scale bar: 0.1 mm.

FIGURES 50–53. Cybaeus schusteri spec. nov. (50–52 male holotype, left palpus; 53 female from south of Monticello, California), copulatory organ (50 genital bulb, ventral; 51 patella and tibia, dorsal; 52 patella and tibia, retrolateral; 53 vulva, ventral). DK—dorsal keel of proximal arm of tegular apophysis, RR—retrolateral ridge dorsal to retrolateral tibial apophysis. Scale bars: 0.1 mm.

FIGURES 31–32. Cybaeus grizzlyi, female from unknown locality, copulatory organ (31 vulva, dorsal; 32 same, detail of Fig. 31). Arrows indicate simple pores on spermathecal head and complex Bennett’s gland at junction of spermathecal stalk and base.