Cybaeus amicus 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 : 251-253

Cybaeus amicus Chamberlin & Ivie 1932

Figs 12–16, 56, 69

Cybaeus amicus Chamberlin & Ivie 1932:24 , fig. 58. Roewer 1954:89. Bonnet 1956:1300. Roth & Brown 1986:3. World Spider Catalog 2019.

Type material. Holotype ♀. U.S.A.: California: Santa Cruz County, Brookdale [midway between Ben Lomond and Boulder Creek, Highway 9], March 1913, R. V. Chamberlin ( AMNH), examined.

Other material examined. U.S.A.: California: Alameda . 1♀, Niles Canyon , 21.iii.1941, W.M. Pearce ( AMNH) ; Monterey . 4 ♀, Aromas , 8.xii.1974, D. Ubick ( DU) ; San Mateo. 1♂, Alpine Road, 0.5 mi. SE of Pesca- dero Road , 18.xi.1988, D. Ubick ( DU) ; 2♂ 1♀, 2 air mi. S of La Honda , 18.xi.1988, D. Ubick ( DU) ; 2♀, Portola [Valley?], 30.x.1921, J.C. Chamberlin ( AMNH) ; 1♀, San Gregorio Beach , 1920/1921, J.C. Chamberlin ( AMNH) ; 1♀, Woodside , winter 1957/1958, Washburn ( AMNH) ; 1♂, S of Woodside , 17.ix.1964, J. & W. Ivie ( AMNH) ; Santa Clara. 1♂, Alum Rock Park , 8.x.1979, D. Ubick ( DU) ; 2♀, Highway 17, 2 mi. N of Holy City, 6.xii.1966, V. D. Roth & Ferguson ( AMNH) ; 1♀, Los Gatos , 18.iii.1984, D. Ubick ( DU) ; 2♀, Stanford University environs, x.1920, no collector data ( AMNH) ; Santa Cruz. 1♀, Ben Lomond , 2000’, iv.1934, L.W. Saylor ( AMNH) ; 2♀, Brookdale , iii.1913, R. V. Chamberlin ( AMNH) , 1♀, Felton , iii.1913, no collector data ( AMNH) .

Diagnosis. The banded femora of male and female C. amicus may often be sufficient to separate them from specimens of other adenes group species except for C. auburn and C. torosus .

In addition, the male of C. amicus is diagnosed by the number and arrangement of peg setae on the patellar apophysis and the morphology of the proximal end of the tegular apophysis. Forty to 50 peg setae are distributed over the entire dorsal surface of the patellar apophysis (Fig. 13). The proximal arm of the tegular apophysis has a single tip and its ventral and retrolateral surfaces are concave (Figs 12, 56). No other known male of the adenes group has this combination of features.

The female of C. amicus may be difficult to differentiate from some of the females of other species of the adenes group. Its strongly concave atrium ( Figs 15–16 ) distinguishes it from females with weakly concave atria: C. auburn ( Figs 21–22 ) and some C. reducens ( Figs 38–39 ). From specimens of C. reducens with moderately concave atria, females of C. amicus can be distinguished by the length-to-width ratio of the atrium and the general form of the vulva: length> width and vulva “normal” in C. amicus ( Figs 15–17 ) versus length <width and vulva appearing reduced or compressed in C. reducens ( Figs 41, 43 ). From females of the other adenes group species with strongly concave atria, females of C. amicus can be distinguished by the atrium being inverted U-shaped and widest posteriorly ( Figs 15–16 ) versus inverted vase-shaped and widest posteriorly in C. schusteri ( Fig. 53 ), inverted lyriform and widest anteriorly in C. adenes ( Figs 4-7 , 9–11 ) and C. grizzlyi ( Figs 28, 30 ), or inverted U-shaped but parallelsided in C. pearcei ( Fig. 33 ); by the lateral ends of the atrium being unmodified ( Figs 15–16 ) versus strongly curved antero-medially in C. sanbruno ( Figs 47–48 ); and by the copulatory ducts being of relatively narrow diameter and lightly sclerotized throughout their length ( Figs 16–17 ) versus very broad and lightly sclerotized anteriorly and narrow and heavily sclerotized posteriorly in females of C. torosus ( Fig. 55 ).

Description. Femora lightly to strongly banded.

Male: (n=5). Very small retrolateral ridge anteriorly on tibia dorsal to carinate retrolateral tibial apophysis (Fig. 14).

(n=5). CL 2.4–2.9 (2.6), CW 1.75–2.03 (1.89), SL 1.17–1.35 (1.28), SW 1.16–1.33 (1.24).

Female: (n=20). Atrium ( Figs 9–11 ) with anterior margin smoothly curved, length (from epigastric groove to anterior margin) 1.2–1.6 times width (between lateral margins). Vulva ( Figs 10–11 ) similar to C. adenes .

(n=20). CL 2.38–3.3 (2.8±0.3), CW 1.55–2.33 (1.91±0.20), SL 1.18–1.50 (1.31±0.09), SW 1.09–1.43 (1.24±0.09). Holotype CL 2.5, CW 1.76, SL 1.22, SW 1.15.

Distribution and natural history. West central California from southern San Francisco Bay area south to northern Monterey County ( Fig. 69 ). Males have been collected from mid–September to mid–November. Oak and redwood forests support populations of this species.

Figures

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

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 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 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 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 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 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 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 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.