Cybaeus reducens 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 : 259-262

Cybaeus reducens Chamberlin & Ivie 1932

Figs 35–43 , 57–58 , 70

Cybaeus reducens Chamberlin & Ivie 1932: 23 , fig. 57. Roewer 1954: 91. Bonnet 1956: 1303. Roth & Brown 1986: 4. Bennett 2006: 479, Figs 13–16. World Spider Catalog 2019.

Type material. Holotype ♀. U.S.A.: California: Monterey County, Pacific Grove , 17 August 1931, W. Ivie ( AMNH), examined.

Other material examined. U.S.A.: California: Monterey. 6♀, 14 mi. S of Big Sur , 22.xii.1953, V . D. Roth ( CAS); 3♀, 17 mi. S of Big Sur , 22.xii.1953, V . D. Roth ( AMNH); 1♀, Carmel , 6.iv.1954, no collector data ( AMNH); 3♀, 1 mi. N of Carmel, 21.xii.1953, V . D. Roth ( CAS); 2♀, Pacific Grove , 1913, R . V . Chamberlin ( AMNH); 2♀, 6.viii.1931, R . V . Chamberlin ( AMNH); 6♀, 17.viii.1931, W. Ivie ( AMNH); 5♀, 1.ix.1931, W. Ivie ( AMNH); 2♀, Pebble Beach, Crest Road, 19.ix.1959, L.M. Smith ( AMNH); Santa Clara. 1♂, 3.6 mi. from San Felipe Road on Silver Creek Road [SE of San Jose], 2.i.1983, T . S. Briggs, D.Ubick & V . F. Lee ( DU) .

Diagnosis. The near absence of peg setae on the patellar apophysis and the morphology of the proximal arm of the tegular apophysis diagnose the male of C. reducens . The patellar apophysis ( Fig. 36 ) in the single known male has only two small peg setae located dorsally near the tip of the apophysis. The proximal arm of the tegular apophysis ( Figs 35 , 57–58 ) has a trifid tip and, dorsally, a prominent angular keel. No other males in the adenes group have this combination of characters.

The female is distinguished by the combination of the broad, slightly to moderately concave atrium located anteriorly on the epigynum ( Figs 38, 41 ) and the compact, apparently strongly reduced vulva ( Figs 39–40, 42–43 ). The females of all other adenes group species have narrow, strongly concave atria and “normal” (well-developed and not apparently reduced) vulvae ( C. adenes : Figs 4–6 , 9 –111; C. amicus : Figs 15–17 ; C. grizzlyi : Figs 28–32 ; C. pearcei : Figs 33–34 ; C. sanbruno : Figs 7–49 ; C. schusteri : Fig. 53 ; C. torosus : Figs 54–55 ). The atrium and vulva of female C. auburn are antero-medially located on the epigynum ( Figs 21–22 ) and “normal” ( Figs 23–24 ), respectively.

Description. Femora unbanded.

Male: (n=1). Proximal arm of tegular apophysis ( Fig. 57 ) with trifid tip: anterior-most termination rounded and prominent, two others smaller and pointed. Very small inconspicuous retrolateral ridge anteriorly on tibia dorsal to carinate retrolateral tibial apophysis ( Fig. 36 ).

CL 2.28, CW 1.65, SL 1.16, SW 1.11.

Note. This male has been paired with the females of C. reducens because of the similarity of all specimens in size, coloration, and range (although the females were all collected in a small area along the coast and the male from about 70 km away and 35 km inland).

Female: (n=31). Length of atrium (from epigastric groove to anterior margin) 0.7–1.0 times width (between lateral margins) ( Figs 38, 41 ). Vulva ( Figs 39–40, 42–43 ) usually very small, compact.

(n=23). CL 1.98–3.1 (2.5+0.3), CW 1.35–2.05 (1.70+0.20), SL 0.99–1.43 (1.21+0.12), SW 0.90–1.30 (1.14+0.11). Holotype CL 2.8, CW 1.98, SL 1.29, SW 1.26.

Distribution and natural history. West central California from coastal northern Monterey County inland to central Santa Clara County ( Fig 70 ). The male was collected in early January at an elevation of 70 meters.

Figures

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

FIGURES 35–37. Cybaeus reducens, male from Santa Clara County, California, genital bulb (35 genital bulb, ventral; 36 patella and tibia, dorsal; 37 patella and tibia, retrolateral). DK—dorsal keel of proximal arm of tegular apophysis, RR—retrolateral ridge dorsal to retrolateral tibial apophysis. 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 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 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 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 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 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.

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 54–55. Cybaeus torosus spec. nov., female holotype, copulatory organ (54 epigynum, ventral; 55 vulva, dorsal). 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.