Cybaeus schusteri 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 : 264-265

Cybaeus schusteri Bennett spec. nov.

Figs 50–53 , 65–66 , 70

Type material. Holotype ♂. U.S.A.: California: Napa County, 10 miles south of Monticello , 6 January 1957, R. O. Schuster ( AMNH).

Paratypes. U.S.A.: California: Napa. 1♀, 5 mi. S of Monticello , 6.i.1957, R . O. Schuster ( AMNH); 2♀, 10 mi. S of Monticello , 16.iii.1956, R . O. Schuster ( AMNH); 1♀, 10 mi. S of Monticello , 17.ii.1957, R . O. Schuster ( AMNH) .

Etymology. The specific name is a patronym honouring the late R.O. Schuster who collected the holotype and paratypes of this species.

Diagnosis. The male of C. schusteri is diagnosed by the combination of about ten small peg setae arranged linearly along the dorsal surface and tip of the patellar apophysis ( Fig. 51 ) and, on the proximal arm of the tegular apophysis ( Figs 50 , 65–66 ), the bifid tip with the terminations small, not pincer-like, and only slightly convergent and the presence of a small but prominent angular dorsal keel. Although no other male of the adenes group has this combination of characters, the males of C. schusteri and C. sanbruno can be confused; see the diagnosis of C. sanbruno for further discussion.

The female is distinguished by the inverted vase-shaped atrium which is narrowest anteriorly and widest posteriorly ( Fig. 53 ). It may be difficult to differentiate some females of this species from females of C. adenes and C. grizzlyi . See the diagnosis of C. adenes for further discussion.

Description. Femora unbanded.

Male: (n=1). Small inconspicuous retrolateral ridge anteriorly on tibia dorsal to carinate retrolateral tibial apophysis ( Fig. 51 ).

Holotype. CL 1.73, CW 1.30, SL 0.94, SW 0.86.

Female. (n=4). Length of atrium (from epigastric groove to anterior margin) about twice width (between lateral margins) ( Fig. 53 ). Vulva ( Fig. 53 ) as for C. adenes .

CL 1.75–2.10 (1.94), CW 1.26–1.45 (1.35), SL 0.94– 1.09 (1.02), SW 0.85–0.99 (0.93).

Note. The female of C. adenes from near St. Helena, Napa County ( Figs 9–11 ), may prove to be a specimen of C. schusteri . Males and a larger sample of females from that area are needed to determine if one or both of C. adenes and C. schusteri occur in the St. Helena area.

Distribution. Monticello area near south end of Lake Berryessa, Napa County, in west 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 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 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 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.