Cybaeus bilectus Bennett, 2021

Bennett, Robb, Copley, Claudia & Copley, Darren, 2021, Cybaeus (Araneae: Cybaeidae) in the Nearctic: the devius and tardatus species groups of the Californian clade, Zootaxa 5026 (4), pp. 451-479 : 453-455

Cybaeus bilectus Bennett spec. nov.

Figs 1–4 , 8–10 , 26 , 29 , 32

Type material. U.S.A.: California: Holotype male. Tulare County, Double Bunk Meadows , six miles west of Johnsondale , 15.ix.1959, V.D. Roth & W.J. Gertsch ( AMNH) . Paratypes. Tulare. 1♀, “dirt road”, 10 mi. N of Hwy 155, 18.vi.1961, A. Maier ( CAS) ; 13♂ 9♀, Double Bunk Meadows , 6 mi. W of Johnsondale, 15.ix.1959, V.D. Roth & W.J. Gertsch ( AMNH) ; 1♀, Johnsondale , Kern R., 4.vii.1956, V.D. Roth & W.J. Gertsch ( CAS) ; 3♂ 3♀, Quaking Aspen Camp , 9.ix.1959, W.J. Gertsch & V.D. Roth ( AMNH) ; 1♀, Quaking Aspen Meadow , 3 mi. SE of Camp

Nelson , 6900’, 3.vii.1988, D. Ubick ( CAS); 1♀ , Sequoia National Park , near Cirque Cave, 3 mi. S of Mineral King, 36°24′N 118°35′W, 15.ix.1968, T. Briggs ( CAS) .

Etymology. The specific epithet, derived from the Latin for “double bed”, refers to the type locality.

Diagnosis. The male of C. bilectus spec. nov. is unlikely to be confused with the males of C. bryoncavus spec. nov. and C. wilsonia spec. nov., the other members of the devius species group with known males. The male of C. bilectus is diagnosed by the morphology of the patellar apophysis ( Figs 1–2 , 26 ) and the proximal arm of the tegular apophysis ( Figs 3–4 , 29 ): the patellar apophysis is short (length about 1/2 the width of the patella) and prolaterally directed with a slightly concave distal margin and approximately 20 to 30 peg setae dorsally along the length of the distal margin; the proximal arm of the tegular apophysis is simple with a short, bluntly hooked tip.

The female of C. bilectus spec. nov. is diagnosed by the form and configuration of the copulatory ducts ( Figs 9–10 ) and is only likely to be confused with the female of C. bryoncavus spec. nov., the only other species of the devius group with elongate convoluted and undifferentiated spermathecal stalks and copulatory ducts. (Note: because of their relatively light sclerotization and similar morphology, it is difficult to trace accurately the pathways of the spermathecal stalks and copulatory ducts in the females of C. bilectus spec. nov. and C. bryoncavus spec. nov., even in well cleared preparations of the vulva.) In C. bilectus spec. nov. the basal section of each copulatory duct travels antero-laterally from the atrium and traverses the ventral surface of the medial section of the copulatory duct (versus basal section travels anteriorly from the atrium along the midline of the vulva prior to diverging and intertwining with loops of the spermathecal stalk [ Figs 12–13 ] in C. bryoncavus spec. nov.)

Description. Ventral tibia I macrosetae: 2-1p-2-1p-2(or 1p).

Male: (n=17). Distal arm of tegular apophysis ( Fig. 3 ) prominent, broad basally, elongate (but length less than twice width), abruptly tapering distally. Embolus narrow.

Measurements (n=17). CL 2.33–3.4 (2.8+0.3), CW 1.73–2.50 (2.06+0.20), SL 1.20–1.65 (1.37+0.11), SW 1.12–1.50 (1.29+0.09). Holotype CL 2.9, CW 2.08, SL 1.43, SW 1.30.

Female: (n=16). Atrium ( Figs 8–9 ) shallow, small, about 1/2 width of vulva. Spermathecal stalks looped once around medial section of copulatory ducts ( Figs 9–10 ).

Measurements (n=14). CL 2.18–3.3 (2.8+0.3), CW 1.50–2.28 (1.95+0.24), SL 1.14–1.58 (1.38+0.13), SW 1.04–1.48 (1.29+0.12).

Distribution and natural history. ( Fig. 32 ). Known only from a small area of Tulare County in the southern Sierra Nevada of eastern California. Males have been collected in September.

Figures

FIGURE 32. Distributions of Cybaeus bilectus spec. nov., C. bryoncavus spec. nov., C. devius, C. echo spec. nov., and C. wilsonia spec. nov. AZ—Arizona, CA—California, ID—Idaho, OR—Oregon, NV—Nevada, UT—Utah, WA—Washington. California county names capitalized.

FIGURES 1–4. Cybaeus bilectus spec. nov., male from Double Bunk Meadows, California, left palpus. 1–2 Patella and tibia (1 retrolateral, 2 dorsal). 3–4 Genital bulb (3 ventral, 4 retrolateral). CY—cymbium, DA—distal arm of tegular apophysis, E— embolus, PA—proximal arm of tegular apophysis, PS—peg setae, PTA—patellar apophysis, RTA—retrolateral tibial apophysis, TG—tegulum.

FIGURES 8–13. Cybaeus spp., females from California, copulatory organ (8–10 C. bilectus spec. nov., from Double Bunk Meadows; 11–13 C. bryoncavus spec. nov., from Pine Grove). 8, 11 Epigynum, ventral. 9–10, 12–13 Vulva (9, 12 ventral, 10, 13 dorsal). BG—Bennett’s gland, CD—copulatory duct, HS—head of spermatheca, SS—stalk of spermatheca.

FIGURES 26–28. Cybaeus spp. males, left palpus, patellar apophysis, dorsal (26 C. bilectus spec. nov., from Double Bunk Meadows, California, 27 C. bryoncavus spec. nov., holotype, 28 C. wilsonia spec. nov., holotype). Arrows indicate diagnostic characters (26 concave distal margin; 28 concave dorsal surface).

FIGURES 29–31. Cybaeus spp. males, left palpus, proximal arm of tegular apophysis, ventral (29 C. bilectus spec. nov., from Double Bunk Meadows, California, 30 C. bryoncavus spec. nov., holotype, 31 C. wilsonia spec. nov., holotype). Arrows indicate diagnostic characters (29 bluntly hooked tip, 30 inconspicuous basal projection).