Cybaeus aspenicolens, Chamberlin & Ivie, 1932

Bennett, Robb, Copley, Claudia & Copley, Darren, 2021, Cybaeus (Araneae: Cybaeidae): the aspenicolens species group of the Californian clade, Zootaxa 4926 (2), pp. 224-244 : 225-226

The aspenicolens species group

Diagnosis. Differentiating the species groups of the Holarctic and Californian clades of Cybaeus is discussed in Copley et al. (2009). The species of the aspenicolens group of the Californian clade are defined by the atrium usually divided and with longitudinal copulatory openings leading into the midline of the vulva ( Figs 16, 18 , 38 ) and the greatly reduced and linearly oriented copulatory ducts and spermathecal stalks ( Figs 19 , 22 , 37 ). Other Californian clade species groups are characterized either by a divided atrium but a more complex vulva with the copulatory ducts and spermathecal stalks not so reduced or linear ( septatus group–Copley et al. 2009: figs 12, 95, 101), an undivided atrium and simple but sinuous copulatory ducts and spermathecal stalks ( adenes group–Bennett et al. 2019: figs 6, 8, 11, 17, 24, 29, 31, 32, 34, 40, 48, 55), or the atrium divided or not and relatively long and complex copulatory ducts ( consocius , devius , and tardatus groups–Copley et al. 2009: figs 8–10, 72, 75, 78, 84).

Two informal subgroups are definable within the aspenicolens group: the aspenicolens subgroup ( C. aspenicolens , C. blasbes , and C. coylei spec. nov.) and the fraxineus subgroup ( C. fraxineus spec. nov. and C. thermydrinos ). Males of the aspenicolens subgroup are characterized by their possession of a large, broad, blunt patellar apophysis with dimorphic peg setae in two groups ( Figs 2 , 5 , 8 , 11–13 ) and the large, C-shaped proximal arm of the tegular apophysis with a retrolaterally directed uncinate tip ( Figs 3 , 6 , 9 ), Males of the fraxineus subgroup can be distinguished by their narrower and tapered patellar apophysis with monomorphic peg setae in a single group ( Figs 25 , 29 ) and the proximal arm of the tegular apophysis smaller with a prolaterally directed bifurcate tip ( Figs 26 , 30 , 32–33 ). Females of the aspenicolens subgroup are characterized by their conspicuous epigynal concavity or depression and atrial openings without a transverse hood ( Figs 14, 16, 18 ). Females of the fraxineus subgroup have an epigynum with a “normal”, relatively convex surface and atrial openings partially obscured anteriorly by a transverse epigynal ridge or hood ( Figs 34–35, 38–39 ).

Description. Medium- to large-sized spiders, carapace lengths averaging 2.6–3.3 mm (males) and 2.4–3.4 mm (females). Abdomen patterned, femora usually at least lightly banded. Two or three complete pairs of ventral tibia I macrosetae (terminal pair absent, incomplete, or present): pattern 2–1p–2–1p–0 (or 1p, or 2).

Male: Patellar apophysis distally directed, species specific; massive, blunt, broader than long, length about 3/4 patellar width, with dimorphic peg seta separated in two groups retrolaterally and dorsally ( Figs 2 , 5 , 8 , 11–13 ); or slenderer, gradually tapering to blunt point, longer than broad, length about equal to width of patella, with monomorphic peg setae in single group dorsally along posterior margin of distinct concavity ( Figs 25 , 29 ). Palpal tibia about as long as wide; retrolateral tibial apophysis carinate, nearly as long as tibia ( Figs 1–2 , 25 ). Embolus relatively short, thick ( Figs 3 , 5 , 9 , 26 , 30 ). Distal arm of tegular apophysis short, not enlarged or lengthened; proximal arm species specific, retrolaterally or prolaterally directed ( Figs 3–4 , 6–7 , 9–10 , 26–28 , 30–31 ).

Female: Epigynum usually ridged anteriorly; atrium inconspicuous with medial paired, longitudinal openings ( Figs 14, 18 , 38 ). Vulva ( Figs 19 , 22 , 39 ) simple with reduced, nearly linear copulatory ducts and spermathecal heads and stalks. Copulatory ducts very short, exiting atria towards midline of vulva, often contiguous along midline. Heads of spermathecae on small dorsal lobes near midline of vulva; often not differentiated from rest of vulva except for presence of primary pores. Stalks very short, not differentiated. Bennett’s glands near junction of stalks with rounded, relatively large spermathecal bases. Fertilization ducts exit bases near junction with stalks.

Composition and distribution. Cybaeus aspenicolens Chamberlin & Ivie , C. blasbes Chamberlin & Ivie , C. coylei Bennett spec. nov., C. fraxineus Bennett spec. nov., and C. thermydrinos Bennett. All species have very restricted distributions on the western slopes of the central and southern Sierra Nevada mountain range in California from Tuolumne County south to northern Kern County ( Figs 41–42 ).

Figures

FIGURE 41. Distributions of Cybaeus aspenicolens (yellow diamonds), C. blasbes (blue circles), C. coylei spec. nov. (green triangle). AZ—Arizona, CA—California, ID—Idaho, OR—Oregon, NV—Nevada, UT—Utah.

FIGURE 42. Distributions of Cybaeus fraxineus spec. nov. (purple circles), C. thermydrinos (white triangles). AZ—Arizona, CA—California, ID—Idaho, OR—Oregon, NV—Nevada, UT—Utah.

FIGURES 14–19. Cybaeus spp., females, copulatory organ (14–15 C. coylei spec. nov. from Pinecrest, California. 16–17 C. aspenicolens from Aspen Valley, California. 18–19 C. blasbes from North Fork, California). 14, 16, 18 epigynum, ventral; 15, 17, 19 vulva, dorsal. AO—atrial opening, BG—Bennett’s gland, BS—base of spermatheca, CD—copulatory duct, HS—head of spermatheca, SS—stalk of spermatheca.

FIGURES 34–40. Cybaeus spp, females, copulatory organ (34–36 C. fraxineus spec. nov. from vicinity of Ash Mountain, California. 37 C. fraxineus spec. nov. from Clough Cave, California. 38–39 C. thermydrinos from near Johnsondale, California. 40 C. thermydrinos from California Hot Springs, California). 34, 38 epigynum, ventral; 35, 39–40 vulva, ventral; 36–37 vulva, dorsal. CD—copulatory duct, ER—epigynal ridge or hood.

FIGURES 20–24. Cybaeus spp., females, copulatory organ, vulva (20–22 C. aspenicolens from Aspen Valley, California. 23 C. blasbes from Shaver Lake, California. 24 C. blasbes from North Fork, California). 20–21, 23–24 ventral; 22 dorsal.

FIGURES 1–4. Cybaeus aspenicolens, male from Aspen Valley, Yosemite National Park, California, left palpus. 1 patella, tibia, and genital bulb, ventral; 2 patella and tibia, dorsal; 3 genital bulb, ventral; 4 genital bulb, retrolateral. DA—distal arm of tegular apophysis, E—embolus, LPS—large peg setae, PA—proximal arm of tegular apophysis, PTA—patellar apophysis, RTA—retrolateral tibial apophysis, SPS—small peg setae.

FIGURES 5–7. Cybaeus blasbes, males, left palpus (5 from near Fish Camp, California. 6–7 from Shaver Lake, California). 5 patella and tibia, dorsal; 6 genital bulb, ventral; 7 genital bulb, retrolateral. PA—proximal arm of tegular apophysis.

FIGURES 8–10. Cybaeus coylei spec. nov., male holotype, left palpus. 8 patella and tibia, dorsal; 9 genital bulb, ventral; 10 proximal arm of tegular apophysis, posterior. Embolus dislodged from usual resting position in folds of tegular apophysis in Fig. 9. PA—proximal arm of tegular apophysis.

FIGURES 11–13. Cybaeus spp., males, left palpus, patellar apophysis, dorsal. 11 C. aspenicolens from Aspen Valley, Yosemite National Park, California; 12 C. blasbes from near Fish Camp, California; 13 C. coylei spec. nov., holotype.

FIGURES 25–28. Cybaeus fraxineus spec. nov., males from vicinity of Ash Mountain, California, left palpus. 25 patella and tibia, dorsal; 26 genital bulb, ventral; 27 tegular apophysis and embolus, ventral prolateral; 28 genital bulb, retrolateral.Arrows indicate bifurcate tip of proximal arm of tegular apophysis.

FIGURES 29–31. Cybaeus thermydrinos, male from near Johnsondale, California, left palpus. 29 patella and tibia, dorsal; 30 genital bulb, ventral; 31 genital bulb, retrolateral.

FIGURES 32–33. Cybaeus spp, males, left palpus, proximal arm of tegular apophysis (32 C. fraxineus spec. nov. from vicinity of Ash Mountain, California. 33 C. thermydrinos from near Johnsondale, California). Arrows indicate bifurcate tip of proximal arm of tegular apophysis.