Cybaeus hesper Chamberlin and Ivie

Bennett, Robb, Copley, Claudia & Copley, Darren, 2021, Cybaeus (Araneae: Cybaeidae): the consocius species group of the Californian clade, Zootaxa 4965 (3), pp. 401-436 : 407-409

Cybaeus hesper Chamberlin and Ivie

Figs 10–15 , 21 , 84

Cybaeus minor Banks 1904: 341 , figs 4, 44 (preoccupied by Chyzer 1897, in Chyzer & Kulczyński, 1897). Chamberlin and Ivie 1932: 27, fig. 63 (not 64 = C. hummeli spec. nov.).

Cybaeus hesper Chamberlin and Ivie 1932: 27 , figs 65–66. Chamberlin and Ivie 1937: 225. Roewer 1954: 90. Roth and Brown 1986: 3. Copley et al. 2009: 372, fig. 8. World Spider Catalog 2021.

Cybaeus minoratus Gertsch 1936: 14 (replacement name for C. minor Banks ).

Cybaeus hesperus: Bonnet 1956: 1301 (unjustified emendation).

Nomenclatural notes. Cybaeus minor Banks is a junior homonym of C. minor Chyzer and therefore unavailable. Cybaeus hesper has age precedence over C. minoratus , Gertsch’s (1936) replacement name for C. minor Banks. Chamberlin and Ivie (1932) were unable to examine Bank’s specimens and based their redescription of C. minor upon a single female from Stanford. The genitalic morphology of their specimen agrees well with Banks’ female syntype but is not the specimen they used for the purpose of illustrating the epigynum of C. minor ( Chamberlin and Ivie 1932, fig. 64). That figure is almost certainly of the epigynum of a previously undescribed species of the consocius group described below as C. hummeli spec. nov.

Chamberlin and Ivie (1932) provided no etymological explanation for the species name hesper . We assume it is a shortened version of the Latin noun hesperus (translated as evening star, evening, or west) and was intended to reflect the western California distribution of this species. If so, then, as suggested by Bonnet (1956: “Il vaut mieux ecrire hesperus ”), the correct spelling should be hesperus . No provision of the Code suggests emending the spelling of a Latin noun lacking its expected suffix, however, and subsequent authors have used the original spelling without commenting upon Bonnet’s emendation. Following Roth and Brown (1986), Copley et al. (2009), and World Spider Catalog (2021) we accept the original spelling, hesper , as correct and consider Bonnet’s emendation to be unjustified.

Type material examined. U.S.A.: California: Holotype male of C. hesper, Santa Clara County, Stanford University, spring 1921, J.C. Chamberlin ( AMNH). 1 male, 1 female, syntypes of C. minor, Los Angeles County, Claremont , no date, Baker, ( MCZ).

Other material examined. U.S.A.: California: San Mateo. 1♀, Page Mill Rd. at Skyline Blvd., ~ 7.2 km E of La Honda, 2.iv.1994, D. Ubick & J. Boutin ( CAS); 1♀, Redwood City, 22.i.1946, P.H. Arnaud ( CAS); 1♂ (palpus only), Skyline Blvd . at King’s Mtn., 18.viii.1928, J.C. Chamberlin ( AMNH); Santa Clara. 1♀, Page Mill Rd. , 0.3 mi. E of Skyline Blvd., 24.v.1992, D. Ubick & J. Boutin ( CAS); 1♀, Stanford [University], no date, R. V. Chamberlin ( AMNH) .

Diagnosis. The male of C. hesper is unlikely to be confused with the males of the other species in the consocius group and is diagnosed by the unique form of the proximal arm of the tegular apophysis ( Figs 11–12 , 21 ), in particular the small terminal indentation producing a distinct (but inconspicuous) bifid tip ( Fig. 11 , 21 ). The female of C. hesper is only likely to be confused with the females of C. consocius or C. hummeli spec. nov.; distinguishing the females of these three species is discussed under C. consocius .

Description. Ventral tibia I macrosetae: 2-1p-2-1p-0.

Male: (n=3). Patellar apophysis ( Fig. 10 ) nearly as long as width of patella, with less than ten peg setae dorsally. Proximal arm of tegular apophysis ( Fig. 11–12 , 21 ) with a rounded ridge anteriorly and extending posterolaterally). Measurements (n=2). Holotype of C. hesper , male syntype of C. minor respectively: CL 2.16, 2.33; CW 1.64, 1.73; SL 1.02, 1.13; SW 0.99, 1.12.

Female: (n=5). Atrium ( Fig. 13 ) with inconspicuous anterior border. Copulatory ducts ( Figs 14–15 ) somewhat membranous, extending anteriorly beyond the anterior margin of the atrium a distance of up to approximately 2/5 the distance between the anterior atrial margin and the epigastric groove. Spermathecal stalks well separated ( Fig. 15 ). Measurements (n=3). Female syntype of C. minor CL 2.05, CW 1.40, SL 1.04, SW 1.00. Redwood City and Stanford females: CL 2.13, 2.7; CW 1.48, 1.83; SL 1.12, 1.30; SW 1.01, 1.24.

Distribution and natural history. Apparently restricted to San Mateo and Santa Clara Counties southwest of San Francisco Bay, California ( Fig. 84 ). We believe the record from the Los Angeles area (two syntypes of C. minor ) to be mislabeled: no other species of the consocius group is known to range that far south and no further specimens of C hesper have been recorded from the Los Angeles area subsequent to the original description of C. minor over 100 years ago. It is not included on the distribution map. Mature males have been collected in “spring” and August.

Figures

FIGURE 84. Distribution of Cybaeus consocius, C. hesper, C. hummeli spec. nov., C. penedentatus, and C. ubicki spec. nov. AZ—Arizona, CA—California, ID—Idaho, OR—Oregon, NV—Nevada, UT—Utah, WA—Washington. California county names capitalized.

FIGURES 10–12. Cybaeus hesper, male from Skyline Boulevard at King’s Mountain, California, right palpus. 10 Patella and tibia, dorsal. 11–12 Genital bulb (11 ventral, 12 retrolateral). PA—proximal arm of tegular apophysis, PTA—patellar apophysis, RTA—retrolateral tibial apophysis.

FIGURES 13–17. Cybaeus spp., females, copulatory organ (13–15 C. hesper, syntype of C. minor; 16–17 C. consocius, holotype of C. marinensis). 13, 16 Epigynum, ventral; 14–15, 17 Vulva (14, 17 ventral, 15 dorsal). CD—copulatory duct. Unlabelled arrows indicate anterior margin of atrium.

FIGURES 20–22. Cybaeus spp., males from California (20 C. consocius from Muir Woods, 21 C. hesper from Skyline Boulevard at King’s Mountain, 22 C. hummeli spec. nov. from Skyline Boulevard at King’s Mountain). 20, 22 Left palpus, proximal tip of tegular apophysis, ventral. 21 Right palpus, proximal tip of tegular apophysis, ventral. Unlabelled arrows indicate diagnostic characters (20 right angle forked tip, 21 inconspicuous bifid tip, 23 small acuminate tip and central longitudinal concavity).