Psilochorus acanthus Chamberlin & Ivie, 1942

Slowik, Jozef, 2009, A review of the cellar spider genus Psilochorus Simon 1893 in America north of Mexico (Araneae: Pholcidae), Zootaxa 2144, pp. 1-53 : 7-8

Psilochorus acanthus Chamberlin & Ivie, 1942

Figs. 5–14, 188

Types. ɗ holotype, Ψ allotype, Santa Barbara (34.42 N, 119.69 W) Santa Barbara County, California, USA; coll: R V Chamberlin, Mar-1913. AMNH. Not examined.

Specimens examined. 2 ɗ, 8 Ψ, USA, California, Calaveras County; 2 Ψ, Hanging Gardens Cave, R E Graham, 17-Aug-1962, AMNH; Santa Barbara County; 1 Ψ, Cold Spring Trail, Santa Barbara, W J Gertsch & V Roth, 14-Aug-1959, AMNH; 1 Ψ, Santa Barbara (MWNH grounds), V Roth, 07-Feb-1967, AMNH; Ventura County; 2 ɗ 2 Ψ, 7mi SE of Carpinteria, W J Gertsch & V Roth, 02-Jul-1958, AMNH; New Mexico, Sandovall County; 2 Ψ, Rio Grande at mile 22, no collector given, 02-Apr-1962, CU.

Diagnosis. Specimens may be distinguished by: males lacking a cheliceral spur (Figs. 5, 6), bulb apophysis is bifurcate with the retrolateral tip thick and rounded (Figs. 7, 8), epigynum with a rounded, sometimes parted, AEP (Fig. 12), rounded MEP (Fig. 11), and a rounded to flat PEP (Fig. 12).

Male: (N=2) Total length: 1.72, 2.44; carapace length: 0.67, 0.75; carapace width: 0.99, 0.75; leg 1 missing segments (4.10, 4.03 + 0.31, n/a + 4.27, n/a + 2.72, n/a); tibia 2: 2.4, 2.56; tibia 3: 1.94, 2.25; tibia 4: 2.50, 2.97. all tarsi missing; femur1/carapace length: 6.10, 5.37; RT at 8.0%; DT at 4.9%. Color pattern usual for the genus. Male procursus stout, distal area lanceolate, end rounded (Figs. 9, 10). Bulb apophysis bifurcate with the retrolateral point broad and rounded (Figs. 7, 8).

Female: (N=4) Total length: 2.37 ± 0.06 mm; carapace length: 0.87 ± 0.11; carapace width: 0.87 ± 0.11; leg 1: 15.18 ± 4.42 (4.32 ± 1.34 + 0.33 ± 0.07 + 4.38 ± 1.25 + 4.99 ± 1.66 + 1.16 ± 0.21); tibia 2: 3.02 ± 0.88; tibia 3: 2.36 ± 0.66; tibia 4: 2.77 ± 0.68. 20–21 leg I tarsal segments; femur 1/carapace length: 4.89 ± 1.1; RT at 7.3-16.7%; DT at 6.6-7.8%. Color same as male. AEP rounded occasionally showing a crease or part along the median (Fig 12). The MEP is entire showing no ridges in posterior view. The PEP is entire, usually flattening out at the apex which allows the MEP to be seen in posterior view (Fig. 13).

Remarks. Females of this species are very similar to P. californiae and P. simoni . They can be separated from P. californiae by the lack of ridges on the MEP and from P. s i m o n i by the flattening of the PEP and lack of lateral modifications on the MEP. The lack of a cheliceral spur is distinctive.

Distribution. Southern California.

PLATE 2. Figures 5–14. Psilochorus acanthus Chamberlin and Ivie. 5–10. Male. 5. Dorsal view of chelicerae. 6. Lateral view of chelicera. 7–8. Dorsal view of bulb apophysis. 9–10. Lateral view of procursus. 11–14 Epigynum. 11. Anterior view. 12. Ventral view. 13. Posterior view. 14. Lateral view.