Psilochorus hesperus Gertsch & Ivie 1936
Creators: name: Slowik, Jozef
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Pholcidae
Psilochorus
Psilochorus hesperus

description: Psilochorus hesperus Gertsch & Ivie, 1936
Figs. 67–76, 191
Types. Ψ holotype, two Ψ paratypes from Pullman (46.73 N, 117.179 W), Whitman County, Washington USA; ɗ allotype, Ψ paratype from Notus (43.72 N, 116.80 W), Canyon County, Idaho, USA; coll: W Ivie, 11- Jun-1931. AMNH. Not examined.
Specimens examined. 11 ɗ, 29 Ψ; USA, California, Inyo County, 1 Ψ, nr Cartago, 06-Aug-1931, AMNH; 1 ɗ, nr Big Pine, W Ivie, 09-Aug-1931, AMNH; 1 Ψ, Inyo County, 06-Aug-1931, AMNH; Mono County, 1 ɗ, 3 Ψ, Benton, 04-Aug-1942, AMNH; 1 ɗ, 3 Ψ, Mono County, 04-Aug-1942, AMNH; Siskiyou County, 1 Ψ, Mt Shasta City, W Ivie, 25-Aug-1931, AMNH; Idaho, Elmore County, 1 ɗ, 1 Ψ, Bosie River, nr entrance of North Fork, W Ivie, 12-Jun-1931, AMNH; Payette County, 2 Ψ, NE Fruitland, W I 116.44, 07- Sep-1941, AMNH; Washington, Adams County, 4 ɗ, 5 Ψ, Herman Lake, 5mi NW Othello, Vogel B, 27 May 1972, DMNS ZA.9087; 1 ɗ, 4 Ψ, Columbia National Wildlife Refuge, Vogel B & W, 21 May 1972, DMNS ZA.9088; 2 ɗ, 1 Ψ, Crab Creek, 8 mi NW Othello, Vogel B, 12 Mar 1978, DMNS ZA.8072; 1 Ψ, Columbia National Wildlife Refuge, Vogel B, 21 May 1977, DMNS ZA.8074; Grant County, 4 Ψ, 5mi NW Othello, Vogel B, 20 Mar 1977, DMNS ZA.8073.
Additionally 40 ɗ and 113 Ψ were examined from throughout Washington by Rod Crawford and are deposited at the Burke Museum at the University of Washington campus in Seattle Washington.
Diagnosis. Specimens may be distinguished by: male spur sharply pointed, tip turn sharply inward and ventrally (Figs. 67, 68), procursus with dorsal step (Fig. 71), epigynum with four ridges on the MEP, in a single line with the interior two being twice the size of the outer (Fig. 74). The outer two may lay flat, directed towards the posterior when viewed ventrally (Fig. 73).
PLATE 9. Figures 67–76. Psilochorus hesperus Gertsch and Ivie. 67– 71 Male. 67. Dorsal view of chelicerae. 68. Lateral view of chelicera. 69–70. Dorsal view of bulb apophysis. 71. Lateral view of procursus. 72–76. Epigynum. 72. Anterior view. 73. Ventral view. 74. Posterior view. 75. Cleared dorsal view. 76. Lateral view.
Male: (N=3) Total length: 2.45 ± 0.63; carapace length: 1.08 ± 0.18; carapace width: 1.03 ± 0.10; leg 1: 20.07 ± 0.91 (5.54 ± 0.18 + 0.39 ± 0.01 + 5.88 ± 0.29 + 7.16 ± 0.48 + 1.11 ± 0.11); tibia 2: 4.12± 0.19; tibia 3: 3.36 ± 0.32; tibia 4: 3.99 ± 0.35. 18 leg I tarsal segments; femur1/carapace length: 5.24 ± 0.82; RT at 12.8–14.3%; DT at 7.5–10.0%. Color typical for the genus. Spur large, originating from the proximal portion of the chelicerae (Fig. 68). Spur curved mesally in dorsal view to sharp point (Fig. 67). Procursus long, distal area occasionally split, with a dorsal tab, end squared, ventral end longer (Fig. 71). The bulb apophysis extends across the bulb end, tapering to a ventrally directed curve just before a pointed tip. Retrolateral tab large, extending to curve in bulb apophysis tip (Figs. 69, 70).
Female: (N=5) Total length: 3.29 ± 0.61; carapace length: 1.22 ± 0.08; carapace width: 1.22± 0.13; leg 1: 17.3 ± 1.92 (4.62 ± 0.56 + 0.38 ± 0.04 + 4.82 ± 0.47 + 5.73 ± 0.49 + 1.17± 0.10); tibia 2: 3.43 ± 0.21; tibia 3: 2.71± 0.26; tibia 4: 3.44 ± 0.28. 18–20 leg I tarsal segments; femur1/carapace length: 3.81 ± 0.57; RT at 12.0–17.5%; DT at 7.3–10.4%. Color typical for genus. No AEP. MEP with two large cylindrical ridges mesally and two smaller ridges on each lateral side (Fig. 74). Lateral ridges may not be visible in posterior view. PEP rounded with small PEP projection (Fig. 74).
Remarks. Males of this species are very similar to P. utahensis, so much so that in areas of convergence, i.e. central California, females should be used as well for positive identification. The male spur of P. h e s p e r u s appears to be longer and have a longer pointed region then P. utahensis. The bulb apophysis of P. hesperus is generally thinner than P. utahensis, the procursi are similar. Females of the two species differ in the presence of MEP ridges in P. hesperus. Specimens of P. hesperus also appear to be more moisture tolerant than those of P. u t a h e n s i s. Although P. cornutus was described by Keyserling as being from "Washington", it is assumed he was referring to Washington, D.C. (Crawford 1988).
Distribution.- Pacific Northwest inland into Idaho.
PLATE 10. Figures 77–81. Psilochorus hooki new species. 77–81. Male holotype 77. Dorsal view of chelicerae. 78. Lateral view of chelicera. 79. Dorsal view of bulb apophysis. 80. Lateral view of procursus. 81. Sternum.
description: Published as part of Slowik, Jozef, 2009, A review of the cellar spider genus Psilochorus Simon 1893 in America north of Mexico (Araneae: Pholcidae), pp. 1-53 in Zootaxa 2144 on pages 19-21, DOI: 10.5281/zenodo.188626