Psilochorus simoni (Berland, 1911)

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 : 39-40

Psilochorus simoni (Berland, 1911)

Figs. 148–157, 189

Psilochorus simplicior Chamberlin & Ivie, 1942 . New synonymy.

Types. P. s i m o n i: in MNHN. Collected by Berland in Paris. MNHN lists having the type but was unable to locate the specimen for examination or confirmation of label information.

P. s i m p l i c i o r: Ψ holotype, two Ψ paratypes from Pacific Grove (36.61 N, 121.91 W), Monterey County, California, USA; coll: W Ivie, 15-Aug-1931, AMNH. Not examined.

Specimens examined. 4 ɗ, 6 Ψ; ENGLAND, 2 ɗ, 2 Ψ, Oxford, Mitre Cellars, 07-Oct-1953, AMNH; 1 ɗ, 1 Ψ, England, no collector, det Millidge, 08-May-1955, AMNH; USA, California, Alameda County, 1 Ψ, Albany, 01-Sep-1975, EM; San Francisco County, 1 Ψ, San Francisco, compared to type by W. Gertsch, 15- Jun-1953, AMNH; Santa Clara County, 1 ɗ, Palo Alto, T Aiken, 29-Mar-1941, AMNH; Oregon, Lane County, 1 Ψ, Belknap Spgs, B Malkin & I Newell, 03-May-1947, AMNH.

Diagnosis. Specimens may be distinguished by: Males spur (Fig. 148), located approximately mid-length on the chelicerae (Fig. 149), procursus tip sinuous (Figs. 152, 153), AEP rounded but not bisected (Fig. 154), MEP and PEP without ridges (Fig. 156).

Male: (AMNH, Oxford, England) Total length: 1.97; carapace length: 0.87; carapace width: 0.89; leg 1: 10.7 (3.11 + 0.20 + 3.21+ 3.23 + 0.95); tibia 2: 2.29; tibia 3: 1.83; tibia 4: 2.30. 17 leg I tarsal segments; femur1/carapace length: 3.57; RT at 22.7%; DT at 11.5%. Color typical for the genus with dark Y on carapace often being light. Spur short, triangular with a rounded end, located about mid-length on the chelicerae (Figs. 148, 149). The procursus is narrow with a swollen distal area (Fig. 152), the end is sinuous with a clear truncate membrane, the tip may be more obvious upon clearing of the procursus (Fig. 153). The bulb apophysis is thick, curving across the bulb to the prolateral side with an acute curve directed distally, end pointed. Retrolateral tab low, extending to about mid-length of the bulb apophysis (Figs. 150, 151).

Female: (N=5) Total length: 2.20 ± 0.15; carapace length: 0.86 ± 0.09; carapace width: 0.87± 0.07; leg 1: 10.49 ± 1.24 (2.91 ± 0.44 + 0.28 ± 0.03 + 3.10 ± 0.32 + 3.31 ± 0.37 + 0.89 ± 0.11); tibia 2: 2.20 ± 0.26; tibia 3: 1.75± 0.17; tibia 4: 2.22 ± 0.17. 17–19 leg I tarsal segments; femur1/carapace length: 3.37 ± 0.24; RT at 20.5–25.3%; DT at 10.8–13.8%. Color same as male. AEP low, rounded with a slight median line in ventral view (Fig. 155). MEP rounded, entire with no ridges (Fig. 154), dark crescent shaped areas located on each lateral edge (Fig. 155). PEP rounded, entire, following the shape of the MEP (Fig. 156).

PLATE 18. Figures 148–157. Psilochorus simoni (Berland) . 148–153. Male. 148. Dorsal view of chelicerae. 149. Lateral view of chelicera. 150–151. Dorsal view of bulb apophysis. 152. Lateral view of procursus. 153. Lateral view of cleared procursus. 154–157. Epigynum. 154. Anterior view. 155. Ventral view. 156. Posterior view. 157. Lateral view.

Remarks. Females may be confused with P. coloradensis new species or P. acanthus in which they differ in the shape of the lateral edges of the MEP and their distribution. Chamberlin and Ivie note that the carapace lacks pigment in the median groove of the carapace; however, specimens examined appear to have this area darkened as usual for the genus. Light morphs have been seen in other species and color alone is not a good indicator of species. Gertsch (in Locket, Millidge & Merrett 1974) made note of the possible synonymy of P. simplicor and P. simoni declared here. Comparison of several P. s i m p l i c o r females and a male from California with males and females from Europe show no differences. Another interesting aspect of this species is how it has become a common synanthropic spider in Europe but rarely found in North America. Distribution. California, Oregon, and Europe.