Psilochorus concolor, Slowik, Jozef, 2009

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 : 16-19

Psilochorus concolor new species

Figs. 56–66, 190

Types. ɗ holotype, ɗ paratype and four Ψ paratypes from Chisos Mountains, Cat Tail Canyon (29.27 N, 103.30 W), Big Bend National Park, Brewster County, Texas, USA; coll: Roth-Schroepfer, 20-Mar-1977, AMNH.

Further paratypes. 2 ɗ, 9 Ψ; USA, Texas, Brewster County, 2 ɗ, 9 Ψ, Big Bend N P, The Basin, Chiso Mtns, Gertsch & Hastings, 25-Aug-1967, AMNH.

Etymology. The specific epithet refers to the lack of typical coloration found in this species.

Diagnosis. Specimens may be distinguished by: lack of a dark median groove on the carapace (Fig. 62) in conjunction with the male spur is short and wide (Fig. 56), the procursus being of similar width throughout with a squared end (Figs. 60, 61), a widely separated bifurcate bulb apophysis (Figs. 58, 59), long conical congruent ridges on the MEP (Fig. 65).

PLATE 6. Figures 47–55. Psilochorus coloradensis new species. 47– 51 Male holotype. 47. Dorsal view of chelicerae. 48. Lateral view of chelicera. 49–50. Dorsal view of bulb apophysis. 51. Lateral view of procursus. 52–55. Epigynum of paratype. 52. Anterior view. 53. Ventral view. 54. Posterior view. 55. Lateral view.

Male: (Holotype) (Figs. 56–58, 61, 62) Total length: 1.90; carapace length: 0.77; carapace width: 0.76; leg 1: 11.59 (3.28 + 0.31 + 3.59+ 3.58 + 0.84); tibia 2: 2.54; tibia 3: 1.86; tibia 4: 2.17. 18 leg I tarsal segments; femur1/carapace length: 4.26; RT missing; DT at 6.7%. Color typical except for the carapace which is light, lacking the typical dark Y mark (Fig. 62). Spur small, located on the proximal area of the chelicerae (Fig. 57), end angled ventrally in lateral view. Procursus thick, entire length of equal width, end square (Fig. 61). Bulb apophysis bifurcate, well separated ends, located on edges of bulb end, tips pointed (Fig. 58).

PLATE 7. Figures 56–62. Psilochorus concolor new species. 56– 62 Male holotype. 56. Dorsal view of chelicerae. 57. Lateral view of chelicera. 58–59. Dorsal view of bulb apophysis. 60–61. Lateral view of procursus.

Female: (N=4) Total length: 2.34± 0.43; carapace length: 0.76 ± 0.07; carapace width: 0.75± 0.06; leg 1: 11.02 ± 0.55 (3.22 ± 0.25 + 0.29 ± 0.01 + 3.33 ± 0.11 + 3.36 ± 0.18 + 0.82 ± 0.03); tibia 2: 2.34 ± 0.15; tibia 3: 1.77± 0.10; tibia 4: 2.09 ± 0.12. 18 leg I tarsal segments; femur1/carapace length: 4.08 ± 0.04; RT at 11.4% (3 missing RT); DT at 7.4–8.5%. Color same as male. AEP rounded, oval (Fig. 63, 66), MEP with two large, conical, mesal ridges (Fig. 65). Ridges longer than wide. PEP rounded (Fig. 65), following the shape of the MEP.

Remarks. This species is similar to P. rockefelleri in which it differs in the shape of the protuberances on the MEP which are taller and more conical. Males are distinct.

Distribution. Big Bend National Park, Texas.

PLATE 8. Figures 63–66. Psilochorus concolor new species. 63–66 Epigynum of paratype. 63. Anterior view. 64. Ventral view. 65. Posterior view. 66. Lateral view.