H. W. Levi.
Spiders of the New Genus Arctachaea (Araneae, Theridiidae).
Psyche 64(3):102-106, 1957.

This article at Hindawi Publishing: https://doi.org/10.1155/1957/83902
CEC's scan of this article: http://psyche.entclub.org/pdf/64/64-102.pdf, 888K
This landing page: http://psyche.entclub.org/64/64-102.html

The following unprocessed text is extracted automatically from the PDF file, and is likely to be both incomplete and full of errors. Please consult the PDF file for the complete article.

SPIDERS OF THE NEW GENUS ARCTACHAEA
(ARANEIAE, THERID'IIDAE)
Museum of Comparative Zoology
Harvard University
The new spider genus Arctachaeu is erected for two rare species from western North America, closely allied to Theridion. Arctachaeu differs from the latter in abdomen shape and in structure of the genitalia. The rarity of the two species accounts for the belatedness of their description. Dr. W. J. Gertsch of the American Museum of Natural History and Dr. R. V. Chamberlin of the University of Utah have made specimens available to me. I extend my sincere thanks for their cooperation.
Arctachaea, new genus
Arctachaea (fern.) has Arctachaea pelyx as type species. Medium sized theridiid spiders.
Carapace longer than
wide, thoracic depression indistinct.
Eyes subequal in size,
anterior eye row procurved as seen from front, posterior row straight as viewed from above. Chelicerae lacking teeth. Sternum convex. First leg longest, fourth or second leg in males second in length, third shortest. Tarsal comb with few setae. Abdomen slightly longer than high with a distinct dorsal posterior hump. Colulus abs,ent.
Epigynum a raised area. Palpus with median apophysis EXPLANATION OF PLATE 8
Figs. 1-2 Arctachaea nordica (Chamberlin and Ivie) Fig. 1. Ventral view of chelicerae and palpus. Fig. 2. Anterior view of left chelicera. Figs. 3-6. A. pelyx new species. Fig. 3. Left palpus, expanded (C, conductor; E, embolus; M, median apophysis; R, radix; Y, cymbium). Fig. 4. Female genitalia. dorsal view. Fig. 5. Epigynum. Fig. 6. Female. Figs. 7-11. A. nw- dica (Chamberlin and Ivie). 7. Female genitalia, dorsal view. 8. Epigynum. 9, 10. Female. 11. Left palpus. Figs. 12-13. A. pelvx new species. 12. Pal- pus (Utah). 13. Palpus (Oregon).




================================================================================




================================================================================

104 Psyche [September
(M in Fig. 3), radix (R), conductor (c) and a long embolus (E) . The cymbium (Y) is modified at its tip. Arctachaea differs from Theridion by having a hump on the abdomen (Figs. 6, 9, lo), and in the shape and direc- tion of the embolus. It differs from both Theridion and the closely allied Chrysso in having the tip of the male cymbium modified (Fig. 3). Arctachaea can be separated from Achaearanea which has a similar shaped abdomen in that the former has a radix in the male palpus while the latter genus does not.
Arctachaea pelyx new species
Plate 8, Figures 3-6, 12, 13 ; Map I
Types. Male holotype from East Canyon, Salt Lake Coun- ty, Utah, June 12, 1943 (W. Ivie) in the American Museum of Natural History.
Description. Carapace yellow-white with a median dusky band, narrowest posterior, enclosing eye region and con- tinuing as a line across the clypeus; sides of carapace with a dusky line. Sternum with a black border on each side. Legs with some black spots. Abdomen (Fig. 6) yellow- white with a dusky median dorsal band bordered by white. Anterior median eyes separated by one and one-quarter diameters, one-quarter from laterals. Posterior eyes sep- arated by one diameter. Abdomen with a tubercle (Fig. 6) that of male longer than high. E'pigynum with a light swollen area illustrated by Figure 5, palpus by Figures 12, 13. Total length of female 3.2 mm. Carapace 1.02 mm. long, 0.92 mm. wide. First femur, 1.71 mm.; patella and tibia, 1.85 mm., metatarsus, 1.58 mm. ; tarsus, 0.68 mm. Second patella and tibia, 1.11 mm.; third 0.78 mm. ; fourth 1.24 mm. Total length of male 2.7 mm.
Carapace 1.15 mm.
long, 1-10 mm., wide. First femur 2.71 mm.; patella and tibia 3.05 mm.; metatarsus 2.72 mm.; tarsus, 0.91 mm. Second patella and tibia, 1.63 mm. ; third, 1.05 mm. ; fourth, 1.70 mm.
Records. Utah: Salt Lake Co.: Elast Canyon, June 14, 1942, 9 paratypes; June 21, 1942 9 paratypes; June 12, 1943, 9 allotype, 9 8 paratypes (W. Ivie). Summit Co.: 3 mi. W. of Wanship, June 20,1941, 9 $ (W. Ivie). Oregon.



================================================================================

19571 Levi - Spider Genus Arctachaea 105 Harney Co.: above Fish Lake, Steens Mtn., 18 mi. E. of Frenchglen, 7000-8000 ft., July 14-16, 1953, s (V. Roth). Arctachaea nordica (Chamberlin and Ivie) Plate 8, Figures 1-2, 7-11; Map 1
Achaea nordica Chamberlin and Ivie, 1947, Bull. Univ. Utah, biol. ser., vol. 37, p. 25. (Juvenile male holotype from College, Alaska, in the American Museum of Natural History).
Description. Carapace white, with a double median line and a dusky border.
Sternum with a narrow dusky border.
Legs white. Eyes on small black spots, anterior medians Map 1. Distribution of Arctachaea no~dica (Chamberlin and Jvie) and A. pelyx new species.
one and one-third diameter apart, one-half from laterals. Posterior medians separated by less than their diameter, by one from laterals. Abdomen white with a black spot



================================================================================

106 Psyche [September
on posterior tip (Figs. 9, 10). Epigynum with two anterior swollen areas, and a posterior median depression (Fig. 8). Palpus of male very large (Fig. Il), cymbium 0.65 mm. long, teeth of cymbium fitting against enlarged fang (bear- ing phlanges on each side) as illustrated by Figure 1. Total length of female from Montana 3.0 mm. Carapace, 1.12 mm. long, 0.97 mm. wide. First femur, 2.20 mm.; patella and tibia, 2.32 mm. ; metarsus, 1.95 mm.; tarsus, 0.71 mm. Second patella and tibia, 1.35 mm. ; third, 0.91 mm. ; fourth 1.56 mm. Total length of male from Colorado 2.7 mm. Carapace, 1.24 mm. long, 0.98 mm. wide. First femur, 2.60 mm. ; patella and tibia, 2.74 mm. ; metatarsus, 2.40 mm.; tarsus, 0.85 mm. Second patella and tibia, 1.72 mm. ; third, 0.92 mm.; fourth, 1.62 mm.
Records. Northwest Territories : Reindeer Depot, 68'42': 134'06', July 1-6, 1948, Q ; Aug. 1948, juv. o , juv. s hav- ing enlarged fangs (J. R. Vockeroth). Montana. Gallatin Co. : Red Cliff Camp Ground, Gallatin Valley, meadow, Aug. 18, 1951, Q (H. and L. Levi). Colorado. Larimer Co. : Estes Park, 7800 ft., 1953, s (H. and A. Jungster). Utah. Salt Lake Co.: East Canyon, June 12, 1943, (W. Ivie). California. Modoc Co. : 20 mi. N. of Canby, June 6, 1944, 8 (W. M. Pearce) .




================================================================================