Current valid name

Trachelas pacificus Chamberlin & Ivie (family Corinnidae)

Recognition and diagnostic features

Wandering hunter, cephalothorax dark magenta color, abdomen tan, eyes with large distance between each other and arranged in two relatively straight rows.

Spider

Body lengths when mature: male: 5.98 ± 0.59 mm, female: 6.86 ± 0.82 mm

Immatures resemble miniature adults.

Egg sac

Description: flat-bottomed dome sac, pure white papery silk with conspicuous flat brim around the circumference which is almost circular, sometimes with vegetative detritus added for camouflage, 7.46 ± 1.7 mm wide, 8.74 ± 0.80 mm long

Number of eggs per sac: 26.0 ± 11.43

Size of egg: 0.99 ± 0.041 mm

Distribution

In California: throughout most of the state except northernmost counties

Elsewhere: northern Baja California

Native to North America

This species has not been transported or become established outside of its range.

Biology

Nocturnal and wandering hunter. Found more often in grape canopy than on ground. Occasionally lays egg sacs in grapes. Often found in homes.

Status in table grapes

Level of Incidence: very common

Level of Concern in New Zealand: WPNZ (May 2010) nr, BORIC (Dec 2011) nr (not listed), MAF-BPRA (2002) nr (coding definition)

Level of Concern in Australia: WPAU (2006) nr (coding definition)

Level of Medical importance: minor, large enough that it can penetrate skin but venom is not especially toxic, there are published reports of bites from eastern species

Common name

None

Taxonomic history

Trachelas was recently transferred from the Clubionidae to the Corinnidae.

Selected references

Costello, M. J., and K. M. Daane. 2003. Spider and leafhopper (Erythroneura spp.) response to vineyard ground cover. Environ. Entomol. 32: 1085-1098.

Platnick, N. I. 1997. Two reports of envenomation by the spider Trachelas tranquillus (Hentz). Cincinnati J. Med 52: 194.

Platnick, N. I., and M. U. Shadab. 1974. A revision of the tranquillus and specious groups of the spider genus Trachelas (Araneae, Clubionidae) in North and Central America. Amer. Mus. Novit. #2553, 34 pp.

Uetz, G. W. 1974. Envenomation by the spider Trachelas tranquillus (Araneae: Clubionidae). J. Med. Entomol. 10: 227.