On the Identities of Some Distinctive, Suspended Spider Egg Sacs (Araneae: Liocranidae, Tetragnathidae)

 

On the Identities of Some Distinctive, Suspended Spider Egg Sacs (Araneae: Liocranidae, Tetragnathidae)

Spider egg sacs come in a wide variety of forms, and they are often sufficiently distinctive to identify to species in the absence of associated adults (Comstock 1940, Vetter and Carroll 2013). However, the egg sacs of many spiders have not yet been described, and, at present, creating a comprehensive guide to the egg sacs of any region is impossible. Eiseman and Charney (2010) devoted 21 pages to categorizing, describing, and illustrating the egg sacs of North American spiders, including two distinctive ones they were unable to identify. One of these was a “rounded bag, about 8 mm long, with upper edges that taper out to the horizontal thread [from which it is suspended], forming two points.” Spiderlings that emerged from one egg sac of this type were believed to be tetragnathids (Eiseman and Charney 2010, pp. 42–43). The other mystery egg sac (p. 45) was a globular, mud-covered sac suspended from a silken cord, attributed to “Micaria limnicunae” McCook, 1884 (Gnaphosidae), which Platnick and Shadab (1988) considered a nomen dubium. I have investigated the identities of both egg sacs using a combination of rearing and DNA barcoding, and here present my findings. Both investigations reveal that the morphology of egg sacs, as with plant galls and leaf mines, can be useful in working out the taxonomy of the arthropods that produce them.

Charles S. Eiseman "On the Identities of Some Distinctive, Suspended Spider Egg Sacs (Araneae: Liocranidae, Tetragnathidae)," Proceedings of the Entomological Society of Washington, 125(2), 278-284, (31 January 2024) https://doi.org/10.4289/0013-8797.125.2.278