The Pirate Spiders
Pirate spiders are superficially similar to spiders in Theridiidae or Araneidae but they belong to the family Mimetidae. There are two genera and four species found in Minnesota. Pirate spiders enter the webs and webbed retreats of other spiders in order to hunt the spiders that spin them (Archer, 1941). Those in the genus Ero are known to spin webs while Mimetus does not (Archer, 1941).
There is only one species of Ero known from Minneosta: E. canionis. The carapace's dark lateral edges are pretty distinctive and are lacking in other members of this family. In addition, the first two pairs of legs are slightly shorter than the rear two pairs of legs (Archer, 1941). An example of this species can be found here: https://www.inaturalist.org/observations/190929274
There are three species of Mimetus known from Minnesota. The first two pairs of legs in this genus are much longer than the two pairs in the rear (Archer, 1942) and have forward pointing spines. Males mature in spring with females maturing in summer (Kaston, 1948).
Mimetus epieroides can be distinguished from the other members of this genus in Minnesota by the dorsal carapace pattern of thin, dark lines that converge toward the posterior. The other two species have a more blotchy pattern on the median portion of the carapace. This species is also paler in coloration than the other two.
Mimetus notius is called the Reticulated Pirate Spider here on iNaturalist. It is similar to M. puritanus but Kaston (1948) suggests its abdomen is "more generally covered with dark areas" (whatever that means). From available images on BugGuide and iNaturalist, I surmise that it lacks the pair of pale transverse abdomen patches of M. puritanus but sometimes has a single pale median patch on the anterior of the abdomen. Many examples of this species have additional dark "splatter" marks to the sides of the main dark median blotch pattern; I'm not sure if that is a significant feature yet or not. Links to examples of this species can be found below:
https://www.inaturalist.org/observations/233018458
https://www.inaturalist.org/observations/161502345
Mimetus puritanus is called the Common Pirate Spider here on iNaturalist and it appears to be the most common based on my collection efforts. It is often found in forest understories and can be swept from bushes (Kaston, 1948). Voucher specimens suggest that this species exhibits two transverse pale patches on the anterior third of the abdomen that are lacking in the similar M. notius; this species sometimes has a pale median patch on the anterior of the abdomen like M. notius. Links to examples of this species can be found below.
https://www.inaturalist.org/observations/7352429
https://www.inaturalist.org/observations/55155686
Happy spidering!
Bibliography:
• Archer, A. F. 1941. Alabama spiders of the family Mimetidae. Papers of the Michigan Academy of Sciences, Arts, and Letters, 26:183-193. (Sometimes cited as Archer, 1942)
• Kaston, B. J. 1948. Spiders of Connecticut. Bulletin of the Connecticut State Geological and Natural History Survey 70: 1-874.
Comentarios
Añade un comentario