Corinnidae

Karsch, 1880

corinnid sac spiders, ground and ant-mimic sac spiders

Corinnidae is a of araneomorph comprising over 800 in 71+ worldwide. Formerly part of the catch-all family Clubionidae, the group was redefined in 2014 to include only Corinninae and Castianeirinae. Members are wandering that construct silken sac retreats, with many genera exhibiting - as a defensive strategy. The family includes notable ant-mimicking genera such as Castianeira, Myrmecotypus, Mazax, and Myrmecium.

Septentrinna by (c) Wendy McCrady, some rights reserved (CC BY), uploaded by Wendy McCrady. Used under a CC-BY license.

Castianeira crucigera by (c) Luke, some rights reserved (CC BY), uploaded by Luke. Used under a CC-BY license.

Castianeira crucigera by no rights reserved, uploaded by Lyn Roueche. Used under a CC0 license.

Pronunciation

How to pronounce Corinnidae: //kəˈrɪn.ɪˌdiː//

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Identification

Corinnidae can be distinguished from similar by the combination of eight arranged in two rows and conical that touch at the base. -mimicking (Castianeirinae) are recognized by their narrow, elongated bodies, constricted with pale transverse , and ant-like including abdominal bobbing and foreleg waving. These differ from true ants by having only two body versus three, and by possessing eight legs rather than six.

Images

Habitat

Members occupy diverse terrestrial including leaf litter, forest floors, savanna woodlands, and occasionally agroecosystems. Many construct silken sac retreats on , between leaves, under bark, or under rocks. Some -mimicking species are found in association with ant colonies.

Distribution

Worldwide distribution with highest diversity in tropical and subtropical regions. The -mimicking Myrmecotypus ranges from the United States to Argentina, with most concentrated from Mexico to Panama. The genus Copa is widespread throughout the Afrotropical region from West Africa to East Africa and South Africa.

Behavior

Wandering that do not build capture webs. Many , particularly in Castianeirinae, are mimics that exhibit behavioral deception including slow movement, abdominal bobbing, and foreleg waving to simulate . Some species overwinter in dense silken sacs in sheltered situations such as rock crevices and decaying log recesses.

Ecological Role

of small in leaf litter and ground . -mimicking may gain protection from predators by resembling aggressive, chemically-defended ants such as .

Human Relevance

Generally harmless to humans; some occasionally enter buildings. The -mimic Castianeira cingulata is frequently encountered in woodland of eastern North America. Some species have been documented in orchard (avocado, macadamia, pistachio) in South Africa.

Similar Taxa

ClubionidaeHistorically included within Corinnidae; now separated based on morphological and molecular data. Clubionidae lacks the - and specific and arrangements characteristic of Corinnidae.
PhrurolithidaeFormerly treated as a of Corinnidae but elevated to status in 2014. Distinguished by different genitalic and ecological preferences.
TrachelidaeFormerly a of Corinnidae, now recognized as a separate . Trachelidae are ground-dwelling hunters but differ in arrangement and structure.