Asagena fulva

(Keyserling, 1884)

Red-and-white Asagena

Asagena fulva is a small cobweb spider in the Theridiidae, found in the southwestern United States and Mexico. Females range from 3–5.9 mm in body length, males from 2.4–5 mm. The appears distinctly redder with more white markings than its A. americana. It has been observed in association with nests, suggesting possible specialization.

Pronunciation

How to pronounce Asagena fulva: /əˈseɪdʒənə ˈfʊlvə/

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Identification

Distinguished from the two-spotted cobweb weaver (Asagena americana) by its redder overall coloration and more extensive white markings. Smaller than most Steatoda with which it was formerly classified. Males can be identified by the stridulating organs on the and leg spurs. The species' association with nests in arid may aid field identification in the Southwest.

Appearance

Small, stout cobweb spider with reddish coloration and more prominent white markings than related . Females measure 3–5.9 mm in body length, males 2.4–5 mm. Males have short, muscular legs with short teeth and/or spurs on the underside of each . The rear of the male bears a stridulating organ on each side of the , which rubs against a semicircular hardened plate on the front edge of the to produce sound.

Habitat

Found in arid and semi-arid environments including the Sonoran Desert. Occurs under stones, garbage barrels, and other ground cover. Frequently observed at the edges of nests.

Distribution

Southwestern United States (north to Oregon, east to Florida) and Mexico. Records from Alberta, Canada. Present in Middle America and North America.

Seasonality

Active year-round in suitable climates; specific seasonal patterns not well documented. Related A. americana shows male activity from May–July and female activity from May–August.

Diet

Possibly an ; observed in webs at nest edges, presumably ambushing ants. Specific prey range otherwise unknown.

Host Associations

Harvester ants - preyObserved in webs at nest edges, presumably ambushing

Life Cycle

Females produce spherical, translucent sacs 4–5 mm in diameter containing 20–30 pale yellow eggs. Based on A. americana: egg sacs are suspended in the web. Developmental details otherwise unknown.

Behavior

Constructs cobwebs under ground-level cover such as stones and debris. Males possess stridulatory organs for sound production, likely used in courtship. Has been observed in close association with colonies, suggesting specialized foraging .

Ecological Role

, possibly with specialized role in . Prey for spider wasps including Black and Yellow Mud Dauber (Sceliphron caementarium), which paralyzes and provisions nests with Asagena .

Human Relevance

No documented medical or economic significance. Too small to be conspicuous to most observers. May be encountered by entomologists studying or arachnologists in the Southwest.

Similar Taxa

Asagena americanaSimilar size and , but A. fulva is redder with more white markings; A. americana has two distinct spots and occurs more broadly across North America
Steatoda speciesFormerly classified in same ; Steatoda generally larger and often mistaken for black widows, whereas A. fulva is smaller and more reddish

More Details

Taxonomic history

Formerly classified in the Steatoda; moved to Asagena based on morphological revisions by Levi (1957)

Male stridulation

One of relatively few spider with documented sound production; the stridulatory mechanism involves rubbing abdominal plates against organs