Theridiosoma

Theridiosoma can be distinguished from other theridiosomatid genera by the combination of: small body size (under 3 mm); ovoid abdomen taller than wide; presence of a pit organ on the anterior sternal margin at both corners; metatarsi shorter than tibiae; and the characteristic reduced-ray web architecture with only four radial threads reaching the hub. The eye arrangement—particularly the closely spaced posterior median eyes—is also diagnostic. Species-level identification requires examination of genitalia.

Mature spiders are extremely small, with body lengths of 0.5–2.5 mm. The carapace ranges from dark brown to light tan, sometimes with distinct markings around the eye region or fovea. The sternum is smooth with sparse bristles, usually darker toward the margin, and features a pit organ on the anterior margin at both corners. The abdomen is ovoid and taller than wide or long; the dorsal side often bears a light, thin median band and/or symmetrical light spots, while the ventral side is dark. The metatarsi of the legs are typically shorter than the tibiae. The tibiae of the 3rd and 4th legs bear groups of long, vibration-sensitive trichobothria. Sexual dimorphism is slight: males are similar to females in coloration but slightly smaller with proportionally longer legs. All eyes are approximately equal in size; the posterior median eyes are very close together, sometimes touching, separated by less than half their diameter, while the anterior median eyes are typically separated by around half their diameter.

Wet, shaded understories of forests. Spiders construct webs in dark, damp microhabitats, typically on vegetation in humid forest environments.

Global distribution across all continents except Antarctica. Documented from North America, Europe, Asia (including Russia, Korea, Japan, China, Taiwan, Sri Lanka, Malaysia, Indonesia, Singapore), Central and South America (Mexico to Brazil, Ecuador, Venezuela, Panama, Caribbean islands including Jamaica and Puerto Rico), Africa (Gabon, Angola, Kenya), and Oceania (Australia, New Zealand region including Samoa). Specific distribution varies by species; for example, T. gemmosum occurs in North America, Europe, Turkey, Caucasus, Iran, and Japan.

Active predators of small flying insects. Prey is captured using the slingshot web mechanism; specific prey taxa are not well documented but likely include small dipterans and other minute flying arthropods.

• egg sac parasitoids - parasitoidEgg sacs of T. gemmosum are subject to parasitoid attack; specific parasitoid taxa not identified in available sources

Egg sacs are produced and attached to vegetation. Development proceeds through spiderling stages to adulthood. Detailed life cycle timing and duration are not documented in available sources.

Constructs a vertical orb web with a highly modified architecture: radial threads are fused at the center so that only four 'rays' reach the hub. The spider holds these rays with its rear legs while grasping an anchor line with its front legs, pulling the web into a cone and maintaining tension. When prey approaches, the spider releases the tension, causing the web to slam into the prey at high speed—documented speeds exceed 4.1 m/s with accelerations exceeding 1300 m/s². The spider then bites and wraps the prey in silk. If the strike misses, the spider can reset the web trap. Web construction and hunting occur in dark, damp conditions; spiders may occupy the web hub during active hunting periods.

Predator of small flying insects in forest understory food webs. Serves as host for egg sac parasitoids. The unique slingshot predation mechanism represents a distinctive foraging strategy among orb-weaving spiders.

Minimal direct human relevance. One species (T. gemmosum) has been studied for its unusual mating behavior involving male silk transfer as a nuptial gift. The genus has attracted scientific and public attention due to the remarkable slingshot hunting behavior documented in online videos.

• NaatloAnother theridiosomatid genus with slingshot web behavior; Naatlo species have been observed using similar web-slingshot predation in Amazonian habitats, but differ in web architecture details and geographic distribution (primarily Neotropical)
• BaalzebubFormerly included species in Theridiosoma; transferred to Baalzebub based on distinct morphological features not specified in available sources
• AndastaFormerly included species in Theridiosoma; distinguished by morphological characteristics warranting separate generic status

• slingshot spider
• ray spider
• orb-weaver
• web-slingshot predation
• nuptial gift
• forest understory

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Theridiosomatidae Archives - Entomology Today
• Bug Eric: Bridge Orbweaver (Gray Cross Spider)
• Botanizing at Meramec State Park, Natural Wonders Trail | Beetles In The Bush
• Bug Eric: Aculepeira Orb Weavers
• How I Discovered a South American Slingshot Spider
• First record of Theridiosoma gemmosum (Araneae, Theridiosomatidae) in the Romanian fauna
• Who wins? Ray spiders (Theridiosoma gemmosum) (Araneae: Theridiosomatidae) versus egg sac parasitoids
• Mating behavior of Theridiosoma gemmosum (araneae: Theridiosomatidae): The unusual role of the male dragline silk
• The web-building behavior and predatory behavior of Theridiosoma epeiroides BÖSENBERG et STRAND (Araneae: Theridiosomatidae) and the origin of the ray-formed web
• Simonia gen. nov., a new spider genus (Araneae, Theridiosomatidae) from Southeast Asia.
• Two new species and a new genus of ray spiders (Araneae, Theridiosomatidae) from the Ryukyu Islands, southwest Japan, with notes on their natural history.