Argyrodes

Simon, 1864

Dewdrop Spiders

Argyrodes is a of -footed (Theridiidae) commonly known as dewdrop spiders. The genus contains approximately 85 distributed worldwide, with highest diversity in tropical regions. These spiders are best known for kleptoparasitism—living on the webs of larger -weaver spiders and feeding on small items that the ignores. Some species exhibit arachnophagy, preying upon host spiders or their when opportunities arise. The genus exhibits notable in structure, with males possessing modified used during copulation.

Argyrodes by (c) Peter Crowcroft, some rights reserved (CC BY), uploaded by Peter Crowcroft. Used under a CC-BY license.

Argyrodes by (c) pimelea, some rights reserved (CC BY), uploaded by pimelea. Used under a CC-BY license.

Pronunciation

How to pronounce Argyrodes: /ˌɑːr.d͡ʒɪˈroʊˌdiːz/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from other Theridiidae by the combination of: small size, conical/triangular body shape, shortened third pair of legs, and silvery markings. The kleptoparasitic lifestyle—found on webs of larger -weavers—is strongly indicative. Males can be identified by cephalic modifications (knobs, notches, ) on the . Two South African (A. stridulator and A. convivans) possess a consisting of two ridged oval on the that scrape against a ring on the . Distinguished from other kleptoparasitic by associations and morphological details; definitive identification often requires examination of male .

Images

Appearance

Most are small-bodied, ranging from approximately 2–12 mm in body length. Many species are black with distinctive silvery or metallic markings that give the its name (from Greek argyros, silver). The body has a characteristic conical or triangular shape, with the third pair of legs shorter than the others—a trait common in web-dwelling . Males exhibit pronounced prosomatic : the cephalic portion of the is modified with knobs, notches, or that are gripped by female during mating.

Habitat

Primarily found in tropical and subtropical regions. Occurs in diverse terrestrial where build webs. In North America, found in southern United States. In South America, commonly inhabits upper strands of colonial spider webs (e.g., Anelosimus eximius). Specific microhabitat is defined by host web architecture—typically occupies periphery of webs or upper strands of colonial webs, areas outside the host's typical range.

Distribution

Worldwide distribution with highest in tropics. Fifteen recorded in the United States, primarily in southern states: A. elevatus in southern US, A. nephilae in Florida, A. pluto in Maryland, Virginia, and Missouri (with reports south to Chihuahua and Jamaica). New records from Kerala, India. Present in Asia, South America, North America, Oceania, Africa, Caribbean, Canary Islands, and Saint Helena.

Diet

Kleptoparasitic: feeds on small items caught in webs that are ignored by the host , including tiny . Some feed on previously digested carcasses remaining on webs. Arachnophagous: preys upon host spiders, particularly during vulnerable periods such as molting, and may feed on host spider offspring. A. gibbosus has been observed feeding opportunistically on host -sacs when hosts disappear from webs. A. flavescens shows state-dependent prey preferences: well-fed individuals prefer houseflies over , while starved individuals prefer fruit flies; both well-fed and starved individuals prefer living prey over wrapped prey.

Host Associations

Nephila pilipes - Primary in Singapore; A. flavescens shows modified foraging in presence/absence of host
Nephila clavata - for A. flavescens and A. bonadea in Japan; documented between these Argyrodes
Cyrtophora citricola - for A. gibbosus in Sicily
Argiope appensa - for A. argentatus in Guam
Argiope aurantia - in North America
Anelosimus eximius - Colonial in South America; Argyrodes inhabit upper strands of large webs
Cyclosa - /Possible use as in colonial webs

Behavior

Kleptoparasitic: invades and resides in webs rather than building their own, though capable of web-spinning. Occupies periphery of host webs as from host . Foraging tactics are state-dependent: alters preferences based on hunger level, prey , and host presence. Multiple individuals often inhabit the same host web, with larger webs preferred. for space is strong; removal of individuals induces rapid . documented between A. flavescens and A. bonadea. Uses host webs for mating and sac placement. Some using specialized structures. A. flavipes exhibits social with parental care.

Ecological Role

that may function as commensal or mutualist: consumes too small for to , potentially reducing web maintenance costs for host. Silver coloration may attract additional prey (particularly ) to host webs, benefiting the host. However, negative impacts include: host show reduced weight gain and increased web relocation frequency when parasitized; some damage webs by eating or creating holes when removing prey. Acts as of host spiders and , potentially regulating host . Competes with and for limited web space.

Human Relevance

Subject of ecological research on kleptoparasitism, competition, and - relationships. Occasionally observed by naturalists and photographers on large webs. No documented economic importance or medical significance.

Similar Taxa

Other TheridiidaeArgyrodes distinguished by kleptoparasitic lifestyle, conical body shape, shortened third legs, and silvery markings; most Theridiidae build their own webs rather than parasitizing others
Other kleptoparasitic spiders (e.g., some Argyrodinae, other genera)Argyrodes is the best-known and most diverse kleptoparasitic ; distinguished by specific associations, morphological details, and geographic distribution

Misconceptions

Common misconception that Argyrodes steals large items from . Research has shown that Argyrodes rarely steals large prey, instead feeding primarily on small prey items that the host typically ignores. The relationship is more often commensal or mutualistic than purely parasitic, though on hosts does occur.

More Details

Sexual dimorphism and mating

Males possess a clypeal or acronal gland (discovered by André Lopez, 1974) whose secretion is contacted during copulation when females grip the male's modified cephalic structures with their .

Stridulation

Two South African (A. stridulator and A. convivans) possess a : two ridged oval on the that scrape against a ring on the .

Social species

A. flavipes from Queensland exhibits social and parental care, unusual for the .