Desidae

Intertidal desids can be recognized by their habitat and retreat construction—silk-sealed chambers in barnacle shells, coral crevices, or kelp holdfasts containing air bubbles. Inland genera such as Badumna construct tangled sheet webs with tubular retreats, often incorporating debris. The family lacks unifying somatic synapomorphies visible without dissection; definitive identification requires examination of genitalic structures, particularly male pedipalps and female epigyna. Subfamily Cedicinae (including Paracedicus) is distinguished by specific genitalic characters including patellar apophyses and epigynal fovea morphology.

Habitats span three distinct categories: (1) marine intertidal zones, where species occupy rocky shores, coral reefs, and kelp beds from high to low tide marks; (2) inland terrestrial environments including sclerophyll forests, semi-arid oak forests, and xeric regions; and (3) synanthropic habitats, where invasive species occupy urban structures, window frames, and cemeteries. Intertidal species require substrates providing shelter from wave action and the ability to retain air during submersion—barnacle shells, coral cavities, and kelp holdfasts are primary nesting substrates.

Native range centered in Australasia and South America, with Australia, New Zealand, and New Caledonia containing the vast majority of genera. South American representation includes Chilean endemic radiations. The family extends north to Malaysia and includes western Palaearctic elements (Turkey, Middle East). Introduced populations established through human-mediated dispersal: Metaltella simoni in the southern United States (California, Louisiana, Mississippi, Florida), Badumna longinqua in Argentina, Uruguay, Brazil, Germany, Japan, New Zealand, and the United States.

Activity patterns vary by habitat. Intertidal species forage nocturnally during low tide exposure. In temperate regions, Phryganoporus candidus nests are founded October–February, with peak growth in October and dispersal of subadults in summer (December–February), leaving nests moribund by March. Desis marina shows reproductive seasonality with egg laying September–January and emergence complete by May; females are reproductively inactive June–August. Juvenile recruitment in D. marina occurs February–May with maturation in 4–5 months.

Intertidal species feed on small arthropods inhabiting the intertidal zone, captured when foraging on exposed rock, coral, and plant surfaces at night. Inland sheet-web spiders are generalist predators capturing flying and crawling insects in their webs. Specific prey records are sparse; diet composition varies by habitat and species.

• Durvillaea antarctica - habitatKelp holdfasts used as nest substrate by Desis marina; spiders occupy holdfasts from +20 to -77 cm below Mean Sea Level
• Echthrodesis lamorali - parasitoidHymenopteran egg parasitoid of Desis formidabilis; endemic to Cape Peninsula, South Africa; parasitoid activity recorded in 43% of nests and 14% of egg sacs
• Zizyphus mauritiana - habitatPrimary host plant for Phryganoporus candidus nests in Queensland, Australia
• Dolichondrone heterophylla - habitatHost plant for Phryganoporus candidus nests

Developmental patterns documented for several species. Desis marina: eggs develop over two months, first two instars remain in nest two additional months; juveniles recruit February–May, mature in 4–5 months, and may live 12–18 months longer; females grow larger than males. Phryganoporus candidus: solitary subadult female founds nest October–February as chambered silk funnel; nest enlarged by female and progeny; 31% of new-founded nests reach stage with thriving spiderlings; nest sizes range 70–20,000+ cm² with 9–224 spiders; only 12% reach peak growth stage with ~90 spiders. Moulting increment (Dyar's Constant) in D. marina is 17.2%, decreasing with size.

Intertidal species exhibit specialized behaviors for surviving marine conditions: sealing retreats with silk to maintain air bubbles during high tide submersion, emerging only at low tide to forage. Nocturnal activity predominates in both intertidal and inland species. Male-male contests occur in sheet-web spiders; in Cambridgea plagiata, males use exaggerated chelicerae in physical contests for female access, with body size determining contest outcome. Contest duration patterns suggest mutual or cumulative assessment models. Phryganoporus candidus shows social behavior with cooperative nest construction and maintenance; adjacent nests may unite capture webbing into compound structures. Badumna insignis exhibits risk-sensitive foraging: diurnal retreat confinement reduces predation risk but compromises foraging success, while nocturnal exposed positioning at retreat edge improves prey capture but increases vulnerability.

Intertidal species function as predators in rocky shore and coral reef communities, contributing to arthropod population regulation in these habitats. Invasive synanthropic species may impact native spider communities; Metaltella simoni is suspected to threaten native titanoecid species Titanoeca brunnea in the southern United States. Social species in arid Australian habitats may influence local insect community structure through extensive web-building.

Several species have become notable synanthropic invasives. Badumna longinqua (grey house spider) and B. insignis (black house spider) are common in Australian and introduced-region buildings; their webs are considered nuisances in window frames and eaves. Metaltella simoni (grey house spider) established in the southern United States, with potential competitive impacts on native spiders. The family includes species of conservation interest: Echthrodesis lamorali, the only known parasitoid of intertidal spider eggs, is endemic to the Cape Peninsula and entirely dependent on Desis formidabilis, with its full distribution within Table Mountain National Park.

• AmphinectidaeMerged into Desidae in 2017; previously recognized as separate family of intertidal and terrestrial spiders from Australasia and South America
• ToxopidaeSeparated from Desidae in 2017; previously included within Desidae, now treated as distinct family
• TitanoecidaeNative North American family potentially impacted by invasive Desidae (Metaltella simoni); similar in occupying rocky habitats and constructing sheet webs

• intertidal
• marine spider
• sheet-web
• social spider
• invasive
• synanthropic
• Australasia
• South America
• kelp-associated
• coral reef

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Evolutionary Systematics | Blog - Part 5
• A new species of Paracedicus Fet, 1993 (Araneae, Desidae) from Turkey
• The taxonomy and distribution of the spider genus Phryganoporus Simon (Araneae: Amaurobioidea: Desidae)
• Contests between male New Zealand sheet‐web spiders, Cambridgea plagiata (Araneae: Desidae)
• Sexual behavior of Metaltella iheringi (Keyserling, 1891) (Araneae: Desidae): sexual patterns, female quiescence and comparisons with other spiders
• Nest of the Social Spider Phryganoporus-Candidus (Araneae, Desidae) - Structure, Annual Growth-Cycle and Host-Plant Relationships
• Foraging behaviour and the risk of predation in the black house spider, Badumna insignis (Desidae)
• Reuniting males and females: redescriptions of Nuisiana arboris (Marples 1959) and Cambridgea reinga Forster & Wilton 1973 (Araneae: Desidae, Stiphidiidae)
• First records of the invasive spider Badumna longinqua (L. Koch) (Desidae) in southern Brazil with notes on the habitats and the species’ dispersion
• The invasive spider Badumna longinqua (L. Koch, 1867) (Araneae: Desidae) in Argentina: new distributional records, with notes on its expansion and establishment
• Reproductive biology of the intertidal spider Desis marina (Araneae: Desidae) on a New Zealand rocky shore
• Population structure and use of Durvillaea antarctica holdfasts by the intertidal spider Desis marina (Araneae: Desidae)
• Natural history and ecology of the New Zealand sheet-web spiders Cambridgea plagiata and C. foliata (Araneae: Desidae)
• Introduction, distribution and habitats of the invasive spiderBadumna longinqua(L. Koch, 1867) (Araneae: Desidae) in Uruguay, with notes on its world dispersion
• Nest site choice by the intertidal spider Desis formidabilis (Araneae: Desidae) and nest utilisation by its hymenopteran egg parasitoid
• A revision of the genus Porteria and the phylogeny and biogeography of Porteriinae (Araneae: Desidae)