Cithaeronidae

Distinguished from other gnaphosoid families by the combination of depressed posterior median eyes and pseudosegmented tarsi. The compact eye arrangement may superficially resemble juvenile Kukulcania hibernalis (Southern House Spider) or small Loxosceles species (recluse spiders), but Cithaeronidae lack the violin-shaped marking of Loxosceles. Active nocturnal hunting behavior and silken retreat construction under rocks are field indicators. Definitive identification requires examination of eye and tarsal structure.

Small spiders with compact bodies. Females of Cithaeron measure 5–7 mm in length, males approximately 4 mm. Body coloration is pale yellowish. The family is characterized by depressed posterior median eyes and pseudosegmented tarsi—traits diagnostic among lower gnaphosoids. Eye arrangement is compact, potentially causing confusion with other small spiders.

Native populations occupy very hot, dry stony places, constructing silken retreats beneath rocks. Introduced populations have established in synanthropic environments including human housings, suburban areas, and urban structures in Florida, Brazil, and Australia.

Genus Inthaeron is endemic to India. Genus Cithaeron occurs in Africa, India, and parts of Eurasia. Cithaeron praedonius has been introduced to Brazil (Piauí, Rio Grande do Sul), Australia (Northern Territory), and the United States (Florida), where breeding populations are established. Cithaeron reimoseri has been recorded from Eritrea and Brazil (Porto Alegre).

Activity patterns are primarily nocturnal. In Florida, observations cluster during winter months (December–February), though this may reflect detection bias rather than true seasonality.

Active predators that hunt without webs. Cithaeron praedonius has been observed feeding on native cobweb weavers and juvenile Latrodectus geometricus (Brown Widow spiders) in captivity; may be a specialized spider predator.

Females produce flat, round egg sacs. Spiders of various ages have been observed in introduced populations, indicating established breeding. Each individual constructs a silken nest for molting and resting.

Nocturnal hunters that actively pursue prey on foot rather than building capture webs. Diurnal retreat in silken shelters constructed under rocks or in crevices. Fast-moving and nomadic. Dispenses with silk except for retreat construction and molting chambers.

Predator, potentially specializing on other spiders. Role in native ecosystems poorly documented; in introduced ranges, may impact native spider communities through predation.

Accidentally introduced to multiple continents via human commerce and travel. Established breeding population in Florida since at least 2011, with records from multiple counties. Frequently mistaken for medically significant spiders (Loxosceles species) due to superficial resemblance, causing unnecessary concern. Not dangerously venomous to humans or pets. Documented through citizen science platforms (BugGuide, iNaturalist, Arachnoboards), demonstrating value of public engagement in detecting non-native species.

• Loxosceles spp. (recluse spiders)Compact eye arrangement and pale coloration cause superficial resemblance; distinguished by lack of violin-shaped cephalic marking and diagnostic eye/tarsal characters
• Kukulcania hibernalis (Southern House Spider)Juvenile males may resemble Cithaeron in size and eye arrangement; distinguished by tarsal structure and behavioral differences

Frequently mistaken for Brown Recluse spiders (Loxosceles reclusa) due to pale coloration and compact eye arrangement, leading to unwarranted medical concern. Not medically significant.

• spider
• arachnid
• ground spider
• gnaphosoid
• nocturnal
• introduced species
• synanthropic
• Florida
• invasive

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Bug Eric: Spider Sunday: Foreign Spider Now in Florida
• First record of Cithaeron reimoseri (Araneae: Cithaeronidae) from the New World and first record of the family from southern Brazil