Selenops aissus
Walckenaer, 1837
Selenops aissus is a of wall crab spider in the Selenopidae, commonly known as a "flattie." It occurs in the Caribbean region, including the Bahamas, Cuba, and the Bahama Islands. Like other members of its , it exhibits the characteristic extremely flattened body and laterigrade legs that allow it to slip into narrow crevices. The species was described by Walckenaer in 1837.
Pronunciation
How to pronounce Selenops aissus: /sɛˈlɛnɒps ˈaɪsʊs/
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Identification
Distinguished from similar-appearing philodromid crab spiders ( Philodromidae) by leg proportions: Selenops has legs increasingly longer from front to back, whereas Philodromus has the second pair of legs longest. The six in one row is a distinctive feature. The rear edge of the sternum is notched, a diagnostic character requiring examination of the surface. Extremely flattened body profile separates it from most other spider families.
Appearance
Extremely flattened body with laterigrade legs oriented almost horizontally to the body. Legs increase in length from front to back. Six of the eight arranged in a single row across the , with the remaining two eyes set back on either side. Mottled gray, brown, or yellowish coloration provides camouflage against rock and bark surfaces. Body length approximately 7.5–13 millimeters in .
Habitat
Occupies narrow cracks and crevices in vertical surfaces including rock , tree trunks, and building walls. Hides during the day in tight spaces under stones, beneath bark, or between leaf bases of dense vegetation. Active on vertical surfaces at night.
Distribution
Caribbean region: Bahamas, Cuba, and Bahama Islands. Records from USA likely refer to specimens from Florida or other southeastern states where related Selenops occur.
Behavior
hunter that waits in ambush for prey on vertical surfaces. When disturbed, capable of rapid sprinting. Can slip into extremely narrow cracks due to flattened body .
Human Relevance
Occasionally encountered on building walls and in homes in its range. Not considered dangerously venomous to humans.
Similar Taxa
- Selenops actophilusAnother Selenops with similar flattened ; occurs in southwestern USA and Mexico, overlapping in general appearance and use
- Philodromus spp.Running crab spiders in Philodromidae resemble flatties superficially but have second pair of legs longest rather than legs increasing in length posteriorly
- Selenops radiatusCongeneric Caribbean with similar and preferences
More Details
Taxonomic note
Selenops aissus is one of approximately five Selenops recorded north of Mexico, though the contains additional species in the Neotropics. Species-level identification within Selenops typically requires examination of genitalic structures.