Sea-green Northern Jumper (Cosmophasis thalassina)

Cosmophasis thalassina is a species of jumping spider in the family Salticidae, tribe Chrysillini (Suborder Araneomorphae, Order Araneae). It is an Old World tropical species, recorded primarily from Southeast Asia, where it inhabits forested and semi-open habitats.

This species is a diurnal, visually oriented predator, relying on keen eyesight and agile jumping to capture small insects. Like other salticids, C. thalassina does not construct prey-capture webs, instead actively stalking prey on foliage, shrubs, tree trunks, and low vegetation.

Morphologically, Cosmophasis thalassina is noted for its metallic and iridescent coloration, a hallmark of the genus Cosmophasis. The body often displays shimmering green, bluish, or bronze tones that change with the angle of light. The carapace is moderately high with a smooth surface, while the abdomen is oval and may bear subtle patterning or reflective scales. Legs are relatively slender and adapted for jumping and agile movement.

The eyes are arranged in the typical salticid pattern, with large anterior median eyes providing high-resolution vision. Males and females may differ slightly in coloration intensity and pattern, with males often showing more vivid iridescence used in courtship displays.

Male genitalia possess species-specific palpal structures that distinguish C. thalassina from closely related species, particularly in the form of the embolus and tegulum. Females have a well-developed epigyne with paired copulatory openings and internal ducts characteristic of the genus.

Behaviorally, Cosmophasis thalassina exhibits visual courtship displays, including body orientation, leg movements, and subtle posturing directed toward females. When threatened, individuals typically rely on rapid movement or short jumps rather than retreating into silk shelters.

Ecologically, C. thalassina plays a role as an active predator of small arthropods within tropical ecosystems. Its striking coloration, agile behavior, and refined visual communication make it a representative example of the diverse and visually elaborate jumping spiders of Southeast Asia.