Micrathena sexspinosa

As with related species, M. sexspinosa shows considerable sexual dimorphism. Females are much larger than males, with total body lengths ranging from 7.7 to 11.8 mm, while males measure only 4.5 to 5.2 mm.The females have a distinctive abdomen with two pairs of slender dorsal spines, rarely with a smaller spine between them. The carapace measures 3.8 mm long and 2.7 mm wide in females. Males can be distinguished from other Micrathena species by their unique long, tubular paracymbium (a spur-like structure), which separates them from all other species in the genus. The male abdomen is trapezoidal with two posterolateral lobes, and the total length is approximately 5.2 mm with a carapace measuring 2.1 mm long and 1.9 mm wide. Both sexes show extreme variability in spine and fork development, often resembling the spination patterns of other endemic species within their geographic regions.

M. sexspinosa has a broad distribution range extending from Mexico through Central America to Brazil, including records from Colombia, Panama, Costa Rica, Nicaragua, Honduras, Guatemala, French Guiana, Suriname, Guyana, and Venezuela. In Brazil, it has been recorded from the states of Pará and Ceará.

The species name sexspinosa derives from Latin sex meaning "six" and spinosa meaning "spiny" or "thorny", referring to the characteristic six abdominal spines that distinguish this species.