Belongs to a group of highly specialized arachnids characterized by a compact, robust body where the prosoma and opisthosoma are fused into a rigid dorsal scutum. This species displays conspicuous sexual dimorphism. Males feature significantly enlarged, curved hind legs, particularly the femur IV, which is adorned with prominent spines and apophyses used during territorial defense and courtship combats, whereas females possess much more slender and unarmed appendages. The general coloration of the body ranges from dark brown to deep black, highlighted by bright yellow or whitish tubercles and granules distributed across the dorsal surface, which function as warning signals or camouflage. Body length varies between 8 and 12 millimeters, although the total leg span can easily reach up to 5 centimeters.

Geographical distribution: Occurs primarily within the southern cone of South America. Its range is well-documented throughout Uruguay, eastern and central provinces of Argentina (including Buenos Aires, Entre Ríos, and Santa Fe), and the state of Rio Grande do Sul in southern Brazil. It is an exceedingly common arachnid in regions surrounding the Río de la Plata basin.

Habitat: Thrives in humid, shaded microhabitats found in temperate forests, gallery forests, grasslands, and human-modified areas such as urban gardens and suburban parks. It is regularly encountered seeking shelter beneath large rocks, fallen logs, decaying tree bark, and dense leaf litter, which collectively offer the high moisture levels essential to prevent desiccation.

Feeding: Exhibits omnivorous and generalist feeding habits, acting as an opportunistic predator of small invertebrates as well as a scavenger of organic debris. Its diet includes small insects, woodlice, terrestrial snails, earthworms, and decaying animal matter, all of which are seized and manipulated using its claw-like, raptorial pedipalps.

Behavior: Displays strictly nocturnal activity patterns to minimize hydric stress and evade diurnal predators like birds and small mammals. During the day, individuals often form dense, multi-individual aggregations within communal shelters, a gregarious behavior that effectively reduces water loss via evaporation. When threatened, it employs passive defense mechanisms such as thanatosis (playing dead) or discharges noxious chemical secretions from repugnatorial glands located on the sides of its prosoma.

Reproduction: Involves a complex mating system followed by remarkable maternal care. After successful copulation, the female selects protected niches on the undersides of rocks or logs to deposit clutches of eggs bound together by an adhesive secretion. The female actively guards these clutches against potential predators, such as ants and other harvestmen, remaining with them until the nymphs hatch, which significantly boosts offspring survival rates.

Conservation status: Has not been formally evaluated by the IUCN Red List due to its high local abundance and adaptability to anthropogenic environments. Nevertheless, local populations are susceptible to localized declines driven by intensive urbanization, widespread use of chemical pesticides in domestic gardens, and the loss of shelter-providing microhabitats.