"theridiosoma gemmosum" is a small spider. females are 2–3 mm long, males smaller still at 1.5–2 mm. in both sexes, the carapace (upper surface of the cephalothorax) is dark brown; the upper surface of the abdomen (opisthosoma) is silvery with variable dark lines and marks. the abdomen is globular, more or less circular from above. the male palpal bulbs and the female epigyne are distinctive.