Male (on the left) and female Linyphia triangularis. Note the male's large fangs on the bottom photo.Unfortunately, I seemed to have disturbed them and the male retreated, so I didn't see the end of the interaction. Field experiments carried out by Nielsen and Toft showed that male L. triangularis use what are known as 'alternative mating tactics'. Males guard subadult females just prior to their final molt in order to access them while they are still virgin, possibly due to a strong sperm preference which results in males mating with a virgin female fathering most of the female's subsequent offspring. These researchers took advantage of this behaviour and took 56 males and paired them with females in the field. Once this relationship was established they introduced an 'intruder' and recorded what happened up to the point when the female was mated. In 64% of the cases, the males resolved the dispute about the female by fighting using their large chelicerae. Larger males are better at winning these direct conflicts. But in 36% of cases, males used a different strategy called 'interference'. After losing a fight, they hang around and 'distract' the courting pair trying to chase the winning male away from the web. They actually succeeded and mated the female first in 7 occasions (12% of all conflicts) showing that this strategy - which is adopted by small males - can pay off. Additional observations suggest that smaller males hang around and try and mate with the female (not virgin at this stage) probably winning some residual paternity in the process.
S. Funke and B. A. Huber (2005). Allometry of Genitalia and Fighting Structures in Linyphia triangularis (Araneae, Linyphiidae) Journal of Arachnology, 870-872 DOI: 10.1636/S04-16.1
Nielsen, N and Toft, S (1990). Alternative male mating strategies in Linyphia triangularis (Araneae, Linyphiidae). Acta Zoologica Fennica