Mud-nest harvestmen are a group of harvestmen (also known as daddy long-legs) belonging to the genus Quindina (family Nomoclastidae), which has only been found in Costa Rica, Panama, and Colombia. There are photographic records of two possible mud-nest harvestmen in Ecuador, but little is known about their taxonomy. Like other daddy long-legs, mud-nest harvestmen do not build webs, but males have a very interesting behavior: they build a nest using mud and decomposing organic material.
The structure and substrate where the nest is built vary from species to species. In the species present in Costa Rica and Panama, males build a nest in the shape of a circular fighting arena, also called cup-like mud nest, usually underneath rotten tree trunks, logs, or branches that fall onto the forest floor. These nests are visited by females that live in the vicinity who may copulate with the nest owner male and lay eggs that are entirely or partially buried in the nest floor. Nests are built exclusively by the male, who also actively cleans the interior of the nest (including the eggs) from fungus growth and actively repels potential predators that enter the nest to feed on the eggs —mostly cannibal individuals of the same species, but also ants, crickets, and flatworms. Males also constantly repair the nest floor and walls from damages caused mainly by the intense rainfall typical of the tropics. Males usually stay inside the same nest for several weeks or months, defending their nest from usurpation by other males that might steal their nest and eggs.
Quindina albomarginis is one of five species of arena-like mud-nest harvestmen. Individuals can be commonly found on Plantation Trail in Soberanía National Park near the Canopy Tower. Individuals are black and can be recognized by having a row of very small yellow dots ending with a yellow spine on each lateral margin of the dorsal scute. Next time you are on this trail, check out underneath fallen logs to find these incredible nests!