ARACHNIDA > OPILIONES > Phalangiidae > Phalanginae

Platybunus triangularis, formerly Rileana triangularis (often still listed as such) is a medium-sized, long-legged harvestman with a prominent and robust ocularium.

The body colour is typically pale brown with lighter patches, coupled with a saddle that is more or less rectilinear in shape, but variable in both colour and contrast. In the males it is usually pale yellow-brown with no more than a vague outline. However, on the female it is typically well-defined with a clear outline. It generally has a strong contrast with the underlying body colour but, as is often the case, it can vary from one individual to another. Although broadly rectangular in shape it may widen slightly at the middle of the abdomen and possibly again at the end.

Body length varies, averaging little more than 4mm in the males, but usually around 6-7mm in the females. Legs are long, pale yellow-brown in colour with longitudinal rows of acute, inclined tubercles on the femora. The pedipalps are a similar colour with a prominent apophysis (natural protuberance) on the patella and lesser ones on the tibia and femur, which also have spine-tipped tubercles. The chelicerae are normal except that the male has a small, although prominent, apophysis, like a blunt tooth, on the distal segment. There is no trident as such, but there is a single small spine in the middle of a narrow dark longitudinal band that runs back to the ocularium.

But, it's the ocularium itself that helps to distinguish the species as it is both prominent and robust, being slightly wider than long with a deep and broad furrow down the middle, which narrows towards the front, and is armed either side with a row of between 7 to 10 very stout blunt tubercles. In juveniles, the ocularium can appear really huge relative to the body.

Platybunus triangularis is a reasonably common and widespread species that can be found in damp woodlands as well as a variety of other habitats as long as they're not too dry. Adults are more usually seen on low and mid-level vegetation, on bushes and tree trunks, rather than down on the ground in leaf-litter. They are one of the earliest species to appear, with adults starting to become active around April or May, which has resulted in the common name of the Spring Harvestman. They usually persist through to August, but with the greatest numbers occurring in May and June. Juveniles though can be found anytime from August on in leaf-litter, where they will overwinter as third or fourth instars right through to the following year.