Armadillidium nasatum

CRUSTACEA > MALACOSTRACA > ISOPODA > Oniscidea > Crinocheta > Armadillidiidae

Although superficially similar, Armadillidium nasatum has some particular features that enable it to be easily distinguished from other members of the genus such as Armadillidium vulgare and Armadillidium depressum. The most visually obvious is the size and shape of the scutellum which, rather than being broad and only slightly or moderately raised as in its two more-common relatives, is narrow and distinctly raised appearing as a 'snout-like' projection when seen from the right angle, often likened to being reminiscent of the peak of a baseball cap. The second is that the telson is noticeably long and pointed to a rounded tip rather than truncated. And finally, if it is found curled up it won't be in a tight, fully enclosed ball like Armadillidium vulgare or the slightly open sphere in the way that Armadillidium depressum rests, but more of a flattened ball with its 'nose' remaining visible and its antennae protruding.

Armadillidium nasatum is also a fair bit smaller with a body length of around 12mm. The typical form is described as being dark grey with pale longitudinal stripes down the back, but darker individuals are not uncommon and brown specimens like the one featured below may occasionally be found.

The species has scattered distribution across southern and central areas, but over recent years is spreading northwards. Many of the more northern records though are coming from garden centres where it appears to be particularly prevalent, but from around my local area here in the south it also occurs in more natural habitats. It is particularly associated with dry, sparsely vegetated sites that are exposed to the sun and, from current records, more likely to be seen closer to the coast than further inland. The best places to search would be under rocks, stones, deadwood or other ground-laying debris on calcareous grasslands, waste ground, limestone screes and in old quarries.

New species added, Sept.26 (v.1)