The Aestivation Chamber of the Giant Earthworm Glossoscolex bergi (Glossoscolecidae) in the Subtropical Rainforest of Misiones (Argentina)

Glossoscolex bergi (Glossoscolecidae) is a giant earthworm from the rainforest of Misiones (Argentina). The large size of its aestivation chamber and the meniscate burrows connected to it allow us to describe morphological details and reinterpret some characteristics of the fossil counterpart Castrichnus incolumis. The concavity of menisci, either in the burrow or in those pellets lining the chamber, shows concentric ridges and radiating striae that result from the impression of the last segments of the body. The meniscate burrows associated to the chamber are different from described ichnospecies of Taenidium, because of the surface texture of the meniscus. The aestivation chamber was produced during an atypical four-month drought in a region that lacks a seasonal climate. This suggests that Castrichnus incolumis would be also an indicator of drought periods even in non seasonal climates.