Earthworm biodiversity in Morocco: First survey of earthworm richness, diversity and distribution in the Souss-Massa region

Although earthworms are the key drivers of most valuable ecosystem services and the main indicators of soil health, the existing ecotypes in Moroccan soils are largely unknown. The lack of records for many regions and limited data for others is a major obstacle to making the most of earthworms in sustaining the key ecosystem services they provide. This study investigates, for the first time, the earthworm biodiversity in cultivated soils in 4 irrigated perimeters of the arid region of Souss-Massa. Soil pits (25 x 25 x 30cm, n = 5) at 40 sampling sites were examined by digging, hand-sorting, and using a chemical expellant solution. From the 200 pits dug, 418 adult earthworms and 1182 juveniles were collected. Five new regional records of earthworms, namely Aporrectodea caliginosa, Aporrectodea longa, Aporrectodea rosea, Eiseniella tetraedra, and Microscolex dubius, were identified. A. longa was identified as a new species record for the earthworm fauna of Morocco raising the numbers from 13 declared species to 14. Most earthworms (60 %) were endogeic species in the majority of sampled sites. The occurrence of A. rosea (50% of sampled sites) and A. caliginosa (48% of sampled sites) reflects their frequent detection in the study area. Our results indicate that earthworms do exist in arid and semi-arid climates at significant densities, particularly along the crop rows where the drip irrigation laterals lie.