Diversity and distribution of earthworm (Annelida: Oligochaeta) in Southeastern Vietnam

Abstract

On analysing 8,114 individuals of earthworms collected at 263 sampling points from 2016 to 2021 and from previous studies, 44 species of 12 genera and six families of earthworms recorded in the Southeastern Vietnam. Among them, the family Megascolecidae dominates with 37 species (accounting for 84.09%), the Moniligastridae and Octochaetidae have two species each, and the remaining families Almidae, Rhinodrilidae, and Ocnerodrilidae each have one species. The genus Metaphire has 21 species, dominant over the rest, followed by Amynthas (eight species) and Polypheretima (five species). The earthworm fauna in the Southeastern region (H' = 3.93) has a higher species diversity than in the Mekong Delta (H' from 1.79 to 3.49) with Pontoscolex corethrurus being the species dominated in the number of individuals while Amynthas polychaetiferus was the dominant species in terms of biomass. The species diversity of earthworms appears to decrease with altitude from the hills to the plain landscape. The alluvial soil group has the highest species diversity, to gray soil, and the lowest is the ferralsols soil group. Short-term crops are most diverse group, followed by forests, perennial crops, and wastelands.