Earthworm diversity in Rio Grande do Sul, Brazil

Abstract

The knowledge regarding earthworm species richness in subtropical Brazil is limited, particularly in the state of Rio Grande do Sul (RS), where only a few sites have been sampled. In this study we assessed earthworm richness in different ecosystems of RS, prioritizing un-sampled regions. Fifteen ecosystems, including native vegetation and other ecosystems with variable levels of disturbance were sampled in 30 counties in RS, totaling 77 sampling points, mainly in the Pampa biome. Qualitative sampling was performed by handsorting soil monoliths and fixing the earthworms in 4% formalin solution. Species identification was based on morphological characters, and species richness and Shannon (H) and McIntosh (U) diversity indices were calculated for each ecosystem. Twenty-one earthworm species were identified, belonging to seven families: Glossoscolecidae (8), Rhinodrilidae (2), Ocnerodrilidae (4), Megascolecidae (4), Acanthodrilidae (1), Lumbricidae (1) and Criodrilidae (1). From these, ten are new species belonging to the genera: Glossoscolex (6), Fimoscolex (1), Kerriona (1), Eukerria (1), and one aquatic species of the Criodrilidae family, belonging to a new genus. Most of the native species (Urobenus brasiliensis, Fimoscolex n.sp.1 and the Glossoscolex spp.) predominated in ecosystems little altered by human activity, while exotic (Amynthas gracilis, Amynthas rodericensis, Metaphire californica, Aporrectodea trapezoides) and peregrine species (Pontoscolex corethrurus) predominated in areas with more human disturbance. Native ecosystems with lower disturbance, particularly forests and native pastures had higher diversity than disturbed sites. This is the first record of A. rodericencis for Brazil and most sites represent new collection records for the known species in RS.

Earthworms (Clitellata, Megadrili) of the world: an updated checklist of valid species and families, with notes on their distribution

“…For now, Almidae are placed between Glossoscolecidae s.s. and Rhinodrilidae in molecular phylogenies; where Alma and Guarani are present in the same analysis, they are sister taxa (James & Davidson 2012;Anderson et al 2017). Will additional genera from South America (Steffen et al 2018;Ferreira et al 2023) change the picture? Preliminary indications say no.…”

At each site its diversity: DNA barcoding reveals remarkable earthworm diversity in neotropical rainforests of French Guiana

“…The mean observed diversity of 32.2 MOTUs (SD = 9.1), potential species, per location is one of the highest reported for earthworm communities in tropical forests. For comparison, 10 to 17 species have been reported at a similar spatial scale in the native forests of Santa Catarina and Rio Grande do Sul, Brazil (Bartz et al, 2014;Steffen et al, 2018), and in the Mexican tropical rainforest of Chiapas (Fragoso and Lavelle, 1987) using s traditional taxonomy approach. We also calculated a mean of 2.7 species (SD = 3.7) per sampling plots with the TSBF sampling method which seems to at least double what would be expected in this region according to the model used in Phillips et al (2019) (about 1 species in French Guiana / Northern Amazonia).…”