Mata Atlântica enchytraeids (Paraná, Brazil): A new genus, Xetadrilus gen. nov., with three new species, and four new species of Guaranidrilus Černosvitov (Enchytraeidae, Oligochaeta)

Abstract

Seven new species of terrestrial Enchytraeidae (Oligochaeta) are described from soils of the southern Brazilian Atlantic rain forest. They were found in the framework of the German-Brazilian project SOLOBIOMA, which studied rain forest recovery. Specimens were investigated in vivo and as stained whole mounts. Three species belong to a new genus, named Xetadrilus. Xetadrilus is similar to Guaranidrilus Č ernosvitov, 1937 and Tupidrilus Righi, 1974; it differs in the absence of lateral chaetae from segment VIII on and in peculiar structures of the prostomium: ganglia, inner papillae, and a frontal epithelial recess. Further peculiarities are small body size, absence of oesophageal appendages, and a variable pattern of pharyngeal glands. The three species are named X. maacki, X. aphanus, and X. fabryi. Three further nominal species are transferred to Xetadrilus: Marionina pituca Righi, 1974, Marionina righiana Xie & Rota, 2001, and Stercutus ugandensis Bell, 1954. The other four new species belong to Guaranidrilus, the species-richest genus at the sampling sites. They are named G. andreolii, G. marquesi, G. cingulatus, and G. hoeferi. All species have elongate transverse epidermal gland cells, three pairs of post-pharyngeal ganglia, and a dorsal vesicle in the nephridial postseptale. These traits may be included in the genus diagnosis. In all species described here, most of the species-specific taxonomic traits are found in non-reproductive structures, which means that specimens of all age groups can be identified to the species level, juveniles included.