Three new species of Hemienchytraeus (Enchytraeidae, Oligochaeta) from Amazonian forest soil

This dataset contains the digitized treatments in Plazi based on the original journal article Schmelz, R. M., Römbke, J. (2005): Three new species of Hemienchytraeus (Enchytraeidae, Oligochaeta) from Amazonian forest soil. Journal of Natural History 39: 2967-2986, URL: http://www.tandfonline.com/doi/full/10.1080/00222930500218664AbstractThe species diversity of tropical enchytraeids is still largely unexplored, although knowledge of them is a desideratum regarding the potential of species-related data as biological soil quality indicators. Here we describe three new species of the mainly terrestrial enchytraeid oligochaete genus Hemienchytraeus from a primary rain forest plot at the Brazilian Agroforestry Research Facility close to Manaus, Brazil (EMBRAPA-CPAA: Empresa Brasileira de Pesquisa Agropecuaria, Centro de Pesquisa Agroflorestal na Amazonia Ocidental). Hemienchytraeus siljae, H. patricii, and H. tanjae spp. nov. were discovered in a study of soil fauna and litter decomposition in the framework of a project series that was aimed at developing methods for sustainable land use in Amazonian rain forests (SHIFT ENV 52: Studies on Human Impact on Floodplains and Forests in the Tropics). The specimens were investigated alive and as stained whole mounts. The detailed descriptions cover almost the entire light-microscopical anatomy of the animals, following results achieved with other enchytraeid genera where it has been demonstrated that taxonomical difficulties in Enchytraeidae can be overcome by more detailed descriptions. The three new species differ among each other in at least 16 different traits. Most notable are: (1) the size difference of chaetae in terminal and preclitellar segments; (2) the branching pattern of the oesophageal appendage; (3) the number and location of secondary pharyngeal gland lobes; (4) the number and location of preclitellar nephridia; and (5) the distribution pattern of clitellar gland cells, especially on the ventral side. About half of the differentiating characters are non-sexual, which increases the possibility of identifying juvenile specimens to the species level-an important point for ecological studies. Most similar to H. siljae and H. patricii is H. stephensoni and most similar to H. tanjae is H. bifurcatus. The comparison of these species is made difficult by the poor original descriptions of H. bifurcatus and H. stephensoni and by an apparent overestimation of their intraspecific morphological variability in following accounts. Hemienchytraeus tanjae is distinguished from H. bifurcatus in coelomocyte size and texture, in the shape of the brain and in the absence of nephridial terminal vesicles. Furthermore, H. bifurcatus is considered as species inquirenda, due to the lack of important details in the original description and to the loss of type material. A literature-based distinction of H. siljae and H. patricii from H. stephensoni remains inconclusive; type specimens of H. stephensoni (syntype specimens of the nominal species Enchytraeus cavicola, E. myrmecophilus and E. rangoonensis), however, differ clearly from H. siljae and H. patricii by a ventrally fully developed clitellum and by strongly thickened preclitellar septa, among other characters.Keywords: Brazil, Enchytraeidae, new species, Oligochaeta, soil biology, South America, species diversity, taxonomy, tropics