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The purpose of this application, under Articles 23.2 and 23.9.3 of the Code, is to conserve the usage of the genus-group name Cognettia Nielsen & Christensen, 1959 (enchytraeidae, Oligochaeta, Annelida) for a genus of annelid worms (type species Pachydrilus sphagnetorum Vejdovský, 1878 (‘1877’)). Cognettia, a name for a Holarctic genus of terrestrial and semi-aquatic annelid worms, is threatened by two subjective senior synonyms, Euenchytraeus Bretscher, 1906 and Chamaedrilus Friend, 1913. If these two names are considered synonyms, Euenchytraeus will replace Cognettia; if they are considered to represent two different genera, Chamaedrilus will replace Cognettia. In 2015 Martinsson et al. adopted the latter course, replacing Cognettia by Chamaedrilus, and allocated its species between both Euenchytraeus and Chamaedrilus. Cognettia is a widely used name and is well-known in the fields of soil biology, ecology, and ecotoxicology, and we propose it be given precedence over Chamaedrilus and Euenchyt...

This article reviews the current knowledge on terrestrial enchytraeid diversity in Latin America and it outlines the research potential that this group offers. Enchytraeids occur worldwide in all soils with sufficient moisture, oxygen and nutrient supply, but knowledge on their diversity and functioning in the tropics is practically non-existent, except in Latin America. Here, taxonomic efforts and research projects have led to the knowledge of currently 62 terrestrial or semi-aquatic species. Abundance of enchytraeids could be determined at the species level, and differences in the ecological behaviour of species were detected concerning factors such as soil type and land use. Especially South America harbours a rich and idiosyncratic enchytraeid fauna, dominated by genera or species absent or rare in other regions of the world, which is interesting from the phylogenetic point of view. However, only a minute fraction of the actual diversity is known to-date. Seventeen species are possibly peregrines. Densities appear to be comparable to those in temperate regions, from below 10,000 to 270,000 ind. m−2, suggesting that enchytraeids may be as important for soil processes as in temperate regions. Site-specific species richness makes enchytraeids good biological indicators. Enchytraeids provide a widely open field for research in Latin America ranging from taxonomy and faunistics over biogeography, phylogenetics, comparative morphology, and developmental biology, to fundamental and applied ecology. The widespread ignorance concerning enchytraeids among scientists and naturalists as well as the current taxonomic impediment should be overcome by sound taxonomical and ecological work, training courses, identification manuals and popularization.

Five new species of terrestrial Enchytraeidae (Oligochaeta, Clitellata) are described from an experimental field area in Portugal. Achaeta coimbrensis sp. nov. belongs to a group of species without pyriform glands and with lateral spermathecal ectal pores. Fridericia sousai sp. nov., F. roembkei sp. nov., F. marginata sp. nov., and F. ciliotheca sp. nov. have a maximum of four chaetae per bundle and two spermathecal diverticula, a character combination shared by c. 30 other species of this genus. The new Fridericia species are distinguished from these congeners by combinations of characters, but the ventral pattern of the clitellum alone is sufficient to separate the new species from each other. Enchylea heteroducta Nielsen & Christensen, 1963 is redescribed, this being the first record after the original description and the first record from a natural habitat. Further 16 species of enchytraeids are recorded, and there are now 32 species of enchytraeids known from Portugal.

Phytotelmata, or plant-held water bodies, often house complex aquatic invertebrate communities. Microdrile oligochaetes (Clitellata, Annelida) are known to be part of that community, but specimens are rarely identified to species level. Here we report three species of Enchytraeidae and three species of Naididae from a collection sampled in phytotelms of bromeliads in Cusuco National Park, Honduras. Two species of enchytraeids are new to science. Bryodrilus hondurensis sp. nov. is distinguished from other members of the genus by the high number of ventral chaetae, up to 11 per bundle. The genus is Holarctic and this is the southernmost record so far of a Bryodrilus species. Hemienchytraeus phytotelmatus sp. nov. is distinguished by a combination of characters, among which the huge spermathecae and seminal vesicles are most conspicuous. The genus is common in tropical and subtropical soils around the world. A third species of enchytraeids in the collection, Cernosvitoviella atrata (Bretscher), is redescribed, together with three known species of Naididae, Pristina jenkinae (Stephenson), Pristina osborni (Walton) and Pristina terrena ColladoSchmelz. Presence of ingested debris and humus in the intestine of most specimens suggests that the collected animals live and reproduce in the phytotelms. We provide a list of oligochaete species recorded so far from bromeliad pools in Central and South America.

A new species of Fridericia (Enchytraeidae, Oligochaeta) is described from soils in Ireland. It was found during sampling campaigns in the framework of a comprehensive taxonomic revision of the genus ( Schmelz, 2003. Taxonomy of Fridericia (Oligochaeta, Enchytraeidae). Revision of species with morphological and biochemical methods. Abh. Naturw. Ver. Hamburg, N.F. 38, 1–415, figs. 1–73 ), but it was not included in that study. Fridericia larix sp. nov., named in reference to the type locality, belongs to the large and taxonomically difficult group of species with two diverticula per spermatheca. It is distinguished from all known congeners by the following combination of characters: (1) a maximum of four chaetae in ventral preclitellar bundles; (2) oesophageal appendages poorly branched; (3) no pharyngeal glands in segment VII; (4) coelomocytes without refractile vesicles; (5) clitellum girdle-shaped, cell distribution alike on all sides; (6) bursal slit of male copulatory organ mainly transverse; (7) no subneural glands; (8) spermathecal diverticula not stalked. Further distinguishing characters are: (9) an asymmetrical arrangement of chaetae in the first lateral postclitellar bundles, with one large chaeta and one small chaeta per bundle (Fig. 1b, “lc XVI”); (10) the length ratio of spermatozoa to spermatozoal nuclei (6:1–7:1); and (11) a wavy inner surface in parts of the epithelium of the spermathecal ampulla (Fig. 1i, arrow). See also Electronic Supplement at: http://www.senckenberg.de/odes/05-05.htm

Populations of Enchytraeus that reproduce by fragmentation are distributed worldwide, but their species-level taxonomy is unresolved because morphological differences are inconclusive. Therefore, we compared the isozyme and RAPD-PCR patterns of 5 populations of fragmenting enchytraeids from widely distant localities (Japan, Iran, Greece, and Brazil). Among these populations, 3 were identified (E. japonensis, E. bigeminus, and E. dudichi) and 2 were unidentified. Multiple isozyme bands suggested polyploidy in all investigated populations. In all RAPD-PCR algorithms except 1, the fragmenting group formed a cluster separate from 2 nonfragmenting Enchytraeus species. All 5 populations were clearly separable on the levels of protein and DNA, but the unidentified Greek populations clustered more closely with E. japonensis. It remains unknown whether the fragmenting group in Enchytraeus is monophyletic or polyphyletic. Although every investigated population may deserve species rank, a consistent classification is impossible at present.

We investigated the effect of contrasting trophic conditions on the distribution and dominance patterns of Oligochaeta species assemblages in lake sediments and their relation to the environmental variables depth, season, and substrate. The study was performed on the highly eutrophic Lake Haussee and the oligotrophic Lake Stechlin, both hardwater lakes in the Baltic Lake District of Northern Germany. Quantitative monthly and seasonal sampling took place over one year at 14 representative sites, covering littoral and profundal sediments of both lakes. Between-lake differences in the profundal were clearcut with an absence of any zoobenthos in Lake Haussee and a peculiar meiobenthic species assemblage in Lake Stechlin ( Collado et al. 1999). Between-lake differences in the littoral, however, were small and mainly attributable to a small number of species exclusive to Lake Stechlin and an overall higher abundance of oligochaetes, especially naidids, in Lake Haussee. Species-richest family in both lakes were Naididae; Tubificidae were dominant in Lake Stechlin; in Lake Haussee Tubificidae and Naididae were equally abundant. Most striking were diversity of habitat types and species distribution patterns in the littoral. Multivariate analysis (CA, CCA) showed that the distribution patterns of oligochaete species assemblages are significantly correlated with depth, season and substrate. Depth is the major factor when the whole water body is considered. When confining to the littoral, species abundance and distribution are strongly related to seasonality and substrate type. Naididae show, in general, maximal abundances in autumn and summer and a preference for plants, plant debris and soft sediments; Tubificidae are more abundant in spring and prefer mineral substrate. The relation between seasonality, substrate and food availability is discussed.

Pristina silvicola and P. terrena spp. nov. are described from soil samples of the primary rain forest at the Brazilian Agroforestry Research Facility near Manaus, Brazil. Living and preserved specimens were studied. The species are among the smallest oligochaetes known (1‐1.5 mm long) but they are conspicuous by their brilliant, highly refractile coelomocytes. Pristina silvicola is also described from sexually mature specimens. Its character combination invalidates Pristinella as a genus separate from Pristina. Both genera are reunited as Pristina. Pristina silvicola and P. terrena, species which lack a proboscis, share a character combination that is unique in the genus: stomach absent, first nephridia in segment VII, ventral chaetae uniform with upper tooth not longer than lower. They differ from one another in the shape of the brain and in other details of the chaetae.

Enchytraeus japonensis, a terrestrial enchytraeid, reproduces asexually by fragmentation and subsequent regeneration. Because of its extreme ability to regenerate, the species has recently been proposed as a new experimental material for regeneration study, and a method has been developed for inducing sexual reproduction in the laboratory. The inducibility of sexual reproduction allowed us to perform, for the first time, a taxonomical analysis of E. japonensis based on the morphology of the genital organs, and to compare it with the morphology of the highly similar E. bigeminus, another fragmenting enchytraeid. Comparisons between the two species were also made for general protein patterns and isozyme patterns of seven enzymes using PAGE-IEF. The morphological investigation revealed that the two species are discriminable by only one character; glandular bodies associated with the male copulatory organs that are present in E. bigeminus but absent in E. japonensis. In contrast to this morphological...

Distribution patterns of aquatic oligochaete assemblages, inhabiting largely unpolluted watercourses, in the Northwestern Iberian Peninsula, and their relationships with chemical and physiographical characteristics were analyzed by means of multivariate analyses. Qualitative and quantitative samples from 47 stations were obtained seasonally during 1983/84 and 1988/90. The variables included in this study were altitude, order number, distance from the origin, mean width, mean depth, substrate, current velocity, oxygen content, pH, conductivity, alkalinity and concentration of different ions.

The species composition and relative abundance of the annelid benthic macrofauna (Polychaeta and Oligochaeta) inhabiting the rocky intertidal zone of the ria of Ferrol (Galicia, NW Spain) were studied during field collections, from 2000 to 2002. A total of 14,619 specimens (11,585 polychaetes belonging to 76 species and 24 families and 3,034 oligochaetes belonging to 18 species and two families) were collected from 98 quantitative samples taken from 13 sampling sites. The general spatial distribution of the annelid fauna reflects an increase of the diversity from the inner to the outer part of the ria. The general patterns found in the annelid composition suggest that the assemblages were dominated by oligochaetes in the inner sheltered sampling sites and polychaetes in the outer more exposed sites. Several faunistical and taxonomical remarks on selected species are presented. Two new species of oligochaetes are described: Coralliodrilus artabrensis sp. n. and Pirodrilus fungithecatus sp. n. (Naididae, Phallodrilinae). A new biological index, based on the oligochaete/polychaete ratio (O/P), is proposed as tool to evaluate environmental quality and to monitor future changes in the environment. Xunta de Galicia. CGL2004-04680-C10-02 Ministerio de Educación y Ciencia. CGL.2006-13417

Phytotelmata, or plant-held water bodies, often house complex aquatic invertebrate communities. Microdrile oligochaetes (Clitellata, Annelida) are known to be part of that community, but specimens are rarely identified to species level. Here we report three species of Enchytraeidae and three species of Naididae from a collection sampled in phytotelms of bromeliads in Cusuco National Park, Honduras. Two species of enchytraeids are new to science. Bryodrilus hondurensis sp. nov. is distinguished from other members of the genus by the high number of ventral chaetae, up to 11 per bundle. The genus is Holarctic and this is the southernmost record so far of a Bryodrilus species. Hemienchytraeus phytotelmatus sp. nov. is distinguished by a combination of characters, among which the huge spermathecae and seminal vesicles are most conspicuous. The genus is common in tropical and subtropical soils around the world. A third species of enchytraeids in the collection, Cernosvitoviella atrata (Bretscher), is redescribed, together with three known species of Naididae, Pristina jenkinae (Stephenson), Pristina osborni (Walton) and Pristina terrena Collado & Schmelz. Presence of ingested debris and humus in the intestine of most specimens suggests that the collected animals live and reproduce in the phytotelms. We provide a list of oligochaete species recorded so far from bromeliad pools in Central and South America.

Three species of the oligochaete genus Pristina (Naididae, Clitellata), one of them new to science, are described from soil and litter samples originating from terra firme sites of the primary rain forest at the Brazilian Agroforestry Research Facility in Central Amazonia: P. marcusi sp. nov., P. jenkinae (Stephenson, 1931) and P. notopora Cernosvitov, 1937. Investigations were carried out on live and preserved material, with emphasis on non-chaetal, non-sexual characters of the live anatomy, usually neglected in recent Naididae taxonomy. P. marcusi sp. nov. is characterized by simple-pointed and bayonet-shaped needle chaetae and by a regular pattern of ellipsoid intra-stomachal cavities. P. notopora is redescribed in full detail for the first time since its original description, including the exceptional dorsal opening of the nephridia.

Lake Haus and Lake Stechlin are well-characterized and intensely studied hardwater lakes located in the Baltic Lake District of Northern Germany. The former is classified as highly eutrophic, the latter is an oligotrophic hardwater lake. The way in which Oligochaeta and Aphanoneura species assemblages reflected the different trophic states of the lakes was investigated by a programme of qualitative and quantitative sampling over one year. This paper gives an account of the species occurrence in the two lakes. There were more species in the oligotrophic Lake Stechlin (56) than in the eutrophic Lake Haus (41), the number in the latter, however, is large for eutrophic lakes. The profundal of Lake Haus was devoid of any zoobenthos, probably because of anoxia, the profundal of Lake Stechlin exhibited an annelid species assemblage not found in other comparable oligotrophic lakes. In the littoral zone, species distribution patterns differ considerably between sites. At one site in Lake Stechlin, Potamodrilus fluviatilis was found, this being the first record of the species in inland lakes.

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 C 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.

A new species of the mainly terrestrial enchytraeid oligochaete genus Achaeta is described from 'terra firme' soils of the Amazonian primary rain forest near Manaus, Brazil. Achaeta becki sp. nov. is about 6 mm long; its main distinguishing characters are a very short vas deferens, thickened septa in almost all segments, and a dorsal blood vessel origin in the clitellar region. Oesophageal appendages, pyriform glands (=setal follicles), and secondary pharyngeal gland lobes are absent. Further distinguishing characters are: pharyngeal glands separate in VI, extending into VII, preclitellar nephridia at 6/7 and 8/9, spermathecal ectal pores lateral. The new species is most similar to A. maorica Benham, 1903, A. neotropica Ñernosvitov, 1937, and A. iridescens Christoffersen, 1979, all from the southern hemisphere. Similarities and differences are discussed in detail.

A new species of the oligochaete genus Pristina (Naididae) is described from Central Amazonian soil and litter samples. Investigations were carried out on living and preserved material, with emphasis on characters of the soft-bodied anatomy as seen in living specimens, including the sexual organs. Regarding the chaetal pattern, Pristina trifida is almost indistinguishable from the syntopic P. silvicola Collado & Schmelz, 2000. Conspicuous differences exist, however, in the presence of a stomach with intracellular canals, in the location of the first nephridium in segment IX, and in details of the male reproductive system such as a large prostate gland and a widening of the distal part of the vas deferens. The new species resembles also a group of taxonomically problematic species, P. sima, P. minuta, and P. osborni, whose synonymy has been assumed by several authors. Pristina trifida differs from this group mainly by smaller needle and ventral chaetae and by equally long teeth in the anterior ventral chaetae. The high similarity in the chaetal pattern between P. trifida and P. silvicola implies that there are more species in Pristina than the chaetae might suggest. It further questions the accuracy of chaetae-based species identifications and synonymizations in the group of P. osborni, P. minuta, and P. sima, and possibly the genus in general.

Among terrestrial enchytraeid oligochaetes, species of the genus Achaeta are conspicuous by their complete absence of chaetae. Knowledge of Achaeta species in South America is scarce, only four species were known so far. Here we describe three more species of Achaeta from South America, A. hanagarthi, A. paranensis and A. singularis spp. nov., and we provide revised and type-based redescriptions of A. neotropica C ernosvitov, 1937 and A. piti Bittencourt, 1974. The species were found in the framework of the German-Brazilian project " SOLOBIOMA, Soil biota and biogeochemistry in the Atlantic rainforest of Brazil", which monitors forest regeneration on previously degraded areas by comparing successional stages from pastures to old-growth forests. Species descriptions are based on observations of specimens in vivo and as stained whole mounts; special attention is given to variations among specimens. The three new species are ascribed to a single author (Schmelz). They lack pyriform glands and have spermathecal ectal pores in lateral position. Further distinguishing traits concern the location of preclitellar nephridia, coelomocyte texture, distribution pattern of epidermal and clitellar gland cells, and the inner topography of the prostomium, the latter a new character in Achaeta taxonomy. In A. hanagarthi all sexual organs except the spermathecae are shifted one segment forward. A. singularis is most peculiar by a short and deeply incised brain and by the apparent absence of a suboesophageal ganglion, the ventral ganglia of segments II, III, and IV being separate. This species was only found in forests and is possibly a true representative of the old autochthonous forest soil fauna. A. hanagarthi and A. singularis are similar to the ill-described A. silvatica Nurminen, 1973; the latter is considered as a species inquirenda here. Type reinvestigations revealed that contrary to the original descriptions, A. piti has six segmental pyriform glands and reproductive organs except spermathecae shifted one segment forward, and that A. neotropica has the first preclitellar nephridium at 6/7 and ectal spermathecal pores inlateral position. A. neotropica is highly variable and probably a species aggregate, difficult to resolve with traditional light-microscopical methods. The recently described A. becki Schmelz & Collado 2005 is tentatively included in A. neotropica. The taxonomic descriptions contribute to the general anatomy of the genus; our study further serves as a guide to neotropical species of Achaeta.