These special publications, below, present overviews of and papers presented during our triennial international symposia on aquatic oligochaete biology. Three similar names for our symposia have been used since we began as a group in 1979: International Symposium on Aquatic Oligochaete Biology (ISAOB), International Symposium on Aquatic Oligochaetes (ISAO), and International Symposium on Aquatic Oligochaeta (ISAO).

During the 1950s, Gordon E. Gates (affiliated at that time with Tall Timbers Research Station near Tallahassee, Florida, USA), initiated compilation of a catalogue of scientific names of the Oligochaeta. Gates transferred his account records to John W. Reynolds in 1972, who enlisted the assistance of David G. Cook, an aquatic biologist working in Canada, to complete this catalogue. The first volume of this catalogue, Nomenclatura Oligochaetologica—a catalogue of names, descriptions, and type specimens of the Oligochaeta [N.O.], was published by Reynolds and Cook (1976). Three supplements—Supplementum Primum (Reynolds and Cook, 1981 [N.O.S.P.]), Supplementum Secundum (Reynolds and Cook, 1989 [N.O.S.S.]), and Supplementum Tertium (Reynolds and Cook, 1993 [N.O.S.T.])—were subsequently published, completing the first volume series of this nomenclator. After the retirement of Cook, Reynolds invited Wetzel to assist in the preparation of a fourth supplement to this first volume series. In 2012, the decision was made to forgo completion of a print version for this fourth supplement, redirecting efforts to compile a second edition, specifically to restructure it for presentation as a dedicated and active website.

This volume is the proceedings for the 15th International Symposium on Aquatic Oligochaeta (ISAO15), held in Brussels, Belgium, from the 19th to 24th of September 2022. Since the first ISAO meeting was hosted by Ralph Brinkhurst in Sidney, British Columbia, Canada in 1979, our meetings have been held without interruption every three years. Just as the years seemed to be passing peacefully and our 15th ISAO was slowly coming together, the SARS-Cov-2 epidemic came suddenly into our lives, causing a complete disruption in our way of life. Although our 15th triennial symposium had originally been scheduled to convene in September 2021, we were only able to meet after going through this ordeal, four long years after our last symposium in Hirosaki, Japan, in September 2018, which was a great moment for all those who attended. Although the virus was losing the battle or, waning, it still retained some medical challenges along with cultural and financial restrictions that prevented some of our colleagues from several countries from joining us.

Professor Dr. Yan-Ling Liang, our family-like friend, respected colleague, and renowned mentor, passed away suddenly and peacefully in Wuhan, Hubei Province, China, on 8 December 2021, at the age of 88, survived by his wife, two sons, and two grandchildren.

Cognettia sphagnetorum (Vejdovský, 1878), a common inhabitant of forest soils and bogs in northern Europe, is a model organism in soil biology. We report the first documented occurrence of C. sphagnetorum in North America, based on DNA sequencing from a Sphagnum bog in western Washington, USA. Sequences were identical to that of worms from Sweden and the Czech Republic.

Zootaxa has been the leading journal on invertebrate systematics especially within Annelida. Our current estimates indicate annelids include approximately 20,200 valid species of polychaetes, oligochaetes, leeches, sipunculans and echiurans. We include herein the impact of Zootaxa on the description of new annelid species in the last two decades. Since 2001, there have been over 1,300 new annelid taxa published in about 630 papers. The majority of these are polychaetes (921 new species and 40 new genera) followed by oligochaetes (308 new species and 10 new genera) and leeches (21 new species). The numerous papers dealing with new polychaete species have provided us a clear picture on which polychaete families have had the most taxonomic effort and which authors and countries have been the most prolific of descriptions of new taxa. An estimated additional 10,000+ species remain to be described in the phylum, thus we urge annelid workers to continue their efforts and aid in training a new generation of taxonomists focused on this ecologically important group.

This volume is the proceedings for the 14th International Symposium on Aquatic Oligochaeta (ISAO), held in Hirosaki, Aomori Prefecture, Honshu, Japan, from 9 through 14 September 2018, organized by the Department of Natural Science, Faculty of Education, Hirosaki University, Hirosaki. The symposium was attended by 43 participants from 16 countries who presented 30 oral and 6 poster contributions. The scientific sessions were convened at the Iwaki Conference Hall in the 50th Anniversary Auditorium, Hirosaki University. In addition to the scientific sessions, there was a one-day excursion to visit a traditional playhouse Kouraku-Kan, lunch along the edge of Lake Towada – an oligotrophic caldera lake, and hiking along the lake’s outlet stream, Oirase-Keiryu, flowing through a cool temperate forest typical of northern Honshu. The symposium organizing committee consisted of Akifumi Ohtaka, Kimio Hirabayashi, Katsutoshi Ito, Mana Ito, Takaaki Torii, Naoya Kimura, Stuart R. Gelder, and Mark J. Wetzel, with invaluable support from students from Hirosaki University.

These special publications, below, present overviews of and papers presented during our triennial international symposia on aquatic oligochaete biology. Three similar names for our symposia have been used since we began as a group in 1979: International Symposium on Aquatic Oligochaete Biology (ISAOB), International Symposium on Aquatic Oligochaetes (ISAO), and International Symposium on Aquatic Oligochaeta (ISAO).

Benthic macroinvertebrates were washed from nearly 1000 federally endangered freshwater mussels that had been collected from Pennsylvania during a reintroduction project to 2 eastern Illinois streams. Most benthic macroinvertebrates collected were larvae of the Neophylax fuscus, but other caddisflies and segmented worms were also observed. No unoccupied caddisfly cases were observed on live mussels, leaving open the question as to the seasonal fate of these microhabitats after caddisflies pupate and emerge in the Autumn of each year. Unionid mussel shells might modify local-scale species diversity by influencing physical and hydrau lic properties of microhabitats.

We analysed samples of Sparganophilus taken at the corners of its distribution area in Europe (UK, Germany and Italy). No mitochondrial genetic divergence within and amongst them was found, neither in COI nor in 16S. Further, the COI haplotype was also identical to two sequences from Ontario, Canada in the Barcoding of Life Data System (BOLD) database. Our European COI and 16S sequences showed only minimal differentiation (only 1 or 2 substitutions) from specimens newly collected in Illinois and Washington states (USA), as well as from a COI haplotype from Tennessee (USA) in BOLD. An additional COI haplotype from Illinois (found in BOLD) is 2.1% different from the other haplotypes but clearly belongs to the same lineage of Sparganophilus . This geographically broad but genetically compact group fits the morphological diagnosis of S. tamesis Benham, 1892 as revised by Jamieson (1971) and is seen as evidence that all European populations 1) belong to the same species, 2) derive from a recent introduction, 3) are conspecific with the most widespread species of Sparganophilus in North America, and that 4) S. tamesis is a senior synonym of S. eiseni Smith, 1895. The single European haplotype does not refute the possibility of its spread from a single introduced source population.

This volume of Biologia journal includes nine papers prepared by authors of presentations at the 13th International Symposium on Aquatic Oligochaeta (ISAO), organized by the Department of Botany and Zoology of the Faculty of Science, Masaryk University, Brno. The symposium was attended by 43 participants from 16 countries, who presented 48 oral and poster contributions. Many of the world’s renowned oligochaete specialists as well as scientists from several countries where research focusing on oligochaete biology is relatively new were present – enabling scientific communication amongst those who are interested in the various fields of fundamental and applied research on this important group of aquatic annelids. The symposium was organized by a small team led by Dr Jana Schenková, Mark Wetzel and Ing Michal Schenk, with invaluable support from many employees and students of the Department of Botany and Zoology. The involvement of other members of the Scientific Committee was invaluable – most of whom were hosts or had assisted in the organization of previous ISAO meetings. This symposium was dedicated to the memory of Dr. Beatrice Sambugar, who passed away in 2014, and also to other deceased members of our global oligochaete family. Beatrice was born in Verona Italy in 1948. She received her undergraduate and doctoral degrees from the University of Padova, Italy. During her professional career, she was employed as a teacher in a Secondary School in Verona, as manager of SARECO, and engineering and consulting firm in Verona, then later as director of Studio SARECO. She was an Associate Researcher at the Museo di Storia Naturale in Verona from 1972 until her death. For many years, Beatrice focused on groundwater fauna and hydrobiology, working closely on many projects with her mentor and professor, Sandro Ruffo – one of the founders of the International Society for Subterranean Biology. During her career, Beatrice prepared numerous reports, and produced pedagogical material and diverse research – primarily related to monitoring and conservation of parks and other protected areas. She was author or coauthor on over 30 publications, focused primarily on the taxonomy, faunistics, distribution and ecology of freshwater oligochaetes, and many specific to subterranean waters in Southern Europe. In collaboration with other colleagues, she described 15 new species in seven genera and four families of oligochaetous Clitellata. Beatrice is survived by her daughter Chiara, a CNRS Researcher at the Institut de Physique Théorique, Paris. Although Chiara expends most of her time doing research on Theoretical Cosmology, she cultivates the love for Nature and Arts that she received from Beatrice. Our family of oligochaetologists, worldwide, will miss the personal warmth, kindness, and professionalism shared by Beatrice, unselfishly, with each of us – yet her spirit, dedication, and enthusiasm lives on in all of us. A more extensive memoriam honoring Beatrice, including citations for her publications, will be published at a later date. The symposium was opened with a welcoming presentation by Dr Jaromír Leichmann, the Dean of the Faculty of Science, Masaryk University. The program consisted of five sessions, which covered a wide range of branches of knowledge dealing with the biology of aquatic oligochaetes: systematics and phylogeny, community ecology, morphology, ecotoxicology and biogeography. Experts from different fields of oligochaetology presented keynote lectures: Dr Christer Erséus: From DNA barcoding and species delimitation to transcriptome phylogenies – on ongoing molecular systematics research on clitellates; Dr Göran Milbrink: Species specific morphological deformities in oligochaetes associated with mercury emissions. Lake Vänern, Southern Sweden, revisited; Dr Pilar Rodriguez: Sperm transfer by spermatophores in microdrile oligochaetes (Annelida, Clitellata); and Dr Tarmo Timm: Fate of Lamprodrilus isoporus Michaelsen, 1901 (Oligochaeta: Lumbriculidae) in eutrophic lakes. A special microscopy session was attended by many symposium participants, with discussions about morphological characters, mounting techniques, and other taxonomic and systematic issues continued late into the night. Similarly, the dedicated poster session initiated broad discussions not only on presented contribution but about all research fields. Social events during this scientific meeting began with an afternoon city walk through Brno with visits to main historical monuments, followed by an evening of comradery at a pleasant pub. The opportunity to become friends continued during a mid-symposium tour, with visits to the medieval Pernštejn Castle and Macocha Abyss and

Cognettia sphagnetorum (Vejdovský, 1878), a common inhabitant of forest soils and bogs in northern Europe, is a model organism in soil biology. We report the first documented occurrence of C. sphagnetorum in North America, based on DNA sequencing from a Sphagnum bog in western Washington, USA. Sequences were identical to that of worms from Sweden and the Czech Republic.

Using DNA-barcoding, we studied the diversity of invasive European earthworms in the south-western corner of Australia. We found six Molecular Operational Taxonomic Units belonging to five morphospecies: Aporrectodea caliginosa, A. trapezoides, Dendrobaena cf. attemsi, Eiseniella tetraedra and Octolasion cyaneum. These were variously collected from indigenous forests and/or alienated land. Two cryptic lineages were found within A. trapezoides, and high intraspecific genetic variation was also found within E. tetraedra—variation that had previously been documented in Europe. Our study demonstrates the usefulness of DNA-barcoding for the identification of earthworms, including cryptic species. Correct identification and high taxonomic resolution is crucial for the monitoring of cryptic diversity, detecting new introductions and monitoring spread of established exotic earthworms.

Dr. Tamara Leont'evna Poddubnaya (nee Protopopova) was born 18 February 1930 in Rostov-na-Donu, a large city on the Don River in Southern Russia. After graduating the Rostov University in 1953 she joined the Biological Station in Borok, which later became the Institute for Biology of Inland Waters at Rybinsk Reservoir, located on the Upper Volga River in Northern Russia. Here she spent the remaining 57 years of her lifetime, working in the same research institute. In 1962, she received her Cand. Biol. Sci. (= Ph.D.) degree in Moscow; her thesis (in Russian) was entitled, "Studies on the biology of mass species of tubificids (Limnodrilus newaensis Mich. and Limnodrilus hoffmeisteri Clap.) of the Rybinsk Reservoir”.

The amphipod Hyalella azteca is commonly used as a model for determining safe concentrations of contaminants in freshwaters. The authors sequenced the mitochondrial cytochrome c oxidase subunit I (COI) gene for representatives of 38 populations of this species complex from US and Canadian toxicology research laboratories and eastern North American field sites to determine their genetic relationships. With 1 exception, all US and Canadian laboratory cultures sampled were identified as conspecific. In 22 wild populations spanning 5 US states and 1 Canadian province, the commonly occurring laboratory species was found only in northern Florida, USA. Therefore, the diversity of the H. azteca species complex detected in the wild is not accurately represented in North American laboratories, questioning the reliability of H. azteca cultures currently in use to accurately predict the responses of wild populations in ecotoxicological assays. The authors also examined the utility of different COI nucleotide fragments presently in use to determine phylogenetic relationships in this group and concluded that saturation in DNA sequences leads to inconsistent relationships between clades. Amino acid sequences for COI were not saturated and may allow a more accurate phylogeny estimate. Hyalella azteca is crucial for developing water-quality regulations; therefore, laboratories should know and standardize the strain(s) they use to confidently compare toxicity tests across laboratories and determine whether they are an appropriate surrogate for their regions.

We read with great interest the correspondence article entitled “Taxonomic certification versus the scientific method” (Rogers 2012), and, as members of the Taxonomic Certification Committee of the Society for Freshwater Science (formerly, the North American Benthological Society [NABS, 1975–2011]) (SFS-TCC 2012), we agreed to respond in a constructive fashion with factual information to correct and provide perspective for a few errors, unfounded and confused assumptions, and misperceptions it presents. The nature and structure of the article and its title requires that our response be segregated into two main parts. First, we briefly describe the philosophy, purpose, and objectives of the Taxonomic Certification Program (TCP [http://www.sfstcp.com/]) as developed and administered by the SFS, including correcting inaccurate statements or false assumptions. Second, we will address the issues Rogers has with terminology used in a paper he cites (Stribling et al. 2003 [not 2002 as cited by Rogers]). The former issue is, by far, most important—primarily because it has the potential of adversely affecting a program that has already had a large positive impact on the quality of biological monitoring in the USA and Canada by recognizing laboratory staff with demonstrated ability to perform taxonomic identifications of benthic macroinvertebrate samples. The terminology issue is trivial, but because the comments are made in print, we correct them in print by rebutting Rogers’ perception that we were in error.

Morphological and molecular characters support that the former clitellate family Naididae Ehrenberg, 1828 is nested within another family, Tubificidae Vejdovský, 1876. To avoid paraphyly of the latter, it has been suggested that the two should be regarded as a single taxon. A recent decision by the International Commission of Zoological Nomenclature [2007; opinion 2167 (Case 3305)] ruled against a proposed reversal of the nomenclatural priority of Naididae over Tubificidae, with the consequence that all former tubificids should now be regarded as members of the Naididae whenever these two names are regarded as synonyms. The paper is a plea to clitellate researchers to conform to this ruling.