The middorsal spine pattern is a traditional, key taxonomic character within Kinorhyncha. However, as known species increase, many exhibit identical or highly similar arrangements, requiring additional traits for species-level identification. Here, two new deep-sea Echinoderes species, both bearing a middorsal acicular spine on segment 9, are formally described, representing a highly unusual condition for adults of the family. Echinoderes prior sp. nov. is characterized by having middorsal acicular spines on segments 4–9, lateroventral spines on segments 6–9, and tubes in lateroventral position on segment 5, in lateral accessory position on segment 8, and in laterodorsal position on segment 10. Specimens from the Northwest Pacific and Atlantic Oceans with considerable morphological variation in certain tubes and glandular structures are treated as Echinoderes aff. prior. Genetic differentiation within populations of E. prior sp. nov. suggests cryptic lineages, and the postembryonic development of E. aff. prior is also described and discussed. Echinoderes shimadai sp. nov. is described from the Northwest Pacific Ocean based on combined molecular and morphological evidence. This species is distinguished by having middorsal acicular spines on segments 5–9, lateroventral spines on segments 6–9, tubes in lateroventral position on segment 5, in midlateral position on segment 8, and in laterodorsal position on segment 10, and type 2 glandular cell outlets in laterodorsal position on segment 2. In light of these findings, the diagnoses of the order Echinorhagata, the family Echinoderidae, and the genus Echinoderes are amended. Phylogenetic implications of the presence of a middorsal spine on segment 9 in adults are discussed, particularly regarding the restriction of middorsal spines to segments 4–8 as a family autapomorphy. These findings underscore the importance of exploring understudied deep-sea habitats and the value of combining morphological and molecular data to understand character evolution and lineage diversity within Kinorhyncha.

The trichostrongylid roundworms of the genus Cooperia, which are important in veterinary medicine, currently comprise 19 valid species that parasitize the small intestine of both free-living and domestic ruminants. Only four Cooperia spp. have been reported in Europe, namely C. oncophora, C. punctata, C. curticei and C. pectinata. In 2018–2022, 25 red deer (Cervus elaphus) and 30 sika deer (Cervus nippon) of both sexes and various ages from several remote locations in the Czech Republic were parasitologically examined. Intestinal nematodes of the genus Cooperia were found only in two northern regions. Using the globally recognized key book on trichostrongylid nematodes, they were preliminarily identified as C. pectinata. However, a molecular analysis of cox2 and ITS rDNA gene sequences revealed that Cooperia sp. parasitizing Czech deer is a separate taxon that is more closely related to C. oncophora than to C. pectinata. A subsequent morphological analysis and literature survey confirmed the independence of deer Cooperia sp., which is similar but not identical to bovid C. pectinata. Previous long-term correct identifications of bovid C. pectinata and misidentifications of deer Cooperia species were caused by a fundamental error in the key book mentioned above. Interestingly, the ancient trichostrongylid nematode Strongylus ventricosus from the type host red deer (Cervus elaphus) shot near Greifswald (Germany) was described by Rudolphi in 1809. Rudolphi's type material (one male and four females) was deposited in the Museum für Naturkunde (Berlin). Later, the ancient species S. ventricosus was taken as a synonym for various Cooperia spp. Our current re-examination of the type male indicated that there is a relatively good agreement with our new material from Czech deer regarding the most important characteristics of S. ventricosus (i.e., the shape and size of the male spicules); however, Rudolphi's type material is in rather poor condition. The suggested resurrection of the deer Cooperia sp. in this study as Cooperia ventricosa (Rudolphi, 1809) requires verification by collecting and analyzing new nematode material from the type locality near Greifswald.

The scientific life of Robert P. Higgins was devoted to meiofauna, microscopically small animals living in aquatic sediments from the intertidal to hadal depths worldwide. He focused on the taxonomy, life-history, and ecology of the marine taxa Kinorhyncha, Tardigrada, and Priapulida and co-discovered the phylum Loricifera. He improved the methods for studying meiofauna and contributed significantly to spreading knowledge about these animals. Aspects of his life are described and lists of his publications, taxa described, contributions to science, and honours received are provided.

Six of the eight species of the genus Setaphyes have been described from Europe. In the present contribution, the European Setaphyes species are revised and two of them, S. dentatus (Reinhard, 1881) and S. kielensis (Zelinka, 1928), are redescribed following the current approaches of Kinorhyncha taxonomy. For this purpose, material from 17 localities throughout the Atlantic Ocean and the Mediterranean and Black Seas was investigated. The redescriptions of two of the most common pycnophyid species in Europe include detailed information on intraspecific variation among populations. Setaphyes dentatus is characterized by the presence of middorsal elevations on segments 2–6, and middorsal processes on segments 1, 7–9, unpaired paradorsal setae on segments 2–9; laterodorsal setae on segments 3, 5 and 7; ventromedial setae on segments 4–5, 7–8 in males and 3–5, 7–9 in females; anterior cuticular, reticulate ridges on the tergal plate of segment 1 and conspicuous patch of laterodorsal and ventrolateral longitudinal, cuticular ridges on segment 10. Setaphyes kielensis is characterized by middorsal elevations on segments 1–9; paired paradorsal setae on segments 2–9 (unpaired on segment 8); laterodorsal setae on segments 2–9; ventromedial setae on segments 3–9. Furthermore, morphometric features of the European Setaphyes are analysed. Specifically, the morphometric analyses revealed sex-specific variability in the LTS/TL proportion, with females of all the European species of Setaphyes showing smaller LTS/TL. Thus, the LTS/TL ratio unveils a conspicuous sexual dimorphism in the genus.

Taxonomic studies of the phylum Kinorhyncha follow a standardised structure, which is extremely useful in many aspects, such as making it easier to read and compare the different species descriptions. Nevertheless, the morphological measurements methods, essential for formal description of species, may differ according to the authors. In the present contribution, we propose a standardised method of taking and representing the measurements, with the aim of obtaining comparable and repeatable morphometric results. Additionally, we propose an online repository to make the measurements accessible to all researchers in the same format, facilitating future comparisons and studies. Finally, a glossary that compiles and defines all the measurements that may be included in Kinorhyncha descriptions is presented.

Specimens of two species of Kinorhyncha, Setaphyes dentatus and S. kielensis, were collected in 1988, 1998, and 2016 at two intertidal sites on the island of Sylt, North Sea, and investigated as preserved material by light microscopy and scanning electron microscopy for their epibionts. One species of Acinetidae (Suctoria), one species of Vaginicolidae (Peritrichia), and two species of bacteria were traced. The most abundant ciliate species with 705 specimens was Trematosoma husselae sp. nov. occurring with 1–46 specimens on a basibiont, mainly on the ventral side and here especially on segment 1. Cothurnia buetschlii was found as 14 specimens. Trematosoma husselae sp. nov. agreed with T. amphiasci and T. pusilla in the calyciform shape of the lorica and with most species in the general size of the body except for the much larger T. constricta and T. pusilla. The new species could be distinguished from T. amphiasci, T. complatana, T. constricta, T. falcata, T. ovata, and T. pusilla by the short length of its stalk and agreed with T. bocqueti and T. rotunda in this character. Cothurnia buetschlii was redescribed for the first time after the descriptions by Zelinka (1914, 1928).

Location and specimen deposition of Kinorhyncha were analysed for the time period 1863–2020 based on data generated from the World Register of Marine Species (WoRMS). From at least 11,760 specimens collected during this time period according to the scientific literature from all fields of research, 41 % were deposited in a reference collection, 21 % in a personal collection, and for 38 % it is unknown whether or not they were deposited at all. Whereas no type material was mentioned in publications to have been deposited in a reference collection before 1938, the situation improved in the 1960s–1980s with most specimens deposited. The most recent time period 2011–2020 suffered again from a low deposition rate of 55 % for the material of new species as types plus 15 % as non-types and an overall deposition rate of 42 % for types plus non-types of new and known species. This is the first time that the deposition behaviour is documented for an entire animal group for all fields of research over a time period of 158 years. The implications for kinorhynch research and for zoological science at large are discussed. The results presented are regarded as a wake-up call for scientists to consider their current deposition behaviour, to the International Commission on Zoological Nomenclature, funding and permitting bodies, as well as journal editors to tighten their deposition requirements, and to the funding bodies to provide funding for the deposition of specimens as soon as ever possible in order to keep the loss of the cultural heritage in natural history to a minimum.

Echinoderes goku sp. nov. is described from adult and juvenile specimens in samples collected from the Argentinean continental shelf in March 2019 during the campaign of the Motorsailer Bernardo Houssay, based on light and scanning electron microscopy studies. Echinoderes goku sp. nov. is differentiated from other species by its unique spine and tube pattern: (1) middorsal spine on segments 4, 6, and 8, (2) spine in lateroventral position on segments 69, (3) tube present in subdorsal position on segment 2, sublateral to midlateral position on segments 7 and 9, lateral accessory position on segment 8, lateroventral position on segment 5 and ventrolateral position on segment 2. Additionally, this species (4) lacks type-2 gland cell outlets and female-specific papillae or subcuticular funnel-like structures. (5) The male possesses a sublateral tube on segment 10 with a basal cylindrical reinforcement structure and three penile spines on segment 11, whereas the female lacks penile spines but reveals a lateral terminal accessory spine on segment 11 and on segment 10 lacks a subdorsal tube but possesses instead a sublateral fringe on the surface connected with a subcuticular conical structure and a basal cylindrical reinforcement structure. Among several juvenile specimens, one was captured in the process of moulting from the last juvenile stage to the female. Whereas the last juvenile stage revealed a sublateral tube on segment 10, the moulting female lacked this tube and showed a conical subcuticular structure with a basal cylindrical reinforcement structure instead. A cylindrical reinforcement structure at the base of a tube and a subcuticular conical structure have not been reported before for Kinorhyncha, and 14 selected species of Echinoderidae available for study were screened for these characters in order to get a first idea of their possible taxonomic importance. This article reports about the second species of Echinoderes from Argentinean waters.

Microscope slide collections represent extremely valuable depositories of research material in a natural history, forensic, veterinary, and medical context. Unfortunately, most mounting media of these slides deteriorate over time, with the reason for this not yet understood at all. In this study, Raman spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, and different types of light microscopy were used to investigate the ageing behaviour of naturally aged slides from museum collections and the experimentally aged media of Canada balsam and Permount™, representing a natural and a synthetic resin, respectively, with both being based on mixtures of various terpenes. Whereas Canada balsam clearly revealed chemical ageing processes, visible as increasing colouration, Permount™ showed physical deterioration recognisable by the increasing number of cracks, which even often impacted a mounted specimen. Noticeable changes to the chemical and physical properties of these mounting media take decades in the case of Canada balsam but just a few years in the case of Permount™. Our results question whether or not Canada balsam should really be regarded as a mounting medium that lasts for centuries, if its increasing degree of polymerisation can lead to a mount which is no longer restorable.

Samples collected from Monte Hermoso, Buenos Aires Province, Argentina revealed the presence of specimens of the genus Franciscideres Dal Zotto et al., 2013, previously known only from Brazil. This morphotype seems to differ from the only known species, Franciscideres kalenesos Dal Zotto et al., 2013, in the following characters: (1) presence of ventrolateral tubes on segment 1, (2) introvert features, (3) each segment composed of a closed cuticular ring, (4) trunk cuticle ornamented by a secondary fringe of knob-like structures, (5) posterior margin of segment 10 ventrally terminating in two lateral and one broad triangular lobes, (6) posterior margin of segment 11 centrally terminating in four lobes (7) lateral terminal spines armed with thorn-like processes, (8) pores/sensory spots/gland cells distribution and (9) sexual dimorphism in segments 10 and 11. Because of the lack of full information about F. kalenesos from Brazil, we consider the new exemplars as Franciscideres cf. kalenesos. Additionally, we provide new information about the movement of this species using light microscopy and we compare these movements with those of other meiofaunal inhabitants.

t Two new species of Kinorhyncha belonging to the genus Condyloderes (Cyclorhagida: Centroderidae) are described herein. The specimens were collected in the Gulf of Castellammare (Tyrrhenian Sea, Sicily, Southern Italy) and off Livorno (Ligurian Sea, Tuscany, Central Italy), respectively. The new taxa represent the first species of Condyloderes described from the Mediterranean basin. Condyloderes agnetis sp. nov. is distinguished from its congeners by bearing cuspidate spines on segment 3 - a character never reported before for Cyclorhagida - in subdorsal position, paradorsally and sublaterally on segment 7, an extremely short midterminal spine, and a combination of cuspidate spines in lateral accessory position on segments 2 and 9, ventrolaterally slightly displaced ventromedially on segment 5, and ventrolaterally on segment 8. Condyloderes clarae sp. nov. is characterized by a combination of cuspidate spines on segments 5, 8, and 9 only, cuspidate spines ventrolaterally on segment 8 and in a lateral accessory position on segment 9, ventromedial appendages on segments 5, 6, and 7 in females. Both species exhibit the recently described type-6 sensory spots. Furthermore, the female morphology and data on the distribution of Condyloderes multispinosus (McIntyre, 1962) within the Mediterranean Sea are reported, along with the record of the co-occurrence of different species of Condyloderes at the same site. We report a certain degree of intraspecific variation of taxonomically diagnostic characters like the presence or absence of cuspidate spines and sensory spots on some segments in C. agnetis sp. nov. and C. multispinosus. The presence of regularly arranged cuticular hairs on most trunk segments and of an acicular spine in lateral accessory position on segment 1, along with the absence of an area of micropapillae on segment 9 in females of C. agnetis sp. nov. and C. clarae sp. nov., unique within the genus, suggest the existence of distinct evolutionary lines within Condyloderes. The discovery of the two new species highlights the potential species richness of a genus considered species-poor until recently. Our findings underscore the importance of promoting further studies even in rather well investigated areas, such as the Mediterranean basin. Beyond the taxonomic and biogeographical interest, the data reported herein provides additional insights for ongoing taxonomic and phylogenetic investigations on the Centroderidae and allies, and on the whole Cyclorhagida. (C) 2019 Published by Elsevier GmbH.

Investigation of Kinorhyncha from Senghor Seamount (tropical northeastern Atlantic Ocean) and the adjacent deep-sea floor revealed seven species of Echinoderes. Of these, Echinoderes kaempfae sp. nov. and Echinoderes schwieringae sp. nov. are described as new species. Echinoderes multiporus originally found on Eratosthenes Seamount, Mediterranean Sea, and Echinoderes cf. adrianovi originally found off Florida, northwestern Atlantic Ocean, were also recovered. In addition, three additional species, which possibly represent undescribed species, occurred on Senghor Seamount. Because of the low number of available specimens or necessity of further observations of closely related congeners for these three undescribed species, we provide only a brief description of them without naming them as new species. The comparison of each species with morphologically similar congeners is also provided. Based on all records of kinorhynchs from seamounts and the adjacent deep-sea floor in the Northeastern Atlantic Ocean, Mediterranean Sea, and Arctic Sea, it is suggested that (1) the kinorhynch fauna on seamounts is partly unique, (2) seamount kinorhynchs originate both from shallow waters and the deep sea, and (3) a few kinorhynch species diversified on seamounts.

The description of a new representative of the species-poor genus Condyloderes Higgins, 1969 from the Northeast Pacific (Alaska) is reported. The analyzed specimens of Condyloderes shirleyi sp. nov. showed a significant variation of numerous morphological characters, along with female-specific traits known also from other congeneric species. These findings stimulated the re-investigation of the type material of the six species of Condyloderes described so far, i.e., C. kurilensis Adrianov Maiorova, 2016, C. megastigma Sørensen, Rho Kim, 2010b, C. multispinosus (McIntyre, 1962) Higgins, 1969, C. paradoxus Higgins, 1969, C. setoensis Adrianov, Murakami Shirayama, 2002, and C. storchi Higgins, 2004 in Martorelli Higgins, 2004. Our study allowed to reveal various morphological novelties and to emend the diagnosis of these species and of the genus Condyloderes. Furthermore, our analysis led to synonymize C. megastigma with C. setoensis. The results of our investigation about the significant variation in C. shirleyi sp. nov. raise a wider question on species identity within Kinorhyncha, underscoring the necessity, if possible, to describe new species from a higher number of specimens and to concentrate on the morphological variation of the going-to-be-described species.

Kinorhynchs rarely show a wide distribution pattern, due to their putatively low dispersal capabilities and/or limited sampling efforts. In this study, a new kinorhynch species is described, Echinoderes pterus sp. n., which shows a geographically and bathymetrically wide distribution, occurring on the Karasik Seamount and off the Svalbard Islands (Arctic Ocean), on the Sedlo Seamount (northeast Atlantic Ocean), and on the deep-sea floor off Crete and on the Anaximenes Seamount (Mediterranean Sea), at a depth range of 675–4,403 m. The new species is characterized by a combination of middorsal acicular spines on segments 4–8, laterodorsal tubes on segment 10, lateroventral tubes on segment 5, lateroventral acicular spines on segments 6–9, tufts of long hairs rising from slits in a laterodorsal position on segment 9, truncated tergal extensions on segment 11, and the absence of any type-2 gland cell outlet. The specimens belonging to the populations from the Arctic Ocean, the Sedlo Seamount, and the Mediterranean Sea show morphological variation in the thickness and length of the spines as well as in the presence/absence of ventromedial sensory spots on segment 7. The different populations are regarded as belonging to a single species because of their overlapping variable characters.

Three new species of Echinoderes (Kinorhyncha: Cyclorhagida: Echinoderidae) are described from two Northeast Atlantic seamounts and the adjacent deep-sea floor. Echinoderes apex sp. nov. from the Great Meteor Seamount and the Sedlo Seamount is characterized by a combination of: a small trunk length (165-215 mu m); middorsal acicular spines on segments 4, 6, and 8; tubes ventrolaterally on segment 2, lateroventrally on segment 5, and laterodorsally on segment 10; lateroventral acicular spines on segments 6-9; long lateral terminal spines, 60.0-80.2% of trunk length; and type-2 glandular cell outlets subdorsally on segment 2, sublaterally on segment 6, and lateral accessorily on segment 8. Echinoderes bathyalis sp. nov. from the deep-sea floor near the Sedlo Seamount is characterized by a combination of: a small trunk length (224-243 mu m); middorsal acicular spines on segments 4-8 with a spine on segment 8 being very long (ca. 50% of trunk length); lateral accessory tubes on segment 5; lateroventral acicular spines on segments 6-9; and type-2 glandular cell outlets midlaterally on segment 2. Echinoderes meteorensis sp. nov. from the Great Meteor Seamount differs from its congeners in a combination of: a small trunk length (157-196 mu m); presence of middorsal acicular spines on segments 4, 6, and 8; tubes lateroventrally on segment 5, lateral accessorily on segment 8, and laterodorsally on segment 10; lateroventral acicular spines on segments 6-9; and type-2 glandular cell outlets in subdorsal and lateral accessory positions on segment 2. Echinoderes apex occurs on two seamount summits, whereas E. meteorensis occurs on one seamount summit, and no species occur both on a seamount summit and on the deep-sea floor.

Two new species of Echinoderes from the Eratosthenes Seamount and a deep-sea station near the Sedlo Seamount are described. Echinoderes multiporus sp. nov. from the Eratosthenes Seamount is characterized by a combination of the presence of middorsal acicular spines on segments 4, 6, and 8, ventrolateral tubes on segment 2, lateroventral tubes on segment 5, lateroventral acicular spines on segments 6-9, midlateral tubes on segment 10, and type-2 glandular cell outlets in subdorsal position on segment 2 and in laterodorsal position on segments 4-9. Echinoderes unispinosus sp. nov. from the deep-sea station differs from its congeners by the combination of middorsal acicular spine on segment 4, lateroventral acicular spines on segments 6 and 7, type-2 glandular cell outlets present in midlateral position on segment 1, in subdorsal, laterodorsal, sublateral, and ventrolateral position on segment 2, in lateral accessory position on segment 5, and in sublateral position on segment 8, and densely aligned pectinate fringe teeth of the primary pectinate fringes similar in width on segments 1-10. In addition, the morphological data of two undescribed species from the Anaximenes Seamount and a deep-sea station near the Sedlo Seamount are given. An undescribed species from the Anaximenes Seamount is morphologically similar to Echinoderes unispinosus sp. nov., but differs in the smaller trunk length, the presence of broader pectinate fringe teeth of the primary pectinate fringe on segment 1, and the absence of ventromedial sensory spots on segment 8. Another undescribed species from the deep-sea station differs from its congeners in the pattern of spines, tubes, and type-2 glandular cell outlets and length of middorsal and lateral terminal spines. New names are not given to both undescribed species in this study, because only one specimen is available for each species, and both of the specimens were damaged during the preparation.

A wide range of aspects concerning microscope slides, their preparation, long-time storage, curatorial measures in collections, deterioration, restoration, and study is summarized based on our own data and by analyzing more than 600 references from the 19th century until 2016, 15 patents, and about 100 Materials Safety Data Sheets. Information from systematic zoology, conservation sciences, chemistry, forensic sciences, pathology, paleopathology, applied sciences like food industry, and most recent advances in digital imaging are put together in order to obtain a better understanding of which and possibly why mounting media and coverslip seals deteriorate, how slides can be salvaged, which studies may be necessary to identify a range of ideal mounting media, and how microscope studies can benefit from improvements in developmental biology and related fields. We also elaborate on confusing usage of concepts like that of maceration and of clearing. The chemical ingredients of a range of mounting media and coverslip seals are identified as much as possible from published data, but this information suffers in so far as the composition of a medium is often proprietary of the manufacturer and may vary over time. Advantages, disadvantages, and signs of deterioration are documented extensively for these media both from references and from our own observations. It turns out that many media degrade within a few years, or decades at the latest, except Canada balsam with a documented life-time of 150 years, Euparal with a documented life-time of 50 years, and glycerol-paraffin mounts sealed with Glyceel, which represents almost the only non-deteriorating and easily reversible mount. Deterioration reveals itself as a yellowing in natural resins and as cracking, crystallization, shrinkage on drying or possibly on loss of a plasticizer, detachment of the coverslip, segregation of the ingredients in synthetic polymers, as well as continued maceration of a specimen to a degree that the specimen virtually disappears. Confusingly, decay does not always appear equally within a collection of slides mounted at the same time in the same medium. The reasons for the deteriorative processes have been discussed but are controversial especially for gum-chloral media. Comparing data from conservation sciences, chemical handbooks, and documented ingredients, we discuss here how far chemical and physical deterioration probably are inherent to many media and are caused by the chemical and physical properties of their components and by chemicals dragged along from previous preparation steps like fixation, chemical maceration, and physical clearing. Some recipes even contain a macerating agent, which proceeds with its destructive work. We provide permeability data for oxygen and water vapor of several polymers contained in mounting media and coverslip seals. Calculation of the penetration rate of moisture in one example reveals that water molecules reach a specimen within a few days up to about a month; this lays to rest extensive discussions about the permanent protection of a mounted specimen by a mounting medium and a coverslip seal. Based on the ever growing evidence of the unsuitable composition and application of many, and possibly almost all, mounting media, we strongly encourage changing the perspective on microscope slides from immediate usability and convenience of preparation towards durability and reversibility, concepts taken from conservation sciences. Such a change has already been suggested by Upton (1993) more than 20 years ago for gum-chloral media, but these media are still encouraged nowadays by scientists. Without a new perspective, taxonomic biology will certainly lose a large amount of its specimen basis for its research within the next few decades. Modern non-invasive techniques like Raman spectroscopy may help to identify mounting media and coverslip seals on a given slide as well as to understand ageing of the media. An outlook is given on potential future studies. In order to improve the situation of existing collections of microscope slides, we transfer concepts as per the Smithsonian Collections Standards and Profiling System, developed for insect collections more than 25 years ago, to collections of slides. We describe historical and current properties and usage of glass slides, coverslips, labels, and adhesives under conservational aspects. In addition, we summarize and argue from published and our own experimental information about restorative procedures, including re-hydration of dried-up specimens previously mounted in a fluid medium. Alternatives to microscope slides are considered. We also extract practical suggestions from the literature concerning microscope equipment, cleaning of optical surfaces, health risks of immersion oil, and recent improvements of temporary observation media especially in connection with new developments in digital software.